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Sample records for parallel shock layers

  1. Parallelization of the Flow Field Dependent Variation Scheme for Solving the Triple Shock/Boundary Layer Interaction Problem

    NASA Technical Reports Server (NTRS)

    Schunk, Richard Gregory; Chung, T. J.

    2001-01-01

    A parallelized version of the Flowfield Dependent Variation (FDV) Method is developed to analyze a problem of current research interest, the flowfield resulting from a triple shock/boundary layer interaction. Such flowfields are often encountered in the inlets of high speed air-breathing vehicles including the NASA Hyper-X research vehicle. In order to resolve the complex shock structure and to provide adequate resolution for boundary layer computations of the convective heat transfer from surfaces inside the inlet, models containing over 500,000 nodes are needed. Efficient parallelization of the computation is essential to achieving results in a timely manner. Results from a parallelization scheme, based upon multi-threading, as implemented on multiple processor supercomputers and workstations is presented.

  2. Parallelization of the Flow Field Dependent Variation Scheme for Solving the Triple Shock/Boundary Layer Interaction Problem

    NASA Technical Reports Server (NTRS)

    Schunk, Greg; chung, T. J.

    1999-01-01

    A parallelized version of the Flowfield Dependent Variation (FDV) Method is developed to analyze a problem of current research interest, the flowfield resulting from a triple shock/boundary layer interaction. Such flowfields are often encountered in the inlets of high speed air-breathing vehicles including NASA's Hyper-X. In order to resolve the complex shock structure and to provide adequate resolution for boundary layer computations of the convective heat transfer from surfaces inside the inlet, models containing over 500,000 nodes are needed. Efficient parallelization of the computation is essential to obtaining the results in a timely manner. Results from different parallelization schemes, based upon multi-threading and message passing, as implemented on multiple processor supercomputers and on distributed workstations are compared.

  3. Theory and simulation of collisionless parallel shocks

    NASA Technical Reports Server (NTRS)

    Quest, K. B.

    1988-01-01

    This paper presents a self-consistent theoretical model for collisionless parallel shock structure, based on the hypothesis that shock dissipation and heating can be provided by electromagnetic ion beam-driven instabilities. It is shown that shock formation and plasma heating can result from parallel propagating electromagnetic ion beam-driven instabilities for a wide range of Mach numbers and upstream plasma conditions. The theoretical predictions are compared with recently published observations of quasi-parallel interplanetary shocks. It was found that low Mach number interplanetary shock observations were consistent with the explanation that group-standing waves are providing the dissipation; two high Mach number observations confirmed the theoretically predicted rapid thermalization across the shock.

  4. Double layers and electrostatic shocks

    NASA Technical Reports Server (NTRS)

    Hershkowitz, N.

    1981-01-01

    It is shown that it is useful to define double layers and shocks so that the ion phase spaces of double layers are the mirror image (about zero ion velocity) of the ion phase spaces for laminar electrostatic shocks. The distinguishing feature is the direction of the free ion velocity. It is also shown that double layers can exist without the presence of trapped ions. The Bohm condition for double layers, that the ion drift velocity on the high potential side must be greater than the ion sound velocity, is shown to be related to a requirement of a lower limit on the Mach number of laminar electrostatic shocks

  5. Modelling Layer parallel stylolites

    NASA Astrophysics Data System (ADS)

    Koehn, Daniel; Pataki Rood, Daisy; Beaudoin, Nicolas

    2016-04-01

    We modeled the geometrical roughening of mainly layer-dominated stylolites in order to understand their structural evolution, to present an advanced classification of stylolite shapes and to relate this classification to chemical compaction and stylolite sealing capabilities. Our simulations show that layer-dominated stylolites can grow in three distinct stages, an initial slow nucleation, a fast layer-pinning phase and a final freezing stage if the layer dissolves completely during growth. Dissolution of the pinning layer and thus destruction of the compaction tracking capabilities is a function of the background noise in the rock and the dissolution rate of the layer itself. Low background noise needs a slower dissolving layer for pinning to be successful but produces flatter teeth than higher background noise. We present an advanced classification based on our simulations and separate stylolites into four classes: rectangular layer type, seismogram pinning type, suture/sharp peak type and simple wave-like type.

  6. Low Mach number parallel and quasi-parallel shocks

    NASA Technical Reports Server (NTRS)

    Omidi, N.; Quest, K. B.; Winske, D.

    1990-01-01

    The properties of low-Mach-number parallel and quasi-parallel shocks are studied using the results of one-dimensional hybrid simulations. It is shown that both the structure and ion dissipation at the shocks differ considerably. In the parallel limit, the shock remains coupled to the piston and consists of large-amplitude magnetosonic-whistler waves in the upstream, through the shock and into the downstream region, where the waves eventually damp out. These waves are generated by an ion beam instability due to the interaction between the incident and piston-reflected ions. The excited waves decelerate the plasma sufficiently that it becomes stable far into the downstream. The increase in ion temperature along the shock normal in the downstream region is due to superposition of incident and piston-rflected ions. These two populations of ions remain distinct through the downstream region. While they are both gyrophase-bunched, their counterstreaming nature results in a 180-deg phase shift in their perpendicular velocities.

  7. Heavy ion acceleration at parallel shocks

    NASA Astrophysics Data System (ADS)

    Galinsky, V. L.; Shevchenko, V. I.

    2010-11-01

    A study of alpha particle acceleration at parallel shock due to an interaction with Alfvén waves self-consistently excited in both upstream and downstream regions was conducted using a scale-separation model (Galinsky and Shevchenko, 2000, 2007). The model uses conservation laws and resonance conditions to find where waves will be generated or damped and hence where particles will be pitch-angle scattered. It considers the total distribution function (for the bulk plasma and high energy tail), so no standard assumptions (e.g. seed populations, or some ad-hoc escape rate of accelerated particles) are required. The heavy ion scattering on hydromagnetic turbulence generated by both protons and ions themselves is considered. The contribution of alpha particles to turbulence generation is important because of their relatively large mass-loading parameter Pα=nαmα/npmp (mp, np and mα, nα are proton and alpha particle mass and density) that defines efficiency of wave excitation. The energy spectra of alpha particles are found and compared with those obtained in test particle approximation.

  8. Internal hypersonic flow. [in thin shock layer

    NASA Technical Reports Server (NTRS)

    Lin, T. C.; Rubin, S. G.

    1974-01-01

    An approach for studying hypersonic internal flow with the aid of a thin-shock-layer approximation is discussed, giving attention to a comparison of thin-shock-layer results with the data obtained on the basis of the imposition theory or a finite-difference integration of the Euler equations. Relations in the case of strong interaction are considered together with questions of pressure distribution and aspects of the boundary-layer solution.

  9. Escape of heated ions upstream of quasi-parallel shocks

    NASA Technical Reports Server (NTRS)

    Edmiston, J. P.; Kennel, C. F.; Eichler, D.

    1982-01-01

    A simple theoretical criterion by which quasi-parallel and quasi-perpendicular collisionless shocks may be distinguished is proposed on the basis of an investigation of the free escape of ions from the post-shock plasma into the region upstream of a fast collisionless shock. It was determined that the accessibility of downstream ions to the upstream region depends on upstream magnetic field shock normal angle, in addition to the upstream plasma parameters, with post-shock ions escaping upstream for shock normal angles of less than 45 deg, in agreement with the observed transition between quasi-parallel and quasi-perpendicular shock structure. Upstream ion distribution functions resembling those of observed intermediate ions and beams are also calculated.

  10. Shock-boundary-layer interaction in flight

    NASA Technical Reports Server (NTRS)

    Bertelrud, Arild

    1989-01-01

    A brief survey is given on the study of transonic shock/boundary layer effects in flight. Then the possibility of alleviating the adverse shock effects through passive shock control is discussed. A Swedish flight experiment on a swept wing attack aircraft is used to demonstrate how it is possible to reduce the extent of separated flow and increase the drag-rise Mach number significantly using a moderate amount of perforation of the surface.

  11. Scale lengths in quasi-parallel shocks. [interplanetary and earth bow waves

    NASA Technical Reports Server (NTRS)

    Scudder, J. D.; Burlaga, L. F.; Greenstadt, E. W.

    1984-01-01

    A review was carried out of ISEE and Voyager spacecraft magnetometer data to determine if quasi-parallel bow shocks are really broad, disordered regions. The key parameter was the deceleration scale (thickness, Lp) across which random energy would need to increase and a localized electrostatic field (E) would be present. Lp would define the breadth of the shock and be associated with a plasma deceleration. The ISEE 1 satellite collected data on the electron density, bulk speed, magnetic intensity, and electron temperature in November 1977 during five traverses of the bow shock. Similar data were gathered from an interplanetary shock wave in 1981. The evidence supported the concept of a plasma deceleration across a thin layer (Lp) in both types of shocks. The layers were about 50 times (interplanetary) and 20 times (earth) thinner than surrounding magnetic fluctuation regions. It is asserted that the regions of deceleration, although much thinner, are the actual shocks and not the entire regions of magnetic fluctuations.

  12. Preliminary investigation of interplanetary shock structure: Quasi-parallel shocks

    NASA Technical Reports Server (NTRS)

    Greenstadt, E. W.

    1974-01-01

    Pioneer 9's magnetic field and plasma data were studied to develop arguments for or against the observation of oblique interplanetary shocks. Structural classifications are defined, and the justification for seeking these classifications in the solar wind are presented.

  13. Ion Acceleration at the Quasi-parallel Bow Shock: Decoding the Signature of Injection

    NASA Astrophysics Data System (ADS)

    Sundberg, Torbjörn; Haynes, Christopher T.; Burgess, D.; Mazelle, Christian X.

    2016-03-01

    Collisionless shocks are efficient particle accelerators. At Earth, ions with energies exceeding 100 keV are seen upstream of the bow shock when the magnetic geometry is quasi-parallel, and large-scale supernova remnant shocks can accelerate ions into cosmic-ray energies. This energization is attributed to diffusive shock acceleration however, for this process to become active, the ions must first be sufficiently energized. How and where this initial acceleration takes place has been one of the key unresolved issues in shock acceleration theory. Using Cluster spacecraft observations, we study the signatures of ion reflection events in the turbulent transition layer upstream of the terrestrial bow shock, and with the support of a hybrid simulation of the shock, we show that these reflection signatures are characteristic of the first step in the ion injection process. These reflection events develop in particular in the region where the trailing edge of large-amplitude upstream waves intercept the local shock ramp and the upstream magnetic field changes from quasi-perpendicular to quasi-parallel. The dispersed ion velocity signature observed can be attributed to a rapid succession of ion reflections at this wave boundary. After the ions’ initial interaction with the shock, they flow upstream along the quasi-parallel magnetic field. Each subsequent wavefront in the upstream region will sweep the ions back toward the shock, where they gain energy with each transition between the upstream and the shock wave frames. Within three to five gyroperiods, some ions have gained enough parallel velocity to escape upstream, thus completing the injection process.

  14. Ion reflection and downstream thermalization at the quasi-parallel bow shock

    NASA Technical Reports Server (NTRS)

    Gosling, J. T.; Thomsen, M. F.; Bame, S. J.; Russell, C. T.

    1989-01-01

    Using the results of ISEE 2 plasma and magnetic field measurements, two features related to the ion thermalization process at high-Mach-number (M above 2) quasi-parallel collisionless shocks are discussed. These are the presence of a coherent secondary beam of ions within the shock layer which is considered to be produced by reflection, and downstream ion distributions which contain both a relatively cold core of directly transmitted ions and a hotter 'shell' of ions, which appear to result from the disruption and scattering of ions initially reflected at the shock. Evidence is presented that coherent ion reflection is an important element of the ion energy dissipation process at high-Mach-number quasi-parallel shocks.

  15. Shock timing measurements in DT ice layers

    NASA Astrophysics Data System (ADS)

    Robey, H. F.; Celliers, P. M.; Moody, J. D.; Sater, J.; Parham, T.; Kozioziemski, B.; Dylla-Spears, R. J.; Ross, J. S.; Lepape, S.; Ralph, J. E.; Berzak Hopkins, L. F.; Kroll, J. J.; Yoxall, B. E.; Hamza, A. V.; Boehly, T. R.; Nikroo, A.; Landen, O. L.; Edwards, M. J.

    2013-10-01

    Shock timing experiments on the National Ignition Facility (NIF) are routinely conducted using the keyhole target geometry, in which the strength and timing of multiple shocks are measured in a liquid-deuterium (D2) filled capsule interior. These targets have recently been modified to improve the surrogacy to ignition implosions by replacing the standard, continuous liquid D2 capsule fill with a deuterium-tritium (DT) ice layer with a central DT gas fill. These experiments remove any possible material surrogacy difference between D2 and DT as well as incorporating the physics of multiple shock release and recompression events from an ice layer of finite thickness, an effect that is absent in the liquid-filled targets. Experimental results and comparisons with numerical simulation are presented. Prepared by LLNL under Contract DE-AC52-07NA27344.

  16. Thermal shock response of layered orthotropic media

    SciTech Connect

    Santhosh, U. )

    1992-09-01

    In this article a coupled thermoelastic theory including inertia effects is used to determine the through-thickness temperature and stress distribution in a laminated medium subjected to thermal shock loading. The solution is obtained using an implicit-explicit finite difference procedure, and numerical results are presented for composites made of layers of a carbon substrate and a coating. 14 refs.

  17. Direct Simulation of Shock Layer Plasmas

    SciTech Connect

    Farbar, E. D.; Boyd, I. D.

    2011-05-20

    Approximate models of the electric field used with the DSMC method all impose quasi-neutrality everywhere in the shock layer plasma. The shortcomings of these models are examined in this study by simulating a weak shock layer plasma with a coupled DSMC-Particle-In-Cell (PIC) method. The stagnation streamline of an axisymmetric shock layer is simulated for entry velocities in air that correspond to both lunar and Mars return trajectories. The atmospheric densities, particle diameters and chemical reaction rates are varied from the actual values to make the computations tractable while retaining the mean free path of air at 85 km altitude. In contrast to DSMC flow field predictions, regions of non-neutrality are predicted by the DSMC-PIC method, and the electrons are predicted to be isothermal. Perhaps the most important result of this study is that the DSMC-PIC results at both reentry energies yield a 14% increase in heat flux to the vehicle surface relative to the DSMC results. Rather unintuitively, this is mostly due to an increase in ion flux to the surface, rather than the potential energy gained by each ion as it traverses the plasma sheath. In this study, an approximate electric field model is presented, with the goal of accounting for this heat flux augmentation without the need for a computationally expensive DSMC-PIC calculation of the entire flow-field. Convective heat flux results obtained with new electric field model are compared to results from the rigorous DSMC-PIC calculations.

  18. Quasi-perpendicular/quasi-parallel divisions of Earth's bow shock

    SciTech Connect

    Greenstadt, E.W. )

    1991-02-01

    Computer-drawn diagrams of the boundaries between quasi-perpendicular and quasi-parallel areas of Earth's bow shock are displayed for a few selected cone angles of static interplanetary magnetic field (IMF). The effect on the boundary of variable IMF in the foreshock is also discussed and shown for one nominal case. The boundaries demand caution in applying them to the realistic, dynamic conditions of the solar wind and in interpreting the effects of small cone angles on the distributions of structures at the shock. However, the calculated, first-order boundaries are helpful in defining areas of the shock where contributions from active structures inherent in quasi-parallel geometry may be distinguishable from those derived secondarily from upstream reflected ion dynamics. The boundaries are also compatible with known behavior of daytime ULF geomagnetic waves and pulsations according to models postulating that cone angle-controlled, time-dependent ULF activity around the subsolar point of the bow shock provides the source of geomagnetic excitation.

  19. Shock-wave boundary layer interactions

    NASA Technical Reports Server (NTRS)

    Delery, J.; Marvin, J. G.; Reshotko, E.

    1986-01-01

    Presented is a comprehensive, up-to-date review of the shock-wave boundary-layer interaction problem. A detailed physical description of the phenomena for transonic and supersonic speed regimes is given based on experimental observations, correlations, and theoretical concepts. Approaches for solving the problem are then reviewed in depth. Specifically, these include: global methods developed to predict sudden changes in boundary-layer properties; integral or finite-difference methods developed to predict the continuous evolution of a boundary-layer encountering a pressure field induced by a shock wave; coupling methods to predict entire flow fields; analytical methods such as multi-deck techniques; and finite-difference methods for solving the time-dependent Reynolds-averaged Navier-Stokes equations used to predict the development of entire flow fields. Examples are presented to illustrate the status of the various methods and some discussion is devoted to delineating their advantages and shortcomings. Reference citations for the wide variety of subject material are provided for readers interested in further study.

  20. Shock interactions with a dense-gas wall layer

    SciTech Connect

    Kuhl, A.L. ); Reichenbach, H. ); Ferguson, R.E. )

    1991-11-19

    Described here are experiments and calculations of the interaction of a planar shock with a dense-gas layer located on the floor of the shock tube test section. The shock front deposited vorticity in the layer by the baroclynic mechanism. The wall shear layer was unstable and rapidly evolved into a turbulent boundary layer with a wide spectrum of mixing scales. Density effects dominated the dynamics in the wall region.

  1. On Nonequilibrium Radiation in Hydrogen Shock Layers

    NASA Technical Reports Server (NTRS)

    Park, Chul

    2005-01-01

    The influence of thermochemical nonequilibrium in the shock layer over a vehicle entering the atmosphere of an outer planet is examined qualitatively. The state of understanding of the heating environment for the Galileo Probe vehicle is first reviewed. Next, the possible reasons for the high recession in the frustum region and the low recession in the stagnation region are examined. The state of understanding of the nonequilibrium in the hydrogen flow is then examined. For the entry flight in Neptune, the possible influence of nonequilibrium is predicted.

  2. Improved method for solving the viscous shock layer equations

    NASA Technical Reports Server (NTRS)

    Gordon, Rachel; Davis, R. T.

    1992-01-01

    An improved method for solving the viscous shock layer equations for supersonic/hypersonic flows past blunt-nosed bodies is presented. The method is capable of handling slender to thick bodies. The solution is obtained by solving a coupled set of five equations, built of the four basic viscous shock layer equations and an additional equation for the standoff distance. The coupling of the equations prevents the local iterations divergence problems encountered by previous methods of solution far downstream on slender bodies. It also eliminates the need for local iterations, which were required by previous methods of solution, for a first-order scheme in the streamwise direction. A new global iteration procedure is employed to impose the shock boundary conditions. The procedure prevents the global iteration instability encountered by the basic method of solution and improves the convergence rate of the global iteration procedure of later methods devised to overcome this difficulty. The new technique reduces the computation time by 65-95 percent as compared to previous methods of solution. The method can efficiently be implemented in vector/parallel computers.

  3. Magnetic pulsations at the quasi-parallel shock

    NASA Technical Reports Server (NTRS)

    Thomsen, M. F.; Gosling, J. T.; Bame, S. J.; Russell, C. T.

    1990-01-01

    The plasma and field properties of large-amplitude magnetic field pulsatins upstream from the quasi-parallel region of the earth's bow shock are examined in high time resolution using data from ISEE 1 and 2. The relative timing of the magnetic field profiles observed at the two spacecraft shows that some of the pulsations are convecting antisunward across the spacecraft while others are brief out/in motions of bow shock across the spacecraft. Pulsations with both timing signatures are the site of slowing and heating of the solar wind plasma. The ions tend to be only weakly heated in the convecting pulsations, while within the out/in pulsations the ion heating can be quite substantial but variable. This variation occurs not only from pulsation to pulsation but also from point to point within a given pulsation. In general, the hottest distributions within the out/in pulsations tend to occur in regions of lower density and field strength. Magnetic pulsations bear a number of similarities to previously identified hot diamagnetic cavity events as well as to more durable crossings of the quasi-parallel shock itself. These various phenomena may be different manifestations of the same basic physical processes, in particular the coupling of coherently reflected ions to the solar wind beam.

  4. Radiography for a Shock-accelerated Liquid Layer

    SciTech Connect

    P. Meekunnasombat J.G. Oakley\\inst M.H. Anderson R. Bonazza

    2005-07-01

    This program supported the experimental study of the itneraction of planar shock waves with both solid structures (a single cylinder or a bank of cylinders) and single and multiple liquid layers. Objectives of the study included: characterization of the shock refraction patterns; measurements of the impulsive loading of the solid structures; observation of the response of the liquid layers to shock acceleration; assessment of the shock-mitigation effects of single and multiple liquid layers. The uploaded paper is intended as a final report for the entire funding period. The poster described in the paper won the Best Poster Award at the 25 International Symposium on Shock Waves.

  5. On Reflection of Shock Waves from Boundary Layers

    NASA Technical Reports Server (NTRS)

    Liepmann, H W; Roshko, A; Dhawan, S

    1952-01-01

    Measurements are presented at Mach numbers from about 1.3 to 1.5 of reflection characteristics and the relative upstream influence of shock waves impinging on a flat surface with both laminar and turbulent boundary layers. The difference between impulse and step waves is discussed and their interaction with the boundary layer is compared. General considerations on the experimental production of shock waves from wedges and cones and examples of reflection of shock waves from supersonic shear layers are also presented.

  6. Shock layer radiance effects on endoatmospheric interceptor seeker performance

    NASA Astrophysics Data System (ADS)

    Trolier, J.; Hudson, D.; Carlson, D.; Krawczyk, W.

    1992-05-01

    A method is described in detail to allow prediction of infrared radiance from shock layers surrounding high altitude hypersonic endoatmospheric interceptors. Flowfield properties calculated with the EXTC code for a representative endoatmospheric interceptor forebody are shown, including thermal and chemical nonequilibrium effects for both clean air and atmospheric trace species. The SIRRM-II radiative transport code was used with a modified version of the NORSE infrared radiance database to predict radiance and transmission through the shock layer. A simple sensor model, including spectral target signatures, window thermal emission noise, and shock layer radiance is employed to illustrate the importance of the shock layer radiance effects. Shock layer radiance is found to increase with decreasing altitude, with significant broadening of spectral emission bands at lower altitudes.

  7. Re-forming supercritical quasi-parallel shocks. I - One- and two-dimensional simulations

    NASA Technical Reports Server (NTRS)

    Thomas, V. A.; Winske, D.; Omidi, N.

    1990-01-01

    The process of reforming supercritical quasi-parallel shocks is investigated using one-dimensional and two-dimensional hybrid (particle ion, massless fluid electron) simulations both of shocks and of simpler two-stream interactions. It is found that the supercritical quasi-parallel shock is not steady. Instread of a well-defined shock ramp between upstream and downstream states that remains at a fixed position in the flow, the ramp periodically steepens, broadens, and then reforms upstream of its former position. It is concluded that the wave generation process is localized at the shock ramp and that the reformation process proceeds in the absence of upstream perturbations intersecting the shock.

  8. Unsteadiness of Shock Wave / Boundary Layer Interactions

    NASA Astrophysics Data System (ADS)

    Clemens, Noel

    2009-11-01

    Shock wave / boundary layer interactions are an important feature of high-speed flows that occur in a wide range of practical configurations including aircraft control surfaces, inlets, missile base flows, nozzles, and rotating machinery. These interactions are often associated with severe boundary layer separation, which is highly unsteady, and exhibits high fluctuating pressure and heat loads. The unsteady motions are characterized by a wide range of frequencies, including low-frequency motions that are about two orders of magnitude lower than those that characterize the upstream boundary layer. It is these low-frequency motions that are of most interest because they have been the most difficult to explain and model. Despite significant work over the past few decades, the source of the low-frequency motions remains a topic of intense debate. Owing to a flurry of activity over the past decade on this single topic we are close to developing a comprehensive understanding of the low-frequency unsteadiness. For example, recent work in our laboratory and others suggests that the driving mechanism is related to low-frequency fluctuations in the upstream boundary layer. However, several recent studies suggest the dominant mechanism is an intrinsic instability of the separated flow. Here we attempt to reconcile these views by arguing that the low-frequency unsteadiness is driven by both upstream and downstream processes, but the relative importance of each mechanism depends on the strength (or length-scale) of separation. In cases where the separation bubble is relatively small, then the flow is intermittently separated, and there exists a strong correlation between upstream velocity fluctuations and the separation bubble dynamics. It appears that superstructures in the upstream boundary layer can play an important role in driving the unsteadiness for this case. It is not clear, however, if the upstream fluctuations directly move the separation point or indirectly couple

  9. Critical pitch angle for electron acceleration in a collisionless shock layer

    NASA Astrophysics Data System (ADS)

    Narita, Y.; Comişel, H.; Motschmann, U.

    2016-07-01

    Collisionless shock waves in space and astrophysical plasmas can accelerate electrons along the shock layer by an electrostatic potential, and scatter or reflect electrons back to the upstream region by the amplified magnetic field or turbulent fluctuations. The notion of the critical pitch angle is introduced for non-adiabatic electron acceleration by balancing the two timescales under a quasi-perpendicular shock wave geometry in which the upstream magnetic field is nearly perpendicular to the shock layer normal direction. An analytic expression of the critical pitch angle is obtained as a function of the electron velocity parallel to the magnetic field, the ratio of the electron gyro- to plasma frequency, the cross-shock potential, the width of the shock transition layer, and the shock angle (which is the angle between the upstream magnetic field and the shock normal direction). For typical non-relativistic solar system applications, the critical pitch angle is predicted to be about 10°. An efficient acceleration is expected below the critical pitch angle.

  10. Planar shock wave sliding over a water layer

    NASA Astrophysics Data System (ADS)

    Rodriguez, V.; Jourdan, G.; Marty, A.; Allou, A.; Parisse, J.-D.

    2016-08-01

    In this work, we conduct experiments to study the interaction between a horizontal free water layer and a planar shock wave that is sliding over it. Experiments are performed at atmospheric pressure in a shock tube with a square cross section (200× 200 mm^2) for depths of 10, 20, and 30 mm; a 1500-mm-long water layer; and two incident planar shock waves having Mach numbers of 1.11 and 1.43. We record the pressure histories and high-speed visualizations to study the flow patterns, surface waves, and spray layers behind the shock wave. We observe two different flow patterns with ripples formed at the air-water interface for the weaker shock wave and the dispersion of a droplet mist for the stronger shock wave. From the pressure signals, we extract the delay time between the arrival of the compression wave into water and the shock wave in air at the same location. We show that the delay time evolves with the distance traveled over the water layer, the depth of the water layer, and the Mach number of the shock wave.

  11. Experimental study of a shock accelerated thin gas layer

    SciTech Connect

    Jacobs, J.W.; Jenkins, D.G.; Klein, D.L.; Benjamin, R.F.

    1993-08-01

    Planar laser-induced fluorescence imaging is utilized in shock-tube experiments to visualize the development of a shock-accelerated thin gas layer. The Richtmyer-Meshkov instability of both sides of the heavy gas layer causes perturbations initially imposed on the two interfaces to develop into one of three distinct flow patterns. Two of the patterns exhibit vortex pairs which travel either upstream or downstream in the shock tube, while the third is a sinuous pattern that shows no vortex development until late in its evolution. The development of the observed patterns as well as the growth in the layer thickness is modeled by considering the dynamics of vorticity deposited in the layer by the shock interaction process. This model yields an expression for the layer growth which is in good agreement with measurements.

  12. Vorticity interaction effects on blunt bodies. [hypersonic viscous shock layers

    NASA Technical Reports Server (NTRS)

    Anderson, E. C.; Wilcox, D. C.

    1977-01-01

    Numerical solutions of the viscous shock layer equations governing laminar and turbulent flows of a perfect gas and radiating and nonradiating mixtures of perfect gases in chemical equilibrium are presented for hypersonic flow over spherically blunted cones and hyperboloids. Turbulent properties are described in terms of the classical mixing length. Results are compared with boundary layer and inviscid flowfield solutions; agreement with inviscid flowfield data is satisfactory. Agreement with boundary layer solutions is good except in regions of strong vorticity interaction; in these flow regions, the viscous shock layer solutions appear to be more satisfactory than the boundary layer solutions. Boundary conditions suitable for hypersonic viscous shock layers are devised for an advanced turbulence theory.

  13. Nonequilibrium effects on shock-layer radiometry during earth entry.

    NASA Technical Reports Server (NTRS)

    Arnold, J. O.; Whiting, E. E.

    1973-01-01

    Radiative enhancement factors for the CN violet and N2(+) first negative band systems caused by nonequilibrium thermochemistry in the shock layer of a blunt-nosed vehicle during earth entry are reported. The results are based on radiometric measurements obtained with the aid of a combustion-driven shock tube. The technique of converting the shock-tube measurements into predictions of the enhancement factors for the blunt-body case is described, showing it to be useful for similar applications of other shock-tube measurements.

  14. Giotto magnetic field observations at the outbound quasi-parallel bow shock of Comet Halley

    NASA Technical Reports Server (NTRS)

    Neubauer, F. M.; Glassmeier, K. H.; Acuna, M. H.; Mariani, F.; Musmann, G.

    1990-01-01

    The investigation of the outbound bow shock of Comet Halley using Giotto magnetometer data leads to the following results: the shock is characterized by strong magnetic turbulence associated with an increasing background magnetic field and a change in direction by 60 deg as one goes inward. In HSE-coordinates, the observed normal turned out to be (0.544, - 0.801, 0.249). The thickness of the quasi-parallel shock was 120,000 km. The shock is shown to be a new type of shock transition called a 'draping shock'. In a draping shock with high beta in the transonic transition region, the transonic region is characterized by strong directional variations of the magnetic field. The magnetic turbulence ahead of the shock is characterized by k-vectors parallel or antiparallel to the average field (and, therefore, also to the normal of the quasi-parallel shock) and almost isotropic magnetic turbulence in the shock transition region. A model of the draping shock is proposed which also includes a hypothetical subshock in which the supersonic-subsonic transition is accomplished.

  15. Plasma and energetic particle structure upstream of a quasi-parallel interplanetary shock

    NASA Technical Reports Server (NTRS)

    Kennel, C. F.; Scarf, F. L.; Coroniti, F. V.; Russell, C. T.; Wenzel, K.-P.; Sanderson, T. R.; Van Nes, P.; Smith, E. J.; Tsurutani, B. T.; Scudder, J. D.

    1984-01-01

    ISEE 1, 2 and 3 data from 1978 on interplanetary magnetic fields, shock waves and particle energetics are examined to characterize a quasi-parallel shock. The intense shock studied exhibited a 640 km/sec velocity. The data covered 1-147 keV protons and electrons and ions with energies exceeding 30 keV in regions both upstream and downstream of the shock, and also the magnitudes of ion-acoustic and MHD waves. The energetic particles and MHD waves began being detected 5 hr before the shock. Intense halo electron fluxes appeared ahead of the shock. A closed magnetic field structure was produced with a front end 700 earth radii from the shock. The energetic protons were cut off from the interior of the magnetic bubble, which contained a markedly increased density of 2-6 keV protons as well as the shock itself.

  16. Ion Dynamics at a Rippled Quasi-parallel Shock: 2D Hybrid Simulations

    NASA Astrophysics Data System (ADS)

    Hao, Yufei; Lu, Quanming; Gao, Xinliang; Wang, Shui

    2016-05-01

    In this paper, two-dimensional hybrid simulations are performed to investigate ion dynamics at a rippled quasi-parallel shock. The results show that the ripples around the shock front are inherent structures of a quasi-parallel shock, and the re-formation of the shock is not synchronous along the surface of the shock front. By following the trajectories of the upstream ions, we find that these ions behave differently when they interact with the shock front at different positions along the shock surface. The upstream particles are transmitted more easily through the upper part of a ripple, and the corresponding bulk velocity downstream is larger, where a high-speed jet is formed. In the lower part of the ripple, the upstream particles tend to be reflected by the shock. Ions reflected by the shock may suffer multiple-stage acceleration when moving along the shock surface or trapped between the upstream waves and the shock front. Finally, these ions may escape further upstream or move downstream; therefore, superthermal ions can be found both upstream and downstream.

  17. Monte Carlo Simulations of Nonlinear Particle Acceleration in Parallel Trans-relativistic Shocks

    NASA Astrophysics Data System (ADS)

    Ellison, Donald C.; Warren, Donald C.; Bykov, Andrei M.

    2013-10-01

    We present results from a Monte Carlo simulation of a parallel collisionless shock undergoing particle acceleration. Our simulation, which contains parameterized scattering and a particular thermal leakage injection model, calculates the feedback between accelerated particles ahead of the shock, which influence the shock precursor and "smooth" the shock, and thermal particle injection. We show that there is a transition between nonrelativistic shocks, where the acceleration efficiency can be extremely high and the nonlinear compression ratio can be substantially greater than the Rankine-Hugoniot value, and fully relativistic shocks, where diffusive shock acceleration is less efficient and the compression ratio remains at the Rankine-Hugoniot value. This transition occurs in the trans-relativistic regime and, for the particular parameters we use, occurs around a shock Lorentz factor γ0 = 1.5. We also find that nonlinear shock smoothing dramatically reduces the acceleration efficiency presumed to occur with large-angle scattering in ultra-relativistic shocks. Our ability to seamlessly treat the transition from ultra-relativistic to trans-relativistic to nonrelativistic shocks may be important for evolving relativistic systems, such as gamma-ray bursts and Type Ibc supernovae. We expect a substantial evolution of shock accelerated spectra during this transition from soft early on to much harder when the blast-wave shock becomes nonrelativistic.

  18. MONTE CARLO SIMULATIONS OF NONLINEAR PARTICLE ACCELERATION IN PARALLEL TRANS-RELATIVISTIC SHOCKS

    SciTech Connect

    Ellison, Donald C.; Warren, Donald C.; Bykov, Andrei M. E-mail: ambykov@yahoo.com

    2013-10-10

    We present results from a Monte Carlo simulation of a parallel collisionless shock undergoing particle acceleration. Our simulation, which contains parameterized scattering and a particular thermal leakage injection model, calculates the feedback between accelerated particles ahead of the shock, which influence the shock precursor and 'smooth' the shock, and thermal particle injection. We show that there is a transition between nonrelativistic shocks, where the acceleration efficiency can be extremely high and the nonlinear compression ratio can be substantially greater than the Rankine-Hugoniot value, and fully relativistic shocks, where diffusive shock acceleration is less efficient and the compression ratio remains at the Rankine-Hugoniot value. This transition occurs in the trans-relativistic regime and, for the particular parameters we use, occurs around a shock Lorentz factor γ{sub 0} = 1.5. We also find that nonlinear shock smoothing dramatically reduces the acceleration efficiency presumed to occur with large-angle scattering in ultra-relativistic shocks. Our ability to seamlessly treat the transition from ultra-relativistic to trans-relativistic to nonrelativistic shocks may be important for evolving relativistic systems, such as gamma-ray bursts and Type Ibc supernovae. We expect a substantial evolution of shock accelerated spectra during this transition from soft early on to much harder when the blast-wave shock becomes nonrelativistic.

  19. Hypersonic flow separation in shock wave boundary layer interactions

    NASA Technical Reports Server (NTRS)

    Hamed, A.; Kumar, Ajay

    1992-01-01

    An assessment is presented for the experimental data on separated flow in shock wave turbulent boundary layer interactions at hypersonic and supersonic speeds. The data base consists mainly of two dimensional and axisymmetric interactions in compression corners or cylinder-flares, and externally generated oblique shock interactions with boundary layers over flat plates or cylindrical surfaces. The conditions leading to flow separation and the subsequent changes in the flow empirical correlations for incipient separation are reviewed. The effects of the Mach number, Reynolds number, surface cooling and the methods of detecting separation are discussed. The pertinent experimental data for the separated flow characteristics in separated turbulent boundary layer shock interaction are also presented and discussed.

  20. Simulation of glancing shock wave and boundary layer interaction

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Mao

    1989-01-01

    Shock waves generated by sharp fins, glancing across a laminar boundary layer growing over a flat plate, are simulated numerically. Several basic issues concerning the resultant three-dimensional flow separation are studied. Using the same number of grid points, different grid spacings are employed to investigate the effects of grid resolution on the origin of the line of separation. Various shock strengths (generated by different fin angles) are used to study the so-called separated and unseparated boundary layer and to establish the existence or absence of the secondary separation. The usual interpretations of the flow field from previous studies and new interpretations arising from the present simulation are discussed.

  1. Turbulence at quasi-parallel and quasi-perpendicular bow shocks

    NASA Astrophysics Data System (ADS)

    Pitna, Alexander; Zastenker, Georgy; Nemecek, Zdenek; Safrankova, Jana

    2016-07-01

    A solar wind is a highly turbulent medium carrying various modes of magnetohydrodynamic and kinetic instabilities. During its supersonic expansion, it meets obstacles like planetary magnetospheres and bow shocks are formed. Depending on the orientation of the ambient magnetic field with respect to the local shock normal, either quasi-parallel or quasi-perpendicular shocks can be formed. Particles reflected at the ramp of the quasi-parallel shock are streaming far upstream along the magnetic field lines, giving rise to all sorts of instabilities like SLAMS and ULF waves. In the case of the quasi-perpendicular bow shock, the reflected particles influence only a narrow upstream region of the order of the proton gyroradius but the downstream plasma becomes highly turbulent regardless of the shock type. We analyze the high cadence (31 ms) data from the BMSW instrument onboard the Spektr-R spacecraft and compare the frequency spectra of observed turbulence in MHD and kinetic ranges in upstream and downstream regions of the supercritical quasi-parallel and quasi-perpendicular bow shocks. We found that the change in the fluctuation level (from upstream to downstream) as well as the spectral indices differ substantially in the MHD and kinetic ranges for both types of bow shock.

  2. Numerical calculations of shock-wave/boundary-layer flow interactions

    NASA Astrophysics Data System (ADS)

    Huang, P. G.; Liou, W. W.

    1994-08-01

    The paper presents results of calculations for 2-D supersonic turbulent compression corner flows. The results seem to indicate that the newer, improved kappa-epsilon models offer limited advantages over the standard kappa-epsilon model in predicting the shock-wave/boundary-layer flows in the 2-D compression corner over a wide range of corner angles and flow conditions.

  3. {open_quotes}Heated layer{close_quotes} effect in interaction of an interplanetary shock wave with a geomagnetic tail

    SciTech Connect

    Aleksandrov, P.E.

    1993-11-01

    Using the numerical solution as the base the conditions of propagating a parallel MGD shock wave in the presence of a heated layer are analyzed, a new {open_quotes}raking regime{open_quotes} of interaction not observed with no magnetic field is revealed. A flow steadiness criterion is obtained, and conditions for the onset of a similarity precursor are estimated.

  4. Search for shock-metamorphosed grains in Precambrian spherule layers

    NASA Astrophysics Data System (ADS)

    Smith, Frank C.

    2014-10-01

    There is minimal physical evidence in only a few of the ˜17 Precambrian spherule layers to support an impact origin. A search was done for shock-metamorphosed grains in the following spherule layers: Carawine, Jeerinah, and Bee Gorge (formerly Wittenoom) in Western Australia, Monteville in South Africa, and Graenseso in South-West Greenland. Samples went through acid digestion, and the residues were wet sieved. The 63-125 mum (+/- 125-250 mum) size fractions went through heavy liquid separation. For most samples, the heavy mineral assemblages consist predominantly of anatase, rutile, tourmaline, and zircon (+/- chrome spinel) grains. Using micro-Raman spectroscopy, the high-pressure, alpha-PbO2 -structured polymorph of TiO2 (TiO2 II) was identified in 27 buff rutile grains from the Carawine, Jeerinah, Bee Gorge, and Monteville spherule layers. For three of the layers, rutile + TiO2 II grains were found only in their upper parts. For a sample or stratigraphic subdivision within a sample, rutile + TiO2 II grains comprise ˜1-5% of the rutile population. The TiO2 II polymorph is interpreted as a shock-induced phase that is syngenetic with respect to its host spherule layer. The rutile + TiO2 II grains provide physical evidence to support an impact origin for these four spherule layers. Using a universal stage microscope, measurements of the crystallographic orientations of planar microstructures in three quartz grains from the Carawine spherule layer support the interpretation that the microstructures are shock-induced planar deformation features. No unequivocal evidence of shock metamorphism was found in the white opaque zircon grains; instead, these grains appear to have varying degrees of metamictization. The physical properties of the chrome spinel, rutile, and zircon grains support the previously proposed hypothesis that the Carawine, Jeerinah, and Monteville spherule layers are parts of a single spherule layer that is older than the Bee Gorge spherule layer

  5. Direct simulation of shock-induced mixing layer

    SciTech Connect

    Greenough, J.A.; Bell, J.B.

    1993-03-01

    The interaction of a shock wave with a dense fluid layer in three dimensions is investigated using direct numerical simulations. The underlying numerical method is a second-order Godunov scheme. This is coupled to an implementation of Adaptive Mesh Refinement which is used to manage the hierarchical grid structure. An anomalous shock refraction is formed as the initiating shock wave impinges on a quiescent thin dense gas layer. One of the two resulting centered waves from the refraction, the contact surface, serves as the site for initial deposition of primarily spanwise vorticity and represents the primary mixing layer instability. The other wave, the transmitted shock wave, through repeated interactions with the free-surface, forms a cellular structure within the dense layer. The initial interaction introduces three dimensional perturbations onto the slip surface. These perturbations are selectively enhanced, due to favorable velocity gradients over part of the cellular structures, and form large-scale counter-rotating streamwise vertical structures. The structures characterize the secondary instability of this mixing layer. These vortices are quite unstable and transition to small-scales within a distance spanned by two of the cellular structures behind the initiating shock. The transition location has been verified in physical experiments. The fine-scale structure contains evidence of hairpin vortices. The evolution of a conserved scalar is used to monitor mixing progress. Increases in the rate of mixing are directly tied to intensification events associated with the streamwise vortices. Overall the large-scale streamwise structures provide an efficient mechanism for mixing the light and dense fluids. Analysis of time-series data from the calculation shows evidence of what are termed energetic smallscales. This is the characteristic signature of the hairpin vortices undergoing intensification.

  6. Interferometric data for a shock-wave/boundary-layer interaction

    NASA Technical Reports Server (NTRS)

    Dunagan, Stephen E.; Brown, James L.; Miles, John B.

    1986-01-01

    An experimental study of the axisymmetric shock-wave / boundary-layer strong interaction flow generated in the vicinity of a cylinder-cone intersection was conducted. The study data are useful in the documentation and understanding of compressible turbulent strong interaction flows, and are part of a more general effort to improve turbulence modeling for compressible two- and three-dimensional strong viscous/inviscid interactions. The nominal free stream Mach number was 2.85. Tunnel total pressures of 1.7 and 3.4 atm provided Reynolds number values of 18 x 10(6) and 36 x 10(6) based on model length. Three cone angles were studied giving negligible, incipient, and large scale flow separation. The initial cylinder boundary layer upstream of the interaction had a thickness of 1.0 cm. The subsonic layer of the cylinder boundary layer was quite thin, and in all cases, the shock wave penetrated a significant portion of the boundary layer. Owing to the thickness of the cylinder boundary layer, considerable structural detail was resolved for the three shock-wave / boundary-layer interaction cases considered. The primary emphasis was on the application of the holographic interferometry technique. The density field was deduced from an interferometric analysis based on the Able transform. Supporting data were obtained using a 2-D laser velocimeter, as well as mean wall pressure and oil flow measurements. The attached flow case was observed to be steady, while the separated cases exhibited shock unsteadiness. Comparisons with Navier-Stokes computations using a two-equation turbulence model are presented.

  7. Shock wave-turbulent boundary layer interactions in transonic flow

    NASA Technical Reports Server (NTRS)

    Adamson, T. C., Jr.; Messiter, A. F.

    1976-01-01

    The method of matched asymptotic expansions is used in analyzing the structure of the interaction region formed when a shock wave impinges on a turbulent flat plate boundary layer in transonic flow. Solutions in outer regions, governed by inviscid flow equations, lead to relations for the wall pressure distribution. Solutions in the inner regions, governed by equations in which Reynolds and/or viscous stresses are included, lead to a relation for the wall shear stress. Solutions for the wall pressure distribution are reviewed for both oblique and normal incoming shock waves. Solutions for the wall shear stress are discussed.

  8. Unsteady Phenomena in Shock Wave/Boundary Layer Interaction

    NASA Technical Reports Server (NTRS)

    Dolling, D. S.

    1993-01-01

    A brief review is given of the unsteadiness of shock wave/turbulent boundary layer interaction. The focus is on interactions generated by swept and unswept compression ramps, by flares, steps and incident shock waves, by cylinders and blunt fins, and by glancing shock waves. The effects of Mach number, Reynolds number, and separated flow scale are discussed as are the physical causes of the unsteadiness. The implications that the unsteadiness has for interpreting time-average surface and flowfield data, and for comparisons of such experimental data with computation, is also briefly discussed. Finally, some suggestions for future work are given. It is clear that there are large gaps in the data base and that many aspects of such phenomena are poorly understood. Much work remains to be done.

  9. NUCLEOSYNTHETIC LAYERS IN THE SHOCKED EJECTA OF CASSIOPEIA A

    SciTech Connect

    Isensee, Karl; Olmschenk, Greg; Rudnick, Lawrence; DeLaney, Tracey; Rho, Jeonghee; Smith, J. D.; Reach, William T.; Kozasa, Takashi; Gomez, Haley E-mail: larry@astro.umn.edu E-mail: jrho@sofia.usra.edu E-mail: reach@ipac.caltech.edu E-mail: haley.morgan@astro.cf.ac.uk

    2012-10-01

    We present a three-dimensional analysis of the supernova remnant Cassiopeia A using high-resolution spectra from the Spitzer Space Telescope. We observe supernova ejecta both immediately before and during the shock-ejecta interaction. We determine that the reverse shock of the remnant is spherical to within 7%, although the center of this sphere is offset from the geometric center of the remnant by 810 km s{sup -1}. We determine that the velocity width of the nucleosynthetic layers is {approx}1000 km s{sup -1} over 4000 arcsec{sup 2} regions, although the velocity width of a layer along any individual line of sight is <250 km s{sup -1}. Si and O, which come from different nucleosynthetic layers in the progenitor star, are observed to be coincident in velocity space in some directions, but segregated by up to {approx}500 km s{sup -1} in other directions. We compare these observations of the nucleosynthetic layers to predictions from supernova explosion models in an attempt to constrain such models. Finally, we observe small-scale, corrugated velocity structures that are likely caused during the supernova explosion itself, rather than hundreds of years later by dynamical instabilities at the remnant's reverse shock.

  10. Uncertainty Analysis of Air Radiation for Lunar Return Shock Layers

    NASA Technical Reports Server (NTRS)

    Kleb, Bil; Johnston, Christopher O.

    2008-01-01

    By leveraging a new uncertainty markup technique, two risk analysis methods are used to compute the uncertainty of lunar-return shock layer radiation predicted by the High temperature Aerothermodynamic Radiation Algorithm (HARA). The effects of epistemic uncertainty, or uncertainty due to a lack of knowledge, is considered for the following modeling parameters: atomic line oscillator strengths, atomic line Stark broadening widths, atomic photoionization cross sections, negative ion photodetachment cross sections, molecular bands oscillator strengths, and electron impact excitation rates. First, a simplified shock layer problem consisting of two constant-property equilibrium layers is considered. The results of this simplified problem show that the atomic nitrogen oscillator strengths and Stark broadening widths in both the vacuum ultraviolet and infrared spectral regions, along with the negative ion continuum, are the dominant uncertainty contributors. Next, three variable property stagnation-line shock layer cases are analyzed: a typical lunar return case and two Fire II cases. For the near-equilibrium lunar return and Fire 1643-second cases, the resulting uncertainties are very similar to the simplified case. Conversely, the relatively nonequilibrium 1636-second case shows significantly larger influence from electron impact excitation rates of both atoms and molecules. For all cases, the total uncertainty in radiative heat flux to the wall due to epistemic uncertainty in modeling parameters is 30% as opposed to the erroneously-small uncertainty levels (plus or minus 6%) found when treating model parameter uncertainties as aleatory (due to chance) instead of epistemic (due to lack of knowledge).

  11. Subgrid-scale turbulence in shock-boundary layer flows

    NASA Astrophysics Data System (ADS)

    Jammalamadaka, Avinash; Jaberi, Farhad

    2015-04-01

    Data generated by direct numerical simulation (DNS) for a Mach 2.75 zero-pressure gradient turbulent boundary layer interacting with shocks of different intensities are used for a priori analysis of subgrid-scale (SGS) turbulence and various terms in the compressible filtered Navier-Stokes equations. The numerical method used for DNS is based on a hybrid scheme that uses a non-dissipative central scheme in the shock-free turbulent regions and a robust monotonicity-preserving scheme in the shock regions. The behavior of SGS stresses and their components, namely Leonard, Cross and Reynolds components, is examined in various regions of the flow for different shock intensities and filter widths. The backscatter in various regions of the flow is found to be significant only instantaneously, while the ensemble-averaged statistics indicate no significant backscatter. The budgets for the SGS kinetic energy equation are examined for a better understanding of shock-tubulence interactions at the subgrid level and also with the aim of providing useful information for one-equation LES models. A term-by-term analysis of SGS terms in the filtered total energy equation indicate that while each term in this equation is significant by itself, the net contribution by all of them is relatively small. This observation is consistent with our a posteriori analysis.

  12. Experimental studies on two dimensional shock boundary layer interactions

    NASA Technical Reports Server (NTRS)

    Skebe, S. A.; Greber, I.; Hingst, W. R.

    1984-01-01

    Experiments have been performed on the interaction of oblique shock waves with flat plate boundary layers in the 30.48 cm x 30.48 cm (1 ft. x 1 ft.) supersonic wind tunnel at NASA Lewis Research Center. High accuracy measurements of the plate surface static pressure and shear stress distributions as well as boundary layer velocity profiles were obtained through the interaction region. Documentation was also performed of the tunnel test section flow field and of the two-dimensionality of the interaction regions. The findings provide detailed description of two-dimensional interaction with initially laminar boundary layers over the Mach number range 2.0 to 4.0. Additional information with regard to interactions involving initially transitional boundary layers is presented over the Mach number range 2.0 to 3.0 and those for initially turbulent boundary layers at Mach 2.0. These experiments were directed toward providing well documented information of high accuracy useful as test cases for analytic and numerical calculations. Flow conditions encompassed a Reynolds number range of 4.72E6 to 2.95E7 per meter. The shock boundary layer interaction results were found to be generally in good agreement with the experimental work of previous authors both in terms of direct numerical comparison and in support of correlations establishing laminar separation characteristics.

  13. Magnetosheath Filamentary Structures Formed by Ion Acceleration at the Quasi-Parallel Bow Shock

    NASA Technical Reports Server (NTRS)

    Omidi, N.; Sibeck, D.; Gutynska, O.; Trattner, K. J.

    2014-01-01

    Results from 2.5-D electromagnetic hybrid simulations show the formation of field-aligned, filamentary plasma structures in the magnetosheath. They begin at the quasi-parallel bow shock and extend far into the magnetosheath. These structures exhibit anticorrelated, spatial oscillations in plasma density and ion temperature. Closer to the bow shock, magnetic field variations associated with density and temperature oscillations may also be present. Magnetosheath filamentary structures (MFS) form primarily in the quasi-parallel sheath; however, they may extend to the quasi-perpendicular magnetosheath. They occur over a wide range of solar wind Alfvénic Mach numbers and interplanetary magnetic field directions. At lower Mach numbers with lower levels of magnetosheath turbulence, MFS remain highly coherent over large distances. At higher Mach numbers, magnetosheath turbulence decreases the level of coherence. Magnetosheath filamentary structures result from localized ion acceleration at the quasi-parallel bow shock and the injection of energetic ions into the magnetosheath. The localized nature of ion acceleration is tied to the generation of fast magnetosonic waves at and upstream of the quasi-parallel shock. The increased pressure in flux tubes containing the shock accelerated ions results in the depletion of the thermal plasma in these flux tubes and the enhancement of density in flux tubes void of energetic ions. This results in the observed anticorrelation between ion temperature and plasma density.

  14. Magnetosheath filamentary structures formed by ion acceleration at the quasi-parallel bow shock

    NASA Astrophysics Data System (ADS)

    Omidi, N.; Sibeck, D.; Gutynska, O.; Trattner, K. J.

    2014-04-01

    Results from 2.5-D electromagnetic hybrid simulations show the formation of field-aligned, filamentary plasma structures in the magnetosheath. They begin at the quasi-parallel bow shock and extend far into the magnetosheath. These structures exhibit anticorrelated, spatial oscillations in plasma density and ion temperature. Closer to the bow shock, magnetic field variations associated with density and temperature oscillations may also be present. Magnetosheath filamentary structures (MFS) form primarily in the quasi-parallel sheath; however, they may extend to the quasi-perpendicular magnetosheath. They occur over a wide range of solar wind Alfvénic Mach numbers and interplanetary magnetic field directions. At lower Mach numbers with lower levels of magnetosheath turbulence, MFS remain highly coherent over large distances. At higher Mach numbers, magnetosheath turbulence decreases the level of coherence. Magnetosheath filamentary structures result from localized ion acceleration at the quasi-parallel bow shock and the injection of energetic ions into the magnetosheath. The localized nature of ion acceleration is tied to the generation of fast magnetosonic waves at and upstream of the quasi-parallel shock. The increased pressure in flux tubes containing the shock accelerated ions results in the depletion of the thermal plasma in these flux tubes and the enhancement of density in flux tubes void of energetic ions. This results in the observed anticorrelation between ion temperature and plasma density.

  15. Structure of medium Mach number quasi-parallel shocks - Upstream and downstream waves

    NASA Technical Reports Server (NTRS)

    Krauss-Varban, D.; Omidi, N.

    1991-01-01

    The transition from steady low-Mach-number to unsteady high-Mach-number quasi-parallel shocks was investigated by performing large-scale 1D hybrid code simulations at increasing Mach numbers. It was found that only at very low Mach number shocks the steepening is limited by upstream phase-standing whistlers, as predicted by the classical theory (Tidman and Northrop, 1968). In the intermediate region of Mach numbers between 1.5 and 3.5, a very diverse behavior is observed. Backstreaming ions generate fast magnetosonic waves which dominate the upstream, with wavelengths longer than phase-standing whistlers. At increasing Mach numbers, the phase and group velocities of the dominant waves are reduced until they point back toward the shock; when there is sufficient energy flux in these waves, they lead to unsteady shock behavior and eventually to shock reformation.

  16. Post-adiabatic supernova remnants in an interstellar magnetic field: parallel and perpendicular shocks

    NASA Astrophysics Data System (ADS)

    Petruk, O.; Kuzyo, T.; Beshley, V.

    2016-03-01

    Gamma-rays from hadronic collisions are expected from supernova remnants (SNRs) located near molecular clouds. The temperature of the shock interacting with the dense environment quickly reaches 105 K. Radiative losses of plasma become essential in the evolution of SNRs. They decrease the thermal pressure and essentially increase the density behind the shock. The presence of an ambient magnetic field may alter the behaviour of the post-adiabatic SNRs considerably compared with the hydrodynamic scenario. In the present article, magnetohydrodynamic simulations of radiative shocks in a magnetic field are performed. High plasma compression due to radiative losses also results in a prominent increase in the strength of the tangential component of magnetic field behind the shock and a decrease of the parallel one. If the strength of the tangential field before the shock is higher than about 3 μG, it prevents formation of a very dense thin shell. The higher the strength of the tangential magnetic field, the larger the thickness and the lower the maximum density in the radiative shell. The parallel magnetic field does not affect the distribution of the hydrodynamic parameters behind the shock. There are almost independent channels of energy transformations: radiative losses are due to thermal energy, magnetic energy increases come from reducing the kinetic energy. The large density and high strength of the perpendicular magnetic field in the radiative shells of SNRs should result in a considerable increase of the hadronic gamma-ray flux compared with the leptonic one.

  17. Energetic particle diffusion coefficients upstream of quasi-parallel interplanetary shocks

    NASA Technical Reports Server (NTRS)

    Tan, L. C.; Mason, G. M.; Gloeckler, G.; Ipavich, F. M.

    1989-01-01

    The properties of about 30 to 130-keV/e protons and alpha particles upstream of six quasi-parallel interplanetary shocks that passed by the ISEE 3 spacecraft during 1978-1979 were analyzed, and the values for the upstream energegic particle diffusion coefficient, kappa, in these six events were deduced for a number of energies and upstream positions. These observations were compared with predictions of Lee's (1983) theory of shock acceleration. It was found that the observations verified the prediction of the A/Q dependence (where A and Q are the particle atomic mass and ionization state, respectively) of kappa for alpha and proton particles upstream of the quasi-parallel shocks.

  18. Stability and modal analysis of shock/boundary layer interactions

    NASA Astrophysics Data System (ADS)

    Nichols, Joseph W.; Larsson, Johan; Bernardini, Matteo; Pirozzoli, Sergio

    2016-06-01

    The dynamics of oblique shock wave/turbulent boundary layer interactions is analyzed by mining a large-eddy simulation (LES) database for various strengths of the incoming shock. The flow dynamics is first analyzed by means of dynamic mode decomposition (DMD), which highlights the simultaneous occurrence of two types of flow modes, namely a low-frequency type associated with breathing motion of the separation bubble, accompanied by flapping motion of the reflected shock, and a high-frequency type associated with the propagation of instability waves past the interaction zone. Global linear stability analysis performed on the mean LES flow fields yields a single unstable zero-frequency mode, plus a variety of marginally stable low-frequency modes whose stability margin decreases with the strength of the interaction. The least stable linear modes are grouped into two classes, one of which bears striking resemblance to the breathing mode recovered from DMD and another class associated with revolving motion within the separation bubble. The results of the modal and linear stability analysis support the notion that low-frequency dynamics is intrinsic to the interaction zone, but some continuous forcing from the upstream boundary layer may be required to keep the system near a limit cycle. This can be modeled as a weakly damped oscillator with forcing, as in the early empirical model by Plotkin (AIAA J 13:1036-1040, 1975).

  19. DSMC Computations for Regions of Shock/Shock and Shock/Boundary Layer Interaction

    NASA Technical Reports Server (NTRS)

    Moss, James N.

    2001-01-01

    This paper presents the results of a numerical study of hypersonic interacting flows at flow conditions that include those for which experiments have been conducted in the Calspan-University of Buffalo Research Center (CUBRC) Large Energy National Shock (LENS) tunnel and the ONERA R5Ch low-density wind tunnel. The computations are made with the direct simulation Monte Carlo (DSMC) method of Bird. The focus is on Mach 9.3 to 11.4 flows about flared axisymmetric configurations, both hollow cylinder flares and double cones. The results presented highlight the sensitivity of the calculations to grid resolution, provide results concerning the conditions for incipient separation, and provide information concerning the flow structure and surface results for the extent of separation, heating, pressure, and skin friction.

  20. Spontaneous Hot Flow Anomalies at Quasi-Parallel Shocks: 2. Hybrid Simulations

    NASA Technical Reports Server (NTRS)

    Omidi, N.; Zhang, H.; Sibeck, D.; Turner, D.

    2013-01-01

    Motivated by recent THEMIS observations, this paper uses 2.5-D electromagnetic hybrid simulations to investigate the formation of Spontaneous Hot Flow Anomalies (SHFA) upstream of quasi-parallel bow shocks during steady solar wind conditions and in the absence of discontinuities. The results show the formation of a large number of structures along and upstream of the quasi-parallel bow shock. Their outer edges exhibit density and magnetic field enhancements, while their cores exhibit drops in density, magnetic field, solar wind velocity and enhancements in ion temperature. Using virtual spacecraft in the simulation, we show that the signatures of these structures in the time series data are very similar to those of SHFAs seen in THEMIS data and conclude that they correspond to SHFAs. Examination of the simulation data shows that SHFAs form as the result of foreshock cavitons interacting with the bow shock. Foreshock cavitons in turn form due to the nonlinear evolution of ULF waves generated by the interaction of the solar wind with the backstreaming ions. Because foreshock cavitons are an inherent part of the shock dissipation process, the formation of SHFAs is also an inherent part of the dissipation process leading to a highly non-uniform plasma in the quasi-parallel magnetosheath including large scale density and magnetic field cavities.

  1. Spontaneous hot flow anomalies at quasi-parallel shocks: 2. Hybrid simulations

    NASA Astrophysics Data System (ADS)

    Omidi, N.; Zhang, H.; Sibeck, D.; Turner, D.

    2013-01-01

    Abstract<p label="1">Motivated by recent THEMIS observations, this paper uses 2.5-D electromagnetic hybrid simulations to investigate the formation of Spontaneous Hot Flow Anomalies (SHFAs) upstream of quasi-<span class="hlt">parallel</span> bow <span class="hlt">shocks</span> during steady solar wind conditions and in the absence of discontinuities. The results show the formation of a large number of structures along and upstream of the quasi-<span class="hlt">parallel</span> bow <span class="hlt">shock</span>. Their outer edges exhibit density and magnetic field enhancements, while their cores exhibit drops in density, magnetic field, solar wind velocity, and enhancements in ion temperature. Using virtual spacecraft in the simulation, we show that the signatures of these structures in the time series data are very similar to those of SHFAs seen in THEMIS data and conclude that they correspond to SHFAs. Examination of the simulation data shows that SHFAs form as the result of foreshock cavitons interacting with the bow <span class="hlt">shock</span>. Foreshock cavitons in turn form due to the nonlinear evolution of ULF waves generated by the interaction of the solar wind with the backstreaming ions. Because foreshock cavitons are an inherent part of the <span class="hlt">shock</span> dissipation process, the formation of SHFAs is also an inherent part of the dissipation process leading to a highly nonuniform plasma in the quasi-<span class="hlt">parallel</span> magnetosheath including large-scale density and magnetic field cavities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930071070&hterms=future+transport+speed&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dfuture%2Btransport%2Bspeed','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930071070&hterms=future+transport+speed&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dfuture%2Btransport%2Bspeed"><span id="translatedtitle">Alfven wave transport effects in the time evolution of <span class="hlt">parallel</span> cosmic-ray-modified <span class="hlt">shocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jones, T. W.</p> <p>1993-01-01</p> <p>This paper presents a numerical study of the time evolution of plane, cosmic-ray modified <span class="hlt">shocks</span> with magnetic field <span class="hlt">parallel</span> to the <span class="hlt">shock</span> normal, based on the diffusive <span class="hlt">shock</span> acceleration formalism and including the effects from the finite propagation speed and energy of Alfven waves responsible for controlling the transport of the cosmic rays. The simulations discussed are based on a three-fluid model for the dynamics, but a more complete formalism is laid out for future work. The results of the simulations confirm earlier steady state analyses that found these Alfven transport effects to be potentially important when the upstream Alfven speed and the gas sound speed are comparable, i.e., when the plasma and magnetic pressures are similar. It is also clear, however, that the impact of Alfven transport effects, which tend to slow <span class="hlt">shock</span> evolution and reduce the time asymptotic cosmic-ray pressure in the <span class="hlt">shock</span>, is strongly dependent upon uncertain details in the transport models. Both cosmic-ray advection tied to streaming Alfven waves and dissipation of wave energy are important to include in the models. Further, Alfven transport properties on both sides of the <span class="hlt">shock</span> are also influential.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930092322','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930092322"><span id="translatedtitle">Attenuation in a <span class="hlt">shock</span> tube due to unsteady-boundary-<span class="hlt">layer</span> action</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mirels, Harold</p> <p>1957-01-01</p> <p>A method is presented for obtaining the attenuation of a <span class="hlt">shock</span> wave in a <span class="hlt">shock</span> tube due to the unsteady boundary <span class="hlt">layer</span> along the <span class="hlt">shock</span>-tube walls. It is assumed that the boundary <span class="hlt">layer</span> is thin relative to the tube diameter and induces one-dimensional longitudinal pressure waves whose strength is proportional to the vertical velocity at the edge of the boundary <span class="hlt">layer</span>. The contributions of the various regions in a <span class="hlt">shock</span> tube to <span class="hlt">shock</span> attenuation are indicated. The method is shown to be in reasonably good agreement with existing experimental data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19960021262&hterms=ENERGY+SOLAR&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DENERGY%2BSOLAR','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19960021262&hterms=ENERGY+SOLAR&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DENERGY%2BSOLAR"><span id="translatedtitle">Electron acceleration to high energies at quasi-<span class="hlt">parallel</span> <span class="hlt">shock</span> waves in the solar corona</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mann, G.; Classen, H.-T.</p> <p>1995-01-01</p> <p>In the solar corona <span class="hlt">shock</span> waves are generated by flares and/or coronal mass ejections. They manifest themselves in solar type 2 radio bursts appearing as emission stripes with a slow drift from high to low frequencies in dynamic radio spectra. Their nonthermal radio emission indicates that electrons are accelerated to suprathermal and/or relativistic velocities at these <span class="hlt">shocks</span>. As well known by extraterrestrial in-situ measurements supercritical, quasi-<span class="hlt">parallel</span>, collisionless <span class="hlt">shocks</span> are accompanied by so-called SLAMS (short large amplitude magnetic field structures). These SLAMS can act as strong magnetic mirrors, at which charged particles can be reflected and accelerated. Thus, thermal electrons gain energy due to multiple reflections between two SLAMS and reach suprathermal and relativistic velocities. This mechanism of accelerating electrons is discussed for circumstances in the solar corona and may be responsible for the so-called 'herringbones' observed in solar type 2 radio bursts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770015092','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770015092"><span id="translatedtitle">Structure of a quasi-<span class="hlt">parallel</span>, quasi-laminar bow <span class="hlt">shock</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Greenstadt, E. W.; Russell, C. T.; Formisano, V.; Hedgecock, P. C.; Scarf, F. L.; Neugebauer, M.; Holzer, R. E.</p> <p>1976-01-01</p> <p>A thick, quasi-<span class="hlt">parallel</span> bow <span class="hlt">shock</span> structure was observed with field and particle detectors of both HEOS 1 and OGO 5. The typical magnetic pulsation structure was at least 1 to 2 earth radii thick radially and was accompanied by irregular but distinct plasma distributions characteristic of neither the solar wind nor the magnetosheath. Waves constituting the large pulsations were polarized principally in the plane of the nominal <span class="hlt">shock</span>, therefore also in the plane perpendicular to the average interplanetary field. A separate interpulsation regime detected between bursts of large amplitude oscillations was similar to the upstream wave region magnetically, but was characterized by disturbed plasma flux and enhanced noise around the ion plasma frequency. The <span class="hlt">shock</span> structure appeared to be largely of an oblique, whistler type, probably complicated by counterstreaming high energy protons. Evidence for firehose instability-based structure was weak at best and probably negative.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22140247','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22140247"><span id="translatedtitle">GYROSURFING ACCELERATION OF IONS IN FRONT OF EARTH's QUASI-<span class="hlt">PARALLEL</span> BOW <span class="hlt">SHOCK</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kis, Arpad; Lemperger, Istvan; Wesztergom, Viktor; Agapitov, Oleksiy; Krasnoselskikh, Vladimir; Dandouras, Iannis E-mail: Kis.Arpad@csfk.mta.hu</p> <p>2013-07-01</p> <p>It is well known that <span class="hlt">shocks</span> in space plasmas can accelerate particles to high energies. However, many details of the <span class="hlt">shock</span> acceleration mechanism are still unknown. A critical element of <span class="hlt">shock</span> acceleration is the injection problem; i.e., the presence of the so called seed particle population that is needed for the acceleration to work efficiently. In our case study, we present for the first time observational evidence of gyroresonant surfing acceleration in front of Earth's quasi-<span class="hlt">parallel</span> bow <span class="hlt">shock</span> resulting in the appearance of the long-suspected seed particle population. For our analysis, we use simultaneous multi-spacecraft measurements provided by the Cluster spacecraft ion (CIS), magnetic (FGM), and electric field and wave instrument (EFW) during a time period of large inter-spacecraft separation distance. The spacecraft were moving toward the bow <span class="hlt">shock</span> and were situated in the foreshock region. The results show that the gyroresonance surfing acceleration takes place as a consequence of interaction between circularly polarized monochromatic (or quasi-monochromatic) transversal electromagnetic plasma waves and short large amplitude magnetic structures (SLAMSs). The magnetic mirror force of the SLAMS provides the resonant conditions for the ions trapped by the waves and results in the acceleration of ions. Since wave packets with circular polarization and different kinds of magnetic structures are very commonly observed in front of Earth's quasi-<span class="hlt">parallel</span> bow <span class="hlt">shock</span>, the gyroresonant surfing acceleration proves to be an important particle injection mechanism. We also show that seed ions are accelerated directly from the solar wind ion population.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013ApJ...771....4K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013ApJ...771....4K"><span id="translatedtitle">Gyrosurfing Acceleration of Ions in Front of Earth's Quasi-<span class="hlt">parallel</span> Bow <span class="hlt">Shock</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kis, Arpad; Agapitov, Oleksiy; Krasnoselskikh, Vladimir; Khotyaintsev, Yuri V.; Dandouras, Iannis; Lemperger, Istvan; Wesztergom, Viktor</p> <p>2013-07-01</p> <p>It is well known that <span class="hlt">shocks</span> in space plasmas can accelerate particles to high energies. However, many details of the <span class="hlt">shock</span> acceleration mechanism are still unknown. A critical element of <span class="hlt">shock</span> acceleration is the injection problem; i.e., the presence of the so called seed particle population that is needed for the acceleration to work efficiently. In our case study, we present for the first time observational evidence of gyroresonant surfing acceleration in front of Earth's quasi-<span class="hlt">parallel</span> bow <span class="hlt">shock</span> resulting in the appearance of the long-suspected seed particle population. For our analysis, we use simultaneous multi-spacecraft measurements provided by the Cluster spacecraft ion (CIS), magnetic (FGM), and electric field and wave instrument (EFW) during a time period of large inter-spacecraft separation distance. The spacecraft were moving toward the bow <span class="hlt">shock</span> and were situated in the foreshock region. The results show that the gyroresonance surfing acceleration takes place as a consequence of interaction between circularly polarized monochromatic (or quasi-monochromatic) transversal electromagnetic plasma waves and short large amplitude magnetic structures (SLAMSs). The magnetic mirror force of the SLAMS provides the resonant conditions for the ions trapped by the waves and results in the acceleration of ions. Since wave packets with circular polarization and different kinds of magnetic structures are very commonly observed in front of Earth's quasi-<span class="hlt">parallel</span> bow <span class="hlt">shock</span>, the gyroresonant surfing acceleration proves to be an important particle injection mechanism. We also show that seed ions are accelerated directly from the solar wind ion population.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930061252&hterms=downstream&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Ddownstream','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930061252&hterms=downstream&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Ddownstream"><span id="translatedtitle">Propagation characteristics of waves upstream and downstream of quasi-<span class="hlt">parallel</span> <span class="hlt">shocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Krauss-Varban, D.; Omidi, N.</p> <p>1993-01-01</p> <p>The propagation characteristics of waves upstream and downstream of quasi-<span class="hlt">parallel</span> <span class="hlt">shocks</span> are investigated by using 2D hybrid simulations. At low Alfven Mach numbers, M(A) below about 2, the <span class="hlt">shock</span> is initially associated with upstream phase-standing whistlers. At later times, backstreaming ions excite longer-wavelength whistlers via the right-hand resonant ion/ion instability. These waves propagate along the magnetic field at a group velocity no smaller than the upstream flow speed, so that the waves remain in the upstream region. At higher MA (above about 3), these waves are convected back into the <span class="hlt">shock</span>, causing its reformation and downstream perturbations. <span class="hlt">Shock</span> transmitted waves mode-convert into Alfven/ion-cyclotron waves which have a wave vector along the <span class="hlt">shock</span> normal (pointing upstream) and convect downstream. The 2D simulation results confirm our earlier suggestion that the upstream waves should be field aligned, and that their convection into the downstream is associated with linear mode conversion into the Alfven/ion-cyclotron branch.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/101967','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/101967"><span id="translatedtitle">Hypersonic hydrogen combustion in the thin viscous <span class="hlt">shock</span> <span class="hlt">layer</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Riabov, V.V.; Botin, A.V.</p> <p>1995-04-01</p> <p>Different models of hypersonic diffusive hydrogen combustion in a thin viscous <span class="hlt">shock</span> <span class="hlt">layer</span> (TVSL) at moderate Reynolds numbers have been developed. The study is based on computations of nonequilibrium multicomponent flowfield parameters of air-hydrogen mixture in the TVSL near the blunt probe. The structure of computed combustion zones is analyzed. Under conditions of slot and uniform injections the zone structures are essentially different. Hydrogen injection conditions are discovered at which the nonreacting hydrogen zone and the zone enriched with the hydrogen combustion products appear near the body surface. Hydrogen, water, and OH concentrations identify these zones. More effective cooling of the probe surface occurs at moderate injections compared to strong ones. Under the blowing conditions at moderate Reynolds numbers the most effective cooling of the body surface occurs at moderate uniform hydrogen injection. The results can be helpful for predicting the degree of supersonic hydrogen combustion in hypersonic vehicle engines. 21 refs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740021535','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740021535"><span id="translatedtitle"><span class="hlt">Shock</span>-induced separation of adiabatic turbulent boundary <span class="hlt">layers</span> in supersonic axially symmetric internal flow</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Page, R. J.; Childs, M. E.</p> <p>1974-01-01</p> <p>An experimental investigation at Mach 4 of <span class="hlt">shock</span>-induced turbulent boundary <span class="hlt">layer</span> separation at the walls of axially symmetric flow passages is discussed, with particular emphasis placed on determining the <span class="hlt">shock</span> strengths required for incipient separation. The <span class="hlt">shock</span> waves were produced by interchangeable sting-mounted cones placed on the axes of the flow passages and aligned with the freestream flow. The interactions under study simulate those encountered in axially symmetric engine inlets of supersonic aircraft. Knowledges of the <span class="hlt">shock</span> strengths required for boundary <span class="hlt">layer</span> separation in inlets is important since for <span class="hlt">shocks</span> of somewhat greater strength rather drastic alterations in the inlet flow field may occur.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22046893','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22046893"><span id="translatedtitle">Evolution of symmetric reconnection <span class="hlt">layer</span> in the presence of <span class="hlt">parallel</span> shear flow</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lu Haoyu; Cao Jinbin</p> <p>2011-07-15</p> <p>The development of the structure of symmetric reconnection <span class="hlt">layer</span> in the presence of a shear flow <span class="hlt">parallel</span> to the antiparallel magnetic field component is studied by using a set of one-dimensional (1D) magnetohydrodynamic (MHD) equations. The Riemann problem is simulated through a second-order conservative TVD (total variation diminishing) scheme, in conjunction with Roe's averages for the Riemann problem. The simulation results indicate that besides the MHD <span class="hlt">shocks</span> and expansion waves, there exist some new small-scale structures in the reconnection <span class="hlt">layer</span>. For the case of zero initial guide magnetic field (i.e., B{sub y0} = 0), a pair of intermediate <span class="hlt">shock</span> and slow <span class="hlt">shock</span> (SS) is formed in the presence of the <span class="hlt">parallel</span> shear flow. The critical velocity of initial shear flow V{sub zc} is just the Alfven velocity in the inflow region. As V{sub z{infinity}} increases to the value larger than V{sub zc}, a new slow expansion wave appears in the position of SS in the case V{sub z{infinity}} < V{sub zc}, and one of the current densities drops to zero. As plasma {beta} increases, the out-flow region is widened. For B{sub y0} {ne} 0, a pair of SSs and an additional pair of time-dependent intermediate <span class="hlt">shocks</span> (TDISs) are found to be present. Similar to the case of B{sub y0} = 0, there exists a critical velocity of initial shear flow V{sub zc}. The value of V{sub zc} is, however, smaller than the Alfven velocity of the inflow region. As plasma {beta} increases, the velocities of SS and TDIS increase, and the out-flow region is widened. However, the velocity of downstream SS increases even faster, making the distance between SS and TDIS smaller. Consequently, the interaction between SS and TDIS in the case of high plasma {beta} influences the property of direction rotation of magnetic field across TDIS. Thereby, a wedge in the hodogram of tangential magnetic field comes into being. When {beta}{yields}{infinity}, TDISs disappear and the guide magnetic field becomes constant.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110023251','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110023251"><span id="translatedtitle">Turbulence Modeling for <span class="hlt">Shock</span> Wave/Turbulent Boundary <span class="hlt">Layer</span> Interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lillard, Randolph P.</p> <p>2011-01-01</p> <p>Accurate aerodynamic computational predictions are essential for the safety of space vehicles, but these computations are of limited accuracy when large pressure gradients are present in the flow. The goal of the current project is to improve the state of compressible turbulence modeling for high speed flows with <span class="hlt">shock</span> wave / turbulent boundary <span class="hlt">layer</span> interactions (SWTBLI). Emphasis will be placed on models that can accurately predict the separated region caused by the SWTBLI. These flows are classified as nonequilibrium boundary <span class="hlt">layers</span> because of the very large and variable adverse pressure gradients caused by the <span class="hlt">shock</span> waves. The lag model was designed to model these nonequilibrium flows by incorporating history effects. Standard one- and two-equation models (Spalart Allmaras and SST) and the lag model will be run and compared to a new lag model. This new model, the Reynolds stress tensor lag model (lagRST), will be assessed against multiple wind tunnel tests and correlations. The basis of the lag and lagRST models are to preserve the accuracy of the standard turbulence models in equilibrium turbulence, when the Reynolds stresses are linearly related to the mean strain rates, but create a lag between mean strain rate effects and turbulence when nonequilibrium effects become important, such as in large pressure gradients. The affect this lag has on the results for SWBLI and massively separated flows will be determined. These computations will be done with a modified version of the OVERFLOW code. This code solves the RANS equations on overset grids. It was used for this study for its ability to input very complex geometries into the flow solver, such as the Space Shuttle in the full stack configuration. The model was successfully implemented within two versions of the OVERFLOW code. Results show a substantial improvement over the baseline models for transonic separated flows. The results are mixed for the SWBLI assessed. Separation predictions are not as good as the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AIPC.1685i0001D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AIPC.1685i0001D"><span id="translatedtitle">Propagation of acoustic <span class="hlt">shock</span> waves between <span class="hlt">parallel</span> rigid boundaries and into shadow zones</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Desjouy, C.; Ollivier, S.; Marsden, O.; Dragna, D.; Blanc-Benon, P.</p> <p>2015-10-01</p> <p>The study of acoustic <span class="hlt">shock</span> propagation in complex environments is of great interest for urban acoustics, but also for source localization, an underlying problematic in military applications. To give a better understanding of the phenomenon taking place during the propagation of acoustic <span class="hlt">shocks</span>, laboratory-scale experiments and numerical simulations were performed to study the propagation of weak <span class="hlt">shock</span> waves between <span class="hlt">parallel</span> rigid boundaries, and into shadow zones created by corners. In particular, this work focuses on the study of the local interactions taking place between incident, reflected, and diffracted waves according to the geometry in both regular or irregular - also called Von Neumann - regimes of reflection. In this latter case, an irregular reflection can lead to the formation of a Mach stem that can modify the spatial distribution of the acoustic pressure. Short duration acoustic <span class="hlt">shock</span> waves were produced by a 20 kilovolts electric spark source and a schlieren optical method was used to visualize the incident shockfront and the reflection/diffraction patterns. Experimental results are compared to numerical simulations based on the high-order finite difference solution of the two dimensional Navier-Stokes equations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22492653','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22492653"><span id="translatedtitle">Propagation of acoustic <span class="hlt">shock</span> waves between <span class="hlt">parallel</span> rigid boundaries and into shadow zones</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Desjouy, C. Ollivier, S.; Dragna, D.; Blanc-Benon, P.; Marsden, O.</p> <p>2015-10-28</p> <p>The study of acoustic <span class="hlt">shock</span> propagation in complex environments is of great interest for urban acoustics, but also for source localization, an underlying problematic in military applications. To give a better understanding of the phenomenon taking place during the propagation of acoustic <span class="hlt">shocks</span>, laboratory-scale experiments and numerical simulations were performed to study the propagation of weak <span class="hlt">shock</span> waves between <span class="hlt">parallel</span> rigid boundaries, and into shadow zones created by corners. In particular, this work focuses on the study of the local interactions taking place between incident, reflected, and diffracted waves according to the geometry in both regular or irregular – also called Von Neumann – regimes of reflection. In this latter case, an irregular reflection can lead to the formation of a Mach stem that can modify the spatial distribution of the acoustic pressure. Short duration acoustic <span class="hlt">shock</span> waves were produced by a 20 kilovolts electric spark source and a schlieren optical method was used to visualize the incident shockfront and the reflection/diffraction patterns. Experimental results are compared to numerical simulations based on the high-order finite difference solution of the two dimensional Navier-Stokes equations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19880059402&hterms=downstream&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddownstream','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19880059402&hterms=downstream&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddownstream"><span id="translatedtitle">Downstream energetic proton and alpha particles during quasi-<span class="hlt">parallel</span> interplanetary <span class="hlt">shock</span> events</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Tan, L. C.; Mason, G. M.; Gloeckler, G.; Ipavich, F. M.</p> <p>1988-01-01</p> <p>This paper considers the energetic particle populations in the downstream region of three quasi-<span class="hlt">parallel</span> interplanetary <span class="hlt">shock</span> events, which was explored using the ISEE 3 Ultra Low Energy Charge Analyzer sensor, which unambiguously identifies protons and alpha particles using the electrostatic deflection versus residual energy technique. The downstream particles were found to exhibit anisotropies due largely to convection in the solar wind. The spectral indices of the proton and the alpha-particle distribution functions were found to be remarkably constant during the downstream period, being generally insensitive to changes in particle flux levels, magnetic field direction, and solar wind densities. In two of the three events, the proton and the alpha spectra were the same throughout the entire downstream period, supporting the prediction of diffusive <span class="hlt">shock</span> acceleration theory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19770040368&hterms=Irregular+Structure&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DIrregular%2BStructure','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19770040368&hterms=Irregular+Structure&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DIrregular%2BStructure"><span id="translatedtitle">Structure of a quasi-<span class="hlt">parallel</span>, quasi-laminar bow <span class="hlt">shock</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Greenstadt, E. W.; Scarf, F. L.; Russell, C. T.; Holzer, R. E.; Formisano, V.; Hedgecock, P. C.; Neugebauer, M.</p> <p>1977-01-01</p> <p>A thick quasi-<span class="hlt">parallel</span> bow <span class="hlt">shock</span> structure was observed on February 14, 1969, with field and particle detectors of both Heos 1 and Ogo 5. The typical magnetic pulsation structure was at least 1-2 R-E thick radially and was accompanied by irregular but distinct (average) plasma distributions characteristic of neither the solar wind nor the magnetosheath. There appeared to be a separate 'interpulsation' regime occurring between bursts of large amplitude oscillations. This regime was magnetically similar to the upstream wave region but was characterized by disturbed plasma flux and enhanced noise around the ion plasma frequency. The <span class="hlt">shock</span> structure appeared to be largely of an oblique whistler type, probably complicated by counterstreaming high-energy protons.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090033728','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090033728"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">Layer</span> Radiation Measurements and Analysis for Mars Entry</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bose, Deepak; Grinstead, Jay Henderson; Bogdanoff, David W.; Wright, Michael J.</p> <p>2009-01-01</p> <p>NASA's In-Space Propulsion program is supporting the development of <span class="hlt">shock</span> radiation transport models for aerocapture missions to Mars. A comprehensive test series in the NASA Antes Electric Arc <span class="hlt">Shock</span> Tube facility at a representative flight condition was recently completed. The facility optical instrumentation enabled spectral measurements of <span class="hlt">shocked</span> gas radiation from the vacuum ultraviolet to the near infrared. The instrumentation captured the nonequilibrium post-<span class="hlt">shock</span> excitation and relaxation dynamics of dispersed spectral features. A description of the <span class="hlt">shock</span> tube facility, optical instrumentation, and examples of the test data are presented. Comparisons of measured spectra with model predictions are also made.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760002932','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760002932"><span id="translatedtitle">Calculation of <span class="hlt">shock</span>-separated turbulent boundary <span class="hlt">layers</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Baldwin, B. S.; Rose, W. C.</p> <p>1975-01-01</p> <p>Numerical solutions of the complete, time-averaged conservation equations using several eddy-viscosity models for the Reynolds shear stress to close the equations are compared with experimental measurements in a compressible, turbulent separated flow. An efficient time-splitting, explicit difference scheme was used to solve the two-dimensional conservation equations. The experiment used for comparison was a turbulent boundary <span class="hlt">layer</span> that was separated by an incident <span class="hlt">shock</span> wave in a Mach 2.93 flow with a unit Reynolds number of 5.7 x 10 to the seventh power m. Comparisons of predicted and experimental values of surface pressure, shear stress along the wall, and velocity profiles are shown. One of the tested eddy-viscosity models which allows the shear stress to be out of equilibrium with the mean flow produces substantially better agreement with the experimental measurements than the simpler models. A tool is thereby provided for inferring additional information about the flow, such as static pressures in the stream, which might not be directly obtainable from experiments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10170379','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10170379"><span id="translatedtitle">Nexus: An interoperability <span class="hlt">layer</span> for <span class="hlt">parallel</span> and distributed computer systems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Foster, I.; Kesselman, C.; Olson, R.; Tuecke, S.</p> <p>1994-05-01</p> <p>Nexus is a set of services that can be used to implement various task-<span class="hlt">parallel</span> languages, data-<span class="hlt">parallel</span> languages, and message-passing libraries. Nexus is designed to permit the efficient portable implementation of individual <span class="hlt">parallel</span> programming systems and the interoperability of programs developed with different tools. Nexus supports lightweight threading and active message technology, allowing integration of message passing and threads.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140005333','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140005333"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">Layer</span> Radiation Modeling and Uncertainty for Mars Entry</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Johnston, Christopher O.; Brandis, Aaron M.; Sutton, Kenneth</p> <p>2012-01-01</p> <p>A model for simulating nonequilibrium radiation from Mars entry <span class="hlt">shock</span> <span class="hlt">layers</span> is presented. A new chemical kinetic rate model is developed that provides good agreement with recent EAST and X2 <span class="hlt">shock</span> tube radiation measurements. This model includes a CO dissociation rate that is a factor of 13 larger than the rate used widely in previous models. Uncertainties in the proposed rates are assessed along with uncertainties in translational-vibrational relaxation modeling parameters. The stagnation point radiative flux uncertainty due to these flowfield modeling parameter uncertainties is computed to vary from 50 to 200% for a range of free-stream conditions, with densities ranging from 5e-5 to 5e-4 kg/m3 and velocities ranging from of 6.3 to 7.7 km/s. These conditions cover the range of anticipated peak radiative heating conditions for proposed hypersonic inflatable aerodynamic decelerators (HIADs). Modeling parameters for the radiative spectrum are compiled along with a non-Boltzmann rate model for the dominant radiating molecules, CO, CN, and C2. A method for treating non-local absorption in the non-Boltzmann model is developed, which is shown to result in up to a 50% increase in the radiative flux through absorption by the CO 4th Positive band. The sensitivity of the radiative flux to the radiation modeling parameters is presented and the uncertainty for each parameter is assessed. The stagnation point radiative flux uncertainty due to these radiation modeling parameter uncertainties is computed to vary from 18 to 167% for the considered range of free-stream conditions. The total radiative flux uncertainty is computed as the root sum square of the flowfield and radiation parametric uncertainties, which results in total uncertainties ranging from 50 to 260%. The main contributors to these significant uncertainties are the CO dissociation rate and the CO heavy-particle excitation rates. Applying the baseline flowfield and radiation models developed in this work, the</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active"><span>4</span></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_4 --> <div id="page_5" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="81"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016AIPC.1759b0102S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016AIPC.1759b0102S&link_type=ABSTRACT"><span id="translatedtitle">Simulation of <span class="hlt">shock</span> wave boundary <span class="hlt">layer</span> interaction in flat channel with jet injection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shakhan, Nurtoleu; Beketaeva, Asel; Naimanova, Altynshash</p> <p>2016-08-01</p> <p>A multispecies supersonic gas flow in the flat channel with perpendicular jet injection is numerically simulated by using the Favre-averaged Navier-Stokes equations coupled with k - ω turbulence model. High order WENO scheme is applied to approximate convective terms. During the investigation of flow physics in detail, the three <span class="hlt">shock</span>-wave structures are observed: in the region of the jet (barrel, bow, oblique and closing <span class="hlt">shocks</span>), on the upper boundary <span class="hlt">layer</span> (reflection, transmitted and reattachment <span class="hlt">shocks</span>), and new structures behind the jet on the lower boundary <span class="hlt">layer</span>, which are analogous to the structures on the upper boundary <span class="hlt">layer</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRA..121.2080H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRA..121.2080H"><span id="translatedtitle">Formation of downstream high-speed jets by a rippled nonstationary quasi-<span class="hlt">parallel</span> <span class="hlt">shock</span>: 2-D hybrid simulations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hao, Y.; Lembege, B.; Lu, Q.; Guo, F.</p> <p>2016-03-01</p> <p>Experimental observations from space missions (including more recently Cluster and Time History of Events and Macroscale Interactions during Substorms data) have clearly revealed the existence of high-speed jets (HSJs) in the downstream region of the quasi-<span class="hlt">parallel</span> terrestrial bow <span class="hlt">shock</span>. Presently, two-dimensional hybrid simulations are performed in order to investigate the formation of such HSJs through a rippled quasi-<span class="hlt">parallel</span> <span class="hlt">shock</span> front. The simulation results show that (i) such <span class="hlt">shock</span> fronts are strongly nonstationary along the <span class="hlt">shock</span> normal, and (ii) ripples are evidenced along the <span class="hlt">shock</span> front as the upstream ULF waves (excited by interaction between incident and reflected ions) are convected back to the front by the solar wind and contribute to the rippling formation. Then, these ripples are inherent structures of a quasi-<span class="hlt">parallel</span> <span class="hlt">shock</span>. As a consequence, new incident solar wind ions interact differently at different locations along the <span class="hlt">shock</span> surface, and the ion bulk velocity strongly differs locally as ions are transmitted downstream. Preliminary results show that (i) local bursty patterns of turbulent magnetic field may form within the rippled front and play the role of local secondary <span class="hlt">shock</span>; (ii) some incident ion flows penetrate the front, suffer some deflection (instead of being decelerated) at the locations of these secondary <span class="hlt">shocks</span>, and are at the origin of well-structured (filamentary) HSJs downstream; and (iii) the spatial scales of HSJs are in a good agreement with experimental observations. Such downstream HSJs are shown to be generated by local curvature effects (front rippling) and the nonstationarity of the <span class="hlt">shock</span> front itself.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/441343','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/441343"><span id="translatedtitle">Interaction of a plane <span class="hlt">shock</span> wave in water with a thin <span class="hlt">layer</span> of lower density</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bergel`son, V.I.; Nemchinov, I.V.; Orlova, T.I.; Khazins, V.M.</p> <p>1992-08-01</p> <p>A numerical analysis is conducted on the interaction of a plane <span class="hlt">shock</span> wave in water with a thin <span class="hlt">layer</span> of lower density, which is perpendicular to the wave front. Parameters are defined for the perturbed flow structure and for large-scale precursors, which arise ahead of the <span class="hlt">shock</span> front. Possibilities are discussed of experimentally investigating this phenomena with a cylindrical <span class="hlt">shock</span> wave using standard explosives. 4 refs., 4 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22252111','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22252111"><span id="translatedtitle"><span class="hlt">Shock</span> waves and double <span class="hlt">layers</span> in electron degenerate dense plasma with viscous ion fluids</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mamun, A. A.; Zobaer, M. S.</p> <p>2014-02-15</p> <p>The properties of ion-acoustic <span class="hlt">shock</span> waves and double <span class="hlt">layers</span> propagating in a viscous degenerate dense plasma (containing inertial viscous ion fluid, non-relativistic and ultra-relativistic degenerate electron fluid, and negatively charged stationary heavy element) is investigated. A new nonlinear equation (viz. Gardner equation with additional dissipative term) is derived by the reductive perturbation method. The properties of the ion-acoustic <span class="hlt">shock</span> waves and double <span class="hlt">layers</span> are examined by the analysis of the <span class="hlt">shock</span> and double <span class="hlt">layer</span> solutions of this new equation (we would like to call it “M-Z equation”). It is found that the properties of these <span class="hlt">shock</span> and double <span class="hlt">layer</span> structures obtained from this analysis are significantly different from those obtained from the analysis of standard Gardner or Burgers’ equation. The implications of our results to dense plasmas in astrophysical objects (e.g., non-rotating white dwarf stars) are briefly discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750023958','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750023958"><span id="translatedtitle">Control of <span class="hlt">shock</span> wave-boundary <span class="hlt">layer</span> interactions by bleed in supersonic mixed compression inlets</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fukuda, M. K.; Hingst, W. G.; Reshotko, E.</p> <p>1975-01-01</p> <p>An experimental investigation was conducted to determine the effect of bleed on a <span class="hlt">shock</span> wave-boundary <span class="hlt">layer</span> interaction in an axisymmetric mixed-compression supersonic inlet. The inlet was designed for a free-stream Mach number of 2.50 with 60-percent supersonic internal area contraction. The experiment was conducted in the NASA Lewis Research Center 10-Foot Supersonic Wind Tunnel. The effects of bleed amount and bleed geometry on the boundary <span class="hlt">layer</span> after a <span class="hlt">shock</span> wave-boundary <span class="hlt">layer</span> interaction were studied. The effect of bleed on the transformed form factor is such that the full realizable reduction is obtained by bleeding of a mass flow equal to about one-half of the incident boundary <span class="hlt">layer</span> mass flow. More bleeding does not yield further reduction. Bleeding upstream or downstream of the <span class="hlt">shock</span>-induced pressure rise is preferable to bleeding across the <span class="hlt">shock</span>-induced pressure rise.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JPhCS.530a2068P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JPhCS.530a2068P"><span id="translatedtitle">Investigations of <span class="hlt">shock</span> wave boundary <span class="hlt">layer</span> interaction on suction side of compressor profile</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Piotrowicz, M.; Flaszyński, P.; Doerffer, P.</p> <p>2014-08-01</p> <p>The <span class="hlt">shock</span> wave boundary <span class="hlt">layer</span> interaction on the suction side of transonic compressor blade is one of main objectives of TFAST project (Transition Location Effect on <span class="hlt">Shock</span> Wave Boundary <span class="hlt">Layer</span> Interaction). In order to look more closely into the flow structure on the suction side of a blade, a design of a generic test section in linear transonic wind tunnel was proposed. The test section which could reproduce flow structure, <span class="hlt">shock</span> wave location, pressure distribution and boundary <span class="hlt">layer</span> development similar to the obtained on a cascade profile is the main objective of the presented here design. The design of the proposed test section is very challenging, because of <span class="hlt">shock</span> wave existence, its interaction with boundary <span class="hlt">layer</span> and its influence on the 3-D flow structure in the test section.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhPl...21b2101M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhPl...21b2101M"><span id="translatedtitle"><span class="hlt">Shock</span> waves and double <span class="hlt">layers</span> in electron degenerate dense plasma with viscous ion fluids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mamun, A. A.; Zobaer, M. S.</p> <p>2014-02-01</p> <p>The properties of ion-acoustic <span class="hlt">shock</span> waves and double <span class="hlt">layers</span> propagating in a viscous degenerate dense plasma (containing inertial viscous ion fluid, non-relativistic and ultra-relativistic degenerate electron fluid, and negatively charged stationary heavy element) is investigated. A new nonlinear equation (viz. Gardner equation with additional dissipative term) is derived by the reductive perturbation method. The properties of the ion-acoustic <span class="hlt">shock</span> waves and double <span class="hlt">layers</span> are examined by the analysis of the <span class="hlt">shock</span> and double <span class="hlt">layer</span> solutions of this new equation (we would like to call it "M-Z equation"). It is found that the properties of these <span class="hlt">shock</span> and double <span class="hlt">layer</span> structures obtained from this analysis are significantly different from those obtained from the analysis of standard Gardner or Burgers' equation. The implications of our results to dense plasmas in astrophysical objects (e.g., non-rotating white dwarf stars) are briefly discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012ExFl...52..591H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012ExFl...52..591H"><span id="translatedtitle">Time-resolved stereo PIV measurements of <span class="hlt">shock</span>-boundary <span class="hlt">layer</span> interaction on a supercritical airfoil</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hartmann, Axel; Klaas, Michael; Schröder, Wolfgang</p> <p>2012-03-01</p> <p>Time-resolved stereo particle-image velocimetry (TR-SPIV) and unsteady pressure measurements are used to analyze the unsteady flow over a supercritical DRA-2303 airfoil in transonic flow. The dynamic <span class="hlt">shock</span> wave-boundary <span class="hlt">layer</span> interaction is one of the most essential features of this unsteady flow causing a distinct oscillation of the flow field. Results from wind-tunnel experiments with a variation of the freestream Mach number at Reynolds numbers ranging from 2.55 to 2.79 × 106 are analyzed regarding the origin and nature of the unsteady <span class="hlt">shock</span>-boundary <span class="hlt">layer</span> interaction. Therefore, the TR-SPIV results are analyzed for three buffet flows. One flow exhibits a sinusoidal streamwise oscillation of the <span class="hlt">shock</span> wave only due to an acoustic feedback loop formed by the <span class="hlt">shock</span> wave and the trailing-edge noise. The other two buffet flows have been intentionally influenced by an artificial acoustic source installed downstream of the test section to investigate the behavior of the interaction to upstream-propagating disturbances generated by a defined source of noise. The results show that such upstream-propagating disturbances could be identified to be responsible for the upstream displacement of the <span class="hlt">shock</span> wave and that the feedback loop is formed by a pulsating separation of the boundary <span class="hlt">layer</span> dependent on the <span class="hlt">shock</span> position and the sound pressure level at the <span class="hlt">shock</span> position. Thereby, the pulsation of the separation could be determined to be a reaction to the <span class="hlt">shock</span> motion and not vice versa.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008APS..DPPUP6013G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008APS..DPPUP6013G"><span id="translatedtitle">Particle acceleration by quasi-<span class="hlt">parallel</span> <span class="hlt">shocks</span> in the solar wind</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Galinsky, V. L.; Shevchenko, V. I.</p> <p>2008-11-01</p> <p>The theoretical study of proton acceleration at a quasi-<span class="hlt">parallel</span> <span class="hlt">shock</span> due to interaction with Alfven waves self-consistently excited in both upstream and downstream regions was conducted using a scale-separation model [1]. The model uses conservation laws and resonance conditions to find where waves will be generated or dumped and hence particles will be pitch--angle scattered as well as the change of the wave energy due to instability or damping. It includes in consideration the total distribution function (the bulk plasma and high energy tail), so no any assumptions (e.g. seed populations, or some ad-hoc escape rate of accelerated particles) are required. The dynamics of ion acceleration by the November 11-12, 1978 interplanetary traveling <span class="hlt">shock</span> was investigated and compared with the observations [2] as well as with solution obtained using the so-called convection-diffusion equation for distribution function of accelerated particles [3]. [1] Galinsky, V.L., and V.I. Shevchenko, Astrophys. J., 669, L109, 2007. [2] Kennel, C.F., F.W. Coroniti, F.L. Scarf, W.A. Livesey, C.T. Russell, E.J. Smith, K.P. Wenzel, and M. Scholer, J. Geophys. Res. 91, 11,917, 1986. [3] Gordon B.E., M.A. Lee, E. Mobius, and K.J. Trattner, J. Geophys. Res., 104, 28,263, 1990.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920043702&hterms=expression+body&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dexpression%2Bbody','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920043702&hterms=expression+body&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dexpression%2Bbody"><span id="translatedtitle">An approximate viscous <span class="hlt">shock</span> <span class="hlt">layer</span> technique for calculating nonequilibrium hypersonic flows about blunt-nosed bodies</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cheatwood, F. M.; Dejarnette, F. R.</p> <p>1992-01-01</p> <p>An approximate axisymmetric method has been developed which can reliably calculate nonequilibrium fully viscous hypersonic flows over blunt-nosed bodies. By substituting Maslen's second-order pressure expression for the normal momentum equation, a simplified form of the viscous <span class="hlt">shock</span> <span class="hlt">layer</span> (VSL) equations is obtained. This approach can solve both the subsonic and supersonic regions of the <span class="hlt">shock</span> <span class="hlt">layer</span> without a starting solution for the <span class="hlt">shock</span> shape. This procedure is significantly faster than the parabolized Navier-Stokes and VSL solvers and would be useful in a preliminary design environment. Solutions have been generated for air flows over several analytic body shapes. Surface heat transfer and pressure predictions are comparable to VSL results. Computed heating rates are in good agreement with experimental data. The present technique generates its own <span class="hlt">shock</span> shape as part of its solution, and therefore could be used to provide more accurate initial <span class="hlt">shock</span> shapes for higher-order procedures which require starting solutions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19830056002&hterms=OM&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DOM','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19830056002&hterms=OM&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DOM"><span id="translatedtitle">An experimental investigation of multiple <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span> interactions in a circular duct</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Om, D.; Childs, M. E.</p> <p>1983-01-01</p> <p>Detailed pitot, static and wall pressure measurements have been obtained for multiple <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span> interactions in a circular duct at a free-stream Mach number of 1.49 and at a unit Reynolds number of 4.90 x 10 to the 6th per meter. The details of the flow field show the formation of a series of normal <span class="hlt">shock</span> waves with successively decreasing strength and with decreasing distance between the successive <span class="hlt">shock</span> waves. The overall pressure recovery is much lower than the single normal <span class="hlt">shock</span> pressure recovery at the same free-stream Mach number. A one-dimensional flow model based on the boundary <span class="hlt">layer</span> displacement buildup is postulated to explain the formation of a series of normal <span class="hlt">shock</span> waves.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920066107&hterms=split+wave&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsplit%2Bwave','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920066107&hterms=split+wave&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsplit%2Bwave"><span id="translatedtitle">Three-dimensional <span class="hlt">shock-wave/boundary-layer</span> interactions with bleed through a circular hole</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rimlinger, M. J.; Shih, T. I.-P.; Chyu, W. J.</p> <p>1992-01-01</p> <p>Computations were performed to study three-dimensional (3-D), <span class="hlt">shock-wave/boundary-layer</span> interactions on a flat plate in which fluid in the boundary <span class="hlt">layer</span> was bled through a circular hole into a plenum to control <span class="hlt">shock</span>-wave induced separation. Results are presented which show the details of the 3-D flowfield about the bleed hole and how bleed-hole placement relative to <span class="hlt">shock</span>-wave impingement affect upstream, spanwise, and downstream influence lengths. This study revealed an underlying mechanisms by which bleed holes can affect <span class="hlt">shock-wave/boundary-layer</span> interactions. This investigation is based on the ensemble-averaged, "full-compressible" Navier-Stokes equations closed by the Baldwin-Lomax turbulence model. Solutions to these equations were obtained by an implicit finite-volume method based on the partially-split, two-factored algorithm of Steger.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016ShWav..26..129C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016ShWav..26..129C&link_type=ABSTRACT"><span id="translatedtitle">A new facility for studying <span class="hlt">shock</span>-wave passage over dust <span class="hlt">layers</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chowdhury, A. Y.; Marks, B. D.; Johnston, H. Greg; Mannan, M. Sam; Petersen, E. L.</p> <p>2016-03-01</p> <p>Dust explosion hazards in areas where coal and other flammable materials are found have caused unnecessary loss of life and halted business operations in some instances. The elimination of secondary dust explosion hazards, i.e., reducing dust dispersion, can be characterized in <span class="hlt">shock</span> tubes to understand <span class="hlt">shock</span>-dust interactions. For this reason, a new <span class="hlt">shock</span>-tube test section was developed and integrated into an existing <span class="hlt">shock</span>-tube facility. The test section has large windows to allow for the use of the shadowgraph technique to track dust-<span class="hlt">layer</span> growth behind a passing normal <span class="hlt">shock</span> wave, and it is designed to handle an initial pressure of 1 atm with an incident <span class="hlt">shock</span> wave Mach number as high as 2 to mimic real-world conditions. The test section features an easily removable dust pan with inserts to allow for adjustment of the dust-<span class="hlt">layer</span> thickness. The design also allows for changing the experimental variables such as initial pressure, <span class="hlt">shock</span> Mach number (Ms), dust-<span class="hlt">layer</span> thickness, and the characteristics of the dust itself. The characterization experiments presented herein demonstrate the advantages of the authors' test techniques toward providing new physical insights over a wider range of data than what have been available heretofore in the literature. Limestone dust with a <span class="hlt">layer</span> thickness of 3.2 mm was subjected to Ms = 1.23, 1.32, and 1.6 <span class="hlt">shock</span> waves, and dust-<span class="hlt">layer</span> rise height was mapped with respect to time after <span class="hlt">shock</span> passage. Dust particles subjected to a Ms = 1.6 <span class="hlt">shock</span> wave rose more rapidly and to a greater height with respect to <span class="hlt">shock</span> wave propagation than particles subjected to Ms = 1.23 and 1.32 <span class="hlt">shock</span> waves. Although these results are in general agreement with the literature, the new data also highlight physical trends for dust-<span class="hlt">layer</span> growth that have not been recorded previously, to the best of the authors' knowledge. For example, the dust-<span class="hlt">layer</span> height rises linearly until a certain time where the growth rate is dramatically reduced, and in this second</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ApJ...808....2W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ApJ...808....2W"><span id="translatedtitle">The Role of Large Amplitude Upstream Low-frequency Waves in the Generation of Superthermal Ions at a Quasi-<span class="hlt">parallel</span> Collisionless <span class="hlt">Shock</span>: Cluster Observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Mingyu; Hao, Yufei; Lu, Quanming; Huang, Can; Guo, Fan; Wang, Shui</p> <p>2015-07-01</p> <p>The superthermal ions at a quasi-<span class="hlt">parallel</span> collisionless <span class="hlt">shock</span> are considered to be generated during the reformation of the <span class="hlt">shock</span>. Recently, hybrid simulations of a quasi-<span class="hlt">parallel</span> <span class="hlt">shock</span> have shown that during the reformation of a quasi-<span class="hlt">parallel</span> <span class="hlt">shock</span> the large-amplitude upstream low-frequency waves can trap the reflected ions at the <span class="hlt">shock</span> front when they try to move upstream, and then these reflected ions can be accelerated several times to become superthermal ions. In this paper, with the Cluster observations of a quasi-<span class="hlt">parallel</span> <span class="hlt">shock</span> event, the relevance between the large-amplitude upstream low-frequency waves and the superthermal ions (about several keV) have been studied. The observations clearly show that the differential energy flux of superthermal ions in the upstream region is modulated by the upstream low-frequency waves, and the maxima of the differential energy flux are usually located between the peaks of these waves (including the <span class="hlt">shock</span> front and the peak of the upstream wave just in front of the <span class="hlt">shock</span> front). These superthermal ions are considered to originate from the reflected ions at the <span class="hlt">shock</span> front, and the modulation is caused due to the trapping of the reflected ions between the upstream waves or the upstream waves and the <span class="hlt">shock</span> front when these reflected ions try to travel upstream. It verifies the results from hybrid simulations, where the upstream waves play an important role in the generation of superthermal ions in a quasi-<span class="hlt">parallel</span> <span class="hlt">shock</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://medlineplus.gov/ency/article/000039.htm','NIH-MEDLINEPLUS'); return false;" href="https://medlineplus.gov/ency/article/000039.htm"><span id="translatedtitle"><span class="hlt">Shock</span></span></a></p> <p><a target="_blank" href="http://medlineplus.gov/">MedlinePlus</a></p> <p></p> <p></p> <p>... problems) Hypovolemic <span class="hlt">shock</span> (caused by too little blood volume) Anaphylactic <span class="hlt">shock</span> (caused by allergic reaction) Septic <span class="hlt">shock</span> ( ... as heart attack or heart failure ) Low blood volume (as with heavy bleeding or dehydration ) Changes in ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.emergencycareforyou.org/Emergency-101/Emergencies-A-Z/Shock/','NIH-MEDLINEPLUS'); return false;" href="http://www.emergencycareforyou.org/Emergency-101/Emergencies-A-Z/Shock/"><span id="translatedtitle"><span class="hlt">Shock</span></span></a></p> <p><a target="_blank" href="http://medlineplus.gov/">MedlinePlus</a></p> <p></p> <p></p> <p>... Emergencies A-Z Share this! Home » Emergency 101 <span class="hlt">Shock</span> <span class="hlt">Shock</span> is a serious, often life-threatening medical condition ... of death for critically ill or injured people. <span class="hlt">Shock</span> results when the body is not getting enough ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910030160&hterms=QUEST&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DQUEST','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910030160&hterms=QUEST&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DQUEST"><span id="translatedtitle">Re-forming supercritical quasi-<span class="hlt">parallel</span> <span class="hlt">shocks</span>. II - Mechanism for wave generation and front re-formation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Winske, D.; Thomas, V. A.; Omidi, N.; Quest, K. B.</p> <p>1990-01-01</p> <p>This paper continues the study of Thomas et al. (1990) in which hybrid simulations of quasi-<span class="hlt">parallel</span> <span class="hlt">shocks</span> were performed in one and two spatial dimensions. To identify the wave generation processes, the electromagnetic structure of the <span class="hlt">shock</span> is examined by performing a number of one-dimensional hybrid simulations of quasi-<span class="hlt">parallel</span> <span class="hlt">shocks</span> for various upstream conditions. In addition, numerical experiments were carried out in which the backstreaming ions were removed from calculations to show their fundamental importance in reformation process. The calculations show that the waves are excited before ions can propagate far enough upstream to generate resonant modes. At some later times, the waves are regenerated at the leading edge of the interface, with properties like those of their initial interactions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23005206','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23005206"><span id="translatedtitle"><span class="hlt">Shock</span> velocity increase due to a heterogeneity produced by a two-gas <span class="hlt">layer</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Elbaz, Déborah; Jourdan, Georges; Houas, Lazhar; Jaouen, Stéphane; Ballereau, Philippe; Dias, Frédéric; Canaud, Benoit</p> <p>2012-06-01</p> <p><span class="hlt">Shock</span> tube experiments are performed in order to study <span class="hlt">shock</span> propagation along a two-gas <span class="hlt">layer</span> in a confined geometry and to compare it to the case of a homogeneous density equivalent mixture. The analysis of the homogeneous case gives values for the adiabatic coefficient and density of the mixture of both gases, while the comparison between heterogeneous and homogeneous media with the same averaged density shows modifications of the <span class="hlt">shock</span> front shape and velocity. In the two-gas <span class="hlt">layer</span>, the <span class="hlt">shock</span> propagates faster than in the homogeneous medium. The <span class="hlt">shock</span> front is curved with a triple point which appears close to the <span class="hlt">shock</span>-tube wall, in the slow medium, while it stays planar during its whole propagation in the homogeneous mixture. A correlation is found between the angle of curvature and the <span class="hlt">shock</span> velocity increase. It is confirmed by two-dimensional Eulerian numerical calculations. Experiments and calculations exhibit very good agreement on all the measurements when molecular diffusion is taken into account in the numerical calculations. A sustained irregular refraction pattern of the <span class="hlt">shock</span> front at the diffuse interface of both gases is obtained experimentally and confirmed by the calculations. PMID:23005206</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070004895','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070004895"><span id="translatedtitle">Optimal Control of <span class="hlt">Shock</span> Wave Turbulent Boundary <span class="hlt">Layer</span> Interactions Using Micro-Array Actuation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Anderson, Bernhard H.; Tinapple, Jon; Surber, Lewis</p> <p>2006-01-01</p> <p>The intent of this study on micro-array flow control is to demonstrate the viability and economy of Response Surface Methodology (RSM) to determine optimal designs of micro-array actuation for controlling the <span class="hlt">shock</span> wave turbulent boundary <span class="hlt">layer</span> interactions within supersonic inlets and compare these concepts to conventional bleed performance. The term micro-array refers to micro-actuator arrays which have heights of 25 to 40 percent of the undisturbed supersonic boundary <span class="hlt">layer</span> thickness. This study covers optimal control of <span class="hlt">shock</span> wave turbulent boundary <span class="hlt">layer</span> interactions using standard micro-vane, tapered micro-vane, and standard micro-ramp arrays at a free stream Mach number of 2.0. The effectiveness of the three micro-array devices was tested using a <span class="hlt">shock</span> pressure rise induced by the 10 <span class="hlt">shock</span> generator, which was sufficiently strong as to separate the turbulent supersonic boundary <span class="hlt">layer</span>. The overall design purpose of the micro-arrays was to alter the properties of the supersonic boundary <span class="hlt">layer</span> by introducing a cascade of counter-rotating micro-vortices in the near wall region. In this manner, the impact of the <span class="hlt">shock</span> wave boundary <span class="hlt">layer</span> (SWBL) interaction on the main flow field was minimized without boundary bleed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013APS..DFDG25003G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013APS..DFDG25003G"><span id="translatedtitle">Effect of Pulsed Plasma Jets on Reflected <span class="hlt">Shock</span>-Turbulent Boundary <span class="hlt">Layer</span> Interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Greene, Benton R.; Clemens, Noel T.; Magari, Patrick; Micka, Daniel</p> <p>2013-11-01</p> <p><span class="hlt">Shock</span>-induced turbulent boundary <span class="hlt">layer</span> separation can have many detrimental effects in supersonic inlets including flow instability, fatigue of structural panels, poor pressure recovery, and unstart. Pulsed plasma jets (or ``spark jets''), zero net mass flow jets characterized by high bandwidth and the ability to direct momentum into the flow, are one promising method of reducing <span class="hlt">shock</span>-induced separation and boundary <span class="hlt">layer</span> distortion. The current study is focused on investigating the efficacy of pulsed plasma jets to reduce the boundary <span class="hlt">layer</span> distortion induced by a reflected <span class="hlt">shock</span> interaction in a Mach 3 flow. A 7° <span class="hlt">shock</span> generator placed outside the tunnel ceiling boundary <span class="hlt">layer</span> produces an incident <span class="hlt">shock</span> on the floor of the tunnel of sufficient strength to induce separation. An array of pulsed plasma jets are placed approximately 2 boundary <span class="hlt">layer</span> thicknesses upstream of the interaction and pulsed at between 1 kHz and 4 kHz. PIV is used to investigate the effect of the jets on the nature of the separation as well as the boundary <span class="hlt">layer</span> distortion and pressure recovery downstream of the interaction. Funded through AFRL in collaboration with Creare, Inc.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_5 --> <div id="page_6" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="101"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19960009427','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19960009427"><span id="translatedtitle">Control and reduction of unsteady pressure loads in separated <span class="hlt">shock</span> wave turbulent boundary <span class="hlt">layer</span> interaction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dolling, David S.; Barter, John W.</p> <p>1995-01-01</p> <p>The focus was on developing means of controlling and reducing unsteady pressure loads in separated <span class="hlt">shock</span> wave turbulent boundary <span class="hlt">layer</span> interactions. Section 1 describes how vortex generators can be used to effectively reduce loads in compression ramp interaction, while Section 2 focuses on the effects of 'boundary-<span class="hlt">layer</span> separators' on the same interaction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19740030715&hterms=structure+atom&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dstructure%2Batom','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19740030715&hterms=structure+atom&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dstructure%2Batom"><span id="translatedtitle">Interrelated structures of the transport <span class="hlt">shock</span> and collisional relaxation <span class="hlt">layer</span> in a multitemperature, multilevel ionized gas</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Vinolo, A. R.; Clarke, J. H.</p> <p>1973-01-01</p> <p>The gas dynamic structures of the transport <span class="hlt">shock</span> and the downstream collisional relaxation <span class="hlt">layer</span> are evaluated for partially ionized monatomic gases. Elastic and inelastic collisional nonequilibrium effects are taken into consideration. In the microscopic model of the atom, three electronic levels are accounted for. By using an asymptotic technique, the <span class="hlt">shock</span> morphology is found on a continuum flow basis. This procedure gives two distinct <span class="hlt">layers</span> in which the nonequilibrium effects to be considered are different. A transport <span class="hlt">shock</span> appears as the inner solution to an outer collisional relaxation <span class="hlt">layer</span>. The results show four main interesting points: (1) on structuring the transport <span class="hlt">shock</span>, ionization and excitation rates must be included in the formulation, since the flow is not frozen with respect to the population of the different electronic levels; (2) an electron temperature precursor appears at the beginning of the transport <span class="hlt">shock</span>; (3) the collisional <span class="hlt">layer</span> is rationally reduced to quadrature for special initial conditions, which (4) are obtained from new Rankine-Hugoniot relations for the inner <span class="hlt">shock</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhFl...27l6103A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhFl...27l6103A"><span id="translatedtitle">Mechanism of <span class="hlt">shock</span> unsteadiness in separated <span class="hlt">shock/boundary-layer</span> interactions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Agostini, L.; Larchevêque, L.; Dupont, P.</p> <p>2015-12-01</p> <p>A large-eddy simulation-based study is presented and focuses on different unsteadiness-source features in a Mach 2.3 <span class="hlt">shock</span> reflection with separation. The sources of unsteadiness are localized and the path taken by disturbance as it spreads out to the whole field is defined. It is shown that the phenomena arising inside the recirculation bubble govern the whole interaction, at both low and intermediate frequencies. Indeed, the <span class="hlt">shock</span> motion appears to mirror phenomena found in the separated zone. Moreover, features of separated-flow unsteadiness bear some resemblance to those occurring in incompressible flows. An equivalent inviscid scheme of the unsteady interaction is established in order to describe the whole <span class="hlt">shock</span>-system unsteadiness at low and intermediate frequencies and the downstream unsteady-pressure field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920022918','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920022918"><span id="translatedtitle">Experimental studies of hypersonic <span class="hlt">shock</span>-wave boundary-<span class="hlt">layer</span> interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lu, Frank K.</p> <p>1992-01-01</p> <p>Two classes of <span class="hlt">shock</span>-wave boundary-<span class="hlt">layer</span> interactions were studied experimentally in a <span class="hlt">shock</span> tunnel in which a low Reynolds number, turbulent flow at Mach 8 was developed on a cold, flat test surface. The two classes of interactions were: (1) a swept interaction generated by a wedge ('fin') mounted perpendicularly on the flat plate; and (2) a two-dimensional, unseparated interaction induced by a <span class="hlt">shock</span> impinging near an expansion corner. The swept interaction, with wedge angles of 5-20 degrees, was separated and there was also indication that the strongest interactions prossessed secondary separation zones. The interaction spread out extensively from the inviscid <span class="hlt">shock</span> location although no indication of quasi-conical symmetry was evident. The surface pressure from the upstream influence to the inviscid <span class="hlt">shock</span> was relatively low compared to the inviscid downstream value but it rose rapidly past the inviscid <span class="hlt">shock</span> location. However, the surface pressure did not reach the downstream inviscid value and reasons were proposed for this anomalous behavior compared to strongly separated, supersonic interactions. The second class of interactions involved weak <span class="hlt">shocks</span> impinging near small expansion corners. As a prelude to studying this interaction, a hypersonic similarity parameter was identified for the pure, expansion corner flow. The expansion corner severely damped out surface pressure fluctuations. When a <span class="hlt">shock</span> impinged upstream of the corner, no significant changes to the surface pressure were found as compared to the case when the <span class="hlt">shock</span> impinged on a flat plate. But, when the <span class="hlt">shock</span> impinged downstream of the corner, a close coupling existed between the two wave systems, unlike the supersonic case. This close coupling modified the upstream influence. Regardless of whether the <span class="hlt">shock</span> impinged ahead or behind the corner, the downstream region was affected by the close coupling between the <span class="hlt">shock</span> and the expansion. Not only was the mean pressure distribution modified but the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ExFl...56..113G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ExFl...56..113G"><span id="translatedtitle">High-resolution PIV measurements of a transitional <span class="hlt">shock</span> wave-boundary <span class="hlt">layer</span> interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Giepman, R. H. M.; Schrijer, F. F. J.; van Oudheusden, B. W.</p> <p>2015-06-01</p> <p>This study investigates the effects of boundary <span class="hlt">layer</span> transition on an oblique <span class="hlt">shock</span> wave reflection. The Mach number was 1.7, the unit Reynolds number was 35 × 106 m-1, and the pressure ratio over the interaction was 1.35. Particle image velocimetry is used as the main flow diagnostics tool, supported by oil-flow and Schlieren visualizations. At these conditions, the thickness of the laminar boundary <span class="hlt">layer</span> is only 0.2 mm, and seeding proved to be problematic as practically no seeding was recorded in the lower 40 % of the boundary <span class="hlt">layer</span>. The top 60 % could, however, still be resolved with good accuracy and is found to be in good agreement with the compressible Blasius solution. Due to the effects of turbulent mixing, the near-wall seeding deficiency disappears when the boundary <span class="hlt">layer</span> transitions to a turbulent state. This allowed the seeding distribution to be used as an indicator for the state of the boundary <span class="hlt">layer</span>, permitting to obtain an approximate intermittency distribution for the boundary <span class="hlt">layer</span> transition region. This knowledge was then used for positioning the oblique <span class="hlt">shock</span> wave in the laminar, transitional (50 % intermittency) or turbulent region of the boundary <span class="hlt">layer</span>. Separation is only recorded for the laminar and transitional interactions. For the laminar interaction, a large separation bubble is found, with a streamwise length of 96. The incoming boundary <span class="hlt">layer</span> is lifted over the separation bubble and remains in a laminar state up to the impingement point of the <span class="hlt">shock</span> wave. After the <span class="hlt">shock</span>, transition starts and a turbulent profile is reached approximately 80-90 downstream of the <span class="hlt">shock</span>. Under the same <span class="hlt">shock</span> conditions, the transitional interaction displays a smaller separation bubble (43), and transition is found to be accelerated over the separation bubble.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130008991','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130008991"><span id="translatedtitle">Validation of <span class="hlt">Shock</span> <span class="hlt">Layer</span> Radiation: Perspectives for Test Cases</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Brandis, Aaron</p> <p>2012-01-01</p> <p>This paper presents a review of the analysis and measurement of radiation data obtained in the NASA Ames Research Center's Electric Arc <span class="hlt">Shock</span> Tube (EAST) facility. The goal of these experiments was to measure the level of radiation encountered during atmospheric entry. The data obtained from these experiments is highlighted by providing the first spectrally and spatially resolved data for high speed Earth entry and measurements of the CO 4th positive band for conditions relevant to Mars entry. Comparisons of the EAST data with experimental results obtained from <span class="hlt">shock</span> tunnels at JAXA and the University of Queensland are presented. Furthermore, the paper will detail initial analyses in to the influence and characterization of the measure non-equilibrium radiation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080026342','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080026342"><span id="translatedtitle">Validation of High-Speed Turbulent Boundary <span class="hlt">Layer</span> and <span class="hlt">Shock</span>-Boundary <span class="hlt">Layer</span> Interaction Computations with the OVERFLOW Code</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Oliver, A. B.; Lillard, R. P.; Blaisdell, G. A.; Lyrintizis, A. S.</p> <p>2006-01-01</p> <p>The capability of the OVERFLOW code to accurately compute high-speed turbulent boundary <span class="hlt">layers</span> and turbulent <span class="hlt">shock</span>-boundary <span class="hlt">layer</span> interactions is being evaluated. Configurations being investigated include a Mach 2.87 flat plate to compare experimental velocity profiles and boundary <span class="hlt">layer</span> growth, a Mach 6 flat plate to compare experimental surface heat transfer,a direct numerical simulation (DNS) at Mach 2.25 for turbulent quantities, and several Mach 3 compression ramps to compare computations of <span class="hlt">shock</span>-boundary <span class="hlt">layer</span> interactions to experimental laser doppler velocimetry (LDV) data and hot-wire data. The present paper describes outlines the study and presents preliminary results for two of the flat plate cases and two small-angle compression corner test cases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850018354','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850018354"><span id="translatedtitle">Investigation to optimize the passive <span class="hlt">shock</span> wave/boundary <span class="hlt">layer</span> control for supercritical airfoil drag reduction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nagamatsu, H. T.; Dyer, R.</p> <p>1984-01-01</p> <p>The passive <span class="hlt">shock</span> wave/boundary <span class="hlt">layer</span> control for reducing the drag of 14%-thick supercritical airfoil was investigated in the 3 in. x 15.4 in. RPI Transonic Wind Tunnel with and without the top wall insert at transonic Mach numbers. Top wall insert was installed to increase the flow Mach number to 0.90 with the model mounted on the test section bottom wall. Various porous surfaces with a cavity underneath were positioned on the area of the airfoil where the <span class="hlt">shock</span> wave occurs. The higher pressure behind the <span class="hlt">shock</span> wave circulates flow through the cavity to the lower pressure ahead of the <span class="hlt">shock</span> wave. The effects from this circulation prevent boundary <span class="hlt">layer</span> separation and enthropy increase hrough the <span class="hlt">shock</span> wave. The static pressure distributions over the airfoil, the wake impact pressure survey for determining the profile drag and the Schlieren photographs for porous surfaces are presented and compared with the results for solid surface airfoil. With a 2.8% uniform porosity the normal <span class="hlt">shock</span> wave for the solid surface was changed to a lambda <span class="hlt">shock</span> wave, and the wake impact pressure data indicate a drag coefficient reduction as much as 45% lower than for the solid surface airfoil at high transonic Mach numbers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhFl...27i1704T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhFl...27i1704T"><span id="translatedtitle">Frequency modulation in <span class="hlt">shock</span> wave-boundary <span class="hlt">layer</span> interaction by repetitive-pulse laser energy deposition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tamba, T.; Pham, H. S.; Shoda, T.; Iwakawa, A.; Sasoh, A.</p> <p>2015-09-01</p> <p>Modulation of <span class="hlt">shock</span> foot oscillation due to energy deposition by repetitive laser pulses in <span class="hlt">shock</span> wave-boundary <span class="hlt">layer</span> interaction over an axisymmetric nose-cylinder-flare model in Mach 1.92 flow was experimentally studied. From a series of 256 schlieren images, density oscillation spectra at each pixel were obtained. When laser pulses of approximately 7 mJ were deposited with a repetition frequency, fe, of 30 kHz or lower, the flare <span class="hlt">shock</span> oscillation had a peak spectrum equivalent to the value of fe. However, with fe of 40 kHz-60 kHz, it experienced frequency modulation down to lower than 20 kHz.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19880063939&hterms=wave+length&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dwave%2Blength','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19880063939&hterms=wave+length&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dwave%2Blength"><span id="translatedtitle">On the inception lengths of swept <span class="hlt">shock</span>-wave/turbulent boundary-<span class="hlt">layer</span> interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Settles, G. S.</p> <p>1986-01-01</p> <p>Experimental data are shown for the inception lengths of swept compression corner-generated and fin-generated <span class="hlt">shock</span>/boundary <span class="hlt">layer</span> interactions at Mach 2.95. These results are found to correlate on the basis of three different flow regimes. The inception lengths of these flows are dominated by a singularity at the cylindrical/conical boundary for swept corners and by an elongation due to <span class="hlt">shock</span> wave sweepback for fin interactions. Similarity rules for both Re(delta)and <span class="hlt">shock</span> generator geometry effects on inception lengths are demonstrated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015shw2.conf.1199E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015shw2.conf.1199E"><span id="translatedtitle">Experimental Investigation of Axisymmetric Transitional <span class="hlt">Shock</span> Wave Boundary <span class="hlt">Layer</span> Interactions at Mach 5</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Erdem, E.; Kontis, K.; Johnstone, E.; Murray, N.; Steelant, J.</p> <p></p> <p><span class="hlt">Shock</span> Wave Boundary <span class="hlt">Layer</span> Interactions (SWBLIs) can induce separation which causes loss of a control surface effectiveness, drop of an air intake efficiency and it may be the origin of large scale fluctuations such as air-intake buzz, buffeting or fluctuating side loads in separated propulsive nozzles. The subsequent reattachment of the separated shear <span class="hlt">layer</span> on a nearby surface gives rise to local heat transfer rates which can be far in excess of those of an attached boundary <span class="hlt">layer</span> [1].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720025616','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720025616"><span id="translatedtitle">Interrelated structures of the transport <span class="hlt">shock</span> and collisional relaxation <span class="hlt">layer</span> in a multitemperature, multilevel ionized gas</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Vinolo, A. R.; Clarke, J. H.</p> <p>1972-01-01</p> <p>The gas dynamic structures of the transport <span class="hlt">shock</span> and the downstream collisional relaxation <span class="hlt">layer</span> are evaluated for partially ionized monatomic gases. Elastic and inelastic collisional nonequilibrium effects are taken into consideration. Three electronic levels are accounted for in the microscopic model of the atom. Nonequilibrium processes with respect to population of levels and species plus temperature are considered. By using an asymptotic technique the <span class="hlt">shock</span> morphology is found on a continuum flow basis. The asymptotic procedure gives two distinct <span class="hlt">layers</span> in which the nonequilibrium effects to be considered are different. A transport <span class="hlt">shock</span> appears as the inner solution to an outer collisional relaxation <span class="hlt">layer</span> in which the gas reaches local equilibrium. A family of numerical examples is displayed for different flow regimes. Argon and helium models are used in these examples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980151085','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980151085"><span id="translatedtitle">An Approximate Axisymmetric Viscous <span class="hlt">Shock</span> <span class="hlt">Layer</span> Aeroheating Method for Three-Dimensional Bodies</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Brykina, Irina G.; Scott, Carl D.</p> <p>1998-01-01</p> <p>A technique is implemented for computing hypersonic aeroheating, shear stress, and other flow properties on the windward side of a three-dimensional (3D) blunt body. The technique uses a 2D/axisymmetric flow solver modified by scale factors for a, corresponding equivalent axisymmetric body. Examples are given in which a 2D solver is used to calculate the flow at selected meridional planes on elliptic paraboloids in reentry flight. The report describes the equations and the codes used to convert the body surface parameters into input used to scale the 2D viscous <span class="hlt">shock</span> <span class="hlt">layer</span> equations in the axisymmetric viscous <span class="hlt">shock</span> <span class="hlt">layer</span> code. Very good agreement is obtained with solutions to finite rate chemistry 3D thin viscous <span class="hlt">shock</span> <span class="hlt">layer</span> equations for a finite rate catalytic body.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120004157','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120004157"><span id="translatedtitle">Experimental Investigation of Normal <span class="hlt">Shock</span> Boundary-<span class="hlt">Layer</span> Interaction with Hybrid Flow Control</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Vyas, Manan A.; Hirt, Stefanie M.; Anderson, Bernhard H.</p> <p>2012-01-01</p> <p>Hybrid flow control, a combination of micro-ramps and micro-jets, was experimentally investigated in the 15x15 cm Supersonic Wind Tunnel (SWT) at the NASA Glenn Research Center. Full factorial, a design of experiments (DOE) method, was used to develop a test matrix with variables such as inter-ramp spacing, ramp height and chord length, and micro-jet injection flow ratio. A total of 17 configurations were tested with various parameters to meet the DOE criteria. In addition to boundary-<span class="hlt">layer</span> measurements, oil flow visualization was used to qualitatively understand <span class="hlt">shock</span> induced flow separation characteristics. The flow visualization showed the normal <span class="hlt">shock</span> location, size of the separation, path of the downstream moving counter-rotating vortices, and corner flow effects. The results show that hybrid flow control demonstrates promise in reducing the size of <span class="hlt">shock</span> boundary-<span class="hlt">layer</span> interactions and resulting flow separation by means of energizing the boundary <span class="hlt">layer</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910058794&hterms=expression+body&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dexpression%2Bbody','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910058794&hterms=expression+body&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dexpression%2Bbody"><span id="translatedtitle">An approximate viscous <span class="hlt">shock</span> <span class="hlt">layer</span> approach to calculating hypersonic flows about blunt-nosed bodies</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cheatwood, F. MCN.; Dejarnette, F. R.</p> <p>1991-01-01</p> <p>An approximate axisymmetric method has been developed which can reliably calculate fully viscous hypersonic flows over blunt-nosed bodies. By substituting Maslen's second order pressure expression for the normal momentum equation, a simplified form of the viscous <span class="hlt">shock</span> <span class="hlt">layer</span> (VSL) equations is obtained. This approach can solve both the subsonic and supersonic regions of the <span class="hlt">shock</span> <span class="hlt">layer</span> without a starting solution for the <span class="hlt">shock</span> shape. Since the method is fully viscous, the problems associated with coupling a boundary-<span class="hlt">layer</span> solution with an inviscid-<span class="hlt">layer</span> solution are avoided. This procedure is significantly faster than the parabolized Navier-Stokes (PNS) or VSL solvers and would be useful in a preliminary design environment. Problems associated with a previously developed approximate VSL technique are addressed. Surface heat transfer and pressure predictions are comparable to both VSL results and experimental data. The present technique generates its own <span class="hlt">shock</span> shape as part of its solution, and therefore could be used to provide more accurate initial <span class="hlt">shock</span> shapes for higher-order procedures which require starting solutions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930051623&hterms=split+wave&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsplit%2Bwave','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930051623&hterms=split+wave&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsplit%2Bwave"><span id="translatedtitle">Numerical study of <span class="hlt">shock-wave/boundary-layer</span> interactions with bleed</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hahn, T. O.; Shih, T. I.-P.; Chyu, W. J.</p> <p>1993-01-01</p> <p>A numerical study was conducted to investigate how bleed through a two-dimensional slot affects <span class="hlt">shock</span>-wave induced, boundary-<span class="hlt">layer</span> separation on a flat plate. This study is based on the ensemble-averaged, compressible, Navier-Stokes equations closed by the Baldwin-Lomax, algebraic turbulence model. The algorithm used to obtain solutions was the implicit, partially split, two-factored scheme of Steger. This study examined the effects of the following parameters in controlling <span class="hlt">shock</span>-wave induced flow separation: location of slot in relation to where the incident <span class="hlt">shock</span> wave impinged on the boundary <span class="hlt">layer</span>, size of slot in relation to the boundary-<span class="hlt">layer</span> thickness, number of slots, spacings between slots, and strength of the incident <span class="hlt">shock</span> wave. This study also showed the nature of the very complex flowfield about the slot or slots and how the plenum affects the bleed process. The results of this study are relevant to problems where bleed is used to control <span class="hlt">shock</span>-wave induced, boundary-<span class="hlt">layer</span> separation (e.g., inside jet engine inlets and wind tunnels).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910057679&hterms=skin+layers&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dskin%2Blayers','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910057679&hterms=skin+layers&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dskin%2Blayers"><span id="translatedtitle">Laser interferometer/Preston tube skin-friction comparison in <span class="hlt">shock/boundary-layer</span> interaction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kim, K.-S.; Lee, Y.; Settles, G. S.</p> <p>1991-01-01</p> <p>An evaluation is conducted of the accuracy of the 'Preston tube' surface pitot-pressure skin friction measurement method relative to the already proven laser interferometer skin-friction meter in a swept <span class="hlt">shock</span> wave/turbulent boundary-<span class="hlt">layer</span> interaction. The Preston tube was used to estimate the total shear-stress distribution in a fin-generated swept <span class="hlt">shock</span>-wave/turbulent boundary-<span class="hlt">layer</span> interaction. The Keener-Hopkins calibration method using the isentropic relation to calculate the Preston-tube Mach number produces the best results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950016044','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950016044"><span id="translatedtitle">Numerical study of boundary <span class="hlt">layer</span> interaction with <span class="hlt">shocks</span>: Method and code validation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Adams, Nikolaus A.</p> <p>1994-01-01</p> <p>A major problem in modeling of turbulent supersonic flows is the correct assessment of viscous-inviscid interaction problems. Of particular interest is the interaction of boundary <span class="hlt">layers</span> with <span class="hlt">shocks</span>. Present turbulence models give in most cases unsatisfactory results in the region of rapid distortion and in the separation region (if one is present) in particular with regard to mean flow profiles and turbulence quantities. The objective of the present work is the direct numerical simulation of <span class="hlt">shock</span> boundary <span class="hlt">layer</span> interaction. This report summarizes the first phase during which a numerical method suitable for this problem has been developed and a computer code has been written and tested.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19960000871','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19960000871"><span id="translatedtitle">An investigation of bleed configurations and their effect on <span class="hlt">shock</span> wave/boundary <span class="hlt">layer</span> interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hamed, Awatef</p> <p>1995-01-01</p> <p>The design of high efficiency supersonic inlets is a complex task involving the optimization of a number of performance parameters such as pressure recovery, spillage, drag, and exit distortion profile, over the flight Mach number range. Computational techniques must be capable of accurately simulating the physics of <span class="hlt">shock</span>/boundary <span class="hlt">layer</span> interactions, secondary corner flows, flow separation, and bleed if they are to be useful in the design. In particular, bleed and flow separation, play an important role in inlet unstart, and the associated pressure oscillations. Numerical simulations were conducted to investigate some of the basic physical phenomena associated with bleed in oblique <span class="hlt">shock</span> wave boundary <span class="hlt">layer</span> interactions that affect the inlet performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/101957','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/101957"><span id="translatedtitle">Heat release effects on the instability of <span class="hlt">parallel</span> shear <span class="hlt">layers</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hegde, U.</p> <p>1994-01-01</p> <p>The influence of time-dependent heat addition on the linear instablity of shear <span class="hlt">layers</span> is of considerable interest in understanding the dynamic behavior of reacting flows and combustion-turbulence interactions. The approach is based upon the Bernoulli enthalpy aeroacoustics theory, which utilizes the specific enthalpy and specific entropy as the primary thermodynamic variables. In addition, velocity oscillations are split into Helmoholtz decomposition theorem.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_6 --> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22252076','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22252076"><span id="translatedtitle"><span class="hlt">Shock</span> timing measurements and analysis in deuterium-tritium-ice <span class="hlt">layered</span> capsule implosions on NIF</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Robey, H. F.; Celliers, P. M.; Moody, J. D.; Sater, J.; Parham, T.; Kozioziemski, B.; Dylla-Spears, R.; Ross, J. S.; LePape, S.; Ralph, J. E.; Dewald, E. L.; Berzak Hopkins, L.; Kroll, J. J.; Yoxall, B. E.; Hamza, A. V.; Landen, O. L.; Edwards, M. J.; Hohenberger, M.; Boehly, T. R.; Nikroo, A.</p> <p>2014-02-15</p> <p>Recent advances in <span class="hlt">shock</span> timing experiments and analysis techniques now enable <span class="hlt">shock</span> measurements to be performed in cryogenic deuterium-tritium (DT) ice <span class="hlt">layered</span> capsule implosions on the National Ignition Facility (NIF). Previous measurements of <span class="hlt">shock</span> timing in inertial confinement fusion implosions [Boehly et al., Phys. Rev. Lett. 106, 195005 (2011); Robey et al., Phys. Rev. Lett. 108, 215004 (2012)] were performed in surrogate targets, where the solid DT ice shell and central DT gas were replaced with a continuous liquid deuterium (D2) fill. These previous experiments pose two surrogacy issues: a material surrogacy due to the difference of species (D2 vs. DT) and densities of the materials used and a geometric surrogacy due to presence of an additional interface (ice/gas) previously absent in the liquid-filled targets. This report presents experimental data and a new analysis method for validating the assumptions underlying this surrogate technique. Comparison of the data with simulation shows good agreement for the timing of the first three <span class="hlt">shocks</span>, but reveals a considerable discrepancy in the timing of the 4th <span class="hlt">shock</span> in DT ice <span class="hlt">layered</span> implosions. Electron preheat is examined as a potential cause of the observed discrepancy in the 4th <span class="hlt">shock</span> timing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhPl...21b2703R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhPl...21b2703R"><span id="translatedtitle"><span class="hlt">Shock</span> timing measurements and analysis in deuterium-tritium-ice <span class="hlt">layered</span> capsule implosions on NIF</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Robey, H. F.; Celliers, P. M.; Moody, J. D.; Sater, J.; Parham, T.; Kozioziemski, B.; Dylla-Spears, R.; Ross, J. S.; LePape, S.; Ralph, J. E.; Hohenberger, M.; Dewald, E. L.; Berzak Hopkins, L.; Kroll, J. J.; Yoxall, B. E.; Hamza, A. V.; Boehly, T. R.; Nikroo, A.; Landen, O. L.; Edwards, M. J.</p> <p>2014-02-01</p> <p>Recent advances in <span class="hlt">shock</span> timing experiments and analysis techniques now enable <span class="hlt">shock</span> measurements to be performed in cryogenic deuterium-tritium (DT) ice <span class="hlt">layered</span> capsule implosions on the National Ignition Facility (NIF). Previous measurements of <span class="hlt">shock</span> timing in inertial confinement fusion implosions [Boehly et al., Phys. Rev. Lett. 106, 195005 (2011); Robey et al., Phys. Rev. Lett. 108, 215004 (2012)] were performed in surrogate targets, where the solid DT ice shell and central DT gas were replaced with a continuous liquid deuterium (D2) fill. These previous experiments pose two surrogacy issues: a material surrogacy due to the difference of species (D2 vs. DT) and densities of the materials used and a geometric surrogacy due to presence of an additional interface (ice/gas) previously absent in the liquid-filled targets. This report presents experimental data and a new analysis method for validating the assumptions underlying this surrogate technique. Comparison of the data with simulation shows good agreement for the timing of the first three <span class="hlt">shocks</span>, but reveals a considerable discrepancy in the timing of the 4th <span class="hlt">shock</span> in DT ice <span class="hlt">layered</span> implosions. Electron preheat is examined as a potential cause of the observed discrepancy in the 4th <span class="hlt">shock</span> timing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19890054707&hterms=wave+length&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dwave%2Blength','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19890054707&hterms=wave+length&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dwave%2Blength"><span id="translatedtitle">Inception length to a fully-developed fin-generated <span class="hlt">shock</span> wave boundary-<span class="hlt">layer</span> interaction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lu, Frank K.; Settles, Gary S.</p> <p>1989-01-01</p> <p>An experimental study of fin-generated <span class="hlt">shock</span> wave turbulent boundary-<span class="hlt">layer</span> interactions confirmed previous observations that, sufficiently far from the fin apex, such interactions become conical. The inception length to conical symmetry was found to increase weakly with Mach number for Mach numbers from 2.5 to 4 and fin angles from 4 to 22 deg. For the range of interactions examined, the inception length was found to depend primarily upon the inviscid <span class="hlt">shock</span> angle, this angle ranging from 21 to 40 deg. The behavior of the inception length with <span class="hlt">shock</span> angle can be broadly divided into two categories. For 'weak' interactions with <span class="hlt">shock</span> angles less than about 35 deg, the inception length decreased as the <span class="hlt">shock</span> angle increased. For 'strong' interactions with <span class="hlt">shock</span> angles greater than about 35 deg, the inception region was small and was approximately constant at three boundary-<span class="hlt">layer</span> thicknesses in length. In the latter, strong interaction case, the inception length was an order of magnitude smaller than that found in the weakest interactions examined, to the extent that strong interactions were practically fully-developed from the apex.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DFDG40003S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DFDG40003S"><span id="translatedtitle">Diffusion-flame ignition by <span class="hlt">shock</span>-wave impingement on a supersonic mixing <span class="hlt">layer</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sanchez, Antonio L.; Huete, Cesar; Williams, Forman A.; Urzay, Javier</p> <p>2015-11-01</p> <p>Ignition in a supersonic mixing <span class="hlt">layer</span> interacting with an oblique <span class="hlt">shock</span> wave is investigated analytically and numerically under conditions such that the post-<span class="hlt">shock</span> flow remains supersonic. The study requires consideration of the structure of the post-<span class="hlt">shock</span> ignition kernel that is found to exist around the point of maximum temperature, which may be located either near the edge of the mixing <span class="hlt">layer</span> or in its interior. The ignition kernel displays a balance between the rates of chemical reaction and of post-<span class="hlt">shock</span> flow expansion, including the acoustic interactions of the chemical heat release with the <span class="hlt">shock</span> wave, leading to increased front curvature. The analysis, which adopts a one-step chemistry model with large activation energy, indicates that ignition develops as a fold bifurcation, the turning point in the diagram of the peak perturbation induced by the chemical reaction as a function of the Damköhler number providing the critical conditions for ignition. Subsequent to ignition the lead <span class="hlt">shock</span> will rapidly be transformed into a thin detonation on the fuel side of the ignition kernel, and, under suitable conditions, a deflagration may extend far downstream, along with the diffusion flame that must separate the rich and lean reaction products.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/878827','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/878827"><span id="translatedtitle">Steady-State Electrostatic <span class="hlt">Layers</span> From Weibel Instability in Relativistic Collisionless <span class="hlt">Shocks</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Milosavljevic, Milos; Nakar, Ehud; Spitkovsky, Anatoly; /KIPAC, Menlo Park</p> <p>2005-08-04</p> <p>It is generally accepted that magnetic fields generated in the nonlinear development of the transverse Weibel instability provide effective collisionality in unmagnetized collisionless <span class="hlt">shocks</span>. Recently, extensive two and three dimensional simulations improved our understanding of the growth and saturation of the instability in colliding plasma shells. However, the steady-state structure of the <span class="hlt">shock</span> wave transition <span class="hlt">layers</span> remains poorly understood. We use basic physical considerations and order-of-magnitude arguments to study the steady state structure in relativistic unmagnetized collisionless <span class="hlt">shocks</span> in pair plasmas. The <span class="hlt">shock</span> contains an electrostatic <span class="hlt">layer</span> resulting from the formation of stationary, magnetically-focused current filaments. The filaments form where the cold upstream plasma and the counterstreaming thermal plasma interpenetrate. The filaments are not entirely neutral and strong electrostatic fields are present. Most of the downstream particles cannot cross this <span class="hlt">layer</span> into the upstream because they are trapped by the electrostatic field. We identify the critical location in the <span class="hlt">shock</span> transition <span class="hlt">layer</span> where the electromagnetic field ceases to be static. At this location, the degree of charge separation in the filaments reaches a maximum value, the current inside the filaments comes close to the Alfven limit, and the phase space distribution function starts to isotropize. We argue that the radius of the current filaments upstream of the critical location is about twice the upstream plasma skin depth. Finally, we show that some downstream particles cross the electrostatic <span class="hlt">layer</span> and run ahead of the <span class="hlt">shock</span> into the preshock medium without causing instability. These particles may play an important role in particle acceleration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015M%26PS...50..483H&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015M%26PS...50..483H&link_type=ABSTRACT"><span id="translatedtitle">A search for <span class="hlt">shocked</span> quartz grains in the Allerød-Younger Dryas boundary <span class="hlt">layer</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hoesel, Annelies; Hoek, Wim Z.; Pennock, Gillian M.; Kaiser, Knut; Plümper, Oliver; Jankowski, Michal; Hamers, Maartje F.; Schlaak, Norbert; Küster, Mathias; Andronikov, Alexander V.; Drury, Martyn R.</p> <p>2015-03-01</p> <p>The Younger Dryas impact hypothesis suggests that multiple airbursts or extraterrestrial impacts occurring at the end of the Allerød interstadial resulted in the Younger Dryas cold period. So far, no reproducible, diagnostic evidence has, however, been reported. Quartz grains containing planar deformation features (known as <span class="hlt">shocked</span> quartz grains), are considered a reliable indicator for the occurrence of an extraterrestrial impact when found in a geological setting. Although alleged <span class="hlt">shocked</span> quartz grains have been reported at a possible Allerød-Younger Dryas boundary <span class="hlt">layer</span> in Venezuela, the identification of <span class="hlt">shocked</span> quartz in this <span class="hlt">layer</span> is ambiguous. To test whether <span class="hlt">shocked</span> quartz is indeed present in the proposed impact <span class="hlt">layer</span>, we investigated the quartz fraction of multiple Allerød-Younger Dryas boundary <span class="hlt">layers</span> from Europe and North America, where proposed impact markers have been reported. Grains were analyzed using a combination of light and electron microscopy techniques. All samples contained a variable amount of quartz grains with (sub)planar microstructures, often tectonic deformation lamellae. A total of one quartz grain containing planar deformation features was found in our samples. This <span class="hlt">shocked</span> quartz grain comes from the Usselo palaeosol at Geldrop Aalsterhut, the Netherlands. Scanning electron microscopy cathodoluminescence imaging and transmission electron microscopy imaging, however, show that the planar deformation features in this grain are healed and thus likely to be older than the Allerød-Younger Dryas boundary. We suggest that this grain was possibly eroded from an older crater or distal ejecta <span class="hlt">layer</span> and later redeposited in the European sandbelt. The single <span class="hlt">shocked</span> quartz grain at this moment thus cannot be used to support the Younger Dryas impact hypothesis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1996ShWav...6....1J&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1996ShWav...6....1J&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Shock</span> induced Richtmyer-Meshkov instability in the presence of a wall boundary <span class="hlt">layer</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jourdan, G.; Billiotte, M.; Houas, L.</p> <p>1996-06-01</p> <p>An experimental investigation on gaseous mixing zones originated from the Richtmyer-Meshkov instability has been undertaken in a square cross section <span class="hlt">shock</span> tube. Mass concentration fields, of one of the two mixing constituents, have been determined within the mixing zone when the <span class="hlt">shock</span> wave passes from the heavy gas to the light one, from one gas to an other of close density, and from the light gas to the heavy one. Results have been obtained before and after the coming back of the reflected <span class="hlt">shock</span> wave. The diagnostic method is based on the infrared absorption of one of the two constituents of the mixing zone. It is shown that the mixing zone is strongly deformed by the wall boundary <span class="hlt">layer</span>. The consequence is the presence of strong gradients of concentration in the direction perpendicular to the <span class="hlt">shock</span> wave propagation. Finally, it is pointed out that the mixing goes more homogeneous when the Atwood number tends to zero.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PrAeS..74...16P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PrAeS..74...16P"><span id="translatedtitle">Micro-vortex generators for <span class="hlt">shock</span> wave/boundary <span class="hlt">layer</span> interactions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Panaras, Argyris G.; Lu, Frank K.</p> <p>2015-04-01</p> <p>The effect of micro-vortex generators (MVGs) on <span class="hlt">shock</span> wave/boundary <span class="hlt">layer</span> interactions (SBLIs) has been reviewed. Experimental and computational evidence has been presented about the dominant role it has in the suppression of <span class="hlt">shock</span>-induced separation the pair of counter-rotating streamwise vortices, which appears downstream of the types of micro-vortex generators used in SBLIs; these streamwise vortices entrain high momentum fluid, increasing the boundary <span class="hlt">layer</span> velocity near the wall. The structure of the wake is examined in detail, with emphasis on the strength and decay of the streamwise vortices and on the ring-type or hairpin vortices which have been detected in the instantaneous flow around the wake. Evaluation of the ability of various types of MVGs to suppress <span class="hlt">shock</span>-induced separation is done. Topics which need to be further studied, like the structure of the flow around devices of small size and the effect of the Reynolds number, are suggested.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003PrAeS..39..121K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003PrAeS..39..121K"><span id="translatedtitle">Advances in CFD prediction of <span class="hlt">shock</span> wave turbulent boundary <span class="hlt">layer</span> interactions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Knight, Doyle; Yan, Hong; Panaras, Argyris G.; Zheltovodov, Alexander</p> <p>2003-04-01</p> <p>The paper presents a summary of recent computational fluid dynamics (CFD) simulations of <span class="hlt">shock</span> wave turbulent boundary <span class="hlt">layer</span> interactions. This survey was prepared as part of the activity of NATO RTO Working Group 10 which was established in December 1998, and considers results obtained subsequent to the previous survey paper on the same topic by Knight and Degrez (“<span class="hlt">Shock</span> Wave Boundary <span class="hlt">Layer</span> Interactions in High Mach Number Flows-A Critical Survey of Current CFD Prediction Capabilities”, AGARD Advisory Report AR-319, Volume II, December 1998). Five configurations are considered: 2-D compression corner, 2-D <span class="hlt">shock</span> impingement, 2-D expansion-compression corner, 3-D single fin and 3-D double fin. Recent direct numerical simulations (DNS), large eddy simulations (LES) and Reynolds-averaged Navier-Stokes (RANS) simulations are compared with experiment. The capabilities and limitations are described, and future research needs identified.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015shw2.conf.1411E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015shw2.conf.1411E"><span id="translatedtitle">Laser Energy Deposition for <span class="hlt">Shock</span> Wave Boundary <span class="hlt">Layer</span> Control at Supersonic Speeds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Erdem, E.; Kontis, K.; Osuka, T.; Majima, R.; Tamba, T.; Sasoh, Akihiro</p> <p></p> <p><span class="hlt">Shock</span> Wave Boundary <span class="hlt">Layer</span> Interactions (SWBLIs) can induce separation which causes loss of a control surface effectiveness, drop of an air intake efficiency and it may be the origin of large scale fluctuations such as air-intake buzz, buffeting or fluctuating side loads in separated propulsive nozzles</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19740027814&hterms=1575&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D%2526%25231575','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19740027814&hterms=1575&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D%2526%25231575"><span id="translatedtitle">Three-dimensional separation for interaction of <span class="hlt">shock</span> waves with turbulent boundary <span class="hlt">layers</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Goldberg, T. J.</p> <p>1973-01-01</p> <p>For the interaction of <span class="hlt">shock</span> waves with turbulent boundary <span class="hlt">layers</span>, obtained experimental three-dimensional separation results and correlations with earlier two-dimensional and three-dimensional data are presented. It is shown that separation occurs much earlier for turbulent three-dimensional than for two-dimensional flow at hypersonic speeds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.2764H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.2764H"><span id="translatedtitle">Evidence of downstream high speed jets by a non-stationary and rippled front of quasi-<span class="hlt">parallel</span> <span class="hlt">shock</span>: 2-D hybrid simulations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hao, Yufei; Lu, Quanming; Lembege, Bertrand; Huang, Can; Wu, Mingyu; Guo, Fan; Shan, Lican; Zheng, Jian; Wang, Shui</p> <p>2015-04-01</p> <p>Experimental observations from space missions (including Cluster more recently) have clearly revealed the existence of high speed jets (HSJ) in the downstream region of the quasi-<span class="hlt">parallel</span> terrestrial bow <span class="hlt">shock</span>. Presently, two-dimensional (2-D) hybrid simulations are performed to reproduce and investigate the formation of such HSJ through a rippled quasi-<span class="hlt">parallel</span> <span class="hlt">shock</span> front. The simulation results show (i) that such <span class="hlt">shock</span> fronts are strongly nonstationary (self reformation) along the <span class="hlt">shock</span> normal, and (ii) that ripples are evidenced along the <span class="hlt">shock</span> front as the upstream ULF waves (excited by interaction between incoming and reflected ions) are convected back to the front by the solar wind and contribute to the rippling formation. Then, these ripples are inherent structures of a quasi-<span class="hlt">parallel</span> <span class="hlt">shock</span> and the self reformation of the <span class="hlt">shock</span> is not synchronous along the surface of the <span class="hlt">shock</span> front. As a consequence, new incoming solar wind ions interact differently at different locations along the <span class="hlt">shock</span> surface, and some can be only deflected (instead of being decelerated) at locations where ripples are large enough to play the role of local « secondary » <span class="hlt">shock</span>. Therefore, the ion bulk velocity is also different locally after ions are transmitted dowstream, and local high-speed jets patterns are formed somewhere downstream. After a short reminder of main quasi-<span class="hlt">parallel</span> <span class="hlt">shock</span> features, this presentation will focus (i) on experimental observations of HSJ, (ii) on our preliminary simulation results obtained on HSJ, (iii) on their relationship with local bursty patterns of (turbulent) magnetic field evidenced at the front, and (iv) on the spatial and time scales of HSJ to be compared later on with experimental observations. Such downstream HSJ are shown to be generated by the nonstationary <span class="hlt">shock</span> front itself and do not require any upstream perturbations (such as tangential/rotational discontinuity, HFA, etc..) to be convected by the solar wind and to interact with the <span class="hlt">shock</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950024920','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950024920"><span id="translatedtitle">Numerical simulation of <span class="hlt">shock</span>/turbulent boundary <span class="hlt">layer</span> interaction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Biringen, Sedat; Hatay, Ferhat F.</p> <p>1993-01-01</p> <p>Most flows of aerodynamic interest are compressible and turbulent. However, our present knowledge on the structures and mechanisms of turbulence is mostly based on incompressible flows. In the present work, compressibility effects in turbulent, high-speed, boundary <span class="hlt">layer</span> flows are systematically investigated using the Direct Numerical Simulation (DNS) approach. Three-dimensional, time-dependent, fully nonlinear, compressible Navier-Stokes equations were numerically integrated by high-order finite-difference methods; no modeling for turbulence is used during the solution because the available resolution is sufficient to capture the relevant scales. The boundary <span class="hlt">layer</span> problem deals with fully-turbulent compressible flows over flat geometries. Apart from its practical relevance to technological flows, turbulent compressible boundary <span class="hlt">layer</span> flow is the simplest experimentally realizable turbulent compressible flow. Still, measuring difficulties prohibit a detailed experimental description of the flow, especially in the near-wall region. DNS studies provide a viable means to probe the physics of compressible turbulence in this region. The focus of this work is to explore the paths of energy transfer through which compressible turbulence is sustained. The structural similarities and differences between the incompressible and compressible turbulence are also investigated. The energy flow patterns or energy cascades are found to be directly related to the evolution of vortical structures which are generated in the near-wall region. Near-wall structures, and mechanisms which are not readily accessible through physical experiments are analyzed and their critical role on the evolution and the behavior of the flow is documented extensively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009A%26A...506.1215O&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009A%26A...506.1215O&link_type=ABSTRACT"><span id="translatedtitle">The propagation of the <span class="hlt">shock</span> wave from a strong explosion in a plane-<span class="hlt">parallel</span> stratified medium: the Kompaneets approximation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Olano, C. A.</p> <p>2009-11-01</p> <p>Context: Using certain simplifications, Kompaneets derived a partial differential equation that states the local geometrical and kinematical conditions that each surface element of a <span class="hlt">shock</span> wave, created by a point blast in a stratified gaseous medium, must satisfy. Kompaneets could solve his equation analytically for the case of a wave propagating in an exponentially stratified medium, obtaining the form of the <span class="hlt">shock</span> front at progressive evolutionary stages. Complete analytical solutions of the Kompaneets equation for <span class="hlt">shock</span> wave motion in further plane-<span class="hlt">parallel</span> stratified media were not found, except for radially stratified media. Aims: We aim to analytically solve the Kompaneets equation for the motion of a <span class="hlt">shock</span> wave in different plane-<span class="hlt">parallel</span> stratified media that can reflect a wide variety of astrophysical contexts. We were particularly interested in solving the Kompaneets equation for a strong explosion in the interstellar medium of the Galactic disk, in which, due to intense winds and explosions of stars, gigantic gaseous structures known as superbubbles and supershells are formed. Methods: Using the Kompaneets approximation, we derived a pair of equations that we call adapted Kompaneets equations, that govern the propagation of a <span class="hlt">shock</span> wave in a stratified medium and that permit us to obtain solutions in parametric form. The solutions provided by the system of adapted Kompaneets equations are equivalent to those of the Kompaneets equation. We solved the adapted Kompaneets equations for <span class="hlt">shock</span> wave propagation in a generic stratified medium by means of a power-series method. Results: Using the series solution for a <span class="hlt">shock</span> wave in a generic medium, we obtained the series solutions for four specific media whose respective density distributions in the direction perpendicular to the stratification plane are of an exponential, power-law type (one with exponent k=-1 and the other with k =-2) and a quadratic hyperbolic-secant. From these series solutions, we deduced</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1986jtht.confQ....H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1986jtht.confQ....H"><span id="translatedtitle">Relaminarization of the boundary <span class="hlt">layer</span> over a flat plate in <span class="hlt">shock</span> tube experiments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hinckel, J. N.; Nagamatsu, H. T.</p> <p>1986-06-01</p> <p>The relaminarization of the boundary <span class="hlt">layer</span> over a flat plate in the <span class="hlt">shock</span> tube was investigated by using the partially reflected <span class="hlt">shock</span> wave technique. The flow Mach number was approximately 0.14, which corresponds to the inleft flow Mach number for the first row of vanes in a gas turbine. The thin film platinum heat gauges were used to measure the heat transfer rate and the Stanton number was calculated from the oscilloscope voltage traces. The Reynolds number was varied by changing the operation pressure of the <span class="hlt">shock</span> tube and the values varied from 2.3 x 10 to the 4th to 5.3 x 10 to the 5th. For a Reynolds number range of 7 x 10 to the 4th to 3.5 x 10 to the 5th, the relaminarization of the boundary <span class="hlt">layer</span> was observed. This phenomenon is due to the decay of the turbulence level in the flow as the reflected <span class="hlt">shock</span> wave moves upstream from the flat plate. As the Reynolds number increased, the relaminarization was delayed and the delay was related to the turbulence generated by the reflected <span class="hlt">shock</span> wave.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006APS..GECSR2036D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006APS..GECSR2036D"><span id="translatedtitle">Double Electric <span class="hlt">Layer</span> in Stationary <span class="hlt">Shock</span> Structures of a Supersonic Flowing Afterglow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Drake, D. J.; Upadyay, J.; Popovic, S.; Vuskovic, L.</p> <p>2006-10-01</p> <p>Mutual interaction between an acoustic <span class="hlt">shock</span> wave and weakly ionized gas produces many effects that have been studied in recent years [1]. This interaction is manifested as plasma-induced <span class="hlt">shock</span> dispersion and acceleration, <span class="hlt">shock</span> wave induced double electric <span class="hlt">layer</span>, localized increase of electron temperature and density, or enhancement of optical emission. A comprehensive review of this research and its significance for high-speed aerodynamics is given in Ref. [2]. We have performed experiments in a microwave flowing afterglow system and observed the enhancement of optical radiation in the interaction of a stationary <span class="hlt">shock</span> wave with weakly ionized argon at 100-600 Pa. The enhancement of optical radiation coincided with the calculated standoff distance of the detached shockwave. We studied the stationary <span class="hlt">shock</span> structures, mainly using the 4p excited state populations of argon, which were measured using absolute emission spectroscopy. Oblique <span class="hlt">shock</span> parameters were evaluated exactly for the given model geometry, which were usually spherical. We will present results at the conference. [1] S. Popovic, L. Vuskovic, Phys. Plasmas 6 (1999) 1448. [2] P. Bletzinger, B. N. Ganguly, D. Van Wie, A. Garscadden, J. Phys. D: App. Phys. 38 (2005) R33.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhDT.......105T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT.......105T"><span id="translatedtitle">Two-dimensional numerical investigation of a normal <span class="hlt">shock</span> wave boundary <span class="hlt">layer</span> interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Turlin, Miranda P.</p> <p></p> <p><span class="hlt">Shock</span> wave boundary <span class="hlt">layer</span> interactions (SWBLIs) occur when a <span class="hlt">shock</span> wave meets a boundary <span class="hlt">layer</span>. This study aims to isolate the interaction through numerical investigation of a normal SWBLI and build knowledge of the computational fluid dynamics software, Wind-US 3.0. The test geometry, based on the experimental work of Bruce et al [16], contains a two-dimensional duct split into upper and lower channels by a <span class="hlt">shock</span> holding plate. The boundary conditions were based on experimental conditions, and include: an inlet Mach number of 1.6; inlet total pressure and temperature of 62.5 psi and 522 degrees R, respectively; and viscous walls on all physical surfaces. Downstream boundary conditions are varied in attempts to produce a correct <span class="hlt">shock</span> structure throughout the domain. This study uses two-dimensional structured grids containing approximately 832,000 elements. Wind-US solves the Reynolds-Averaged Navier-Stokes equations using Roe's second-order upwind-biased flux-difference splitting algorithm with a total variation diminishing (TVD) limiting parameter. The turbulence model selected for this study was the Menter SST k-o model. Attempts to produce the correct <span class="hlt">shock</span> structure have included varying the downstream boundary conditions, changing the number of cycles and associated Courant-Friedrichs-Lewy, TVD, and grid sequencing parameters. This study used several tutorial files available through the NPARC Alliance to establish the analysis settings needed to produce a <span class="hlt">shock</span> wave in the lower channel. This enables progress to be made on the next step of this project which is to simulate and analyze the interaction of a normal SWBLI in two dimensions. Results illustrate the correct combination of boundary conditions necessary to generate a <span class="hlt">shock</span> in the expected location. In addition, an appropriate zonal configuration has been determined to eliminate the horizontal zone interfaces which can cause non-physical behavior in those locations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRA..121.3310S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRA..121.3310S"><span id="translatedtitle">Reconnection <span class="hlt">layer</span> bounded by switch-off <span class="hlt">shocks</span>: Dayside magnetopause crossing by THEMIS D</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sonnerup, Bengt; Paschmann, Götz; Haaland, Stein; Phan, Tai; Eriksson, Stefan</p> <p>2016-04-01</p> <p>We discuss observations of reconnection, obtained by Time History of Events and Macroscale Interactions during Substorms (THEMIS) D during an outward bound traversal of the low-latitude dayside magnetopause. The reconnection signatures include high magnetic shear, a southward directed Alfvénic jet, bounded by slow-mode <span class="hlt">shocks</span> near the switch-off limit (as in the symmetric Petschek geometry), a small, sunward directed normal magnetic field and plasma inflow into the jet from both sides. We conclude that cold, unmeasured ionospheric ions helped establish the symmetry. The effective ion mass, estimated from the switch-off condition, was 2.39 amu on the magnetospheric side, where the number density was inferred from the spacecraft potential, and 1.09 amu on the magnetosheath side. After a modest pressure correction in the magnetospheric <span class="hlt">shock</span>, the MHD jump conditions for density, pressure, temperature, and entropy were well satisfied. The <span class="hlt">shock</span> jumps were much larger on the magnetosphere side than on the magnetosheath side; we show this to be a plasma β effect. The main dissipation mechanism appears to be irreversible transfer between thermal motion <span class="hlt">parallel</span> and perpendicular to the field, such that both <span class="hlt">shocks</span> bring about approximate downstream temperature isotropy. Hall currents and electric fields were present, albeit in a strongly asymmetric configuration. The magnetospheric <span class="hlt">shock</span> had longer duration than the magnetosheath one, possibly as a result of a nonconstant magnetopause speed. We infer an average earthward magnetopause speed (14 km/s), corresponding nominal <span class="hlt">shock</span> thicknesses (12 and 6 λi), dimensionless reconnection rates (0.061-0.085), and reconnection wedge angles (5° between <span class="hlt">shocks</span>; 13° between separatrices).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ShWav.tmp...46S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ShWav.tmp...46S"><span id="translatedtitle">Characterization of an incipiently separated <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span> interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schreyer, A.-M.; Dussauge, J.-P.; Krämer, E.</p> <p>2016-05-01</p> <p>The turbulence structure in a <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span> interaction at incipient separation was investigated in order to get insight into turbulence generation and amplification mechanisms in such flow fields. The flow along a two-dimensional 11.5° compression corner was studied experimentally at a Mach number of M=2.53 and with a momentum-thickness Reynolds number of Re_{θ }=5370 . From hot-wire boundary <span class="hlt">layer</span> traverses and surface heat-flux density fluctuation measurements with the fast-response atomic <span class="hlt">layer</span> thermopile, the turbulence structure and amplification was described. Space-time correlations of the mass-flux fluctuations across the boundary <span class="hlt">layer</span> and the surface heat-flux density fluctuations were measured to further characterize the development of the turbulence structure across the interaction. The large-scale boundary <span class="hlt">layer</span> structures are concealed by <span class="hlt">shock</span>-related effects in the strongly disturbed <span class="hlt">shock</span>-foot region. Shortly downstream, however, large-scale structures dominate the signal again, just as in the incoming flow. A mechanism explaining this behavior is suggested.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910005246','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910005246"><span id="translatedtitle">Numerical study of <span class="hlt">shock</span>-wave/boundary <span class="hlt">layer</span> interactions in premixed hydrogen-air hypersonic flows</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Yungster, Shaye</p> <p>1990-01-01</p> <p>A computational study of <span class="hlt">shock</span> wave/boundary <span class="hlt">layer</span> interactions involving premixed combustible gases, and the resulting combustion processes is presented. The analysis is carried out using a new fully implicit, total variation diminishing (TVD) code developed for solving the fully coupled Reynolds-averaged Navier-Stokes equations and species continuity equations in an efficient manner. To accelerate the convergence of the basic iterative procedure, this code is combined with vector extrapolation methods. The chemical nonequilibrium processes are simulated by means of a finite-rate chemistry model for hydrogen-air combustion. Several validation test cases are presented and the results compared with experimental data or with other computational results. The code is then applied to study <span class="hlt">shock</span> wave/boundary <span class="hlt">layer</span> interactions in a ram accelerator configuration. Results indicate a new combustion mechanism in which a <span class="hlt">shock</span> wave induces combustion in the boundary <span class="hlt">layer</span>, which then propagates outwards and downstream. At higher Mach numbers, spontaneous ignition in part of the boundary <span class="hlt">layer</span> is observed, which eventually extends along the entire boundary <span class="hlt">layer</span> at still higher values of the Mach number.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920071754&hterms=lateral+flow&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dlateral%2Bflow','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920071754&hterms=lateral+flow&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dlateral%2Bflow"><span id="translatedtitle">A three-dimensional axisymmetric photochemical flow model of the cometary 'inner' <span class="hlt">shock</span> <span class="hlt">layer</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Damas, M. C.; Mendis, D. A.</p> <p>1992-01-01</p> <p>Assuming the Newtonian thin <span class="hlt">layer</span> approximation to describe the structure of the <span class="hlt">shock</span> <span class="hlt">layer</span> between the cometary 'ionopause' and the inner <span class="hlt">shock</span>, a 3D axisymmetric photochemical flow model of this <span class="hlt">layer</span> is constructed. While sources of ions in this <span class="hlt">layer</span> are the flow across the inner <span class="hlt">shock</span> and photoionization of neutrals within it, the sinks are the flow into the flanks and dissociative recombination, the latter being the dominant one. For Halley's comet at the time of the Giotto encounter, the calculated thickness of the <span class="hlt">layer</span> is very small, typically about 100 km for expected values of the dissociative-recombination coefficient. This is not inconsistent with the observations. The lateral flow speed near the point of encounter (inbound) is about 0.9 km/s, while the sonic line is at an angle of about 50 deg to the sun-comet line. Testing the validity of this model will have to await a cometary rendezvous mission such as the proposed CRAF/Cassini mission.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750004171','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750004171"><span id="translatedtitle">Weak incident <span class="hlt">shock</span> interactions with Mach 8 laminar boundary <span class="hlt">layers</span>. [of flat plate</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kaufman, L. G., II; Johnson, C. B.</p> <p>1974-01-01</p> <p>Weak <span class="hlt">shock</span>-wave interactions with boundary <span class="hlt">layers</span> on a flat plate were investigated experimentally in Mach 8 variable-density tunnel for plate-length Reynolds numbers. The undisturbed boundary <span class="hlt">layers</span> were laminar over the entire plate length. Pressure and heat-transfer distributions were obtained for wedge-generated incident <span class="hlt">shock</span> waves that resulted in pressure rises ranging from 1.36 to 4.46 (both nonseparated and separated boundary-<span class="hlt">layer</span> flows). The resulting heat-transfer amplifications ranged from 1.45 to 14. The distributions followed established trends for nonseparated flows, for incipient separation, and for laminar free-interaction pressure rises. The experimental results corroborated established trends for the extent of the pressure rise and for certain peak heat-transfer correlations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970009931','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970009931"><span id="translatedtitle">Experimental Investigation of Crossing <span class="hlt">Shock</span> Wave-Turbulent Boundary <span class="hlt">Layer</span>-Bleed Interaction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kim, Hyun; Hingst, Warren R.; Davis, David O.</p> <p>1996-01-01</p> <p>Results of an experimental investigation of a symmetric crossing <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span>/bleed interaction are presented for a freestream unit Reynolds number of 1.68 x 10(exp 7)/m, a Mach number of 2.81, and deflection angles of 8 degrees. The data obtained in this study are bleed mass flow rate using a trace gas technique, qualitative information in the form of oil flow visualization, flow field Pitot pressures, and static pressure measurements using pressure sensitive paint. The main objective of this test is two-fold. First, this study is conducted to explore boundary <span class="hlt">layer</span> control through mass flow removal near a large region of separated flow caused by the interaction of a double fin-induced <span class="hlt">shock</span> wave and an incoming turbulent boundary <span class="hlt">layer</span>. Also, a comprehensive data set is needed for computational fluid dynamics code validation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JThSc..24..510F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JThSc..24..510F"><span id="translatedtitle"><span class="hlt">Shock</span> wave boundary <span class="hlt">layer</span> interaction on suction side of compressor profile in single passage test section</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Flaszynski, Pawel; Doerffer, Piotr; Szwaba, Ryszard; Kaczynski, Piotr; Piotrowicz, Michal</p> <p>2015-11-01</p> <p>The <span class="hlt">shock</span> wave boundary <span class="hlt">layer</span> interaction on the suction side of transonic compressor blade is one of the main objectives of TFAST project (Transition Location Effect on <span class="hlt">Shock</span> Wave Boundary <span class="hlt">Layer</span> Interaction). In order to investigate the flow structure on the suction side of a profile, a design of a generic test section in linear transonic wind tunnel was proposed. The experimental and numerical results for the flow structure investigations are shown for the flow conditions as the existing ones on the suction side of the compressor profile. Near the sidewalls the suction slots are applied for the corner flow structure control. It allows to control the Axial Velocity Density Ratio (AVDR), important parameter for compressor cascade investigations. Numerical results for Explicit Algebraic Reynolds Stress Model with transition modeling are compared with oil flow visualization, schlieren and Pressure Sensitive Paint. Boundary <span class="hlt">layer</span> transition location is detected by Temperature Sensitive Paint.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830013929','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830013929"><span id="translatedtitle">Experimental investigation of a two-dimensional <span class="hlt">shock</span>-turbulent boundary <span class="hlt">layer</span> interaction with bleed</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hingst, W. R.; Tanji, F. T.</p> <p>1983-01-01</p> <p>The two-dimensional interaction of an oblique <span class="hlt">shock</span> wave with a turbulent boundary <span class="hlt">layer</span> that included the effect of bleed was examined experimentally using a <span class="hlt">shock</span> generator mounted across a supersonic wind tunnel The studies were performed at Mach numbers 2.5 and 2.0 and unit Reynolds number of approximately 2.0 x 10 to the 7th/meter. The study includes surface oil flow visualization, wall static pressure distributions and boundary <span class="hlt">layer</span> pitot pressure profiles. In addition, the variation of the local bleed rates were measured. The results show the effect of the bleed on the boundary <span class="hlt">layer</span> as well as the effect of the flow conditions on the local bleed rate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930064187&hterms=wave+equation+2D&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dwave%2Bequation%2B2D','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930064187&hterms=wave+equation+2D&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dwave%2Bequation%2B2D"><span id="translatedtitle">An investigation of <span class="hlt">shock</span> wave turbulent boundary <span class="hlt">layer</span> interaction with bleed through slanted slots</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hamed, A.; Yeuan, J. J.; Shih, S. H.</p> <p>1993-01-01</p> <p>Flow-field characteristics are simulated numerically in an oblique <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span> interactions with six different bleed slot configurations. The strong conservation-law form of the 2D compressible Navier-Stokes equations and the k-epsilon equations are solved throughout the interaction region and inside the bleed slot. The computed results are presented for a normal and 20-deg slanted bleed slots at three different locations, upstream, across and downstream of the impingement point of an oblique <span class="hlt">shock</span> of sufficient strength to cause boundary <span class="hlt">layer</span> separation without bleed. The detailed flow characteristics in the interaction zone and inside the bleed slot are compared for the different bleed slot configurations. The resulting surface pressure and shear stress distributions as well as the boundary <span class="hlt">layer</span> characteristics downstream of the interaction region are also presented for the mix bleed configurations at different bleed mass flows up to choking.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100037235','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100037235"><span id="translatedtitle">CFL3D Contribution to the AIAA Supersonic <span class="hlt">Shock</span> Boundary <span class="hlt">Layer</span> Interaction Workshop</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rumsey, Christopher L.</p> <p>2010-01-01</p> <p>This paper documents the CFL3D contribution to the AIAA Supersonic <span class="hlt">Shock</span> Boundary <span class="hlt">Layer</span> Interaction Workshop, held in Orlando, Florida in January 2010. CFL3D is a Reynolds-averaged Navier-Stokes code. Four <span class="hlt">shock</span> boundary <span class="hlt">layer</span> interaction cases are computed using a one-equation turbulence model widely used for other aerodynamic problems of interest. Two of the cases have experimental data available at the workshop, and two of the cases do not. The effect of grid, flux scheme, and thin-<span class="hlt">layer</span> approximation are investigated. Comparisons are made to the available experimental data. All four cases exhibit strong three-dimensional behavior in and near the interaction regions, resulting from influences of the tunnel side-walls.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130010178','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130010178"><span id="translatedtitle">Wind-US Code Contributions to the First AIAA <span class="hlt">Shock</span> Boundary <span class="hlt">Layer</span> Interaction Prediction Workshop</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Georgiadis, Nicholas J.; Vyas, Manan A.; Yoder, Dennis A.</p> <p>2013-01-01</p> <p>This report discusses the computations of a set of <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span> interaction (SWTBLI) test cases using the Wind-US code, as part of the 2010 American Institute of Aeronautics and Astronautics (AIAA) <span class="hlt">shock</span>/boundary <span class="hlt">layer</span> interaction workshop. The experiments involve supersonic flows in wind tunnels with a <span class="hlt">shock</span> generator that directs an oblique <span class="hlt">shock</span> wave toward the boundary <span class="hlt">layer</span> along one of the walls of the wind tunnel. The Wind-US calculations utilized structured grid computations performed in Reynolds-averaged Navier-Stokes mode. Four turbulence models were investigated: the Spalart-Allmaras one-equation model, the Menter Baseline and Shear Stress Transport k-omega two-equation models, and an explicit algebraic stress k-omega formulation. Effects of grid resolution and upwinding scheme were also considered. The results from the CFD calculations are compared to particle image velocimetry (PIV) data from the experiments. As expected, turbulence model effects dominated the accuracy of the solutions with upwinding scheme selection indicating minimal effects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6901192','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6901192"><span id="translatedtitle">Instability growth patterns of a <span class="hlt">shock</span>-accelerated thin fluid <span class="hlt">layer</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jacobs, J.W. ); Klein, D.L.; Jenkins, D.G.; Benjamin, R.F. )</p> <p>1993-02-01</p> <p>Laser-induced fluorescence imaging of a <span class="hlt">shock</span>-accelerated thin gas <span class="hlt">layer</span>, produced by a planar SF[sub 6] jet in air, shows multiple flow evolutions. Richtmyer-Meshkov instability causes spatially periodic perturbations initially imposed on the jet to develop into one of three distinct flow patterns, indicating nonlinear instability growth. Slight differences in the vorticity distribution deposited on the air-SF[sub 6] interfaces by the <span class="hlt">shock</span> interaction produce a bifurcated flow, observed as mushroom-shaped or sinuous-shaped interfacial patterns.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19900043444&hterms=Chalk&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DChalk','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19900043444&hterms=Chalk&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DChalk"><span id="translatedtitle">Color surface-flow visualization of fin-generated <span class="hlt">shock</span> wave boundary-<span class="hlt">layer</span> interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lu, F. K.; Settles, G. S.</p> <p>1990-01-01</p> <p>Kerosene-lampblack mixtures with addition of a ground colored chalk were used in an experiment on visualizing surface flows of swept <span class="hlt">shock</span> boundary-<span class="hlt">layer</span> interactions. The results show that contrasting colors intensify the visualization of different regions of the interaction surface, and help the eye in following the fine streaks to locate the upstream influence. The study confirms observations of the separation occurring at <span class="hlt">shock</span> strength below accepted values. The superiority of the reported technique over the previous monochrome technique is demonstrated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.9404A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.9404A"><span id="translatedtitle">Folder: a MATLAB-based tool for modelling deformation in <span class="hlt">layered</span> media subject to <span class="hlt">layer</span> <span class="hlt">parallel</span> shortening or extension</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Adamuszek, Marta; Dabrowski, Marcin; Schmid, Daniel W.</p> <p>2016-04-01</p> <p>We present Folder, a numerical tool to simulate and analyse the structure development in mechanically <span class="hlt">layered</span> media during the <span class="hlt">layer</span> <span class="hlt">parallel</span> shortening or extension. Folder includes a graphical user interface that allows for easy designing of complex geometrical models, defining material parameters (including linear and non-linear rheology), and specifying type and amount of deformation. It also includes a range of features that facilitate the visualization and examination of various relevant quantities e.g. velocities, stress, rate of deformation, pressure, and finite strain. Folder contains a separate application, which illustrates analytical solutions of growth rate spectra for <span class="hlt">layer</span> <span class="hlt">parallel</span> shortening and extension of a single viscous <span class="hlt">layer</span>. In the study, we also demonstrate a Folder application, where the role of confinement on the growth rate spectrum and the fold shape evolution during the deformation of a single <span class="hlt">layer</span> subject to the <span class="hlt">layer</span> <span class="hlt">parallel</span> shortening is presented. In the case of the linear viscous materials used for the <span class="hlt">layer</span> and matrix, the close wall proximity leads to a decrease of the growth rate values. The decrease is more pronounced for the larger wavelengths than for the smaller wavelengths. The growth rate reduction is greater when the walls are set closer to the <span class="hlt">layer</span>. The presence of the close confinement can also affect the wavelength selection process and significantly shift the position of the dominant wavelength. The influence of the wall proximity on the growth rate spectrum for the case of non-linear viscous materials used for the <span class="hlt">layer</span> and/or matrix is very different as compared to the linear viscous case. We observe a multiple maxima in the growth rate spectrum. The number of the growth rate maxima, their value and the position strongly depend on the closeness of the confinement. The maximum growth rate value for a selected range of <span class="hlt">layer</span>-wall distances is much larger than in the case when the confinement effect is not taken</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015APS..DFDL21008G&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015APS..DFDL21008G&link_type=ABSTRACT"><span id="translatedtitle">Effect of Pulsed Plasma Jets on the Recovering Boundary <span class="hlt">Layer</span> Downstream of a Reflected <span class="hlt">Shock</span> Interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Greene, Benton; Clemens, Noel; Magari, Patrick; Micka, Daniel; Ueckermann, Mattheus</p> <p>2015-11-01</p> <p><span class="hlt">Shock</span>-induced turbulent boundary <span class="hlt">layer</span> separation can have many detrimental effects in supersonic inlets including flow distortion and instability, structural fatigue, poor pressure recovery, and unstart. The current study investigates the effect of pulsed plasma jets on the recovering boundary <span class="hlt">layer</span> downstream of a reflected <span class="hlt">shock</span> wave-boundary <span class="hlt">layer</span> interaction. The effects of pitch and skew angle of the jet as well as the heating parameter and discharge time scale are tested using several pulsing frequencies. In addition, the effect of the plasma jets on the undisturbed boundary <span class="hlt">layer</span> at 6 mm and 11 mm downstream of the jets is measured. A pitot-static pressure probe is used to measure the velocity profile of the boundary <span class="hlt">layer</span> 35 mm downstream of the plasma jets, and the degree of boundary <span class="hlt">layer</span> distortion is compared between the different models and run conditions. Additionally, the effect of each actuator configuration on the shape of the mean separated region is investigated using surface oil flow visualization. Previous studies with lower energy showed a weak effect on the downstream boundary <span class="hlt">layer</span>. The current investigation will attempt to increase this effect using a higher-energy discharge. Funded by AFRL through and SBIR in collaboration with Creare, LLC.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850027059','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850027059"><span id="translatedtitle">Computation of three-dimensional <span class="hlt">shock</span> wave and boundary-<span class="hlt">layer</span> interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hung, C. M.</p> <p>1985-01-01</p> <p>Computations of the impingement of an oblique <span class="hlt">shock</span> wave on a cylinder and a supersonic flow past a blunt fin mounted on a plate are used to study three dimensional <span class="hlt">shock</span> wave and boundary <span class="hlt">layer</span> interaction. In the impingement case, the problem of imposing a planar impinging <span class="hlt">shock</span> as an outer boundary condition is discussed and the details of particle traces in windward and leeward symmetry planes and near the body surface are presented. In the blunt fin case, differences between two dimensional and three dimensional separation are discussed, and the existence of an unique high speed, low pressure region under the separated spiral vortex core is demonstrated. The accessibility of three dimensional separation is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPC.1754d0024J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1754d0024J"><span id="translatedtitle">A computational study on oblique <span class="hlt">shock</span> wave-turbulent boundary <span class="hlt">layer</span> interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Joy, Md. Saddam Hossain; Rahman, Saeedur; Hasan, A. B. M. Toufique; Ali, M.; Mitsutake, Y.; Matsuo, S.; Setoguchi, T.</p> <p>2016-07-01</p> <p>A numerical computation of an oblique <span class="hlt">shock</span> wave incident on a turbulent boundary <span class="hlt">layer</span> was performed for free stream flow of air at M∞ = 2.0 and Re1 = 10.5×106 m-1. The oblique <span class="hlt">shock</span> wave was generated from a 8° wedge. Reynolds averaged Navier-Stokes (RANS) simulation with k-ω SST turbulence model was first utilized for two dimensional (2D) steady case. The results were compared with the experiment at the same flow conditions. Further, to capture the unsteadiness, a 2D Large Eddy Simulation (LES) with sub-grid scale model WMLES was performed which showed the unsteady effects. The frequency of the <span class="hlt">shock</span> oscillation was computed and was found to be comparable with that of experimental measurement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820014335','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820014335"><span id="translatedtitle">Investigation of passive <span class="hlt">shock</span> wave-boundary <span class="hlt">layer</span> control for transonic airfoil drag reduction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nagamatsu, H. T.; Brower, W. B., Jr.; Bahi, L.; Ross, J.</p> <p>1982-01-01</p> <p>The passive drag control concept, consisting of a porous surface with a cavity beneath it, was investigated with a 12-percent-thick circular arc and a 14-percent-thick supercritical airfoil mounted on the test section bottom wall. The porous surface was positioned in the <span class="hlt">shock</span> wave/boundary <span class="hlt">layer</span> interaction region. The flow circulating through the porous surface, from the downstream to the upstream of the terminating <span class="hlt">shock</span> wave location, produced a lambda <span class="hlt">shock</span> wave system and a pressure decrease in the downstream region minimizing the flow separation. The wake impact pressure data show an appreciably drag reduction with the porous surface at transonic speeds. To determine the optimum size of porosity and cavity, tunnel tests were conducted with different airfoil porosities, cavities and flow Mach numbers. A higher drag reduction was obtained by the 2.5 percent porosity and the 1/4-inch deep cavity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070003681','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070003681"><span id="translatedtitle">Assessment of Turbulent <span class="hlt">Shock</span>-Boundary <span class="hlt">Layer</span> Interaction Computations Using the OVERFLOW Code</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Oliver, A. B.; Lillard, R. P.; Schwing, A. M.; Blaisdell, G> A.; Lyrintzis, A. S.</p> <p>2007-01-01</p> <p>The performance of two popular turbulence models, the Spalart-Allmaras model and Menter s SST model, and one relatively new model, Olsen & Coakley s Lag model, are evaluated using the OVERFLOWcode. Turbulent <span class="hlt">shock</span>-boundary <span class="hlt">layer</span> interaction predictions are evaluated with three different experimental datasets: a series of 2D compression ramps at Mach 2.87, a series of 2D compression ramps at Mach 2.94, and an axisymmetric coneflare at Mach 11. The experimental datasets include flows with no separation, moderate separation, and significant separation, and use several different experimental measurement techniques (including laser doppler velocimetry (LDV), pitot-probe measurement, inclined hot-wire probe measurement, preston tube skin friction measurement, and surface pressure measurement). Additionally, the OVERFLOW solutions are compared to the solutions of a second CFD code, DPLR. The predictions for weak <span class="hlt">shock</span>-boundary <span class="hlt">layer</span> interactions are in reasonable agreement with the experimental data. For strong <span class="hlt">shock</span>-boundary <span class="hlt">layer</span> interactions, all of the turbulence models overpredict the separation size and fail to predict the correct skin friction recovery distribution. In most cases, surface pressure predictions show too much upstream influence, however including the tunnel side-wall boundary <span class="hlt">layers</span> in the computation improves the separation predictions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1615976K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1615976K"><span id="translatedtitle">Enhanced diffusive ion scattering in front of the Earth's quasi-<span class="hlt">parallel</span> bow <span class="hlt">shock</span>: a case study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kis, Arpad; Scholer, Manfred; Klecker, Berndt; Lucek, Elisabeth; Dandouras, Iannis; Lemperger, István; Wesztergom, Viktor; Novák, Attila; Szalai, Sándor</p> <p>2014-05-01</p> <p>In our study we report on observations of energetic ions upstream of the Earth's quasi-<span class="hlt">parallel</span> bow <span class="hlt">shock</span> by Cluster at times of large inter-spacecraft separation distance. For the analysis we use the ion data provided by the CIS-HIA in the 10-32 keV energy range and the magnetic data recorded by the FGM instrument. We determine the spatial gradient of partial energetic ion densities at various distances from the bow <span class="hlt">shock</span>. The gradient in all energy channels decreases exponentially with distance and the e-folding distance of the gradients depends approximately linearly on energy but there is a significant difference in their values obtained at the observed three upstream ion events. We demonstrate for the first time that under specific interplanetary conditions the mechanism of the diffuse ion scattering can change significantly and results in an anomalous diffusive process charactized by an unusually small e-folding distance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016JHyd..535..737Z&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016JHyd..535..737Z&link_type=ABSTRACT"><span id="translatedtitle">Double-<span class="hlt">layer</span> <span class="hlt">parallelization</span> for hydrological model calibration on HPC systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Ang; Li, Tiejian; Si, Yuan; Liu, Ronghua; Shi, Haiyun; Li, Xiang; Li, Jiaye; Wu, Xia</p> <p>2016-04-01</p> <p>Large-scale problems that demand high precision have remarkably increased the computational time of numerical simulation models. Therefore, the <span class="hlt">parallelization</span> of models has been widely implemented in recent years. However, computing time remains a major challenge when a large model is calibrated using optimization techniques. To overcome this difficulty, we proposed a double-<span class="hlt">layer</span> <span class="hlt">parallel</span> system for hydrological model calibration using high-performance computing (HPC) systems. The lower-<span class="hlt">layer</span> <span class="hlt">parallelism</span> is achieved using a hydrological model, the Digital Yellow River Integrated Model, which was <span class="hlt">parallelized</span> by decomposing river basins. The upper-<span class="hlt">layer</span> <span class="hlt">parallelism</span> is achieved by simultaneous hydrological simulations with different parameter combinations in the same generation of the genetic algorithm and is implemented using the job scheduling functions of an HPC system. The proposed system was applied to the upstream of the Qingjian River basin, a sub-basin of the middle Yellow River, to calibrate the model effectively by making full use of the computing resources in the HPC system and to investigate the model's behavior under various parameter combinations. This approach is applicable to most of the existing hydrology models for many applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20030063222&hterms=mineral+discoveries&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmineral%2Bdiscoveries','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20030063222&hterms=mineral+discoveries&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmineral%2Bdiscoveries"><span id="translatedtitle">Discovery of coesite and <span class="hlt">shocked</span> quartz associated with the upper Eocene cpx spherule <span class="hlt">layer</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Liu, S.; Kyte, T.; Glass, B. P.</p> <p>2002-01-01</p> <p>At least two major impact ejecta <span class="hlt">layers</span> have been discovered in upper Eocene strata. The upper <span class="hlt">layer</span> is the North American microtektite <span class="hlt">layer</span>. lt consists tektite fragments, microtektites, and <span class="hlt">shocked</span> mineral grains (e.g., quartz and feldspar with multiple sets of PDFs, coesite and reidite (a high-pressure polymorph of zircon)). The slightly older <span class="hlt">layer</span> contains clinopyroxene-bearing (cpx) spherules and microtektites associated with an Ir anomaly. The North American tektite <span class="hlt">layer</span> may be derived from the Chesapeake Bay impact structure, and the cpx spherule <span class="hlt">layer</span> may from the Popigai impact crater. A cpx spherule <span class="hlt">layer</span> associated with a positive Ir anomaly was recently found at ODP Site 709, western Indian Ocean. A large sample (Hole 709C, core 31, section 4, 145-150 cm), originally used for a study of interstitial water by shipboard scientists, was acquired for the purpose of recovering a large number of spherules for various petrographic and geochemical studies. A split of the sample (50.35 g) was disaggregated and wet-sieved. More than 17,000 cpx spherules and several hundred microtektites (larger than 125 microns) were recovered from the sample. Rare white opaque grains were observed in the 125-250 micron size fraction after removal of the carbonate component using dilute HCI. Seven of the white opaque grains were X-rayed using a Gandolfi camera and six were found to be coesite (probably mixed with lechatelierite). Eighty translucent colorless grains from the 63-125 micron size fraction were studied with a petrographic microscope. Four of the grains exhibit one to two sets of planar deformation features (PDFs). The only other possible known occurrence of <span class="hlt">shocked</span> minerals associated with the cpx spherule <span class="hlt">layer</span> is at Massignano, Italy, where pancake-shaped clay spherules (thought to be diagenetically altered cpx spherules are associated with a positive Ir anomaly and Ni- rich spinel crystals. <span class="hlt">Shocked</span> quartz grains with multiple sets of PDFs also occur at this site</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940023299','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940023299"><span id="translatedtitle">Flowfield dynamics in blunt fin-induced <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span> interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dolling, David S.; Brusniak, Leon</p> <p>1994-01-01</p> <p>Fluctuating wall pressure measurements have been made on centerline upstream of a blunt fin in a Mach 5 turbulent boundary <span class="hlt">layer</span>. By examining the ensemble averaged wall pressure distributions for different separation <span class="hlt">shock</span> foot positions, it has been shown that local fluctuating wall pressure measurements are due to a distinct pressure distribution, Rho(sub i), which undergoes a stretching and flattening effect as its upstream boundary translates aperiodically between the upstream influence and separation lines. The locations of the maxima and minima in the wall pressure standard deviation can be accurately predicted using this distribution, providing quantitative confirmation of the model. This model also explains the observed cross-correlations and ensemble average measurements within the interaction. Using the Rho(sub i) model, wall pressure signals from under the separated flow region were used to reproduce the position-time history of the separation <span class="hlt">shock</span> foot. Further, the negative time delay peak in the cross-correlation between the predicted and actual <span class="hlt">shock</span> foot histories suggests that the separated region fluctuations precede <span class="hlt">shock</span> foot motion. The unsteady behavior of the primary horseshoe vortex and its relation to the unsteady separation <span class="hlt">shock</span> are described.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DFDL21010S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DFDL21010S"><span id="translatedtitle">Investigation of <span class="hlt">Shock</span>-Induced Laminar Separation Bubble in a Supersonic Boundary <span class="hlt">Layer</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sivasubramanian, Jayahar; Fasel, Hermann</p> <p>2015-11-01</p> <p>The interaction between an impinging oblique <span class="hlt">shock</span> and a laminar boundary-<span class="hlt">layer</span> on a flat plate is investigated using DNS. In particular, the two-dimensional separation bubble resulting from the <span class="hlt">shock/boundary-layer</span> interaction (SBLI) at freestream Mach number of 2.0 is investigated in detail. The flow parameters used for the present investigation match the laboratory conditions in the experiments by Hakkinen et al. The skin friction and pressure distribution from the simulations are compared to the experimental measurements and numerical results available in the literature. Our results confirm the asymmetric nature of the separation bubble as reported in the literature. In addition to the steady flow field calculations, the response to low-amplitude disturbances is investigated in order to study the linear stability behavior of the separation bubble. For comparison, both the development of two-dimensional and three-dimensional (oblique) disturbances are studied with and without the impinging oblique <span class="hlt">shock</span>. Furthermore, the effects of the <span class="hlt">shock</span> incidence angle and Reynolds number are also investigated. Finally, three-dimensional simulations were performed in order to explore the laminar-turbulent transition process in the presence of a laminar separation bubble. Funded by the Air Force Office of Scientific Research under grant FA9550-14-1-0195.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19800012047','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19800012047"><span id="translatedtitle">Calculation of oblique-<span class="hlt">shock</span>-wave laminar-boundary-<span class="hlt">layer</span> interaction on a flat plate</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Goldberg, U.; Reshotko, E.</p> <p>1980-01-01</p> <p>A finite difference solution to the problem of the interaction between an impinging oblique <span class="hlt">shock</span> wave and the laminar boundary <span class="hlt">layer</span> on a flat plate is presented. The boundary <span class="hlt">layer</span> equations coupled with the Prandtl-Meyer relation for the external flow are used to calculate the flow field. A method for the calculation of the separated flow region is presented and discussed. Comparisons between this theory and the experimental results of other investigators show fairly good agreement. Results are presented for the case of a cooled wall with an oncoming flow at Mach number 2.0 without and with suction. The results show that a small amount of suction greatly reduces the extent of the separated region in the vicinity of the <span class="hlt">shock</span> impingement location.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19750050138&hterms=tecnica&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dtecnica','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19750050138&hterms=tecnica&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dtecnica"><span id="translatedtitle">Interaction between a <span class="hlt">shock</span> wave and a turbulent boundary <span class="hlt">layer</span> in transonic flow</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Adamson, T. C., Jr.; Feo, A.</p> <p>1975-01-01</p> <p>Interaction between a <span class="hlt">shock</span> wave and an unseparated turbulent boundary <span class="hlt">layer</span> is considered. The method of matched asymptotic expansions is used, with solutions valid in the double limit as Reynolds number tends to infinity and Mach number tends to unity. The <span class="hlt">shock</span> is weak enough that interaction effects can be considered as perturbations to the undisturbed flow; the case considered is that where the sonic line is near the outer edge of the boundary <span class="hlt">layer</span>. It is shown that, with order estimates for Reynolds stress perturbations, the induced wall pressure distribution can be calculated using only the two outer interaction regions, independent of a specific closure condition and that this solution is in fact a turbulent free interaction solution. A detailed analysis of the inner regions, for which an eddy viscosity model for the Reynolds shear stress is used, provides a description of the variations in velocity, temperature and density near and at the wall.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19940010724&hterms=archetypes&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Darchetypes','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19940010724&hterms=archetypes&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Darchetypes"><span id="translatedtitle">Swept <span class="hlt">shock/boundary-layer</span> interactions: Scaling laws, flowfield structure, and experimental methods</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Settles, Gary S.</p> <p>1993-01-01</p> <p>A general review is given of several decades of research on the scaling laws and flowfield structures of swept <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span> interactions. Attention is further restricted to the experimental study and physical understanding of the steady-state aspects of these flows. The interaction produced by a sharp, upright fin mounted on a flat plate is taken as an archetype. An overall framework of quasiconical symmetry describing such interactions is first developed. Boundary-<span class="hlt">layer</span> separation, the interaction footprint, Mach number scaling, and Reynolds number scaling are then considered, followed by a discussion of the quasiconical similarity of interactions produced by geometrically-dissimilar <span class="hlt">shock</span> generators. The detailed structure of these interaction flowfields is next reviewed, and is illustrated by both qualitative visualizations and quantitative flow images in the quasiconical framework. Finally, the experimental techniques used to investigate such flows are reviewed, with emphasis on modern non-intrusive optical flow diagnostics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950056083&hterms=knowledge+transfer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dknowledge%2Btransfer','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950056083&hterms=knowledge+transfer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dknowledge%2Btransfer"><span id="translatedtitle">Heat-transfer measurements and computations of swept-<span class="hlt">shock</span>-wave boundary-<span class="hlt">layer</span> interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lee, Y.; Settles, G. S.; Horstman, C. C.</p> <p>1994-01-01</p> <p>An experimental and computational research program providing new knowledge of the heat transfer in swept-<span class="hlt">shock-wave/boundary-layer</span> interactions is described. An equilibrium turbulent boundary <span class="hlt">layer</span> on a flat plate is subjected to impingement by a swept planar <span class="hlt">shock</span> wave generated by a sharp fin. Five different interactions with fin angles ranging from 10 to 20 deg at freestream Mach numbers of 3 and 4 produce a variety of interaction strengths ranging from weak to very strong. A foil heater generates a uniform heat flux over the flat plate surface, and miniature thin-film-resistance sensors are used to measure the local surface temperature. The heat convection equation is then solved for the heat transfer distribution within an interaction, yielding an uncertainty of about +/- 10%. These data are compared with numerical Navier-Stokes solutions that employ a k-epsilon turbulence model. A simple peak heat transfer correlation for fin interactions is suggested.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21241943','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21241943"><span id="translatedtitle">A point radiator <span class="hlt">parallel</span> to a plane <span class="hlt">layer</span> with negative refractive index</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Petrin, A. B.</p> <p>2008-09-15</p> <p>Focusing of an electromagnetic wave radiated by a point source and transmitted through a plane <span class="hlt">layer</span> filled with a medium with negative refractive index is considered. An elementary electric Hertzian dipole located in the air (or vacuum) <span class="hlt">parallel</span> to the boundaries of the <span class="hlt">layer</span> is considered as a point source of radiation. It is rigorously shown that, after transmitting through a <span class="hlt">layer</span> with negative refractive index, the electromagnetic wave of the dipole is focused into a certain domain. The dimensions of the focusing region are investigated. The results of the investigation show that the use of homogeneous materials with negative refraction does not allow one to overcome the diffraction limit.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750020301','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750020301"><span id="translatedtitle">Viscous-<span class="hlt">shock-layer</span> solutions for turbulent flow of radiating gas mixtures in chemical equilibrium</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Anderson, E. C.; Moss, J. N.</p> <p>1975-01-01</p> <p>The viscous-<span class="hlt">shock-layer</span> equations for hypersonic laminar and turbulent flows of radiating or nonradiating gas mixtures in chemical equilibrium are presented for two-dimensional and axially-symmetric flow fields. Solutions were obtained using an implicit finite-difference scheme and results are presented for hypersonic flow over spherically-blunted cone configurations at freestream conditions representative of entry into the atmosphere of Venus. These data are compared with solutions obtained using other methods of analysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760003327','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760003327"><span id="translatedtitle">Viscous <span class="hlt">shock</span> <span class="hlt">layer</span> solutions for turbulent flow of radiating gas mixtures in chemical equilibrium</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Anderson, E. C.; Moss, J. N.</p> <p>1975-01-01</p> <p>The viscous <span class="hlt">shock</span> <span class="hlt">layer</span> equations for hypersonic laminar and turbulent flows of radiating or nonradiating gas mixtures in chemical equilibrium are presented for two-dimensional and axially symmetric flow fields. Solutions are obtained using an implicit finite difference scheme and results are presented for hypersonic flow over spherically blunted cone configurations at free stream conditions representative of entry into the atmosphere of Venus. These data are compared with solutions obtained using other methods of analysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150021042','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150021042"><span id="translatedtitle">CFD Validation Experiment of a Mach 2.5 Axisymmetric <span class="hlt">Shock-Wave/Boundary-Layer</span> Interaction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Davis, David Owen</p> <p>2015-01-01</p> <p>Preliminary results of an experimental investigation of a Mach 2.5 two-dimensional axisymmetric <span class="hlt">shock</span>-wave/ boundary-<span class="hlt">layer</span> interaction (SWBLI) are presented. The purpose of the investigation is to create a SWBLI dataset specifically for CFD validation purposes. Presented herein are the details of the facility and preliminary measurements characterizing the facility and interaction region. These results will serve to define the region of interest where more detailed mean and turbulence measurements will be made.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900010219','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900010219"><span id="translatedtitle">Swept <span class="hlt">shock</span>/boundary <span class="hlt">layer</span> interaction experiments in support of CFD code validation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Settles, G. S.; Lee, Y.</p> <p>1990-01-01</p> <p>Research on the topic of <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span> interaction was carried out. Skin friction and surface pressure measurements in fin-induced, swept interactions were conducted, and heat transfer measurements in the same flows are planned. The skin friction data for a strong interaction case (Mach 4, fin-angles equal 16 and 20 degrees) were obtained, and their comparison with computational results was published. Surface pressure data for weak-to-strong fin interactions were also obtained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950047148&hterms=steady+state&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dsteady%2Bstate','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950047148&hterms=steady+state&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dsteady%2Bstate"><span id="translatedtitle">Investigation of intrinsic variability in one-dimensional <span class="hlt">parallel</span> <span class="hlt">shocks</span> using steady state hybrid simulations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bennett, Lee; Ellison, Donald C.</p> <p>1995-01-01</p> <p>We have developed a means of producing a steady state hybrid simulation of a collisionless <span class="hlt">shock</span>. The <span class="hlt">shock</span> is stopped in the simulation box by transforming into the <span class="hlt">shock</span> frame and by modifying the downstream boundary conditions to allow the plasma to flow through the simulation box. Once the <span class="hlt">shock</span> is stationary in the box frame, the simulation can be run for an arbitrary time with a fixed box size and a fixed number of simulation particles. Using this technique, we have shown that certain gross properties associated with the <span class="hlt">shock</span>, such as the particle distribution function (including energetic particles produced by Fermi acceleration) and the flow speed profile, are constant (except for statistical variations) over hundreds of gyroperiods when averaged over times short compared to the average residence time of energetic particles. Our results imply that any microphysical processes responsible for particle heating and/or injection into the Fermi mechanism can be viewed as smooth and continuous on timescales longer than a few gyroperiods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016IJMPS..4260186Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016IJMPS..4260186Y"><span id="translatedtitle">Large-Eddy Simulation of <span class="hlt">Shock</span>-Wave Boundary <span class="hlt">Layer</span> Interaction and its Control Using Sparkjet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, Guang; Yao, Yufeng; Fang, Jian; Gan, Tian; Lu, Lipeng</p> <p>2016-06-01</p> <p>Large-eddy simulation (LES) of an oblique <span class="hlt">shock</span>-wave generated by an 8° sharp wedge impinging onto a spatially-developing Mach 2.3 turbulent boundary <span class="hlt">layer</span> and their interactions has been carried out in this study. The Reynolds number based on the incoming flow property and the boundary <span class="hlt">layer</span> displacement thickness at the impinging point without <span class="hlt">shock</span>-wave is 20,000. The detailed numerical approaches are described and the inflow turbulence is generated using the digital filter method to avoid artificial temporal or streamwise periodicity. Numerical results are compared with the available wind tunnel PIV measurements of the same flow conditions. Further LES study on the control of flow separation due to the strong <span class="hlt">shock</span>-viscous interaction is also conducted by using an active control actuator “SparkJet” concept. The single-pulsed characteristics of the control device are obtained and compared with the experiments. Instantaneous flowfield shows that the “SparkJet” promotes the flow mixing in the boundary <span class="hlt">layer</span> and enhances its ability to resist the flow separation. The time and spanwise averaged skin friction coefficient distribution demonstrates that the separation bubble length is reduced by maximum 35% with the control exerted.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EUCAS...3..141S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EUCAS...3..141S"><span id="translatedtitle">Effect on a <span class="hlt">shock</span> wave boundary <span class="hlt">layer</span> interaction of air jet vortex generators</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Souverein, L. J.; Debiève, J.-F.</p> <p>2012-01-01</p> <p>The effect of upstream injection by means of continuous Air Jet Vortex Generators (AJVGs) on a <span class="hlt">shock</span> wave turbulent boundary <span class="hlt">layer</span> interaction is experimentally investigated. The baseline interaction is of the impinging type, with a flow deflection angle of 9.5° , a Mach number Me = 2.3, and a momentum thickness based Reynolds number of 5,000. Considered are the effects of the AJVGs on the upstream boundary <span class="hlt">layer</span> flow topology and on the spatial and dynamical characteristics of the interaction. To this aim, Stereoscopic Particle Image Velocimetry has been employed, in addition to hot-wire anemometry (HWA) for the investigation of the dynamical characteristics of the reflected <span class="hlt">shock</span>. It is shown that the AJVGs significantly modify the three-dimensionality of the upstream boundary <span class="hlt">layer</span>. Overall, the AJVGs cause a reduction of the separation bubble length and height. In addition, the energetic frequency range of the reflected <span class="hlt">shock</span> is increased by approximately 50%, which is in qualitative agreement with the smaller separation bubble size.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920023250','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920023250"><span id="translatedtitle">Swept <span class="hlt">shock</span>/boundary <span class="hlt">layer</span> interaction experiments in support of CFD code validation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Settles, G. S.; Lee, Y.</p> <p>1992-01-01</p> <p>Research on the topic of <span class="hlt">shock</span> wave/turbulent boundary-<span class="hlt">layer</span> interaction was carried out during the past three years at the Penn State Gas Dynamics Laboratory. This report describes the experimental research program which provides basic knowledge and establishes new data on heat transfer in swept <span class="hlt">shock</span> wave/boundary-<span class="hlt">layer</span> interactions. An equilibrium turbulent boundary-<span class="hlt">layer</span> on a flat plate is subjected to impingement by swept planar <span class="hlt">shock</span> waves generated by a sharp fin. Five different interactions with fin angle ranging from 10 deg to 20 deg at freestream Mach numbers of 3.0 and 4.0 produce a variety of interaction strengths from weak to very strong. A foil heater generates a uniform heat flux over the flat plate surface, and miniature thin-film-resistance sensors mounted on it are used to measure the local surface temperature. The heat convection equation is then solved for the heat transfer distribution within an interaction, yielding a total uncertainty of about +/- 10 percent. These experimental data are compared with the results of numerical Navier-Stokes solutions which employ a k-epsilon turbulence model. Finally, a simplified form of the peak heat transfer correlation for fin interactions is suggested.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930046822&hterms=earths+magnetic+field&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dearths%2Bmagnetic%2Bfield','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930046822&hterms=earths+magnetic+field&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dearths%2Bmagnetic%2Bfield"><span id="translatedtitle">Nonthermal ions and associated magnetic field behavior at a quasi-<span class="hlt">parallel</span> earth's bow <span class="hlt">shock</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wilkinson, W. P.; Pardaens, A. K.; Schwartz, S. J.; Burgess, D.; Luehr, H.; Kessel, R. L.; Dunlop, M.; Farrugia, C. J.</p> <p>1993-01-01</p> <p>Attention is given to ion and magnetic field measurements at the earth's bow <span class="hlt">shock</span> from the AMPTE-UKS and -IRM spacecraft, which were examined in high time resolution during a 45-min interval when the field remained closely aligned with the model bow <span class="hlt">shock</span> normal. Dense ion beams were detected almost exclusively in the midst of short-duration periods of turbulent magnetic field wave activity. Many examples of propagation at large elevation angles relative to the ecliptic plane, which is inconsistent with reflection in the standard model <span class="hlt">shock</span> configuration, were discovered. The associated waves are elliptically polarized and are preferentially left-handed in the observer's frame of reference, but are less confined to the maximum variance plane than other previously studied foreshock waves. The association of the wave activity with the ion beams suggests that the former may be triggered by an ion-driven instability, and possible candidates are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1991thph.confQ....G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991thph.confQ....G"><span id="translatedtitle">A viscous-<span class="hlt">shock-layer</span> analysis of the Martian aerothermal environment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gupta, R. N.; Moss, J. N.; Sutton, K.; Lee, K. P.</p> <p>1991-06-01</p> <p>Surface heating and flow field results for the stagnation region of a planetary exploration vehicle entering the Martian atmosphere are presented. Solutions for the high-energy viscous flow fields with complete radiative heating are derived from a viscous-<span class="hlt">shock-layer</span> analysis for laminar flow under chemical equilibrium conditions. Results are shown with and without coupled radiation ablation injection utilizing the recently developed curve fits for the transport and thermodynamic properties of Martian atmospheric and ablation species. This analysis includes a strongly absorbing boundary <span class="hlt">layer</span> and, therefore, gives much lower radiative heat transfer rates than those obtained from inviscid analyses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890010729','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890010729"><span id="translatedtitle">Documentation of Two- and Three-Dimensional Hypersonic <span class="hlt">Shock</span> Wave/Turbulent Boundary <span class="hlt">Layer</span> Interaction Flows</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kussoy, Marvin I.; Horstman, Clifford C.</p> <p>1989-01-01</p> <p>Experimental data for a series of two- and three-dimensional <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span> interaction flows at Mach 7 are presented. Test bodies, composed of simple geometric shapes, were designed to generate flows with varying degrees of pressure gradient, boundary-<span class="hlt">layer</span> separation, and turning angle. The data include surface-pressure and heat-transfer distributions as well as limited mean-flow-field surveys in both the undisturbed and the interaction regimes. The data are presented in a convenient form for use in validating existing or future computational models of these generic hypersonic flows.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24476280','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24476280"><span id="translatedtitle">Megavolt <span class="hlt">parallel</span> potentials arising from double-<span class="hlt">layer</span> streams in the Earth's outer radiation belt.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mozer, F S; Bale, S D; Bonnell, J W; Chaston, C C; Roth, I; Wygant, J</p> <p>2013-12-01</p> <p>Huge numbers of double <span class="hlt">layers</span> carrying electric fields <span class="hlt">parallel</span> to the local magnetic field line have been observed on the Van Allen probes in connection with in situ relativistic electron acceleration in the Earth's outer radiation belt. For one case with adequate high time resolution data, 7000 double <span class="hlt">layers</span> were observed in an interval of 1 min to produce a 230,000 V net <span class="hlt">parallel</span> potential drop crossing the spacecraft. Lower resolution data show that this event lasted for 6 min and that more than 1,000,000 volts of net <span class="hlt">parallel</span> potential crossed the spacecraft during this time. A double <span class="hlt">layer</span> traverses the length of a magnetic field line in about 15 s and the orbital motion of the spacecraft perpendicular to the magnetic field was about 700 km during this 6 min interval. Thus, the instantaneous <span class="hlt">parallel</span> potential along a single magnetic field line was the order of tens of kilovolts. Electrons on the field line might experience many such potential steps in their lifetimes to accelerate them to energies where they serve as the seed population for relativistic acceleration by coherent, large amplitude whistler mode waves. Because the double-<span class="hlt">layer</span> speed of 3100  km/s is the order of the electron acoustic speed (and not the ion acoustic speed) of a 25 eV plasma, the double <span class="hlt">layers</span> may result from a new electron acoustic mode. Acceleration mechanisms involving double <span class="hlt">layers</span> may also be important in planetary radiation belts such as Jupiter, Saturn, Uranus, and Neptune, in the solar corona during flares, and in astrophysical objects. PMID:24476280</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhRvL.111w5002M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhRvL.111w5002M"><span id="translatedtitle">Megavolt <span class="hlt">Parallel</span> Potentials Arising from Double-<span class="hlt">Layer</span> Streams in the Earth's Outer Radiation Belt</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mozer, F. S.; Bale, S. D.; Bonnell, J. W.; Chaston, C. C.; Roth, I.; Wygant, J.</p> <p>2013-12-01</p> <p>Huge numbers of double <span class="hlt">layers</span> carrying electric fields <span class="hlt">parallel</span> to the local magnetic field line have been observed on the Van Allen probes in connection with in situ relativistic electron acceleration in the Earth’s outer radiation belt. For one case with adequate high time resolution data, 7000 double <span class="hlt">layers</span> were observed in an interval of 1 min to produce a 230 000 V net <span class="hlt">parallel</span> potential drop crossing the spacecraft. Lower resolution data show that this event lasted for 6 min and that more than 1 000 000 volts of net <span class="hlt">parallel</span> potential crossed the spacecraft during this time. A double <span class="hlt">layer</span> traverses the length of a magnetic field line in about 15 s and the orbital motion of the spacecraft perpendicular to the magnetic field was about 700 km during this 6 min interval. Thus, the instantaneous <span class="hlt">parallel</span> potential along a single magnetic field line was the order of tens of kilovolts. Electrons on the field line might experience many such potential steps in their lifetimes to accelerate them to energies where they serve as the seed population for relativistic acceleration by coherent, large amplitude whistler mode waves. Because the double-<span class="hlt">layer</span> speed of 3100km/s is the order of the electron acoustic speed (and not the ion acoustic speed) of a 25 eV plasma, the double <span class="hlt">layers</span> may result from a new electron acoustic mode. Acceleration mechanisms involving double <span class="hlt">layers</span> may also be important in planetary radiation belts such as Jupiter, Saturn, Uranus, and Neptune, in the solar corona during flares, and in astrophysical objects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016ShWav.tmp...67I&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016ShWav.tmp...67I&link_type=ABSTRACT"><span id="translatedtitle">Effects of boundary <span class="hlt">layer</span> on flame propagation generated by forced ignition behind an incident <span class="hlt">shock</span> wave</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ishihara, S.; Tamura, S.; Ishii, K.; Kataoka, H.</p> <p>2016-07-01</p> <p>To study the effects of the boundary <span class="hlt">layer</span> on the deflagration to detonation transition (DDT) process, the mixture behind an incident <span class="hlt">shock</span> wave was ignited using laser breakdown. Ignition timing was controlled so that the interaction of the resulting flame with a laminar or turbulent boundary <span class="hlt">layer</span> could be examined. In the case of the interaction with a laminar boundary <span class="hlt">layer</span>, wrinkling of the flame was observed after the flame reached the corner of the channel. On the other hand, interaction with the turbulent boundary <span class="hlt">layer</span> distorted the flame front and increased the spreading rate of the flame followed by prompt DDT. The inner structure of the turbulent boundary <span class="hlt">layer</span> plays an important role in the DDT process. The region that distorted the flame within the turbulent boundary <span class="hlt">layer</span> was found to be the intermediate region 0.01< y/δ < 0.4 , where y is the distance from the wall and δ is the boundary <span class="hlt">layer</span> thickness. The flame disturbance by the turbulent motions is followed by the flame interaction with the inner <span class="hlt">layer</span> near the wall, which in turn generates a secondary-ignition kernel that produced a spherical accelerating flame, which ultimately led to the onset of detonation. After the flame reached the intermediate region, the time required for DDT was independent of the ignition position. The effect of the boundary <span class="hlt">layer</span> on the propagating flame, thus, became relatively small after the accelerating flame was generated.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930015972','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930015972"><span id="translatedtitle">Alfven wave transport effects in the time evolution of <span class="hlt">parallel</span> cosmic-ray modified <span class="hlt">shocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jones, T. W.</p> <p>1993-01-01</p> <p>Some of the issues associated with a more complete treatment of Alfven transport in cosmic ray <span class="hlt">shocks</span> are explored qualitatively. The treatment is simplified in some important respects, but some new issues are examined and for the first time a nonlinear, time dependent study of plane cosmic ray mediated <span class="hlt">shocks</span> with both the entropy producing effects of wave dissipation and effects due to the Alfven wave advection of the cosmic ray relative to the gas is included. Examination of the direct consequences of including the pressure and energy of the Alfven waves in the formalism began.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1015686','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1015686"><span id="translatedtitle"><span class="hlt">Parallel</span> adaptive Cartesian upwind methods for <span class="hlt">shock</span>-driven multiphysics simulation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Deiterding, Ralf</p> <p>2011-01-01</p> <p>The multiphysics fluid-structure interaction simulation of <span class="hlt">shock</span>-loaded thin-walled structures requires the dynamic coupling of a <span class="hlt">shock</span>-capturing flow solver to a solid mechanics solver for large deformations. By combining a Cartesian embedded boundary approach with dynamic mesh adaptation a generic software framework for such flow solvers has been constructed that allows easy exchange of the specific hydrodynamic finite volume upwind scheme and coupling to various explicit finite element solid dynamics solvers. The paper gives an overview of the computational approach and presents first simulations that couple the software to the general purpose solid dynamics code DYNA3D.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760012293','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760012293"><span id="translatedtitle">Flowfield analysis for successive oblique <span class="hlt">shock</span> wave-turbulent boundary <span class="hlt">layer</span> interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sun, C. C.; Childs, M. E.</p> <p>1976-01-01</p> <p>A computation procedure is described for predicting the flowfields which develop when successive interactions between oblique <span class="hlt">shock</span> waves and a turbulent boundary <span class="hlt">layer</span> occur. Such interactions may occur, for example, in engine inlets for supersonic aircraft. Computations are carried out for axisymmetric internal flows at M 3.82 and 2.82. The effect of boundary <span class="hlt">layer</span> bleed is considered for the M 2.82 flow. A control volume analysis is used to predict changes in the flow field across the interactions. Two bleed flow models have been considered. A turbulent boundary <span class="hlt">layer</span> program is used to compute changes in the boundary <span class="hlt">layer</span> between the interactions. The results given are for flows with two <span class="hlt">shock</span> wave interactions and for bleed at the second interaction site. In principle the method described may be extended to account for additional interactions. The predicted results are compared with measured results and are shown to be in good agreement when the bleed flow rate is low (on the order of 3% of the boundary <span class="hlt">layer</span> mass flow), or when there is no bleed. As the bleed flow rate is increased, differences between the predicted and measured results become larger. Shortcomings of the bleed flow models at higher bleed flow rates are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013PhDT.......247W&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013PhDT.......247W&link_type=ABSTRACT"><span id="translatedtitle">Control of a <span class="hlt">shock</span> wave-boundary <span class="hlt">layer</span> interaction using localized arc filament plasma actuators</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Webb, Nathan Joseph</p> <p></p> <p>Supersonic flight is currently possible, but expensive. Inexpensive supersonic travel will require increased efficiency of high-speed air entrainment, an integral part of air-breathing propulsion systems. Although mixed compression inlet geometry can significantly improve entrainment efficiency, numerous <span class="hlt">Shock</span> Wave-Boundary <span class="hlt">Layer</span> Interactions (SWBLIs) are generated in this configuration. The boundary <span class="hlt">layer</span> must therefore develop through multiple regions of adverse pressure gradient, causing it to thicken, and, in severe cases, separate. The associated increase in unsteadiness can have adverse effects on downstream engine hardware. The most severe consequence of these interactions is the increased aerodynamic blockage generated by the thickened boundary <span class="hlt">layer</span>. If the increase is sufficient, it can choke the flow, causing inlet unstart, and resulting in a loss of thrust and high transient forces on the engine, airframe, and aircraft occupants. The potentially severe consequences associated with SWBLIs require flow control to ensure proper operation. Traditionally, boundary <span class="hlt">layer</span> bleed has been used to control the interaction. Although this method is effective, it has inherent efficiency penalties. Localized Arc Filament Plasma Actuators (LAFPAs) are designed to generate perturbations for flow control. Natural flow instabilities act to amplify certain perturbations, allowing the LAFPAs to control the flow with minimal power input. LAFPAs also have the flexibility to maintain control over a variety of operating conditions. This work seeks to examine the effectiveness of LAFPAs as a separation control method for an oblique, impinging SWBLI. The low frequency unsteadiness in the reflected <span class="hlt">shock</span> was thought to be the natural manifestation of a Kelvin-Helmholtz instability in the shear <span class="hlt">layer</span> above the separation region. The LAFPAs were therefore placed upstream of the interaction to allow their perturbations to convect to the receptivity region (near the shear <span class="hlt">layer</span> origin</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950058842&hterms=Computers+Dependent&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DComputers%2BDependent','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950058842&hterms=Computers+Dependent&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DComputers%2BDependent"><span id="translatedtitle">Implementation of a 3D mixing <span class="hlt">layer</span> code on <span class="hlt">parallel</span> computers</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Roe, K.; Thakur, R.; Dang, T.; Bogucz, E.</p> <p>1995-01-01</p> <p>This paper summarizes our progress and experience in the development of a Computational-Fluid-Dynamics code on <span class="hlt">parallel</span> computers to simulate three-dimensional spatially-developing mixing <span class="hlt">layers</span>. In this initial study, the three-dimensional time-dependent Euler equations are solved using a finite-volume explicit time-marching algorithm. The code was first programmed in Fortran 77 for sequential computers. The code was then converted for use on <span class="hlt">parallel</span> computers using the conventional message-passing technique, while we have not been able to compile the code with the present version of HPF compilers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010PhRvB..82s5327Y&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010PhRvB..82s5327Y&link_type=ABSTRACT"><span id="translatedtitle">Energy spectrum of <span class="hlt">layered</span> semiconductors in a magnetic field <span class="hlt">parallel</span> to the <span class="hlt">layers</span>: Voigt geometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yoo, K. H.; Ram-Mohan, L. R.</p> <p>2010-11-01</p> <p>The electronic band structure of zinc-blende <span class="hlt">layered</span> semiconductor heterostructures is investigated theoretically in the presence of an in-plane magnetic field, a configuration we label as the Voigt geometry. We use a Lagrangian formulation for modeling the band structure in the individual <span class="hlt">layers</span> within the kṡP model. This approach has been shown by us to provide the correct ordering of the derivatives appearing in the multiband description of Schrödinger’s equations for the envelope functions through the application of the principle of stationary action. Finite element modeling of the action integral provides a natural and efficient approach to the inclusion of in-plane magnetic fields in the energy-level analysis. Calculations for quantum wells and superlattices are presented, and the complex energy-level structure obtained for the <span class="hlt">layered</span> structures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012ShWav..22..327V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012ShWav..22..327V"><span id="translatedtitle">Control of <span class="hlt">shock</span> unsteadiness in <span class="hlt">shock</span> boundary-<span class="hlt">layer</span> interaction on a compression corner using mechanical vortex generators</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Verma, S. B.; Manisankar, C.; Raju, C.</p> <p>2012-07-01</p> <p>An experimental study was conducted to control the unsteadiness of separation <span class="hlt">shock</span> in a Mach 2 24° compression ramp-induced interaction using mechanical vortex generators (VG). Control devices in the form of an array of single-row delta-ramps were placed upstream of the interaction region and tested for two streamwise locations with respect to the boundary <span class="hlt">layer</span> thickness ( δ) at the interaction location and height ` h' of the delta-ramps, i.e., at 27.5 δ or h/ δ = 0.65 and at 12.5 δ or h/ δ = 0.26, respectively. Surface oil study revealed traces of streamwise counter-rotating vortex pairs generated downstream of these devices. Measurements using pressure-sensitive paint also showed a spanwise sinusoidal pattern of wall pressure variation indicating generation of streamwise vortices from these control devices. These vortices, on interaction with the reverse flow in the separation bubble, replaced a well-defined separation line (for no control) by a highly corrugated separation line. In the region of separation, the mean pressure distribution gets modified while the peak rms value in the intermittent region of separation showed significant changes. Additionally, the spanwise spacing ` s' of the vertex of the delta ramps seemed to be an important parameter in controlling the peak rms value. A decrease in this spacing, i.e., VG1 with s = 0, significantly reduced the peak rms value (by 50 and 35 %) while an increase in the spacing, i.e., VG2 with s = 1 mm, consistently showed an increase (by 12 and 30 %) in the separation <span class="hlt">shock</span> unsteadiness relative to no control, irrespective of their placement location (of h/ δ = 0.65 and 0.26, respectively).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013PhDT.......338H&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013PhDT.......338H&link_type=ABSTRACT"><span id="translatedtitle">The effects of micro-vortex generators on normal <span class="hlt">shock</span> wave/boundary <span class="hlt">layer</span> interactions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Herges, Thomas G.</p> <p></p> <p><span class="hlt">Shock</span> wave/boundary-<span class="hlt">layer</span> interactions (SWBLIs) are complex flow phenomena that are important in the design and performance of internal supersonic and transonic flow fields such as engine inlets. This investigation was undertaken to study the effects of passive flow control devices on normal <span class="hlt">shock</span> wave/boundary <span class="hlt">layer</span> interactions in an effort to gain insight into the physics that govern these complex interactions. The work concentrates on analyzing the effects of vortex generators (VGs) as a flow control method by contributing a greater understanding of the flowfield generated by these devices and characterizing their effects on the SWBLI. The vortex generators are utilized with the goal of improving boundary <span class="hlt">layer</span> health (i.e., reducing/increasing the boundary-<span class="hlt">layer</span> incompressible shape factor/skin friction coefficient) through a SWBLI, increasing pressure recovery, and reducing flow distortion at the aerodynamic interface plane while adding minimal drag to the system. The investigation encompasses experiments in both small-scale and large-scale inlet testing, allowing multiple test beds for improving the characterization and understanding of vortex generators. Small-scale facility experiments implemented instantaneous schlieren photography, surface oil-flow visualization, pressure-sensitive paint, and particle image velocimetry to characterize the effects of an array of microramps on a normal <span class="hlt">shock</span> wave/boundary-<span class="hlt">layer</span> interaction. These diagnostics measured the time-averaged and instantaneous flow organization in the vicinity of the microramps and SWBLI. The results reveal that a microramp produces a complex vortex structure in its wake with two primary counter-rotating vortices surrounded by a train of Kelvin- Helmholtz (K-H) vortices. A streamwise velocity deficit is observed in the region of the primary vortices in addition to an induced upwash/downwash which persists through the normal <span class="hlt">shock</span> with reduced strength. The microramp flow control also increased the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012APS..DFDR25006G&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012APS..DFDR25006G&link_type=ABSTRACT"><span id="translatedtitle">Control of <span class="hlt">Shock</span>-Induced Boundary <span class="hlt">Layer</span> Separation by using Pulsed Plasma Jets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Greene, Benton R.; Clemens, Noel T.; Micka, Daniel</p> <p>2012-11-01</p> <p><span class="hlt">Shock</span>-induced turbulent boundary <span class="hlt">layer</span> separation can have many detrimental effects in supersonic flow including flow instability, fatigue of structural panels, and unstart in supersonic inlets. Pulsed plasma jets (or ``spark jets''), which are characterized by high bandwidth and the ability to direct momentum into the flow, are one promising method of reducing <span class="hlt">shock</span>-induced separation. The current study is focused on investigating the efficacy of plasma jets to reduce the separated flow induced by a compression ramp in a Mach 3 flow. Three different 3-jet actuator configurations are tested: 20° pitched, 45° pitched, and 22° pitched and 45° skewed. The jets are pulsed at frequencies between 2 kHz and 4 kHz with duty cycles between 5 and 15%. The <span class="hlt">shock</span> wave is generated using a 20° compression ramp, and the location of the <span class="hlt">shock</span>-induced separation is visualized using surface oil streak visualization as well as particle image velocimetry. The results of the study show that of the three configurations, the plasma jets pitched at 20° from the streamwise direction cause the greatest reduction in separation, and when pulsed at a frequency of 3.2 kHz and 12% duty cycle can reduce the size of the separation region by up to 40%. This work is supported by AFRL under SBIR contract.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013APS..DFDA30009R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013APS..DFDA30009R"><span id="translatedtitle">Simultaneous Concentration and Velocity Field Measurements in a <span class="hlt">Shock</span>-accelerated Mixing <span class="hlt">Layer</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Reese, Daniel; Oakley, Jason; Weber, Chris; Rothamer, David; Navarro, Jose; Bonazza, Riccardo</p> <p>2013-11-01</p> <p>The Richtmyer-Meshkov instability (RMI) is experimentally investigated at the Wisconsin <span class="hlt">Shock</span> Tube Laboratory. Simultaneous concentration and velocity field measurements from the mixing <span class="hlt">layer</span> of experimental RMI images are obtained through the application of the Advection-Corrected Correlation Image Velocimetry (ACCIV) technique. A statistically repeatable broadband initial condition is created by first setting up a gravitationally stable stagnation plane of helium +acetone over argon and then injecting the gases horizontally at the interface to create a shear <span class="hlt">layer</span>. The shear <span class="hlt">layer</span> is then accelerated by a Mach 2.2 planar <span class="hlt">shock</span> wave that causes the growth of any perturbations present at the interface, and time-separated image pair data of the mixing <span class="hlt">layer</span> are obtained using planar laser induced fluorescence (PLIF). The image pair is corrected to show relative acetone concentration, and is then used as input to the ACCIV algorithm to obtain velocity field results. These velocity field measurements are compared with those obtained from numerical simulations. Turbulent kinetic energy spectra are compared with particle imaging velocimetry (PIV) and simulation results to validate regions of applicability. We wish to thank the Department of Energy National Nuclear Security Administration for supporting this work.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950053670&hterms=left-handed&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dleft-handed','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950053670&hterms=left-handed&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dleft-handed"><span id="translatedtitle">Observation of a slow-mode <span class="hlt">shock</span> in the dayside magnetopause reconnection <span class="hlt">layer</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Walthour, D. W.; Sonnerup, B. U. O.; Russell, C. T.</p> <p>1995-01-01</p> <p>Plasma and magnetic field data from the International Sun Earth Explorer (ISEE) 2 spacecraft recorded on 29 Oct 1979 provide evidence for a slow <span class="hlt">shock</span> (SS) in the reconnection <span class="hlt">layer</span> of the dayside magnetopause. This <span class="hlt">layer</span> is bounded on the magnetosheath side by the SS and on the magnetospheric side by a rotational discontinuity (RD). The direction of the accelerated plasma flow, the earthward sense of the normal magnetic field across both discontinuities, and the relative orientation of the SS and the RD all indicate that the reconnection site was located south of the spacecraft. Examination of the substantial pressure anisotropy downstream of the SS explains two unusual properties of the <span class="hlt">shock</span>: (1) the slow-mode and intermediate-mode phase speeds are inverted downstream of the SS such that the RD propagates behind the SS rather than ahead of it; (2) the magnetic wave polarization reserves such that the SS initially displays a left-handed polarization and then switches to a right-handed polarization inside the <span class="hlt">shock</span> structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930064296&hterms=Wei+Li&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D60%26Ntt%3DWei%2BLi','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930064296&hterms=Wei+Li&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D60%26Ntt%3DWei%2BLi"><span id="translatedtitle">Numerical simulation of a <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span> interaction in a duct</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Yang, Wei-Li; Greber, Isaac</p> <p>1993-01-01</p> <p>A numerical investigation of the interaction of an incident oblique <span class="hlt">shock</span> wave with a turbulent duct flow is presented. The investigation consists of solving the three-dimensional, unsteady, compressible, mass averaged Navier-Stokes equations, using an implicit finite volume, lower-upper time marching code and incorporates the three-dimensional Baldwin-Lomax turbulence model. Computed results are obtained Mach number 2.9 for a turning angle of 13 degrees and Reynolds number based on duct width of 1.36 x 10 exp 7. Under various inlet conditions, the results clearly depict the flow characteristics, including the <span class="hlt">shock</span> geometry, the separated flow region, the wall pressure distribution, and the skin friction distribution. The findings provide a physical understanding of the three-dimensional vortex structure of the flow in a duct in which a <span class="hlt">shock</span> wave interacts with a turbulent boundary <span class="hlt">layer</span>. The results show that the ratio of the boundary <span class="hlt">layer</span> thickness to the duct width is the critical parameter in determining the separation structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980201099','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980201099"><span id="translatedtitle">Flowfield Measurements in a Slot-Bled Oblique <span class="hlt">Shock</span> Wave and Turbulent Boundary-<span class="hlt">Layer</span> Interaction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Davis, D. O.; Willis, B. P.; Hingst, W. R.</p> <p>1998-01-01</p> <p>An experimental investigation was conducted to determine the flowfield inside a bleed slot used to control an oblique <span class="hlt">shock</span>-wave and turbulent boundary-<span class="hlt">layer</span> interaction. The slot was oriented normal to the primary flow direction and had a width of 1.0 cm (primary flow direction), a length of 2.54 cm, and spanned 16.5 cm. The approach boundary <span class="hlt">layer</span> upstream of the interaction was nominally 3.0 cm thick. Two operating conditions were studied: M = 1.98 with a <span class="hlt">shock</span> generator deflection angle of 6 deg and M= 2.46 with a <span class="hlt">shock</span> generator deflection angle of 8 deg. Measurements include surface and flowfield static pressure, Pitot pressure, and total mass-flow through the slot. The results show that despite an initially two-dimensional interaction for the zero bleed-flow case, the slot does not remove mass uniformly in the spanwise direction. Inside the slot, the flow is characterized by two separation regions which significantly reduce the effective flow area. The upper separation region acts as an aerodynamic throat resulting in supersonic flow through much of the slot.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007APS..DFD.GO007B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007APS..DFD.GO007B&link_type=ABSTRACT"><span id="translatedtitle">Unsteady effects in normal <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span> interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bernardini, Matteo; Pirozzoli, Sergio; Grasso, Francesco</p> <p>2007-11-01</p> <p>The interaction of a spatially developing supersonic turbulent boundary <span class="hlt">layer</span> with a normal <span class="hlt">shock</span> wave is analyzed by means of direct numerical simulation of the compressible Navier-Stokes equations. At the selected flow conditions, corresponding to a mild <span class="hlt">shock</span>, no mean flow separation is observed. However, the flow is strongly unsteady, and intermittent regions of flow reversal are found near the wall, while large vortical structures are observed away from it. Such structures are mainly responsible for the amplification of noise and turbulence across the interaction zone. In particular, the sound field attains very large values (up to 162 dB) near the nominal impingement point. The intense acoustic loads occurring in the interaction zone are found to be strictly related to the Reynolds shear stress distribution. The analysis of the pressure energy spectra shows a behavior consistent with that observed in incompressible boundary <span class="hlt">layers</span> in adverse pressure gradient. In particular, a power-law scaling is recovered: at low frequencies the spectra scale as St^0.4, while at high frequencies they decay as St-5. The results show that the interacting <span class="hlt">shock</span> primarily acts as a low-pass filter for the turbulence spectra. The main effect is to enhance the low-frequency components while inhibiting the higher ones. We acknowledge the CASPUR computing consortium (University of Rome `La Sapienza') for providing the computational resources to perform the numerical simulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22011845','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22011845"><span id="translatedtitle">COULD COSMIC RAYS AFFECT INSTABILITIES IN THE TRANSITION <span class="hlt">LAYER</span> OF NONRELATIVISTIC COLLISIONLESS <span class="hlt">SHOCKS</span>?</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Stroman, Thomas; Pohl, Martin; Niemiec, Jacek; Bret, Antoine</p> <p>2012-02-10</p> <p>There is an observational correlation between astrophysical <span class="hlt">shocks</span> and nonthermal particle distributions extending to high energies. As a first step toward investigating the possible feedback of these particles on the <span class="hlt">shock</span> at the microscopic level, we perform particle-in-cell (PIC) simulations of a simplified environment consisting of uniform, interpenetrating plasmas, both with and without an additional population of cosmic rays. We vary the relative density of the counterstreaming plasmas, the strength of a homogeneous <span class="hlt">parallel</span> magnetic field, and the energy density in cosmic rays. We compare the early development of the unstable spectrum for selected configurations without cosmic rays to the growth rates predicted from linear theory, for assurance that the system is well represented by the PIC technique. Within the parameter space explored, we do not detect an unambiguous signature of any cosmic-ray-induced effects on the microscopic instabilities that govern the formation of a <span class="hlt">shock</span>. We demonstrate that an overly coarse distribution of energetic particles can artificially alter the statistical noise that produces the perturbative seeds of instabilities, and that such effects can be mitigated by increasing the density of computational particles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PPCF...58h5004C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PPCF...58h5004C"><span id="translatedtitle">Effect of collisional temperature isotropisation on ELM <span class="hlt">parallel</span> transport in a tokamak scrape-off <span class="hlt">layer</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Coulette, David; Hirstoaga, Sever A.; Manfredi, Giovanni</p> <p>2016-08-01</p> <p>We develop a hybrid model to describe the <span class="hlt">parallel</span> transport in a tokamak scrape-off <span class="hlt">layer</span> following an edge-localized mode (ELM) event. The <span class="hlt">parallel</span> dynamics is treated with a kinetic Vlasov–Poisson model, while the evolution of the perpendicular temperature {{T}\\bot} is governed by a fluid equation. The coupling is ensured by isotropising collisions. The model generalises an earlier approach where {{T}\\bot} was constant in space and time (Manfredi et al 2011 Plasma Phys. Control. Fusion 53 015012). Numerical results show that the main effect comes from electron–electron collisions, which limit the decrease of the <span class="hlt">parallel</span> electron temperature and increase the potential drop in the Debye sheath in front of the surface. Ion–ion collisions have an almost negligible impact. The net effect is an increased peak power load on the target plates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2835280','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2835280"><span id="translatedtitle"><span class="hlt">Parallel</span> combinatorial chemical synthesis using single-<span class="hlt">layer</span> poly(dimethylsiloxane) microfluidic devices</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dexter, Joseph P.; Parker, William</p> <p>2009-01-01</p> <p>Improving methods for high-throughput combinatorial chemistry has emerged as a major area of research because of the importance of rapidly synthesizing large numbers of chemical compounds for drug discovery and other applications. In this investigation, a novel microfluidic chip for performing <span class="hlt">parallel</span> combinatorial chemical synthesis was developed. Unlike past microfluidic systems designed for <span class="hlt">parallel</span> combinatorial chemistry, the chip is a single-<span class="hlt">layer</span> device made of poly(dimethylsiloxane) that is extremely easy and inexpensive to fabricate. Using the chip, a 2×2 combinatorial series of amide-formation reactions was performed. The results of this combinatorial synthesis indicate that the new device is an effective platform for running <span class="hlt">parallel</span> organic syntheses at significantly higher throughput than with past methodologies. Additionally, a design algorithm for scaling up the 2×2 combinatorial synthesis chip to address more complex cases was developed. PMID:20216962</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19790011875','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19790011875"><span id="translatedtitle">A study of the interaction of a normal <span class="hlt">shock</span> wave with a turbulent boundary <span class="hlt">layer</span> at transonic speeds</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Messiter, A. F.; Adamson, T. C., Jr.</p> <p>1979-01-01</p> <p>An asymptotic description is derived for the interaction of a weak normal <span class="hlt">shock</span> wave and a turbulent boundary <span class="hlt">layer</span> along a plane wall. In the case studied the nondimensional friction velocity is small in comparison with the nondimensional <span class="hlt">shock</span> strength, and the <span class="hlt">shock</span> wave extends well into the boundary <span class="hlt">layer</span>. Analytical results are described for the local pressure distribution and wall shear, and a criterion for incipient separation is proposed. A comparison of predicted pressures with available experimental data includes the effect of longitudinal wall curvature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016JKPS...68..520D&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016JKPS...68..520D&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Shock</span> waves and double <span class="hlt">layers</span> in a quantum electron-positron-ion plasma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dip, P. R.; Hossen, M. A.; Salahuddin, M.; Mamun, A. A.</p> <p>2016-02-01</p> <p>The ion-acoustic (IA) <span class="hlt">shock</span> waves and double <span class="hlt">layers</span> (DLs) in an unmagnetized, dissipative, quantum electron-positron-ion (EPI) plasma (composed of a viscous heavy ion fluid, Fermi electrons and positrons) have been theoretically investigated. The higher-order Burgers and Gardner equations are derived by employing the reductive perturbation method. The basic features of the IA <span class="hlt">shock</span> waves and the DLs are identified by analyzing the solutions of both the higher-order Burgers and Gardner equations. The ratio of the Fermi temperature of the positron to that of the electron, the Fermi pressure of electrons and positrons, the viscous force, the plasma particle number densities, etc. are found to change remarkably the basic features (viz. amplitude, width, phase speed, etc.) of the IA waves. The results of our investigation may be helpful in understanding the nonlinear features of localized IA waves propagating in quantum EPI plasmas which are ubiquitous in astrophysical, as well as laboratory, environments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19820054149&hterms=1082&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3D%2526%25231082','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19820054149&hterms=1082&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3D%2526%25231082"><span id="translatedtitle">Tangential blowing for control of strong normal <span class="hlt">shock</span> - Boundary <span class="hlt">layer</span> interactions on inlet ramps</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schwendemann, M. F.; Sanders, B. W.</p> <p>1982-01-01</p> <p>The use of tangential blowing from a row of holes in an aft facing step is found to provide good control of the ramp boundary <span class="hlt">layer</span>, normal <span class="hlt">shock</span> interaction on a fixed geometry inlet over a wide range of inlet mass flow ratios. Ramp Mach numbers of 1.36 and 1.96 are investigated. The blowing geometry is found to have a significant effect on system performance at the highest Mach number. The use of high-temperature air in the blowing system, however, has only a slight effect on performance. The required blowing rates are significantly high for the most severe test conditions. In addition, the required blowing coefficient is found to be proportional to the normal <span class="hlt">shock</span> pressure rise.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19870035428&hterms=doppler+scaling&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Ddoppler%2Bscaling','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19870035428&hterms=doppler+scaling&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Ddoppler%2Bscaling"><span id="translatedtitle">Two-component LDV investigation of 3-dimensional <span class="hlt">shock</span>/turbulent boundary <span class="hlt">layer</span> interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Brown, J. D.; Brown, J. L.; Kussoy, M. I.; Horstman, C. C.; Holt, M.</p> <p>1987-01-01</p> <p>Mean-velocity and turbulence measurements obtained by two-component laser Doppler velocimetry are presented, together with numerical predictions, for the <span class="hlt">shock</span>-related separation of a turbulent boundary <span class="hlt">layer</span> at Mach 2.85. The basic geometry, a 30 deg half-angle flare mounted on a long cylinder, is made three-dimensional by tipping the flare at an angle of attack, alpha. The separation length and general upstream influence increase with alpha. A recirculating vortex in the separated zone becomes stronger as three-dimensionality increases. A large-scale unsteadiness of the separation <span class="hlt">shock</span> wave and surrounding flowfields grows in amplitude with alpha, and appears to strongly influence the amplification of turbulence correlations ahead of detachment. Scaling of the streamwise coordinate by separation length causes two-dimensional and three-dimensional data profiles on the cylinder to collapse for most measured quantities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19880018135','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19880018135"><span id="translatedtitle">A documentation of two- and three-dimensional <span class="hlt">shock</span>-separated turbulent boundary <span class="hlt">layers</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Brown, J. D.; Brown, J. L.; Kussoy, M. I.</p> <p>1988-01-01</p> <p>A <span class="hlt">shock</span>-related separation of a turbulent boundary <span class="hlt">layer</span> has been studied and documented. The flow was that of an axisymmetric turbulent boundary <span class="hlt">layer</span> over a 5.02-cm-diam cylinder that was aligned with the wind tunnel axis. The boundary <span class="hlt">layer</span> was compressed by a 30 deg half-angle conical flare, with the cone axis inclined at an angle alpha to the cylinder axis. Nominal test conditions were P sub tau equals 1.7 atm and M sub infinity equals 2.85. Measurements were confined to the upper-symmetry, phi equals 0 deg, plane. Data are presented for the cases of alpha equal to 0. 5. and 10 deg and include mean surface pressures, streamwise and normal mean velocities, kinematic turbulent stresses and kinetic energies, as well as reverse-flow intermittencies. All data are given in tabular form; pressures, streamwise velocities, turbulent shear stresses, and kinetic energies are also presented graphically.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/pages/biblio/1321421-technique-forming-solid-d2-layers-shock-timing-experiments-national-ignition-facility','SCIGOV-DOEP'); return false;" href="http://www.osti.gov/pages/biblio/1321421-technique-forming-solid-d2-layers-shock-timing-experiments-national-ignition-facility"><span id="translatedtitle">Technique for Forming Solid D2 and D-T <span class="hlt">Layers</span> for <span class="hlt">Shock</span> Timing Experiments at the National Ignition Facility</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGESBeta</a></p> <p>Sater, J. D.; Espinosa-Loza, F.; Kozioziemski, B.; Mapoles, E. R.</p> <p>2016-07-11</p> <p>Capsule implosion experiments on the National Ignition Facility (NIF) are driven with a carefully tailored laser pulse that delivers a sequence of <span class="hlt">shocks</span> to the ablator and fuel. In order to ensure the <span class="hlt">shocks</span> converge at the desired position, the <span class="hlt">shock</span> strength and velocity are measured in experimental platforms referred to as keyhole targets. We made <span class="hlt">shock</span> measurements on capsules completely filled with liquid deuterium for the solid deuterium tritide (D-T) <span class="hlt">layer</span> campaigns. Modeling has been used to extend these results to form an estimate of the <span class="hlt">shock</span> properties in solid D-T <span class="hlt">layers</span>. Furthermore, to verify and improve the surrogacymore » of the liquid-filled keyhole measurements, we have developed a technique to form a solid <span class="hlt">layer</span> inside the keyhole capsule. The <span class="hlt">layer</span> is typically uniform over a 400-μm-diameter area. This is sufficient to allow direct measurement of the <span class="hlt">shock</span> velocity. This <span class="hlt">layering</span> technique has been successfully applied to 13 experiments on the NIF. The technique may also be applicable to fast-igniter experiments since some proposed designs resemble keyhole targets. We discuss our method in detail and give representative results.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMSH21A2189L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMSH21A2189L"><span id="translatedtitle">A Focused Transport Approach to SEP acceleration at a Fast <span class="hlt">Parallel</span> <span class="hlt">Shock</span> in the Corona Including Self-excitation of Alfvén Waves</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>le Roux, J. A.</p> <p>2012-12-01</p> <p>It has been argued that the acceleration of SEPS at a quasi-<span class="hlt">parallel</span> CME-driven <span class="hlt">shock</span> to GeV energies in the corona only occurs if strong wave-excitation by SEPs ahead of the <span class="hlt">shock</span> reduces the <span class="hlt">parallel</span> mean free path upstream, thus boosting the rate of diffusive <span class="hlt">shock</span> acceleration. To investigate this issue, we modeled SEP acceleration at a fast <span class="hlt">parallel</span> traveling <span class="hlt">shock</span> in the corona with an existing time-dependent focused transport model. The model has been expanded recently to also feature time-dependent self-excitation and damping of Alfvén waves by SEP anisotropies ahead of the <span class="hlt">shock</span> based on standard quasi-linear theory. Alfvén wave propagation near the traveling <span class="hlt">shock</span> is modeled based on standard theory for wave transport in a slowly varying non-uniform plasma medium. Preliminary results will be shown to illustrate the increase in wave power driven by SEP anisotropies upstream, the effect of the <span class="hlt">shock</span> wave in shortening the wave length and increasing the wave amplitude of Alfvén waves, and the associated acceleration of SEPs by 1st order Fermi acceleration to high energies. The role of the acceleration of the cross-<span class="hlt">shock</span> solar wind flow, which was found to create a downstream population of <span class="hlt">shock</span> pre-heated particles which forms an additional source for injection into 1st order Fermi acceleration, will be discussed in terms of how it affects self-excitation of Alfvén waves and the formation of high-energy SEPs by 1st order Fermi acceleration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25441032','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25441032"><span id="translatedtitle"><span class="hlt">Shock</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wacker, David A; Winters, Michael E</p> <p>2014-11-01</p> <p>Critically ill patients with undifferentiated <span class="hlt">shock</span> are complex and challenging cases in the ED. A systematic approach to assessment and management is essential to prevent unnecessary morbidity and mortality. The simplified, systematic approach described in this article focuses on determining the presence of problems with cardiac function (the pump), intravascular volume (the tank), or systemic vascular resistance (the pipes). With this approach, the emergency physician can detect life-threatening conditions and implement time-sensitive therapy. PMID:25441032</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930083553','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930083553"><span id="translatedtitle">Study of the Pressure Rise Across <span class="hlt">Shock</span> Waves Required to Separate Laminar and Turbulent Boundary <span class="hlt">Layers</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Donaldson, Coleman Dup; Lange, Roy H</p> <p>1952-01-01</p> <p>Results are presented of a dimensional study and an experimental investigation of the pressure rise across a <span class="hlt">shock</span> wave which causes separation of the boundary <span class="hlt">layer</span> on a flat plate. The experimental part of the investigation was conducted at a Mach number of 3.03 for a Reynolds number range of 2 x 10 (sup) 6 to 19 x 10 (sup) 6. The available experimental data are compared with the predictions of the present study, and the significance of the results obtained is discussed relative to certain practical design problems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910004339','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910004339"><span id="translatedtitle">Turbulence modeling for sharp-fin-induced <span class="hlt">shock</span> wave/turbulent boundary-<span class="hlt">layer</span> interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Horstman, C. C.</p> <p>1990-01-01</p> <p>Solutions of the Reynolds averaged Navier-Stokes equations are presented and compared with a family of experimental results for the 3-D interaction of a sharp fin induced <span class="hlt">shock</span> wave with a turbulent boundary <span class="hlt">layer</span>. Several algebraic and two equation eddy viscosity turbulence models are employed. The computed results are compared with experimental surface pressure, skin friction, and yaw angle data as well as the overall size of the interaction. Although the major feature of the flow fields are correctly predicted, several discrepancies are noted. Namely, the maximum skin friction values are significantly underpredicted for the strongest interaction cases. These and other deficiencies are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890011581','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890011581"><span id="translatedtitle">Turbulent eddy viscosity modeling in transonic <span class="hlt">shock/boundary-layer</span> interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Inger, G. R.</p> <p>1989-01-01</p> <p>The treatment of turbulence effects on transonic <span class="hlt">shock</span>/turbulent boundary <span class="hlt">layer</span> interaction is addressed within the context of a triple deck approach valid for arbitrary practical Reynolds numbers between 1000 and 10 billion. The modeling of the eddy viscosity and basic turbulent boundary profile effects in each deck is examined in detail using Law-of-the-Wall/Law-of-the-Wake concepts as the foundation. Results of parametric studies showing how each of these turbulence model aspects influences typical interaction zone property distributions (wall pressure, displacement thickness and local skin friction) are presented and discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750022397','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750022397"><span id="translatedtitle">Computer user's guide for a chemically reacting viscous <span class="hlt">shock-layer</span> program</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Miner, E. W.; Lewis, C. H.</p> <p>1975-01-01</p> <p>A description is given of the computer code for predicting viscous <span class="hlt">shock-layer</span> flows over nonanalytic blunt bodies (Program VISLNABB) for hypersonic, low Reynolds number flows. Four specific and one general body geometries are considered. In addition to sphere-cones, cylinder wedges and geometries defined in tabular form, options for hyperboloids and paraboloids are included. Details of the theory and results are included in a separate engineering report. The program, subroutines, variables in common, and input and output data are described. Listings of the program code, output data for a sample case, and the input data for this sample case are included.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19880035137&hterms=you+measure+friction&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dyou%2Bmeasure%2Bfriction','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19880035137&hterms=you+measure+friction&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dyou%2Bmeasure%2Bfriction"><span id="translatedtitle">Skin friction measurements by laser interferometry in swept <span class="hlt">shock</span> wave/turbulent boundary-<span class="hlt">layer</span> interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kim, Kwang-Soo; Settles, Gary S.</p> <p>1988-01-01</p> <p>The laser interferometric skin friction meter was used to measure wall shear stress distributions in two interactions of fin-generated swept <span class="hlt">shock</span> waves with turbulent boundary <span class="hlt">layers</span>. The basic research configuration was an unswept sharp-leading-edge fin of variable angle mounted on a flatplate. The results indicate that such measurements are practical in high-speed interacting flows, and that a repeatability of + or - 6 percent or better is possible. Marked increases in wall shear were observed in both swept interactions tested.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19900032767&hterms=upstream&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DTitle%26N%3D0%26No%3D90%26Ntt%3Dupstream','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19900032767&hterms=upstream&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DTitle%26N%3D0%26No%3D90%26Ntt%3Dupstream"><span id="translatedtitle">Upstream-influence scaling of fin-generated <span class="hlt">shock</span> wave boundary-<span class="hlt">layer</span> interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lu, Frank K.; Settles, Gary S.</p> <p>1990-01-01</p> <p>An upstream-influence scaling law, previously formulated through analysis of Mach 3 data, has been extended to Mach numbers from 2.5 through 4. For adiabatic, equilibrium, turbulent boundary <span class="hlt">layers</span>, there is no Mach number effect on the constants in the Reynolds number parameters of this law. In addition, based on local similarity, a new Mach number parameter, namely, the Mach number component of the incoming stream normal to the farfield upstream influence, is proposed. Scaling by either the incoming Mach number normal to the inviscid <span class="hlt">shock</span> or by the incoming Mach number normal to the farfield upstream influence is equivalent to scaling by the hypersonic similarity parameter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26813145','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26813145"><span id="translatedtitle">Bi-directional series-<span class="hlt">parallel</span> elastic actuator and overlap of the actuation <span class="hlt">layers</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Furnémont, Raphaël; Mathijssen, Glenn; Verstraten, Tom; Lefeber, Dirk; Vanderborght, Bram</p> <p>2016-02-01</p> <p>Several robotics applications require high torque-to-weight ratio and energy efficient actuators. Progress in that direction was made by introducing compliant elements into the actuation. A large variety of actuators were developed such as series elastic actuators (SEAs), variable stiffness actuators and <span class="hlt">parallel</span> elastic actuators (PEAs). SEAs can reduce the peak power while PEAs can reduce the torque requirement on the motor. Nonetheless, these actuators still cannot meet performances close to humans. To combine both advantages, the series <span class="hlt">parallel</span> elastic actuator (SPEA) was developed. The principle is inspired from biological muscles. Muscles are composed of motor units, placed in <span class="hlt">parallel</span>, which are variably recruited as the required effort increases. This biological principle is exploited in the SPEA, where springs (<span class="hlt">layers</span>), placed in <span class="hlt">parallel</span>, can be recruited one by one. This recruitment is performed by an intermittent mechanism. This paper presents the development of a SPEA using the MACCEPA principle with a self-closing mechanism. This actuator can deliver a bi-directional output torque, variable stiffness and reduced friction. The load on the motor can also be reduced, leading to a lower power consumption. The variable recruitment of the <span class="hlt">parallel</span> springs can also be tuned in order to further decrease the consumption of the actuator for a given task. First, an explanation of the concept and a brief description of the prior work done will be given. Next, the design and the model of one of the <span class="hlt">layers</span> will be presented. The working principle of the full actuator will then be given. At the end of this paper, experiments showing the electric consumption of the actuator will display the advantage of the SPEA over an equivalent stiff actuator. PMID:26813145</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhDT.......338H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT.......338H"><span id="translatedtitle">The effects of micro-vortex generators on normal <span class="hlt">shock</span> wave/boundary <span class="hlt">layer</span> interactions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Herges, Thomas G.</p> <p></p> <p><span class="hlt">Shock</span> wave/boundary-<span class="hlt">layer</span> interactions (SWBLIs) are complex flow phenomena that are important in the design and performance of internal supersonic and transonic flow fields such as engine inlets. This investigation was undertaken to study the effects of passive flow control devices on normal <span class="hlt">shock</span> wave/boundary <span class="hlt">layer</span> interactions in an effort to gain insight into the physics that govern these complex interactions. The work concentrates on analyzing the effects of vortex generators (VGs) as a flow control method by contributing a greater understanding of the flowfield generated by these devices and characterizing their effects on the SWBLI. The vortex generators are utilized with the goal of improving boundary <span class="hlt">layer</span> health (i.e., reducing/increasing the boundary-<span class="hlt">layer</span> incompressible shape factor/skin friction coefficient) through a SWBLI, increasing pressure recovery, and reducing flow distortion at the aerodynamic interface plane while adding minimal drag to the system. The investigation encompasses experiments in both small-scale and large-scale inlet testing, allowing multiple test beds for improving the characterization and understanding of vortex generators. Small-scale facility experiments implemented instantaneous schlieren photography, surface oil-flow visualization, pressure-sensitive paint, and particle image velocimetry to characterize the effects of an array of microramps on a normal <span class="hlt">shock</span> wave/boundary-<span class="hlt">layer</span> interaction. These diagnostics measured the time-averaged and instantaneous flow organization in the vicinity of the microramps and SWBLI. The results reveal that a microramp produces a complex vortex structure in its wake with two primary counter-rotating vortices surrounded by a train of Kelvin- Helmholtz (K-H) vortices. A streamwise velocity deficit is observed in the region of the primary vortices in addition to an induced upwash/downwash which persists through the normal <span class="hlt">shock</span> with reduced strength. The microramp flow control also increased the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012PhDT.......176P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012PhDT.......176P"><span id="translatedtitle">Direct Numerical Simulation of Two <span class="hlt">Shock</span> Wave/Turbulent Boundary <span class="hlt">Layer</span> Interactions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Priebe, Stephan</p> <p></p> <p>Direct numerical simulations (DNSs) of two <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span> interactions (STBLIs) are presented in this thesis. The first interaction is a 24° compression ramp at Mach 2.9, and the second interaction is an 8° compression ramp at Mach 7.2. The large-scale low-frequency unsteadiness in the Mach 2.9 DNS is investigated with the aim of shedding some light on its physical origin. Previous experimental and computational works have linked the unsteadiness either to fluctuations in the incoming boundary <span class="hlt">layer</span> or to a mechanism in the downstream separated flow. Consistent with experimental observations, the <span class="hlt">shock</span> in the DNS is found to undergo streamwise oscillations, which are broadband and occur at frequencies that are about two orders of magnitude lower than the characteristic frequency of the energy-containing turbulent scales in the incoming boundary <span class="hlt">layer</span>. Based on a coherence and phase analysis of signals at the wall and in the flow field, it is found that the low frequency <span class="hlt">shock</span> unsteadiness is statistically linked to pulsations of the downstream separated flow. The statistical link with fluctuations in the upstream boundary <span class="hlt">layer</span> is also investigated. A weak link is observed: the value of the low-frequency coherence with the upstream flow is found to lie just above the limit of statistical significance, which is determined by means of a Monte Carlo study. The dynamics of the downstream separated flow are characterized further based on low-pass filtered DNS fields. The results suggest that structural changes occur in the downstream separated flow during the low-frequency motions, including the breaking-up of the separation bubble, which is observed when the <span class="hlt">shock</span> moves downstream. The structural changes are described based on the Cf distribution through the interaction, as well as the velocity and vorticity fields. The possible link between the low-frequency dynamics observed in the DNS and results from global instability theory is explored. It</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19730051995&hterms=atomic+composition&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Datomic%2Bcomposition','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19730051995&hterms=atomic+composition&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Datomic%2Bcomposition"><span id="translatedtitle">Composition of the earth's atmosphere by <span class="hlt">shock-layer</span> radiometry during the PAET entry probe experiment.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Whiting, E. E.; Arnold, J. O.; Page, W. A.; Reynolds, R. M.</p> <p>1973-01-01</p> <p>A determination of the composition of the earth's atmosphere obtained from onboard radiometer measurements of the spectra emitted from the bow <span class="hlt">shock</span> <span class="hlt">layer</span> of a high-speed entry probe is reported. The N2, O2, CO2, and noble gas concentrations in the earth's atmosphere were determined to good accuracy by this technique. The results demonstrate unequivocally the feasibility of determining the composition of an unknown planetary atmosphere by means of a multichannel radiometer viewing optical emission from the heated atmospheric gases in the region between the bow <span class="hlt">shock</span> wave and the vehicle surface. The spectral locations in this experiment were preselected to enable the observation of CN violet, N2(+) first negative and atomic oxygen emission at 3870, 3910, and 7775 A, respectively. The atmospheric gases were heated and compressed by the <span class="hlt">shock</span> wave to a peak temperature of about 6100 K and a corresponding pressure of 0.4 atm. Complete descriptions of the data analysis technique and the onboard radiometer and its calibration are given.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013APS..DFD.1A017J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013APS..DFD.1A017J"><span id="translatedtitle">On the critical radii for ramp induced <span class="hlt">shock</span> wave and laminar boundary <span class="hlt">layer</span> interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>John, Bibin; Kulkarni, Vinayak</p> <p>2013-11-01</p> <p>The <span class="hlt">shock</span> wave and laminar boundary <span class="hlt">layer</span> interaction is classical example of viscous and inviscid interaction. All the characteristic features of this interaction like separation length, separation and reattachment locations, upstream influence etc. are dependent on the leading edge bluntness. Upstream over pressure region and interaction of entropy <span class="hlt">layer</span> with boundary <span class="hlt">layer</span> alter this dynamics in the presence of blunt leading edge. Two critical radii corresponding to maximum separation size and separation length equal to reference sharp leading edge case are observed for this interaction during the present numerical studies. Freestream Mach number, wall temperature and freestream stagnation enthalpy are the governing parameters for the two critical radii for given configuration. Numerical simulations are then carried out to understand the effect of these parameters on the magnitude of the critical radii. Entropy <span class="hlt">layer</span> swallowing by boundary <span class="hlt">layer</span> and extension of over pressure region are reconsidered for alterations in these radii. Present studies are found very useful in devising mechanism for estimation of critical radii and as well for incorporating the amendment in the same due to change in governing parameters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19780057957&hterms=bangalore&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dbangalore','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19780057957&hterms=bangalore&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dbangalore"><span id="translatedtitle">Injection slot location for boundary-<span class="hlt">layer</span> control in <span class="hlt">shock</span>-induced separation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Viswanath, P. R.; Sankaran, L.; Sagdeo, P. M.; Narasimha, R.; Prabhu, A.</p> <p>1978-01-01</p> <p>An experimental investigation of the effect of tangential air injection, when the injection slot is located inside of what would otherwise have been the dead air zone in a separated flow, in controlling <span class="hlt">shock</span>-induced turbulent boundary <span class="hlt">layer</span> separation is presented. The experiments were carried out at a free-stream Mach number of 2.5 in the separated flow induced by a compression corner with a 20 deg angle. The observations made were wall static pressures, pitot profiles, and schlieren visualizations of the flow. The results show that the present location for injection is more effective in suppressing boundary-<span class="hlt">layer</span> separation than the more conventional one, where the slot is located upstream of where separation would occur in the absence of injection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015DokPh..60...89S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015DokPh..60...89S"><span id="translatedtitle">Spatial ionization effects of a <span class="hlt">shock</span> <span class="hlt">layer</span> in the RAM-C-II flight experiment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Surzhikov, S. T.</p> <p>2015-02-01</p> <p>A three-dimensional computer model of the nonequilibrium ionization aerophysics of descent moduli entering dense atmospheric <span class="hlt">layers</span> with orbital velocity in the height range of 60-90 km is developed. A three-dimensional numerical analysis of the experimental data on the ionization of the <span class="hlt">shock</span> <span class="hlt">layer</span> near the surface of a hypersonic flying module having the form of a blunt-sphere cone with the flight velocity higher than 7.5 km/s at heights of 61-81 km is fulfilled. The data of the flight experiment are obtained in the framework of the RAM-C-II investigatory program. The use of a three-dimensional computer model made it possible to find the calculated data in good agreement with the flight experiment data, as well as to explain some spatial effects not considered before.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930015348','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930015348"><span id="translatedtitle">Intersecting <span class="hlt">Shock</span>-Wave/Turbulent Boundary-<span class="hlt">Layer</span> Interactions at Mach 8.3</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kussoy, M. I.; Horstman, K. C.</p> <p>1992-01-01</p> <p>Experimental data for two three-dimensional intersecting <span class="hlt">shock</span>-wave/turbulent boundary-<span class="hlt">layer</span> interaction flows at Mach 8.3 are presented. The test bodies, composed of two sharp fins fastened to a flat-plate test bed, were designed to generate flows with varying degrees of pressure gradient, boundary-<span class="hlt">layer</span> separation, and turning angle. The data include surface pressure and heat transfer distributions as well as mean flow-field surveys both in the undisturbed and interaction regimes. The data are presented in a convenient form to be used to validate existing or future computational models of these hypersonic flows. The data are also on a 3.5-inch diskette included and are available through E-mail.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013ExFl...54.1598E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013ExFl...54.1598E"><span id="translatedtitle">Experiments on transitional <span class="hlt">shock</span> wave--boundary <span class="hlt">layer</span> interactions at Mach 5</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Erdem, E.; Kontis, K.; Johnstone, E.; Murray, N. P.; Steelant, J.</p> <p>2013-10-01</p> <p>An experimental campaign was carried out to investigate transitional <span class="hlt">shock</span> wave--boundary <span class="hlt">layer</span> interactions (SWBLI) at Mach and unit Reynolds numbers of 5 and 15.9 × 106 1/m, respectively. An impinging <span class="hlt">shock</span> that generates 7° flow deflection resulted in separated SWBLI flowfield on axisymmetric centrebody. Various flow diagnostics were utilised such as schlieren photography, quantitative infrared thermography, shear sensitive liquid crystals, pressure sensitive paints and particle image velocimetry (PIV) to provide a complete time-averaged experimental data set. One nominally laminar case (with triggered transition due to SWBLI) and four natural transition cases with varying intermittency were tested. Heat transfer and shear stress peaks occurred around the reattachment point. For nominally laminar case, the separation induces transition, and thus, heat transfer and pressure peaks were found to be the highest. For the cases with natural transition with different intermittency levels, where incoming boundary <span class="hlt">layer</span> is in state of transition, the magnitude of pressure and heat transfer peaks initially started to increase reaching a maximum and afterwards decreased towards the highest intermittency case. The presence of streamwise vortices was apparent for laminar case. Pressure peaks were found to occur slightly downstream of heat flux/shear stress peaks. PIV results (for laminar case only) showed high levels of turbulence above the separation region, proving triggered transition behaviour.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080043603','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080043603"><span id="translatedtitle">Non-Boltzmann Modeling for Air <span class="hlt">Shock-Layer</span> Radiation at Lunar-Return Conditions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Johnston, Christopher O.; Hollis, Brian R.; Sutton, Kenneth</p> <p>2008-01-01</p> <p>This paper investigates the non-Boltzmann modeling of the radiating atomic and molecular electronic states present in lunar-return <span class="hlt">shock-layers</span>. The Master Equation is derived for a general atom or molecule while accounting for a variety of excitation and de-excitation mechanisms. A new set of electronic-impact excitation rates is compiled for N, O, and N2+, which are the main radiating species for most lunar-return <span class="hlt">shock-layers</span>. Based on these new rates, a novel approach of curve-fitting the non-Boltzmann populations of the radiating atomic and molecular states is developed. This new approach provides a simple and accurate method for calculating the atomic and molecular non-Boltzmann populations while avoiding the matrix inversion procedure required for the detailed solution of the Master Equation. The radiative flux values predicted by the present detailed non-Boltzmann model and the approximate curve-fitting approach are shown to agree within 5% for the Fire 1634 s case.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22038530','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22038530"><span id="translatedtitle">Modeling of the plasma generated in a rarefied hypersonic <span class="hlt">shock</span> <span class="hlt">layer</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Farbar, Erin D.; Boyd, Iain D.</p> <p>2010-10-15</p> <p>In this study, a rigorous numerical model is developed to simulate the plasma generated in a rarefied, hypersonic <span class="hlt">shock</span> <span class="hlt">layer</span>. The model uses the direct simulation Monte Carlo (DSMC) method to treat the particle collisions and the particle-in-cell (PIC) method to simulate the plasma dynamics in a self-consistent manner. The model is applied to compute the flow along the stagnation streamline in front of a blunt body reentering the Earth's atmosphere at very high velocity. Results from the rigorous DSMC-PIC model are compared directly to the standard DSMC modeling approach that uses the ambipolar diffusion approximation to simulate the plasma dynamics. It is demonstrated that the self-consistent computation of the plasma dynamics using the rigorous DSMC-PIC model captures many physical phenomena not accurately predicted by the standard modeling approach. These computations represent the first assessment of the validity of the ambipolar diffusion approximation when predicting the rarefied plasma generated in a hypersonic <span class="hlt">shock</span> <span class="hlt">layer</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19830055174&hterms=OM&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DOM','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19830055174&hterms=OM&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DOM"><span id="translatedtitle">An integral analysis of transonic normal <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span> interactions in internal flow</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Om, D.; Childs, M. E.</p> <p>1983-01-01</p> <p>An approximate integral viscous-inviscid interaction method is presented for calculating the development of a turbulent boundary <span class="hlt">layer</span> subjected to a normal <span class="hlt">shock</span> wave induced adverse pressure gradient in an internal axisymmetric flow. The inflow conditions and the downstream pressure are provided for the computation. In the supersonic region of <span class="hlt">shock</span> pressure rise, the Prandtl-Meyer function is used to couple the viscous and inviscid flows. An analytical model for the coupling process is postulated and appropriate equations are defined. Downstream of the sonic point, one-dimensional inviscid flow is assumed for coupling with the viscous flow. The turbulent boundary <span class="hlt">layer</span> is calculated using Green's integral lag-entrainment method. Comparisons of the solutions with the experimental data are made for interactions which are unseparated, near separation and separated. For comparison purposes, solutions to the time-dependent, mass-averaged, Navier-Stokes equations incorporating a two-equation, Wilcox-Rubesin turbulence model are also shown. The computed results from the integral method show good agreement with experimental data for unseparated interactions and reasonable agreement with the trend of the viscous effects when the interaction becomes increasingly separated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150006750','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150006750"><span id="translatedtitle">Mitigation of Adverse Effects Caused by <span class="hlt">Shock</span> Wave Boundary <span class="hlt">Layer</span> Interactions Through Optimal Wall Shaping</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Liou, May-Fun; Lee, Byung Joon</p> <p>2013-01-01</p> <p>It is known that the adverse effects of <span class="hlt">shock</span> wave boundary <span class="hlt">layer</span> interactions in high speed inlets include reduced total pressure recovery and highly distorted flow at the aerodynamic interface plane (AIP). This paper presents a design method for flow control which creates perturbations in geometry. These perturbations are tailored to change the flow structures in order to minimize <span class="hlt">shock</span> wave boundary <span class="hlt">layer</span> interactions (SWBLI) inside supersonic inlets. Optimizing the shape of two dimensional micro-size bumps is shown to be a very effective flow control method for two-dimensional SWBLI. In investigating the three dimensional SWBLI, a square duct is employed as a baseline. To investigate the mechanism whereby the geometric elements of the baseline, i.e. the bottom wall, the sidewall and the corner, exert influence on the flow's aerodynamic characteristics, each element is studied and optimized separately. It is found that arrays of micro-size bumps on the bottom wall of the duct have little effect in improving total pressure recovery though they are useful in suppressing the incipient separation in three-dimensional problems. Shaping sidewall geometry is effective in re-distributing flow on the side wall and results in a less distorted flow at the exit. Subsequently, a near 50% reduction in distortion is achieved. A simple change in corner geometry resulted in a 2.4% improvement in total pressure recovery.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014APS..DFDD35007S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APS..DFDD35007S"><span id="translatedtitle">Space-time measurements in a <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span> interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schreyer, Anne-Marie; Dupont, Pierre</p> <p>2014-11-01</p> <p>We study a reflected <span class="hlt">shock</span> interaction with separation at Mach 2, contributing to a better understanding of rocket engine nozzle flows. The flow field contains a wide range of characteristic frequencies between O (100) Hz for the oscillation of the reflected <span class="hlt">shock</span> and O (100) kHz for the turbulent microscales. To explain the origin and interdependence of the physical phenomena in the interaction, we need access to the spatio-temporal links. We thus require a measurement technique allowing the resolution of the entire frequency range while also providing sufficient spatial resolution and a large field of view. Our newly developed Dual-PIV system satisfies these requirements. First measurements with this system in an interaction flow field were performed in the continuous hypo-turbulent wind-tunnel at IUSTI at a momentum thickness Reynolds number of Reθ = 5024 and a deflection angle of θ = 8 .75° . We present a detailed characterization of the flow field including turbulence measurements. From measurements at a range of temporal delays, we determined autocorrelations at crucial points in the flow field (incoming boundary <span class="hlt">layer</span>, mixing <span class="hlt">layer</span>, relaxation zone). From these, spatio-temporal information like the integral scales and the convection velocity are deduced. This work received financial support by the CNES within the research program ATAC and also the ANR within the program DECOMOS. This support is gratefully acknowledged.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920071486&hterms=knowledge+transfer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dknowledge%2Btransfer','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920071486&hterms=knowledge+transfer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dknowledge%2Btransfer"><span id="translatedtitle">Heat transfer measurements and CFD comparison of swept <span class="hlt">shock</span> wave/boundary-<span class="hlt">layer</span> interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lee, Y.; Settles, G. S.; Horstman, C. C.</p> <p>1992-01-01</p> <p>An experimental research program providing basic knowledge and establishing new data on the heat transfer in swept <span class="hlt">shock</span> wave/boundary-<span class="hlt">layer</span> interactions is described. An equilibrium turbulent boundary-<span class="hlt">layer</span> on a flat plate is subjected to impingement by swept planar <span class="hlt">shock</span> waves generated by a sharp fin. Five different interactions with fin angles ranging from 10 to 20 deg at freestream Mach numbers of 3.0 and 4.0 produce a variety of interaction strengths from weak to very strong. A foil heater generates a uniform heat flux over the flat plate surface and miniature thin-film-resistance sensors mounted on it are used to measure the local surface temperature. The heat convection equation is then solved for the heat transfer distribution within an interaction, yielding a total uncertainty of about +/- 10 percent. These experimental data are compared with the results of numerical Navier-Stokes solutions which employ a kappa-epsilon turbulence model. Finally, a simplified form of the peak heat transfer correlation for fin interactions is suggested.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhDT.......156C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT.......156C"><span id="translatedtitle">Study of <span class="hlt">shock</span> wave boundary <span class="hlt">layer</span> interaction phenonemon using color schlieren and snapshot Proper Orthogonal Decomposition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chaganti Subrahmanya Datta, Narendra</p> <p></p> <p>The flow structure of shockwave boundary <span class="hlt">layer</span> interaction (SWBLI) has been studied using Rainbow Schlieren Deflectometry (RSD), Ensemble Averaging, Fast Fourier Transform (FFT), and snapshot Proper Orthogonal Decomposition (POD) techniques. The Mach number of the approach free-stream was Mach = 3. Shockwave was generated with a 12° wedge. The color schlieren pictures are used to determine the transverse ray deflections at each pixel of the pictures taken using a high speed camera. The interaction region structure is described statistically with the ensemble average and, root mean square deflections. FFT technique is used to determine the dominant frequencies at different regions of the flow field. Results indicate that low frequency oscillations dominate the flow field. The POD technique results complement the findings of the ensemble averaging technique and show that distinct regions contain most of the energy in the flow field. These distinct regions are located around the reflected <span class="hlt">shock</span>, around the <span class="hlt">shock</span> wave reaching into the approach boundary <span class="hlt">layer</span> and around the separation region over the edge of the separation bubble.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004RScI...75.4789S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004RScI...75.4789S"><span id="translatedtitle">On the efficiency of Gore-Tex <span class="hlt">layer</span> for brain protection from <span class="hlt">shock</span> wave damage in cranioplasty</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saito, T.; Voinovich, P. A.; Nakagawa, A.; Hosseini, S. H. R.; Takayama, K.; Hirano, T.</p> <p>2004-11-01</p> <p>The effectiveness of a Gore-Tex <span class="hlt">layer</span> for protecting soft tissue from damage in <span class="hlt">shock</span> wave therapy is investigated analytically, numerically and experimentally. Analytical considerations based on the fundamentals of wave dynamics and two-dimensional numerical simulations based on the elastodynamic equations are carried out for underwater <span class="hlt">shock</span> wave propagation and interaction with Gore-Tex membrane models of different complexity. The results clearly demonstrate that considerable attenuation of <span class="hlt">shock</span> waves with Gore-Tex is due to the air trapped inside the membrane. The experimental results confirm that a Gore-Tex sheet placed in the liquid reduces the transmitted <span class="hlt">shock</span> wave peak overpressure significantly, by up to two orders of magnitude. Another experimental series reveals what kind of damage in the rat brain tissue can be caused by <span class="hlt">shock</span> waves of different intensity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940010307','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940010307"><span id="translatedtitle">Interaction of two glancing, crossing <span class="hlt">shock</span> waves with a turbulent boundary-<span class="hlt">layer</span> at various Mach numbers</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hingst, Warren R.; Williams, Kevin E.</p> <p>1991-01-01</p> <p>A preliminary experimental investigation was conducted to study two crossing, glancing <span class="hlt">shock</span> waves of equal strengths, interacting with the boundary-<span class="hlt">layer</span> developed on a supersonic wind tunnel wall. This study was performed at several Mach numbers between 2.5 and 4.0. The <span class="hlt">shock</span> waves were created by fins (<span class="hlt">shock</span> generators), spanning the tunnel test section, that were set at angles varying from 4 to 12 degrees. The data acquired are wall static pressure measurements, and qualitative information in the form of oil flow and schlieren visualizations. The principle aim is two-fold. First, a fundamental understanding of the physics underlying this flow phenomena is desired. Also, a comprehensive data set is needed for computational fluid dynamic code validation. Results indicate that for small <span class="hlt">shock</span> generator angles, the boundary-<span class="hlt">layer</span> remains attached throughout the flow field. However, with increasing <span class="hlt">shock</span> strengths (increasing generator angles), boundary <span class="hlt">layer</span> separation does occur and becomes progressively more severe as the generator angles are increased further. The location of the separation, which starts well downstream of the <span class="hlt">shock</span> crossing point, moves upstream as <span class="hlt">shock</span> strengths are increased. At the highest generator angles, the separation appears to begin coincident with the generator leading edges and engulfs most of the area between the generators. This phenomena occurs very near the 'unstart' limit for the generators. The wall pressures at the lower generator angles are nominally consistent with the flow geometries (i.e. <span class="hlt">shock</span> patterns) although significantly affected by the boundary-<span class="hlt">layer</span> upstream influence. As separation occurs, the wall pressures exhibit a gradient that is mainly axial in direction in the vicinity of the separation. At the limiting conditions the wall pressure gradients are primarily in the axial direction throughout.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009APS..DFD.AD001W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009APS..DFD.AD001W"><span id="translatedtitle"><span class="hlt">Shock</span> Wave/Boundary <span class="hlt">Layer</span> Interaction Control in a Supersonic Inlet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Webb, Nathan; Caraballo, Edgar; Little, Jesse; Kim, Jin-Hwa; Samimy, Mo</p> <p>2009-11-01</p> <p>A <span class="hlt">shock</span> wave/boundary <span class="hlt">layer</span> interaction (SWBLI) occurs in a supersonic mixed compression inlet. The SWBLI could cause boundary <span class="hlt">layer</span> separation resulting in adverse consequences such as reduced pressure recovery and non-uniform fan loading. Boundary <span class="hlt">layer</span> bleed is currently used to prevent separation, which incurs a significant performance penalty. We have recently used Localized Arc Filament Plasma Actuators (LAFPAs) with high amplitude and wide bandwidth to control the SWBLI in a Mach 1.9 flow. The preliminary results are promising and show excellent potential for this technique. These actuators may affect the SWBLI by two mechanisms: manipulation of flow instabilities and/or streamwise vorticity generation. Particle image velocimetry measurements have confirmed that instability manipulation is the key to the LAFPAs' ability to significantly energize the boundary <span class="hlt">layer</span> in the interaction region. The streamwise vorticity effects are currently being investigated. The LAFPAs have been tested at varying frequency, duty cycle, and mode to determine the parameters with the maximum effectiveness. Supported by AFRL and AFOSR.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730022509','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730022509"><span id="translatedtitle">Prediction and measurement of heat transfer rates for the <span class="hlt">shock</span>-induced unsteady laminar boundary <span class="hlt">layer</span> on a flat plate</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cook, W. J.</p> <p>1972-01-01</p> <p>The unsteady laminar boundary <span class="hlt">layer</span> induced by the flow-initiating <span class="hlt">shock</span> wave passing over a flat plate mounted in a <span class="hlt">shock</span> tube was theoretically and experimentally studied in terms of heat transfer rates to the plate for <span class="hlt">shock</span> speeds ranging from 1.695 to 7.34 km/sec. The theory presented by Cook and Chapman for the <span class="hlt">shock</span>-induced unsteady boundary <span class="hlt">layer</span> on a plate is reviewed with emphasis on unsteady heat transfer. A method of measuring time-dependent heat-transfer rates using thin-film heat-flux gages and an associated data reduction technique are outlined in detail. Particular consideration is given to heat-flux measurement in short-duration ionized shocktube flows. Experimental unsteady plate heat transfer rates obtained in both air and nitrogen using thin-film heat-flux gages generally agree well with theoretical predictions. The experimental results indicate that the theory continues to predict the unsteady boundary <span class="hlt">layer</span> behavior after the <span class="hlt">shock</span> wave leaves the trailing edge of the plate even though the theory is strictly applicable only for the time interval in which the <span class="hlt">shock</span> remains on the plate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970018536','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970018536"><span id="translatedtitle">Experimental Investigation of Unsteady <span class="hlt">Shock</span> Wave Turbulent Boundary <span class="hlt">Layer</span> Interactions About a Blunt Fin</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Barnhart, Paul J.; Greber, Isaac</p> <p>1997-01-01</p> <p>A series of experiments were performed to investigate the effects of Mach number variation on the characteristics of the unsteady <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span> interaction generated by a blunt fin. A single blunt fin hemicylindrical leading edge diameter size was used in all of the experiments which covered the Mach number range from 2.0 to 5.0. The measurements in this investigation included surface flow visualization, static and dynamic pressure measurements, both on centerline and off-centerline of the blunt fin axis. Surface flow visualization and static pressure measurements showed that the spatial extent of the <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span> interaction increased with increasing Mach number. The maximum static pressure, normalized by the incoming static pressure, measured at the peak location in the separated flow region ahead of the blunt fin was found to increase with increasing Mach number. The mean and standard deviations of the fluctuating pressure signals from the dynamic pressure transducers were found to collapse to self-similar distributions as a function of the distance perpendicular to the separation line. The standard deviation of the pressure signals showed initial peaked distribution, with the maximum standard deviation point corresponding to the location of the separation line at Mach number 3.0 to 5.0. At Mach 2.0 the maximum standard deviation point was found to occur significantly upstream of the separation line. The intermittency distributions of the separation <span class="hlt">shock</span> wave motion were found to be self-similar profiles for all Mach numbers. The intermittent region length was found to increase with Mach number and decrease with interaction sweepback angle. For Mach numbers 3.0 to 5.0 the separation line was found to correspond to high intermittencies or equivalently to the downstream locus of the separation <span class="hlt">shock</span> wave motion. The Mach 2.0 tests, however, showed that the intermittent region occurs significantly upstream of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720010625','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720010625"><span id="translatedtitle">A thin-<span class="hlt">shock-layer</span> solution for nonequilibrium, inviscid hypersonic flows in earth, Martian, and Venusian atmospheres</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Grose, W. L.</p> <p>1971-01-01</p> <p>An approximate inverse solution is presented for the nonequilibrium flow in the inviscid <span class="hlt">shock</span> <span class="hlt">layer</span> about a vehicle in hypersonic flight. The method is based upon a thin-<span class="hlt">shock-layer</span> approximation and has the advantage of being applicable to both subsonic and supersonic regions of the <span class="hlt">shock</span> <span class="hlt">layer</span>. The relative simplicity of the method makes it ideally suited for programming on a digital computer with a significant reduction in storage capacity and computing time required by other more exact methods. Comparison of nonequilibrium solutions for an air mixture obtained by the present method is made with solutions obtained by two other methods. Additional cases are presented for entry of spherical nose cones into representative Venusian and Martian atmospheres. A digital computer program written in FORTRAN language is presented that permits an arbitrary gas mixture to be employed in the solution. The effects of vibration, dissociation, recombination, electronic excitation, and ionization are included in the program.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012SPIE.8539E..08H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012SPIE.8539E..08H"><span id="translatedtitle">GPU-based <span class="hlt">parallel</span> implementation of 5-<span class="hlt">layer</span> thermal diffusion scheme</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, Melin; Mielikainen, Jarno; Huang, Bormin; Huang, H.-L. A.; Goldberg, Mitchell D.</p> <p>2012-10-01</p> <p>The Weather Research and Forecasting (WRF) is a system of numerical weather prediction and atmospheric simulation with dual purposes for forecasting and research. The WRF software infrastructure consists of several components such as dynamic solvers and physical simulation modules. WRF includes several Land-Surface Models (LSMs). The LSMs use atmospheric information, the radiative and precipitation forcing from the surface <span class="hlt">layer</span> scheme, the radiation scheme, and the microphysics/convective scheme all together with the lands state variables and land-surface properties, to provide heat and moisture fluxes over land and sea-ice points. The WRF 5-<span class="hlt">layer</span> thermal diffusion simulation is an LSM based on the MM5 5-<span class="hlt">layer</span> soil temperature model with an energy budget that includes radiation, sensible, and latent heat flux. The WRF LSMs are very suitable for massively <span class="hlt">parallel</span> computation as there are no interactions among horizontal grid points. More and more scientific applications have adopted graphics processing units (GPUs) to accelerate the computing performance. This study demonstrates our GPU massively <span class="hlt">parallel</span> computation efforts on the WRF 5-<span class="hlt">layer</span> thermal diffusion scheme. Since this scheme is only an intermediate module of the entire WRF model, the I/O transfer does not involve in the intermediate process. Without data transfer, this module can achieve a speedup of 36x with one GPU and 108x with four GPUs as compared to a single threaded CPU processor. With CPU/GPU hybrid strategy, this module can accomplish a even higher speedup, ~114x with one GPU and ~240x with four GPUs. Meanwhile, we are seeking other approaches to improve the speeds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19780015447','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19780015447"><span id="translatedtitle">A numerical solution of the Navier-Stokes equations for chemically nonequilibrium, merged stagnation <span class="hlt">shock</span> <span class="hlt">layers</span> on spheres and two-dimensional cylinders in air</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Johnston, K. D.; Hendricks, W. L.</p> <p>1978-01-01</p> <p>Results of solving the Navier-Stokes equations for chemically nonequilibrium, merged stagnation <span class="hlt">shock</span> <span class="hlt">layers</span> on spheres and two-dimensional cylinders are presented. The effects of wall catalysis and slip are also examined. The thin <span class="hlt">shock</span> <span class="hlt">layer</span> assumption is not made, and the thick viscous <span class="hlt">shock</span> is allowed to develop within the computational domain. The results show good comparison with existing data. Due to the more pronounced merging of <span class="hlt">shock</span> <span class="hlt">layer</span> and boundary <span class="hlt">layer</span> for the sphere, the heating rates for spheres become higher than those for cylinders as the altitude is increased.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910023127','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910023127"><span id="translatedtitle">An approximate viscous <span class="hlt">shock</span> <span class="hlt">layer</span> technique for calculating chemically reacting hypersonic flows about blunt-nosed bodies</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cheatwood, F. Mcneil; Dejarnette, Fred R.</p> <p>1991-01-01</p> <p>An approximate axisymmetric method was developed which can reliably calculate fully viscous hypersonic flows over blunt nosed bodies. By substituting Maslen's second order pressure expression for the normal momentum equation, a simplified form of the viscous <span class="hlt">shock</span> <span class="hlt">layer</span> (VSL) equations is obtained. This approach can solve both the subsonic and supersonic regions of the <span class="hlt">shock</span> <span class="hlt">layer</span> without a starting solution for the <span class="hlt">shock</span> shape. The approach is applicable to perfect gas, equilibrium, and nonequilibrium flowfields. Since the method is fully viscous, the problems associated with a boundary <span class="hlt">layer</span> solution with an inviscid <span class="hlt">layer</span> solution are avoided. This procedure is significantly faster than the parabolized Navier-Stokes (PNS) or VSL solvers and would be useful in a preliminary design environment. Problems associated with a previously developed approximate VSL technique are addressed before extending the method to nonequilibrium calculations. Perfect gas (laminar and turbulent), equilibrium, and nonequilibrium solutions were generated for airflows over several analytic body shapes. Surface heat transfer, skin friction, and pressure predictions are comparable to VSL results. In addition, computed heating rates are in good agreement with experimental data. The present technique generates its own <span class="hlt">shock</span> shape as part of its solution, and therefore could be used to provide more accurate initial <span class="hlt">shock</span> shapes for higher order procedures which require starting solutions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1984cals.reptR....H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984cals.reptR....H"><span id="translatedtitle">Experimental studies of Quasi-Two-Dimensional and three-dimensional viscous interaction regions induced by skewed-<span class="hlt">shock</span> and swept-<span class="hlt">shock</span> boundary <span class="hlt">layer</span> interactions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Holden, M. S.</p> <p>1984-07-01</p> <p>This report describes results from 3 experimental studies designed to examine the aerothermal characteristics of regions of three-dimensional <span class="hlt">shock</span> wave/boundary <span class="hlt">layer</span> interaction in high-speed flow over non-adiabatic surfaces. The objectives were: (1) to explore the basic mechanisms associated with 3D boundary <span class="hlt">layer</span> separation in high-speed flows with special emphasis on the large heat transfer rates and gradients developed in the separation and reattachment regions of these flows; and (2) to obtain detailed sets of experimental measurements with which to extend the simple semi-empirical prediction methods to the hypersonic/cooled wall regime where no previous data existed. These studies were conducted at Mach 11 for Reynolds number of up to 40 million in Calspan's 96-Inch <span class="hlt">Shock</span> Tunnel. In the first study we examined the effects of crossflow on the scale and properties of attached and separated region induced over a flat plate at the base of skewed/oblique <span class="hlt">shocks</span>. Analysis of the detailed heat transfer and pressure measurements together with flow visualization demonstrated that, for sweep angles of up to 45 deg, crossflow had little effect on the size or characteristics of the interaction regions. In the second study the swept-<span class="hlt">shock</span> was induced normal to the flat plate boundary <span class="hlt">layer</span> by a <span class="hlt">shock</span> generator mounted perpendicular to the flat plate. Our corner flow measurements demonstrated that, in highly-cooled hypersonic flows, the pressure rise to induce incipient separation is significantly larger than predicted by the semi-empirical methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5975895','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5975895"><span id="translatedtitle">Turbulent heat transfer in <span class="hlt">parallel</span> flow boundary <span class="hlt">layers</span> with streamwise step changes in surface conditions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lindberg, W.R.; Lee, R.C.; Smathers, L.B. )</p> <p>1989-11-01</p> <p>This paper examines the convective heat/mass transfer behavior of a turbulent boundary <span class="hlt">layer</span> with <span class="hlt">parallel</span> streamlines. The most notable example of such flow is an atmospheric boundary <span class="hlt">layer</span> with a steady mean wind in the absence of topography. The classic, two-dimensional problem involves the surface boundary condition of a finite-length step change in temperature/concentration in the streamwise direction of an atmospheric flow. In the literature on geophysical evapotranspiration, this problem is known as Sutton's problem (cf. Sutton, 1934, and Brutsaert, 1984). This flow situation is equally applicable to heat/mass transfer in solar ponds, ground solar collectors, and heated roadways, as examples. The present note revisits the Sutton problem, with the can Driest eddy diffusivity model, and expands the types of boundary conditions that are examined to include surface changes in temperature/concentration and fluxes. The <span class="hlt">parallel</span> streamline condition allows for Graetz-type solutions, with boundary conditions at the surface and in the far flow field. The predicted results are presented as a series of power law correlations of the relevant nondimensional parameters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040090527','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040090527"><span id="translatedtitle"><span class="hlt">Shock-Wave/Boundary-Layer</span> Interactions in Hypersonic Low Density Flows</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Moss, James N.; Olejniczak, Joseph</p> <p>2004-01-01</p> <p>Results of numerical simulations of Mach 10 air flow over a hollow cylinder-flare and a double-cone are presented where viscous effects are significant. The flow phenomena include <span class="hlt">shock-shock</span> and <span class="hlt">shock</span>- boundary-<span class="hlt">layer</span> interactions with accompanying flow separation, recirculation, and reattachment. The purpose of this study is to promote an understanding of the fundamental gas dynamics resulting from such complex interactions and to clarify the requirements for meaningful simulations of such flows when using the direct simulation Monte Carlo (DSMC) method. Particular emphasis is placed on the sensitivity of computed results to grid resolution. Comparisons of the DSMC results for the hollow cylinder-flare (30 deg.) configuration are made with the results of experimental measurements conducted in the ONERA RSCh wind tunnel for heating, pressure, and the extent of separation. Agreement between computations and measurements for various quantities is good except that for pressure. For the same flow conditions, the double- cone geometry (25 deg.- 65 deg.) produces much stronger interactions, and these interactions are investigated numerically using both DSMC and Navier-Stokes codes. For the double-cone computations, a two orders of magnitude variation in free-stream density (with Reynolds numbers from 247 to 24,7 19) is investigated using both computational methods. For this range of flow conditions, the computational results are in qualitative agreement for the extent of separation with the DSMC method always predicting a smaller separation region. Results from the Navier-Stokes calculations suggest that the flow for the highest density double-cone case may be unsteady; however, the DSMC solution does not show evidence of unsteadiness.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19800050160&hterms=wall+shear+stress&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dwall%2Bshear%2Bstress','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19800050160&hterms=wall+shear+stress&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dwall%2Bshear%2Bstress"><span id="translatedtitle">Interaction between a normal <span class="hlt">shock</span> wave and a turbulent boundary <span class="hlt">layer</span> at high transonic speeds. II - Wall shear stress</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Liou, M. S.; Adamson, T. C., Jr.</p> <p>1980-01-01</p> <p>Asymptotic methods are used to calculate the shear stress at the wall for the interaction between a normal <span class="hlt">shock</span> wave and a turbulent boundary <span class="hlt">layer</span> on a flat plate. A mixing length model is used for the eddy viscosity. The <span class="hlt">shock</span> wave is taken to be strong enough that the sonic line is deep in the boundary <span class="hlt">layer</span> and the upstream influence is thus very small. It is shown that unlike the result found for laminar flow an asymptotic criterion for separation is not found; however, conditions for incipient separation are computed numerically using the derived solution for the shear stress at the wall. Results are compared with available experimental measurements.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20030068449','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20030068449"><span id="translatedtitle">Drag Reduction by Suction of the Boundary <span class="hlt">Layer</span> Separated Behind <span class="hlt">Shock</span> Wave Formation at High Mach Numbers</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Regenscheit, B.</p> <p>1947-01-01</p> <p>With an approach of the velocity of flight of a ship to the velocity of sound, there occurs a considerable increase of the drag. The reason for this must be found in the boundary <span class="hlt">layer</span> separation caused by formation of <span class="hlt">shock</span> waves. It will be endeavored to reduce the drag increase by suction of the boundary <span class="hlt">layer</span>. Experimental results showed that drag increase may be considerably reduced by this method. It was, also, observed that, by suction, the position of <span class="hlt">shock</span> waves can be altered to a considerable extent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009PhDT.......293M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009PhDT.......293M"><span id="translatedtitle">Physics of unsteady cylinder-induced transitional <span class="hlt">shock</span> wave boundary <span class="hlt">layer</span> interactions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Murphree, Zachary Ryan</p> <p></p> <p>The mean flowfield and time-dependent characteristics of a Mach 5 cylinder-induced transitional <span class="hlt">shock-wave/boundary-layer</span> interaction have been studied experimentally. The interactions were generated with a right circular cylinder mounted on a flat plate. The Reynolds number based on distance from the leading edge of the plate to the cylinder leading edge ranged from 4.5 x 106 to 6.1 x 106, and the incoming boundary-<span class="hlt">layer</span> was transitional. The objectives of the study were to: (i) provide a detailed description of the mean flow structure of the interaction, and (ii) characterize the unsteadiness of the interaction based on fluctuating pressure measurements. Mean wall-pressure measurements coupled with planar laser scattering and surface visualization showed that the transitional interaction exhibits characteristics that are essentially a "composite" of an upstream laminar interaction and a downstream turbulent interaction. In the upstream region there is a laminar separation bubble that is characterized by a weak separation <span class="hlt">shock</span>, a pressure plateau, and low relative mass/heat flux. The separated boundary-<span class="hlt">layer</span> reattaches downstream of this bubble, about 4 diameters upstream of the cylinder. This reattached flow is characterized by high relative mass/heat flux, an increase in pressure and a rapidly thickening boundary-<span class="hlt">layer</span>. The flow then separates again in a manner very similar to a low Reynolds number turbulent interaction. Statistical analysis of the pressure histories suggest that the entire interaction stretches and contracts in concert. Power spectral densities of the pressure fluctuations showed unsteadiness throughout the interaction with energy content in one of two frequency bands: one with a sharp peak from 1-2 kHz and the other with a broader peak at 7-10 kHz. The lower frequency is attributed to the interaction motion, whereas the higher frequency is found underneath the reattached boundary-<span class="hlt">layer</span>. Cross-correlations and coherence functions in the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ShWav..25..535V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ShWav..25..535V"><span id="translatedtitle">Control of <span class="hlt">shock</span>-wave boundary <span class="hlt">layer</span> interaction using steady micro-jets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Verma, S. B.; Manisankar, C.; Akshara, P.</p> <p>2015-09-01</p> <p>An experimental investigation was conducted to control the amplitude of <span class="hlt">shock</span> unsteadiness associated with the interaction induced by a cylindrical protuberance on a flat plate in a Mach 2.18 flow. The control was applied in the form of an array of steady micro air-jets of different configurations with variation in pitch and skew angle of the jets. The effect of air-jet supply pressure on control was also studied. Each of the micro-jet configurations was placed 20 boundary <span class="hlt">layer</span> thicknesses upstream of the leading edge of the cylinder. The overall interaction is seen to get modified for all control configurations and shows a reduction in both separation- and bow-<span class="hlt">shock</span> strengths and in triple-point height. A significant reduction in the peak rms value is also observed in the intermittent region of separation for each case. For pitched jets placed in a zig-zag configuration, good control effectiveness is achieved at control pressures similar to the stagnation pressure of the freestream. At higher control pressures, however, their obstruction component increases and if these jets are not spaced sufficiently far apart, the effectiveness of their control begins to drop due to the beginning of spanwise jet-to-jet interaction. On the other hand, pitching or skewing the jets to reduces the obstruction component considerably which at lower control pressures shows lower effectiveness. But at higher control pressure, the effectiveness of these configurations continues to increase unlike the pitched jets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EUCAS...5..247G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EUCAS...5..247G"><span id="translatedtitle">Numerical analysis of three complex three-dimensional <span class="hlt">shock</span> wave / turbulent boundary <span class="hlt">layer</span> interaction flows</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grosvenor, A. D.; Zheltovodov, A. A.; Matheson, M. A.; Sailer, L. M.; Krzysztopik, M.; Gutzwiller, D. P.</p> <p>2013-06-01</p> <p>A set of Reynolds-averaged Navier-Stokes (RANS) computations with turbulence closure provided by the Spalart-Allmaras (SA) model have been carried out for prediction of <span class="hlt">shock</span>-induced three-dimensional (3D) turbulent separated flows. The experimental data for different aerodynamic test configurations have been used for assessing credibility of the numerical method employed. Particularly, <span class="hlt">shock</span> wave / turbulent boundary <span class="hlt">layer</span> interactions (SWTBLI) in the vicinity of an asymmetric sharp double-fin (DF) with different (7° and 11°) deflection angles mounted on a flat plate and two conically sharp cylindrical bodies at varying interbody distances and nose cone angles 60° and 40° mounted over a flat plate at freestream Mach number 4, as well as a transonic fan stage operating in the near-stall regime are considered. The gas dynamic structure and topology of 3D separated flows, surface flow patterns, and pressure distributions as well as body aerodynamic force prediction are analyzed. A transonic fan stage operating in the near-stall regime and a possibility of applying flow control is investigated. High Performance Computing was employed to make high resolution computations of these flows possible, and advanced 3D visualization techniques were employed in order to improve understanding of the separating flow phenomena.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19960054470','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19960054470"><span id="translatedtitle">Transonic <span class="hlt">Shock</span> Oscillations and Wing Flutter Calculated with an Interactive Boundary <span class="hlt">Layer</span> Coupling Method</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Edwards, John W.</p> <p>1996-01-01</p> <p>A viscous-inviscid interactive coupling method is used for the computation of unsteady transonic flows involving separation and reattachment. A lag-entrainment integral boundary <span class="hlt">layer</span> method is used with the transonic small disturbance potential equation in the CAP-TSDV (Computational Aeroelasticity Program - Transonic Small Disturbance) code. Efficient and robust computations of steady and unsteady separated flows, including steady separation bubbles and self-excited <span class="hlt">shock</span>-induced oscillations are presented. The buffet onset boundary for the NACA 0012 airfoil is accurately predicted and shown computationally to be a Hopf bifurcation. <span class="hlt">Shock</span>-induced oscillations are also presented for the 18 percent circular arc airfoil. The oscillation onset boundaries and frequencies are accurately predicted, as is the experimentally observed hysteresis of the oscillations with Mach number. This latter stability boundary is identified as a jump phenomenon. Transonic wing flutter boundaries are also shown for a thin swept wing and for a typical business jet wing, illustrating viscous effects on flutter and the effect of separation onset on the wing response at flutter. Calculations for both wings show limit cycle oscillations at transonic speeds in the vicinity of minimum flutter speed indices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930062842&hterms=upstream&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DTitle%26N%3D0%26No%3D60%26Ntt%3Dupstream','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930062842&hterms=upstream&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DTitle%26N%3D0%26No%3D60%26Ntt%3Dupstream"><span id="translatedtitle">Control of unsteady <span class="hlt">shock</span>-induced turbulent boundary <span class="hlt">layer</span> separation upstream of blunt fins</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kleifges, K.; Dolling, D. S.</p> <p>1993-01-01</p> <p>Fluctuating wall pressure measurements have been made on centerline upstream of blunt fins in a Mach 5 turbulent boundary <span class="hlt">layer</span>. Standard time series analysis and conditional sampling algorithms have been used to examine the effects of leading edge sweepback, leading edge shape, and fin root modifications on the fluctuating pressures. Leading edge sweep considerably reduces the mean and rms pressure loading at the fin root, the extent of the region of unsteady separation <span class="hlt">shock</span> motion, and the separation length. The frequency of pressure fluctuations in the intermittent region increases with leading edge sweepback, while the spectral content of pressure fluctuations in the separated region is virtually unchanged by leading edge sweep. A swept hemicylindrically blunted root fillet reduces the centerline upstream influence and intermittent region length by 50 percent, and reduces the mean and rms pressure loading at the fin root by about 75 percent and 95 percent respectively. Experiments using hemicylindrical, wedge shaped and flat leading edges show that while separated flow scales increase with increasing 'bluntness', intermittent region length and root loading decrease, and separation <span class="hlt">shock</span> frequency increases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970006988','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970006988"><span id="translatedtitle">Skin-Friction Measurements in a 3-D, Supersonic <span class="hlt">Shock-Wave/Boundary-Layer</span> Interaction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wideman, J. K.; Brown, J. L.; Miles, J. B.; Ozcan, O.</p> <p>1994-01-01</p> <p>The experimental documentation of a three-dimensional <span class="hlt">shock-wave/boundary-layer</span> interaction in a nominal Mach 3 cylinder, aligned with the free-stream flow, and 20 deg. half-angle conical flare offset 1.27 cm from the cylinder centerline. Surface oil flow, laser light sheet illumination, and schlieren were used to document the flow topology. The data includes surface-pressure and skin-friction measurements. A laser interferometric skin friction data. Included in the skin-friction data are measurements within separated regions and three-dimensional measurements in highly-swept regions. The skin-friction data will be particularly valuable in turbulence modeling and computational fluid dynamics validation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840008067','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840008067"><span id="translatedtitle">Investigation to optimize the passive <span class="hlt">shock</span> wave-boundary <span class="hlt">layer</span> control for supercritical airfoil drag reduction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nagamatsu, H. T.; Ficarra, R.; Orozco, R.</p> <p>1983-01-01</p> <p>The optimization of passive <span class="hlt">shock</span> wave/boundary <span class="hlt">layer</span> control for supercritical airfoil drag reduction was investigated in a 3 in. x 15.4 in. Transonic Blowdown Wind Tunnel. A 14% thick supercritical airfoil was tested with 0%, 1.42% and 2.8% porosities at Mach numbers of .70 to .83. The 1.42% case incorporated a linear increase in porosity with the flow direction while the 2.8% case was uniform porosity. The static pressure distributions over the airfoil, the wake impact pressure data for determining the profile drag, and the Schlieren photographs for porous surface airfoils are presented and compared with the results for solid-surface airfoils. While the results show that linear 1.42% porosity actually led to a slight increase in drag it was found that the uniform 2.8% porosity can lead to a drag reduction of 46% at M = .81.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920002551','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920002551"><span id="translatedtitle">Spectral fitting, <span class="hlt">shock</span> <span class="hlt">layer</span> modeling, and production of nitrogen oxides and excited nitrogen</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Blackwell, H. E.</p> <p>1991-01-01</p> <p>An analysis was made of N2 emission from 8.72 MJ/kg <span class="hlt">shock</span> <span class="hlt">layer</span> at 2.54, 1.91, and 1.27 cm positions and vibrational state distributions, temperatures, and relative electronic state populations was obtained from data sets. Other recorded arc jet N2 and air spectral data were reviewed and NO emission characteristics were studied. A review of operational procedures of the DSMC code was made. Information on other appropriate codes and modifications, including ionization, were made as well as a determination of the applicability of codes reviewed to task requirement. A review was also made of computational procedures used in CFD codes of Li and other codes on JSC computers. An analysis was made of problems associated with integration of specific chemical kinetics applicable to task into CFD codes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19900051345&hterms=Chemical+Equilibria+Earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DChemical%2BEquilibria%2BEarth','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19900051345&hterms=Chemical+Equilibria+Earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DChemical%2BEquilibria%2BEarth"><span id="translatedtitle">Viscous-<span class="hlt">shock-layer</span> solutions with coupled radiation and ablation injection for earth entry</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gupta, Roop N.; Lee, Kam-Pui; Moos, James N.; Sutton, Kenneth</p> <p>1990-01-01</p> <p>Results are obtained for the forebody of a planetary exploration vehicle entering the earth's atmosphere. A viscous-<span class="hlt">shock-layer</span> analysis is used assuming the flow to be laminar and in chemical equilibrium. Presented results include coupled radiation and ablation injection. This study further includes the effect of different transport and thermodynamic properties and radiation models. A Lewis number of 1.4 appears adequate for the radiation-dominated flows. Five velocities corresponding to different possible trajectory points at an altitude of 70 km have been further analyzed in detail. Sublimation and radiative equilibrium wall temperatures are employed for cases with and without coupled injection, respectively. For the cases analyzed here, the mass injection rates are small. However, the rates could become large if a lower altitude is used for aerobraking and/or the body size is increased. A comparison of the equilibrium results with finite-rate chemistry calculation shows the flowfield to be in chemical equilibrium.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19900033703&hterms=Recombination&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DRecombination','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19900033703&hterms=Recombination&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DRecombination"><span id="translatedtitle">Observations of a <span class="hlt">shock</span> and a recombination <span class="hlt">layer</span> at the contact surface of Comet Halley</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Goldstein, B. E.; Altwegg, K.; Balsiger, H.; Fuselier, S. A.; Ip, W.-H.</p> <p>1989-01-01</p> <p>Results are presented on observations in the vicinity of the contact surface of the Comet Halley, obtained by the Giotto ion mass spectrometer, with emphasis placed on two specific events observed in this region on the inbound pass. One was a burst of energized ions (about 20 eV) of 2-sec duration observed two seconds before the contact surface was encountered, which coincided with a pulse in magnetic field strength interpreted by Neubauer (1988) as a fast-mode <span class="hlt">shock</span> traveling away from the contact surface. The second was a sharp spike in ion densities observed at the contact surface by the mass analyzer, centered approximately at the inner edge of the contact surface. This ion-density spike is interpreted as a boundary <span class="hlt">layer</span> into which the radial ionospheric flow enters and piles up; the density increase is limited by recombination.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110008240','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110008240"><span id="translatedtitle">Assessment of Computational Fluid Dynamics (CFD) Models for <span class="hlt">Shock</span> Boundary-<span class="hlt">Layer</span> Interaction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>DeBonis, James R.; Oberkampf, William L.; Wolf, Richard T.; Orkwis, Paul D.; Turner, Mark G.; Babinsky, Holger</p> <p>2011-01-01</p> <p>A workshop on the computational fluid dynamics (CFD) prediction of <span class="hlt">shock</span> boundary-<span class="hlt">layer</span> interactions (SBLIs) was held at the 48th AIAA Aerospace Sciences Meeting. As part of the workshop numerous CFD analysts submitted solutions to four experimentally measured SBLIs. This paper describes the assessment of the CFD predictions. The assessment includes an uncertainty analysis of the experimental data, the definition of an error metric and the application of that metric to the CFD solutions. The CFD solutions provided very similar levels of error and in general it was difficult to discern clear trends in the data. For the Reynolds Averaged Navier-Stokes methods the choice of turbulence model appeared to be the largest factor in solution accuracy. Large-eddy simulation methods produced error levels similar to RANS methods but provided superior predictions of normal stresses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26180007','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26180007"><span id="translatedtitle">PREVALENCE AND SIGNIFICANCE OF AN ULTRASONOGRAPHIC COLONIC MUSCULARIS HYPERECHOIC BAND <span class="hlt">PARALLELING</span> THE SEROSAL <span class="hlt">LAYER</span> IN DOGS.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Heng, Hock Gan; Lim, Chee Kin; Miller, Margaret A; Broman, Meaghan M</p> <p>2015-01-01</p> <p>The muscularis <span class="hlt">layer</span> of the canine colon has been reported to appear homogeneously hypoechoic on ultrasonography. A hyperechoic band in the muscularis <span class="hlt">layer</span> <span class="hlt">paralleling</span> the serosal surface has been observed by authors in routine canine abdominal ultrasound examinations. The purpose of this prospective and retrospective cross-sectional study was to determine the prevalence of this lesion, characterize its ultrasonographic and postmortem histologic features, and correlate its presence with clinical signs of gastrointestinal disease. In the prospective study, all dogs that underwent routine abdominal ultrasonography by one of two observers during a 4-week period were included without any exclusion criteria. One observer reviewed ultrasound images and recorded the presence or absence of this lesion and its distribution, e.g. focal (< 2 cm long) or diffuse (> 2 cm long). In the retrospective study, all dogs that had both abdominal ultrasonography and necropsy from January 2011 to December 2013 were included without any exclusion criteria. Histologic examinations were performed by two observers and Masson's trichrome stain was used to identify fibrous collagen. Prevalence for the hyperechoic band was 32% in the prospective and 4.8% in the retrospective sample populations, respectively. The hyperechoic band appeared as diffuse, focal, or a combination of both. Histologic sections were available for six dogs. In a few cases, the lesion corresponded to the presence of fibrous tissue in the myenteric plexus or in the tunica muscularis. None of the dogs had a history of diarrhea. Findings supported the hypothesis that a colonic muscularis hyperechoic band <span class="hlt">paralleling</span> the serosal <span class="hlt">layer</span> in dogs could be a normal variant rather than a marker of disease. PMID:26180007</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19960022322','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19960022322"><span id="translatedtitle">Numerical Study of Boundary <span class="hlt">Layer</span> Interaction with <span class="hlt">Shocks</span>: Method Improvement and Test Computation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Adams, N. A.</p> <p>1995-01-01</p> <p>The objective is the development of a high-order and high-resolution method for the direct numerical simulation of <span class="hlt">shock</span> turbulent-boundary-<span class="hlt">layer</span> interaction. Details concerning the spatial discretization of the convective terms can be found in Adams and Shariff (1995). The computer code based on this method as introduced in Adams (1994) was formulated in Cartesian coordinates and thus has been limited to simple rectangular domains. For more general two-dimensional geometries, as a compression corner, an extension to generalized coordinates is necessary. To keep the requirements or limitations for grid generation low, the extended formulation should allow for non-orthogonal grids. Still, for simplicity and cost efficiency, periodicity can be assumed in one cross-flow direction. For easy vectorization, the compact-ENO coupling algorithm as used in Adams (1994) treated whole planes normal to the derivative direction with the ENO scheme whenever at least one point of this plane satisfied the detection criterion. This is apparently too restrictive for more general geometries and more complex <span class="hlt">shock</span> patterns. Here we introduce a localized compact-ENO coupling algorithm, which is efficient as long as the overall number of grid points treated by the ENO scheme is small compared to the total number of grid points. Validation and test computations with the final code are performed to assess the efficiency and suitability of the computer code for the problems of interest. We define a set of parameters where a direct numerical simulation of a turbulent boundary <span class="hlt">layer</span> along a compression corner with reasonably fine resolution is affordable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920044390&hterms=wave+length&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dwave%2Blength','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920044390&hterms=wave+length&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dwave%2Blength"><span id="translatedtitle">Crossing <span class="hlt">shock</span> wave turbulent boundary <span class="hlt">layer</span> interactions - Variable angle and <span class="hlt">shock</span> generator length geometry effects at Mach 3</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bogdonoff, S. M.; Stokes, W. L.</p> <p>1992-01-01</p> <p>By comparing the detailed wall static pressure distributions for 9 inch and 11 inch long fins generating a crossing <span class="hlt">shock</span> configuration at M = 2.93, the high resolution results of the 9 inch fins are shown to be free of exit effects. Analysis of the static pressure profiles have delineated the limited regions where the single fin results are valid. The characteristics of the complex interaction, with varying <span class="hlt">shock</span> wave strength, have been described. The data provide a critical test for computational fluid dynamics which, in its initial phase, has performed poorly in predicting the measured wall static pressure distributions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890011585','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890011585"><span id="translatedtitle">An LDA (Laser-Doppler Anemometry) investigation of three-dimensional normal <span class="hlt">shock</span> wave boundary-<span class="hlt">layer</span> interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chriss, R. M.; Hingst, W. R.; Strazisar, A. J.; Keith, T. G., Jr.</p> <p>1989-01-01</p> <p>Nonintrusive measurements were made of a normal <span class="hlt">shock</span> wave/boundary <span class="hlt">layer</span> interaction. Two dimensional measurements were made throughout the interaction region while 3-D measurements were made in the vicinity of the <span class="hlt">shock</span> wave. The measurements were made in the corner of the test section of a continuous supersonic wind tunnel in which a normal <span class="hlt">shock</span> wave had been stabilized. Laser Doppler Anemometry, surface pressure measurement and flow visualization techniques were employed for two freestream Mach number test cases: 1.6 and 1.3. The former contained separated flow regions and a system of <span class="hlt">shock</span> waves. The latter was found to be far less complicated. The results define the flow field structure in detail for each case.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GMD.....8.2977H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GMD.....8.2977H"><span id="translatedtitle">Development of efficient GPU <span class="hlt">parallelization</span> of WRF Yonsei University planetary boundary <span class="hlt">layer</span> scheme</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, M.; Mielikainen, J.; Huang, B.; Chen, H.; Huang, H.-L. A.; Goldberg, M. D.</p> <p>2015-09-01</p> <p>The planetary boundary <span class="hlt">layer</span> (PBL) is the lowest part of the atmosphere and where its character is directly affected by its contact with the underlying planetary surface. The PBL is responsible for vertical sub-grid-scale fluxes due to eddy transport in the whole atmospheric column. It determines the flux profiles within the well-mixed boundary <span class="hlt">layer</span> and the more stable <span class="hlt">layer</span> above. It thus provides an evolutionary model of atmospheric temperature, moisture (including clouds), and horizontal momentum in the entire atmospheric column. For such purposes, several PBL models have been proposed and employed in the weather research and forecasting (WRF) model of which the Yonsei University (YSU) scheme is one. To expedite weather research and prediction, we have put tremendous effort into developing an accelerated implementation of the entire WRF model using graphics processing unit (GPU) massive <span class="hlt">parallel</span> computing architecture whilst maintaining its accuracy as compared to its central processing unit (CPU)-based implementation. This paper presents our efficient GPU-based design on a WRF YSU PBL scheme. Using one NVIDIA Tesla K40 GPU, the GPU-based YSU PBL scheme achieves a speedup of 193× with respect to its CPU counterpart running on one CPU core, whereas the speedup for one CPU socket (4 cores) with respect to 1 CPU core is only 3.5×. We can even boost the speedup to 360× with respect to 1 CPU core as two K40 GPUs are applied.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840008063','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840008063"><span id="translatedtitle">Self-sustained oscillations of a <span class="hlt">shock</span> wave interacting with a boundary <span class="hlt">layer</span> on a supercritical airfoil</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ventres, C. S.; Howe, M. S.</p> <p>1983-01-01</p> <p>A theory is proposed of the self-sustaining oscillations of a weak <span class="hlt">shock</span> on an airfoil in steady, transonic flow. The interaction of the <span class="hlt">shock</span> with the boundary <span class="hlt">layer</span> on the airfoil produces displacement thickness fluctuations which convect downstream and generate sound by interaction with the trailing edge. A feedback loop is established when this sound impinges on the <span class="hlt">shock</span> wave, resulting in the production of further fluctuations in the displacement thickness. The details are worked out for an idealized mean boundary <span class="hlt">layer</span> velocity profile, but strong support for the basic hypotheses of the theory is provided by a comparison with recent experiments involving the generation of acoustic "tone bursts' by a supercritical airfoil section.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AIPC.1683b0223S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AIPC.1683b0223S"><span id="translatedtitle">Structure-phase state and mechanical properties of surface <span class="hlt">layers</span> in titanium nikelide single crystals after <span class="hlt">shock</span> mechanical treatment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Surikova, N.; Panin, V.; Vlasov, I.; Narkevich, N.; Surikov, N.; Tolmachev, A.</p> <p>2015-10-01</p> <p>The influence of ultrasonic <span class="hlt">shock</span> surface treatment (USST) on refine structure and mechanical characteristics of surface <span class="hlt">layers</span> and deformation behaviour of volume samples of TiNi(Fe, Mo) shape memory effect alloy single crystals is studied using optical and transmission electron microscope, X-ray diffraction, nanoindentation, mechanical attrition testing and experiments on uniaxial tension.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22492593','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22492593"><span id="translatedtitle">Structure-phase state and mechanical properties of surface <span class="hlt">layers</span> in titanium nikelide single crystals after <span class="hlt">shock</span> mechanical treatment</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Surikova, N. Panin, V. Vlasov, I.; Narkevich, N. Tolmachev, A.; Surikov, N.</p> <p>2015-10-27</p> <p>The influence of ultrasonic <span class="hlt">shock</span> surface treatment (USST) on refine structure and mechanical characteristics of surface <span class="hlt">layers</span> and deformation behaviour of volume samples of TiNi(Fe, Mo) shape memory effect alloy single crystals is studied using optical and transmission electron microscope, X-ray diffraction, nanoindentation, mechanical attrition testing and experiments on uniaxial tension.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4689869','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4689869"><span id="translatedtitle">A Model of In vitro Plasticity at the <span class="hlt">Parallel</span> Fiber—Molecular <span class="hlt">Layer</span> Interneuron Synapses</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Lennon, William; Yamazaki, Tadashi; Hecht-Nielsen, Robert</p> <p>2015-01-01</p> <p>Theoretical and computational models of the cerebellum typically focus on the role of <span class="hlt">parallel</span> fiber (PF)—Purkinje cell (PKJ) synapses for learned behavior, but few emphasize the role of the molecular <span class="hlt">layer</span> interneurons (MLIs)—the stellate and basket cells. A number of recent experimental results suggest the role of MLIs is more important than previous models put forth. We investigate learning at PF—MLI synapses and propose a mathematical model to describe plasticity at this synapse. We perform computer simulations with this form of learning using a spiking neuron model of the MLI and show that it reproduces six in vitro experimental results in addition to simulating four novel protocols. Further, we show how this plasticity model can predict the results of other experimental protocols that are not simulated. Finally, we hypothesize what the biological mechanisms are for changes in synaptic efficacy that embody the phenomenological model proposed here. PMID:26733856</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/7043822','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/7043822"><span id="translatedtitle">Management of recurrent hernias with two <span class="hlt">parallel</span> rows of four-<span class="hlt">layer</span> fascioplasty.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Badejo, O A</p> <p>1982-04-01</p> <p>A hundred and fifty-two patients with recurrent inguinal hernias, 10 females and 142 males seen over a ten-year period have been reported. The patients, none of whom were earlier seen or operated on by the author were managed with two <span class="hlt">parallel</span> rows of four-<span class="hlt">layer</span> fascioplasty held with nonabsorbable Astralen sutures. The complications which may arise from the method applied were reviewed. The recurrence rate in advanced countries ranges between 7% and 30% for all types of inguinal hernias, but in Nigeria is higher. The author does not claim that recurrence cannot occur with this method but he has not recorded any. The technique has also alleviated the fears of many and removed the social problems of having just one testis, an important factor in this environment. PMID:7043822</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110011133','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110011133"><span id="translatedtitle">A Source-Term Based Boundary <span class="hlt">Layer</span> Bleed/Effusion Model for Passive <span class="hlt">Shock</span> Control</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Baurle, Robert A.; Norris, Andrew T.</p> <p>2011-01-01</p> <p>A modeling framework for boundary <span class="hlt">layer</span> effusion has been developed based on the use of source (or sink) terms instead of the usual practice of specifying bleed directly as a boundary condition. This framework allows the surface boundary condition (i.e. isothermal wall, adiabatic wall, slip wall, etc.) to remain unaltered in the presence of bleed. This approach also lends itself to easily permit the addition of empirical models for second order effects that are not easily accounted for by simply defining effective transpiration values. Two effusion models formulated for supersonic flows have been implemented into this framework; the Doerffer/Bohning law and the Slater formulation. These models were applied to unit problems that contain key aspects of the flow physics applicable to bleed systems designed for hypersonic air-breathing propulsion systems. The ability of each model to predict bulk bleed properties was assessed, as well as the response of the boundary <span class="hlt">layer</span> as it passes through and downstream of a porous bleed system. The model assessment was performed with and without the presence of <span class="hlt">shock</span> waves. Three-dimensional CFD simulations that included the geometric details of the porous plate bleed systems were also carried out to supplement the experimental data, and provide additional insights into the bleed flow physics. Overall, both bleed formulations fared well for the tests performed in this study. However, the sample of test problems considered in this effort was not large enough to permit a comprehensive validation of the models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DFD.D4010C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DFD.D4010C"><span id="translatedtitle"><span class="hlt">Shock</span> Wave Boundary <span class="hlt">Layer</span> Interaction Mechanism on a Double Wedge Geometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Celik, Bayram; Barada, Mohammad Adel El Hajj Ali; Durna, Ahmet Selim</p> <p>2015-11-01</p> <p>A hypersonic test series by Swantek & Austin report complex <span class="hlt">shock</span> wave boundary <span class="hlt">layer</span> interaction mechanisms and unsteady surface heat flux from a double wedge geometry in a low enthalpy Mach 7 flow. In order to understand the physics of the flow and the heat transfer, we study the flow computationally and compare the results for the double wedge geometries, whose second angle is higher and lower than the maximum deflection angle at Mach 7. Apart from the numbers of comprehensive computational studies on the subject available in open literature, our study aims to describe the flow physics by taking the influence of both boundary <span class="hlt">layers</span> that are formed on the two walls of the wedge into account. In addition to describing the flow and heat transfer mechanisms, we investigate the time for the flows to reach steady state. We evaluate the interaction mechanisms in term of instant and time average surface heat flux distributions. We perform all computations using a finite volume based compressible Navier-Stokes solver, rhoCentralFoam, which is one of the several compressible flow solvers of an open source software, openFOAM.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015APS..DFD.G5002L&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015APS..DFD.G5002L&link_type=ABSTRACT"><span id="translatedtitle">Mapping the Interactions between <span class="hlt">Shocks</span> and Mixing <span class="hlt">Layers</span> in a 3-Stream Supersonic Jet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lewalle, Jacques; Ruscher, Christopher; Kan, Pinqing; Tenney, Andrew; Gogineni, Sivaram; Kiel, Barry</p> <p>2015-11-01</p> <p>Pressure is obtained from an LES calculation of the supersonic jet (Ma1 = 1 . 6) issuing from a rectangular nozzle in a low-subsonic co-flow; a tertiary flow, also rectangular with Ma3 = 1 insulates the primary jet from an aft-deck plate. The developing jet exhibits complex three-dimensional interactions between oblique <span class="hlt">shocks</span>, multiple mixing <span class="hlt">layers</span> and corner vortices, which collectively act as a skeleton for the flow. Our study is based on several plane sections through the pressure field, with short signals (0.1 s duration at 80 kHz sampling rate). Using wavelet-based band-pass filtering and cross-correlations, we map the directions of propagation of information among the various ``bones'' in the skeleton. In particular, we identify upstream propagation in some frequency bands, 3-dimensional interactions between the various shear <span class="hlt">layers</span>, and several key bones from which the pressure signals, when taken as reference, provide dramatic phase-locking for parts of the skeleton. We acknowledge the support of AFRL through an SBIR grant.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016ShWav..26..231O&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016ShWav..26..231O&link_type=ABSTRACT"><span id="translatedtitle">Mach waves produced in the supersonic jet mixing <span class="hlt">layer</span> by <span class="hlt">shock</span>/vortex interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Oertel Sen, H.; Seiler, F.; Srulijes, J.; Hruschka, R.</p> <p>2016-05-01</p> <p>The noise emission of free jets has been extensively investigated for many decades. At subsonic jet velocities, coherent structures of the mixing <span class="hlt">layer</span> move at subsonic speed and emit sound waves. Free jets blowing at supersonic speeds, however, can emit weak <span class="hlt">shock</span> waves, called Mach waves. At supersonic speeds, two cases must be distinguished: the structures move either subsonically or supersonically relative to the inside and/or outside speed of sound. In the case of supersonic movement, the Mach waves exist inside as well as outside the jet. At subsonic speeds, no Mach waves appear. Although numerous theories have been established to find the origin of the Mach waves, to the authors' best knowledge, the mechanism of the Mach wave formation has not yet been clearly explained. Recently another theory of Mach waves in supersonic jets was developed, as described herein, which outlines the causes for the Mach wave production and stability as well as their dynamics. The theory's principle is that the Mach waves are initiated by vortices which move downstream at three speeds w, {w}' and {w}'' inside of the mixing <span class="hlt">layer</span>. These three types of vortices and Mach waves are described in a comprehensive manner by the theory and are called the " w-, {w}'- and {w}''-vortices" and " w-, {w}'- and {w}''-Mach waves," respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1984rsu..rept.....K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984rsu..rept.....K"><span id="translatedtitle">Theoretical investigation of three-dimensional <span class="hlt">shock</span> wave turbulent boundary <span class="hlt">layer</span> interactions. Part 3</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Knight, D. D.</p> <p>1984-12-01</p> <p>The focus of the research effort is the understanding of three-dimensional <span class="hlt">shock</span> wave-turbulent boundary <span class="hlt">layer</span> interactions. The approach uses the full mean compressible Navier-Stokes equations with turbulence incorporated through the algebraic turbulent eddy viscosity model of Baldwin and Lomax. This year's principle accomplishments are: (1) the Baldwin-Lomax model was evaluated for a series of non-separated two-dimensional turbulent boundary <span class="hlt">layers</span>; (2) the 3-D Navier-Stokes codes was rewritten innto CYBER 200 FORTRAN; (3) the computed results for the 3-D sharp fin alpha sub g = 10 deg were compared with the results of a separate calculation by C. Horstmann using the k-epsilon turbulence model, and the experimental data of McClure and Dolling; and (4) the 3-D sharp fin at alpha sub g =20 deg was computed, and the results compared with the available experimental data. The examination of the flowfield structure of the 3-D sharp fin at alphaa sub g = 20 deg was initiated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ShWav.tmp....9O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ShWav.tmp....9O"><span id="translatedtitle">Mach waves produced in the supersonic jet mixing <span class="hlt">layer</span> by <span class="hlt">shock</span>/vortex interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Oertel Sen, H.; Seiler, F.; Srulijes, J.; Hruschka, R.</p> <p>2016-02-01</p> <p>The noise emission of free jets has been extensively investigated for many decades. At subsonic jet velocities, coherent structures of the mixing <span class="hlt">layer</span> move at subsonic speed and emit sound waves. Free jets blowing at supersonic speeds, however, can emit weak <span class="hlt">shock</span> waves, called Mach waves. At supersonic speeds, two cases must be distinguished: the structures move either subsonically or supersonically relative to the inside and/or outside speed of sound. In the case of supersonic movement, the Mach waves exist inside as well as outside the jet. At subsonic speeds, no Mach waves appear. Although numerous theories have been established to find the origin of the Mach waves, to the authors' best knowledge, the mechanism of the Mach wave formation has not yet been clearly explained. Recently another theory of Mach waves in supersonic jets was developed, as described herein, which outlines the causes for the Mach wave production and stability as well as their dynamics. The theory's principle is that the Mach waves are initiated by vortices which move downstream at three speeds w, {w}' and {w}'' inside of the mixing <span class="hlt">layer</span>. These three types of vortices and Mach waves are described in a comprehensive manner by the theory and are called the "w-, {w}' - and {w}'' -vortices" and "w-, {w}' - and {w}'' -Mach waves," respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27627387','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27627387"><span id="translatedtitle">Observation and analysis of emergent coherent structures in a high-energy-density <span class="hlt">shock</span>-driven planar mixing <span class="hlt">layer</span> experiment.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Doss, F W; Flippo, K A; Merritt, E C</p> <p>2016-08-01</p> <p>Coherent emergent structures have been observed in a high-energy-density supersonic mixing <span class="hlt">layer</span> experiment. A millimeter-scale <span class="hlt">shock</span> tube uses lasers to drive Mbar <span class="hlt">shocks</span> into the tube volume. The <span class="hlt">shocks</span> are driven into initially solid foam (60 mg/cm^{3}) hemicylinders separated by an Al or Ti metal tracer strip; the components are vaporized by the drive. Before the experiment disassembles, the <span class="hlt">shocks</span> cross at the tube center, creating a very fast (ΔU> 200 km/s) shear-unstable zone. After several nanoseconds, an expanding mixing <span class="hlt">layer</span> is measured, and after 10+ ns we observe the appearance of streamwise-periodic, spanwise-aligned rollers associated with the primary Kelvin-Helmholtz instability of mixing <span class="hlt">layers</span>. We additionally image roller pairing and spanwise-periodic streamwise-aligned filaments associated with secondary instabilities. New closures are derived to connect length scales of these structures to estimates of fluctuating velocity data otherwise unobtainable in the high-energy-density environment. This analysis indicates shear-induced specific turbulent energies 10^{3}-10^{4} times higher than the nearest conventional experiments. Because of difficulties in continuously driving systems under these conditions and the harshness of the experimental environment limiting the usable diagnostics, clear evidence of these developing structures has never before been observed in this regime. PMID:27627387</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016PhRvE..94b3101D&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016PhRvE..94b3101D&link_type=ABSTRACT"><span id="translatedtitle">Observation and analysis of emergent coherent structures in a high-energy-density <span class="hlt">shock</span>-driven planar mixing <span class="hlt">layer</span> experiment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Doss, F. W.; Flippo, K. A.; Merritt, E. C.</p> <p>2016-08-01</p> <p>Coherent emergent structures have been observed in a high-energy-density supersonic mixing <span class="hlt">layer</span> experiment. A millimeter-scale <span class="hlt">shock</span> tube uses lasers to drive Mbar <span class="hlt">shocks</span> into the tube volume. The <span class="hlt">shocks</span> are driven into initially solid foam (60 mg /cm3 ) hemicylinders separated by an Al or Ti metal tracer strip; the components are vaporized by the drive. Before the experiment disassembles, the <span class="hlt">shocks</span> cross at the tube center, creating a very fast (Δ U > 200 km/s) shear-unstable zone. After several nanoseconds, an expanding mixing <span class="hlt">layer</span> is measured, and after 10+ ns we observe the appearance of streamwise-periodic, spanwise-aligned rollers associated with the primary Kelvin-Helmholtz instability of mixing <span class="hlt">layers</span>. We additionally image roller pairing and spanwise-periodic streamwise-aligned filaments associated with secondary instabilities. New closures are derived to connect length scales of these structures to estimates of fluctuating velocity data otherwise unobtainable in the high-energy-density environment. This analysis indicates shear-induced specific turbulent energies 103-104 times higher than the nearest conventional experiments. Because of difficulties in continuously driving systems under these conditions and the harshness of the experimental environment limiting the usable diagnostics, clear evidence of these developing structures has never before been observed in this regime.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870006547','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870006547"><span id="translatedtitle"><span class="hlt">Shock</span> wave/turbulent boundary <span class="hlt">layer</span> interaction in the flow field of a tri-dimension wind tunnel</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Benay, R.; Pot, T.</p> <p>1986-01-01</p> <p>The first results of a thorough experimental analysis of a strong three-dimensional <span class="hlt">shock</span>-wave/turbulent boundary-<span class="hlt">layer</span> interaction occurring in a three dimensional transonic channel are presented. The aim of this experiment is to help in the physical understanding of a complex field, including several separations, and to provide a well documented case to test computational methods. The flowfield has been probed in many points by means of a three-component laser Doppler velocimeter. The results presented relate only to the mean velocity field. They clearly show the formation in the flow of a strong vortical motion resulting from the <span class="hlt">shock</span> wave interaction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19800050159&hterms=PIPES+PRESSURE&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DPIPES%2BPRESSURE','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19800050159&hterms=PIPES+PRESSURE&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DPIPES%2BPRESSURE"><span id="translatedtitle">Interaction between a normal <span class="hlt">shock</span> wave and a turbulent boundary <span class="hlt">layer</span> at high transonic speeds. I - Pressure distribution</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Messiter, A. F.</p> <p>1980-01-01</p> <p>Asymptotic solutions are derived for the pressure distribution in the interaction of a weak normal <span class="hlt">shock</span> wave with a turbulent boundary <span class="hlt">layer</span>. The undisturbed boundary <span class="hlt">layer</span> is characterized by the law of the wall and the law of the wake for compressible flow. In the limiting case considered, for 'high' transonic speeds, the sonic line is very close to the wall. Comparisons with experiment are shown, with corrections included for the effect of longitudinal wall curvature and for the boundary-<span class="hlt">layer</span> displacement effect in a circular pipe.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720024667','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720024667"><span id="translatedtitle">Experimental study of wall boundary <span class="hlt">layer</span> growth in the 10 deg half angle conical nozzle of a reflected <span class="hlt">shock</span> tunnel</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Menees, G. P.</p> <p>1972-01-01</p> <p>Calibration studies of <span class="hlt">shock</span>-tunnel nozzle flow were made in both N2 and Ar for a reservoir temperature of 2000 deg K and reservoir pressures of 15, 85, and 130 atm. The results for both test gases showed that the boundary <span class="hlt">layer</span> was turbulent and the growth nonlinear, with the thickness being greater in Ar than N2 at comparable reservoir conditions. The boundary-<span class="hlt">layer</span> thickness decreased with increasing reservoir pressure, but only small differences occurred between the two largest reservoir pressures. Good correlations of the boundary <span class="hlt">layer</span> and displacement thickness were obtained for both N2 and Ar in terms of Reynolds number based on a reference temperature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770026496','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770026496"><span id="translatedtitle">An experimental investigation of <span class="hlt">shock</span> wave-turbulent boundary <span class="hlt">layer</span> interactions with and without boundary <span class="hlt">layer</span> suction: A data summary report</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sun, C. C.; Childs, M. E.</p> <p>1977-01-01</p> <p>Tabulated data from a series of experimental studies of the interaction of a <span class="hlt">shock</span> wave with a turbulent boundary <span class="hlt">layer</span> in axisymmetric flow configurations is presented. The studies were conducted at the walls of circular wind tunnels and on the cylindrical centerbody of an annular flow channel. Detailed pitot pressure profiles and wall static pressure profiles upstream of, within and downstream of the interaction region are given. Results are presented for flows at nominal freestream Mach Numbers of 2, 3 and 4. For studies at the tunnel sidewalls, the <span class="hlt">shock</span> waves were produced by conical <span class="hlt">shock</span> generators mounted on the centerline of the wind tunnel at zero angle of attack. The annular ring generator was used to produce the <span class="hlt">shock</span> wave at the centerbody of the annular flow channel. The effects of boundary <span class="hlt">layer</span> bleed were examined in the investigation. Both bleed rate and bleed location were studied. Most of the bleed studies were conducted with bleed holes drilled normal to the wall surface but the effects of slot suction were also examined. A summary of the principal results and conclusions is given.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890014554','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890014554"><span id="translatedtitle">Cracking of a <span class="hlt">layered</span> medium on an elastic foundation under thermal <span class="hlt">shock</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rizk, Abd El-Fattah A.; Erdogan, Fazil</p> <p>1988-01-01</p> <p>The cladded pressure vessel under thermal <span class="hlt">shock</span> conditions which is simulated by using two simpler models was studied. The first model (Model 1) assumes that, if the crack size is very small compared to the vessel thickness, the problem can be treated as a semi-infinite elastic medium bonded to a very thin <span class="hlt">layer</span> of different material. However, if the crack size is of the same order as the vessel thickness, the curvature effects may not be negligible. In this case it is assumed that the relatively thin walled hollow cylinder with cladding can be treated as a composite beam on an elastic foundation (Model 2). In both models, the effect of surface cooling rate is studied by assuming the temperature boundary condition to be a ramp function. The calculated results include the transient temperature, thermal stresses in the uncracked medium and stress intensity factors which are presented as a function of time, and the duration of cooling ramp. The stress intensity factors are also presented as a function of the size and the location of the crack. The problem is solved for two bonded materials of different thermal and mechanical properties. The mathematical formulation results in two singular integral equations which are solved numerically. The results are given for two material pairs, namely an austenitic steel <span class="hlt">layer</span> welded on a ferritic steel substrate, and a ceramic coating on ferritic steel. In the case of the yielded clad, the stress intensity factors for a crack under the clad are determined by using a plastic strip model and are compared with elastic clad results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JTePh..60..645K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JTePh..60..645K"><span id="translatedtitle">Influence of vibrational relaxation on perturbations in a <span class="hlt">shock</span> <span class="hlt">layer</span> on a plate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kirilovskiy, S. V.; Maslov, A. A.; Poplavskaya, T. V.; Tsyryul'nikov, I. S.</p> <p>2015-05-01</p> <p>The influence of excitation of molecular vibrational degrees of freedom on the mean flow and perturbation development in a hypersonic (M = 6-14) viscous <span class="hlt">shock</span> <span class="hlt">layer</span> is studied. The <span class="hlt">layer</span> originates on a plate placed in a flow of air, carbon dioxide, or their mixture at high stagnation temperatures (2000-3000 K). The mean flow and pressure pulsation on the surface of the plate are measured in an IT-302M pulsed wind tunnel (Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences). Numerical simulation is carried out in terms of a model of a thermally perfect gas using the ANSYS Fluent program package based on solving nonstationary two-dimensional Navier-Stokes equations. External flow perturbations are introduced into the computational domain in the form of plane monochromatic acoustic waves using UDF modules built in the computational code. It is shown that the excitation of vibrational degrees of freedom in carbon dioxide molecules considerably influences the position of the head wave and intensifies perturbations in contrast to air in which the fraction of vibrationally excited molecules is low at the same parameters of the oncoming low. The influence of the excitation of vibrational degrees of freedom is studied both for equilibrium gas and for a vibrationally nonequilibrium gas. Nonequilibrium vibrational degrees of freedom are simulated using a two-temperature model of relaxation flows in which the time variation of the vibrational energy is described by the Landau-Teller equation with regard to a finite time of energy exchange between vibrational and translational-rotational degrees of freedom of molecules. It is found that the vibrational nonequilibrium has a damping effect on perturbations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhRvL.111f5003R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhRvL.111f5003R"><span id="translatedtitle">Measurement of High-Pressure <span class="hlt">Shock</span> Waves in Cryogenic Deuterium-Tritium Ice <span class="hlt">Layered</span> Capsule Implosions on NIF</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Robey, H. F.; Moody, J. D.; Celliers, P. M.; Ross, J. S.; Ralph, J.; Le Pape, S.; Berzak Hopkins, L.; Parham, T.; Sater, J.; Mapoles, E. R.; Holunga, D. M.; Walters, C. F.; Haid, B. J.; Kozioziemski, B. J.; Dylla-Spears, R. J.; Krauter, K. G.; Frieders, G.; Ross, G.; Bowers, M. W.; Strozzi, D. J.; Yoxall, B. E.; Hamza, A. V.; Dzenitis, B.; Bhandarkar, S. D.; Young, B.; Van Wonterghem, B. M.; Atherton, L. J.; Landen, O. L.; Edwards, M. J.; Boehly, T. R.</p> <p>2013-08-01</p> <p>The first measurements of multiple, high-pressure <span class="hlt">shock</span> waves in cryogenic deuterium-tritium (DT) ice <span class="hlt">layered</span> capsule implosions on the National Ignition Facility have been performed. The strength and relative timing of these <span class="hlt">shocks</span> must be adjusted to very high precision in order to keep the DT fuel entropy low and compressibility high. All previous measurements of <span class="hlt">shock</span> timing in inertial confinement fusion implosions [T. R. Boehly et al., Phys. Rev. Lett. 106, 195005 (2011), H. F. Robey et al., Phys. Rev. Lett. 108, 215004 (2012)] have been performed in surrogate targets, where the solid DT ice shell and central DT gas regions were replaced with a continuous liquid deuterium (D2) fill. This report presents the first experimental validation of the assumptions underlying this surrogate technique.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23971581','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23971581"><span id="translatedtitle">Measurement of high-pressure <span class="hlt">shock</span> waves in cryogenic deuterium-tritium ice <span class="hlt">layered</span> capsule implosions on NIF.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Robey, H F; Moody, J D; Celliers, P M; Ross, J S; Ralph, J; Le Pape, S; Berzak Hopkins, L; Parham, T; Sater, J; Mapoles, E R; Holunga, D M; Walters, C F; Haid, B J; Kozioziemski, B J; Dylla-Spears, R J; Krauter, K G; Frieders, G; Ross, G; Bowers, M W; Strozzi, D J; Yoxall, B E; Hamza, A V; Dzenitis, B; Bhandarkar, S D; Young, B; Van Wonterghem, B M; Atherton, L J; Landen, O L; Edwards, M J; Boehly, T R</p> <p>2013-08-01</p> <p>The first measurements of multiple, high-pressure <span class="hlt">shock</span> waves in cryogenic deuterium-tritium (DT) ice <span class="hlt">layered</span> capsule implosions on the National Ignition Facility have been performed. The strength and relative timing of these <span class="hlt">shocks</span> must be adjusted to very high precision in order to keep the DT fuel entropy low and compressibility high. All previous measurements of <span class="hlt">shock</span> timing in inertial confinement fusion implosions [T. R. Boehly et al., Phys. Rev. Lett. 106, 195005 (2011), H. F. Robey et al., Phys. Rev. Lett. 108, 215004 (2012)] have been performed in surrogate targets, where the solid DT ice shell and central DT gas regions were replaced with a continuous liquid deuterium (D2) fill. This report presents the first experimental validation of the assumptions underlying this surrogate technique. PMID:23971581</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160003109','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160003109"><span id="translatedtitle">HIFiRE-1 Turbulent <span class="hlt">Shock</span> Boundary <span class="hlt">Layer</span> Interaction - Flight Data and Computations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kimmel, Roger L.; Prabhu, Dinesh</p> <p>2015-01-01</p> <p>The Hypersonic International Flight Research Experimentation (HIFiRE) program is a hypersonic flight test program executed by the Air Force Research Laboratory (AFRL) and Australian Defence Science and Technology Organisation (DSTO). This flight contained a cylinder-flare induced <span class="hlt">shock</span> boundary <span class="hlt">layer</span> interaction (SBLI). Computations of the interaction were conducted for a number of times during the ascent. The DPLR code used for predictions was calibrated against ground test data prior to exercising the code at flight conditions. Generally, the computations predicted the upstream influence and interaction pressures very well. Plateau pressures on the cylinder were predicted well at all conditions. Although the experimental heat transfer showed a large amount of scatter, especially at low heating levels, the measured heat transfer agreed well with computations. The primary discrepancy between the experiment and computation occurred in the pressures measured on the flare during second stage burn. Measured pressures exhibited large overshoots late in the second stage burn, the mechanism of which is unknown. The good agreement between flight measurements and CFD helps validate the philosophy of calibrating CFD against ground test, prior to exercising it at flight conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950056496&hterms=skin+layers&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dskin%2Blayers','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950056496&hterms=skin+layers&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dskin%2Blayers"><span id="translatedtitle">Laser interferometer skin-friction measurements of crossing-<span class="hlt">shock-wave/turbulent-boundary-layer</span> interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Garrison, T. J.; Settles, G. S.; Narayanswami, N.; Knight, D. D.</p> <p>1994-01-01</p> <p>Wall shear stress measurements beneath crossing-<span class="hlt">shock</span>-wave/turbulent boundary-<span class="hlt">layer</span> interactions have been made for three interactions of different strengths. The interactions are generated by two sharp fins at symetric angles of attack mounted on a flat plate. The shear stress measurements were made for fin angles of 7 and 11 deg at Mach 3 and 15 deg at Mach 3.85. The measurements were made using a laser interferometer skin-friction meter, a device that determines the wall shear by optically measuring the time rate of thinning of an oil film placed on the test model surface. Results of the measurements reveal high skin-friction coefficients in the vicinity of the fin/plate junction and the presence of quasi-two-dimensional flow separation on the interaction center line. Additionally, two Navier-Stokes computations, one using a Baldwin-Lomax turbulence model and one using a k-epsilon model, are compared with the experimental results for the Mach 3.85, 15-deg interaction case. Although the k-epsilon model did a reasonable job of predicting the overall trend in portions of the skin-friction distribution, neither computation fully captured the physics of the near-surface flow in this complex interaction.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150022184','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150022184"><span id="translatedtitle">CFD Validation Experiment of a Mach 2.5 Axisymmetric <span class="hlt">Shock-Wave/Boundary-Layer</span> Interaction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Davis, David O.</p> <p>2015-01-01</p> <p>Experimental investigations of specific flow phenomena, e.g., <span class="hlt">Shock</span> Wave Boundary-<span class="hlt">Layer</span> Interactions (SWBLI), provide great insight to the flow behavior but often lack the necessary details to be useful as CFD validation experiments. Reasons include: 1.Undefined boundary conditions Inconsistent results 2.Undocumented 3D effects (CL only measurements) 3.Lack of uncertainty analysis While there are a number of good subsonic experimental investigations that are sufficiently documented to be considered test cases for CFD and turbulence model validation, the number of supersonic and hypersonic cases is much less. This was highlighted by Settles and Dodsons [1] comprehensive review of available supersonic and hypersonic experimental studies. In all, several hundred studies were considered for their database.Of these, over a hundred were subjected to rigorous acceptance criteria. Based on their criteria, only 19 (12 supersonic, 7 hypersonic) were considered of sufficient quality to be used for validation purposes. Aeschliman and Oberkampf [2] recognized the need to develop a specific methodology for experimental studies intended specifically for validation purposes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140003148','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140003148"><span id="translatedtitle">Understanding the Flow Physics of <span class="hlt">Shock</span> Boundary-<span class="hlt">Layer</span> Interactions Using CFD and Numerical Analyses</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Friedlander, David J.</p> <p>2013-01-01</p> <p>Computational fluid dynamic (CFD) analyses of the University of Michigan (UM) <span class="hlt">Shock/Boundary-Layer</span> Interaction (SBLI) experiments were performed as an extension of the CFD SBLI Workshop held at the 48th AIAA Aerospace Sciences Meeting in 2010. In particular, the UM Mach 2.75 Glass Tunnel with a semi-spanning 7.75deg wedge was analyzed in attempts to explore key physics pertinent to SBLI's, including thermodynamic and viscous boundary conditions as well as turbulence modeling. Most of the analyses were 3D CFD simulations using the OVERFLOW flow solver, with additional quasi-1D simulations performed with an in house MATLAB code interfacing with the NIST REFPROP code to explore perfect verses non-ideal air. A fundamental exploration pertaining to the effects of particle image velocimetry (PIV) on post-processing data is also shown. Results from the CFD simulations showed an improvement in agreement with experimental data with key contributions including adding a laminar zone upstream of the wedge and the necessity of mimicking PIV particle lag for comparisons. Results from the quasi-1D simulation showed that there was little difference between perfect and non-ideal air for the configuration presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DFDL21012F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DFDL21012F"><span id="translatedtitle">Investigation of corner <span class="hlt">shock</span> boundary <span class="hlt">layer</span> interactions to understand inlet unstart</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Funderburk, Morgan</p> <p>2015-11-01</p> <p>Inlet unstart is a detrimental phenomenon in dual-mode ramjet/scramjet engines that causes severe loss of thrust, large transient structural load, and potentially a loss of the aircraft. In order to analyze the effects that the corner <span class="hlt">shock</span> boundary <span class="hlt">layer</span> interaction (SBLI) has on initiating and perpetuating inlet unstart, a qualitative and quantitative investigation into mean and dynamic features of corner SBLI at various Mach numbers is made. Surface streakline visualization showed that the corner SBLI is highly three-dimensional with a dominant presence of corner separation vortex. Further, the peak r.m.s. pressure was located at the periphery of corner separation vortex, suggesting that the unsteady loading is caused by the corner vortex. Power spectral densities of wall-pressure fluctuations in the peak r.m.s. location were analyzed in order to characterize the dominant frequencies of oscillation of the flow structures and to unravel the dynamic interactions between them in order to expand the operating margin of future hypersonic air breathing vehicles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013ShWav..23..263K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013ShWav..23..263K"><span id="translatedtitle">Experimental and numerical investigation into the dynamics of dust lifting up from the <span class="hlt">layer</span> behind the propagating <span class="hlt">shock</span> wave</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Klemens, R.; Oleszczak, P.; Zydak, P.</p> <p>2013-05-01</p> <p>In a number of industrial facilities and factory buildings dust <span class="hlt">layers</span> cover floors, walls, ceilings and various installations. The dust can be easily dispersed by pressure waves generated by weak explosions or as a result of damage of a compressed gas systems. If the obtained explosive dust-air mixture is ignited, a devastating explosion may occur. The aim of the work was to study the dust lifting process from the <span class="hlt">layer</span> behind the propagating <span class="hlt">shock</span> wave and to determine some important parameters, which later could be used for development and validation of the numerical model of the process. The experiments were conducted with the use of a <span class="hlt">shock</span> tube. For measuring the dust concentration in the mixture with air, a special five-channel optical device was constructed, enabling measurements at five positions located in one vertical plane along the height of the tube. The delay in lifting of the dust from the <span class="hlt">layer</span> and the vertical velocity of the dust cloud were calculated from the dust concentration measurements. The research was carried out for various initial conditions and for various types of dusts. The results obtained in tests with black coal dust are presented in the paper. Three <span class="hlt">shock</span> wave velocities: 450, 490 and 518 m/s and three dust <span class="hlt">layer</span> thicknesses, equal to 1.0, 1.5 and 2.0 mm, were taken into consideration. Measurements results of the mean vertical component of the dust cloud velocity between the <span class="hlt">layer</span> and the first laser beam were used in a new model, where the dust dispersing process is modeled as an injection of the dust from the <span class="hlt">layer</span>. The numerical simulations were based on the Euler or Lagrange model of the dust phase. In case of Euler model, the dust <span class="hlt">layer</span> was replaced by injection of dust from the bottom of the channel. The calculations were performed for two models of the investigated process. In the first model, correlation was worked out for all tested dusts and in the new model, the individual correlations for every tested dust were</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016ApJ...827..124A&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016ApJ...827..124A&link_type=ABSTRACT"><span id="translatedtitle">Collisionless Electron–ion <span class="hlt">Shocks</span> in Relativistic Unmagnetized Jet–ambient Interactions: Non-thermal Electron Injection by Double <span class="hlt">Layer</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ardaneh, Kazem; Cai, Dongsheng; Nishikawa, Ken-Ichi</p> <p>2016-08-01</p> <p>The course of non-thermal electron ejection in relativistic unmagnetized electron–ion <span class="hlt">shocks</span> is investigated by performing self-consistent particle-in-cell simulations. The <span class="hlt">shocks</span> are excited through the injection of a relativistic jet into ambient plasma, leading to two distinct <span class="hlt">shocks</span> (referred to as the trailing <span class="hlt">shock</span> and leading <span class="hlt">shock</span>) and a contact discontinuity. The Weibel-like instabilities heat the electrons up to approximately half of the ion kinetic energy. The double <span class="hlt">layers</span> formed in the trailing and leading edges then accelerate the electrons up to the ion kinetic energy. The electron distribution function in the leading edge shows a clear, non-thermal power-law tail which contains ˜1% of electrons and ˜8% of the electron energy. Its power-law index is ‑2.6. The acceleration efficiency is ˜23% by number and ˜50% by energy, and the power-law index is ‑1.8 for the electron distribution function in the trailing edge. The effect of the dimensionality is examined by comparing the results of three-dimensional simulations with those of two-dimensional simulations. The comparison demonstrates that electron acceleration is more efficient in two dimensions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...827..124A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...827..124A"><span id="translatedtitle">Collisionless Electron–ion <span class="hlt">Shocks</span> in Relativistic Unmagnetized Jet–ambient Interactions: Non-thermal Electron Injection by Double <span class="hlt">Layer</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ardaneh, Kazem; Cai, Dongsheng; Nishikawa, Ken-Ichi</p> <p>2016-08-01</p> <p>The course of non-thermal electron ejection in relativistic unmagnetized electron–ion <span class="hlt">shocks</span> is investigated by performing self-consistent particle-in-cell simulations. The <span class="hlt">shocks</span> are excited through the injection of a relativistic jet into ambient plasma, leading to two distinct <span class="hlt">shocks</span> (referred to as the trailing <span class="hlt">shock</span> and leading <span class="hlt">shock</span>) and a contact discontinuity. The Weibel-like instabilities heat the electrons up to approximately half of the ion kinetic energy. The double <span class="hlt">layers</span> formed in the trailing and leading edges then accelerate the electrons up to the ion kinetic energy. The electron distribution function in the leading edge shows a clear, non-thermal power-law tail which contains ∼1% of electrons and ∼8% of the electron energy. Its power-law index is ‑2.6. The acceleration efficiency is ∼23% by number and ∼50% by energy, and the power-law index is ‑1.8 for the electron distribution function in the trailing edge. The effect of the dimensionality is examined by comparing the results of three-dimensional simulations with those of two-dimensional simulations. The comparison demonstrates that electron acceleration is more efficient in two dimensions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830012642','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830012642"><span id="translatedtitle">An experimental study of three-dimensional <span class="hlt">shock</span> wave/boundary <span class="hlt">layer</span> interactions generated by sharp fins</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lu, F. K.; Settles, G. S.; Bogdonoff, S. M.</p> <p>1983-01-01</p> <p>The interaction between a turbulent boundary <span class="hlt">layer</span> and a <span class="hlt">shock</span> wave generated by a sharp fin with leading edge sweepback was investigated. The incoming flow was at Mach 2.96 and at a unit Reynolds number of 63 x 10 to the 6th power 0.1 m. The approximate incoming boundary <span class="hlt">layer</span> thickness was either 4 mm or 17 mm. The fins used were at 5 deg, 9 deg and 15 deg incidence and had leading edge sweepback from 0 deg to 65 deg. The tests consisted of surface kerosene lampblack streak visualization, surface pressure measurements, <span class="hlt">shock</span> wave shape determination by shadowgraphs, and localized vapor screen visualization. The upstream influence lengths of the fin interactions were correlated using viscous and inviscid flow parameters. The parameters affecting the surface features close to the fin and way from the fin were also identified. Essentially, the surface features in the farfield were found to be conical.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19870032772&hterms=electrodynamics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Delectrodynamics','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19870032772&hterms=electrodynamics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Delectrodynamics"><span id="translatedtitle">The resolved <span class="hlt">layer</span> of a collisionless, high beta, supercritical, quasi-perpendicular <span class="hlt">shock</span> wave. III - Vlasov electrodynamics</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Scudder, J. D.; Mangeney, A.; Lacombe, C.; Harvey, C. C.; Wu, C. S.</p> <p>1986-01-01</p> <p>The analysis of the fluid continuum level within the <span class="hlt">shock</span> <span class="hlt">layer</span> observed on November 7, 1977 by the ISEE satellites (Scudder et al., 1986) is extended to examine, within the framework of Vlasov electrodynamics, direct observational evidence for 'collisionless' resistivity. The analysis is based on the measured wave turbulence and the deviation of the observed electron velocity distribution function from the form predicted using the reversible individual electron trajectories in the presence of dc forces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150015493','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150015493"><span id="translatedtitle">CFD Validation Experiment of a Mach 2.5 Axisymmetric <span class="hlt">Shock</span>-Wave Boundary-<span class="hlt">Layer</span> Interaction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Davis, David O.</p> <p>2015-01-01</p> <p>Preliminary results of an experimental investigation of a Mach 2.5 two-dimensional axisymmetric <span class="hlt">shock-wave/boundary-layer</span> interaction (SWBLI) are presented. The purpose of the investigation is to create a SWBLI dataset specifically for CFD validation purposes. Presented herein are the details of the facility and preliminary measurements characterizing the facility and interaction region. The results will serve to define the region of interest where more detailed mean and turbulence measurements will be made.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..1412285K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..1412285K"><span id="translatedtitle">Ion acceleration by electro-magnetic plasma waves in the vicinity of SLAMS boundary observed in the front of the Earth's quasi-<span class="hlt">parallel</span> bow <span class="hlt">shock</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kis, A.; Agapitov, O.; Krasnoselskikh, V.; Dandouras, I.; Lucek, E. A.</p> <p>2012-04-01</p> <p>A well known feature of collisionless <span class="hlt">shocks</span> which are formed in space plasmas is their capability to accelerate particles to high energies. On the other hand, the exact mechanism how this acceleration takes place is still unknown. This is especially true in the case of the so-called seed particle population, i.e. those particles which are being injected into the process of acceleration. In our study we present a case study of Gyroresonant Surfing Acceleration (GSA) observed on the quasi-<span class="hlt">parallel</span> side of the Earth's bow <span class="hlt">shock</span>. For our analysis we use simultaneous multi-spacecraft measurement data provided by the Cluster spacecraft ion (CIS), magnetic (FGM) and electric field and wave instrument (EFW) during a time period of large inter-spacecraft separation distance. Our results show evidence that the gyroresonance surfing acceleration takes place as a consequence of interaction between monochromatic (or quasi-monochromatic) electromagnetic plasma waves and short large amplitude magnetic structures (SLAMS). The magnetic field inhomogenity mirror force keeps the ions trapped by the wave in resonant condition which results in effective particle velocity increase and thus energy gain. Since monochromatic wave packets with circular polarization and various magnetic structures are very commonly observed in the front of the Earth's quasi-<span class="hlt">parallel</span> bow <span class="hlt">shock</span>, the gyroresonant surfing acceleration proves to be an effective particle injection mechanism resulting in the formation of the seed particle population.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006PhDT.......107B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006PhDT.......107B"><span id="translatedtitle">The effects of upstream mass injection by vortex generator jets on <span class="hlt">shock</span>-induced turbulent boundary <span class="hlt">layer</span> separation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bueno, Pablo Cesar</p> <p></p> <p>An experimental study was conducted to investigate the effects of upstream mass injection, by means of vortex generator jets (VGJs), on the <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span> interaction (SWTBLI) generated by cylinder in a Mach 2 flow. The objectives of the study were: (i) to characterize the changes to the global structure of the flowfield introduced by the VGJs, and (ii) to study how the injection affected the dynamics of the separation <span class="hlt">shock</span> foot. The injection was provided by three high-speed valves, placed across the span of the test section, which generated underexpanded jets. Two jet orientations were studied: normal to the wall, and pitched at 60° and skewed at 90° with respect to the freestream. In addition, the effects of both continuous and pulsed injection were investigated. Velocity measurements of the upstream boundary <span class="hlt">layer</span>, VGJs, and -<span class="hlt">shock</span> system were made using a wide-field particle image velocimetry (PIV) system, and an array of fast-response pressure transducers was used to monitor the wall pressure under the intermittent region of the interaction. The velocity measurements of the baseline case captured nearly all the relevant flow structures including the -<span class="hlt">shock</span> and primary and secondary vortices. However, neither mean supersonic reversed flow nor the supersonic jet that presumably exists downstream of the triple point were observed. When injection was applied, the scale of the separated flow changed considerably. For normal injection, the primary vortex was nearly suppressed, while for pitched/skewed injection, the secondary vortex increased in size. Mean streamwise and transverse velocity profiles upstream of the separation <span class="hlt">shock</span> showed that, for both jet orientations, the VGJs caused the flow in the boundary <span class="hlt">layer</span> to accelerate. However, for normal injection, the acceleration did not extend down to the wall. Phase-averaged velocity measurements of the opening phase of the valves indicated that there is a phase lag between the jets and the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011ShWav..21..273K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011ShWav..21..273K"><span id="translatedtitle">Comparison of different models for non-equilibrium CO2 flows in a <span class="hlt">shock</span> <span class="hlt">layer</span> near a blunt body</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kustova, E. V.; Nagnibeda, E. A.; Shevelev, Yu. D.; Syzranova, N. G.</p> <p>2011-06-01</p> <p>The paper presents results of a numerical simulation of a supersonic two-dimensional (2D) viscous flow containing CO2 molecules near a spacecraft entering the Mars atmosphere. The gas-dynamic equations in the <span class="hlt">shock</span> <span class="hlt">layer</span> are coupled to the equations of non-equilibrium vibrational and chemical kinetics in the five-component mixture CO2/CO/O2/C/O. Transport and relaxation processes in the flow are studied on the basis of the rigorous kinetic theory methods; the developed transport algorithms are incorporated in the numerical scheme. The influence of the vibrational excitation of CO2 and chemical reactions on the gas flow parameters and heat transfer is analyzed. The obtained results are compared with those found using two simplified models based on the two-temperature and one-temperature vibrational distributions in CO2. The accuracy of the simplified models and the limits of their validity within the <span class="hlt">shock</span> <span class="hlt">layer</span> are evaluated. The effect of bulk viscosity in a flow near a re-entry body is discussed. The role of different diffusion processes, chemical reactions, and surface catalytic properties in a flow of the considered mixture in the <span class="hlt">shock</span> <span class="hlt">layer</span> is estimated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19990100650','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19990100650"><span id="translatedtitle">Static Performance of a Fixed-Geometry Exhaust Nozzle Incorporating Porous Cavities for <span class="hlt">Shock</span>-Boundary <span class="hlt">Layer</span> Interaction Control</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Asbury, Scott C.; Hunter, Craig A.</p> <p>1999-01-01</p> <p>An investigation was conducted in the model preparation area of the Langley 16-Foot Transonic Tunnel to determine the internal performance of a fixed-geometry exhaust nozzle incorporating porous cavities for <span class="hlt">shock</span>-boundary <span class="hlt">layer</span> interaction control. Testing was conducted at static conditions using a sub-scale nozzle model with one baseline and 27 porous configurations. For the porous configurations, the effects of percent open porosity, hole diameter, and cavity depth were determined. All tests were conducted with no external flow at nozzle pressure ratios from 1.25 to approximately 9.50. Results indicate that baseline nozzle performance was dominated by unstable, <span class="hlt">shock</span>-induced, boundary-<span class="hlt">layer</span> separation at over-expanded conditions. Porous configurations were capable of controlling off-design separation in the nozzle by either alleviating separation or encouraging stable separation of the exhaust flow. The ability of the porous nozzle concept to alternately alleviate separation or encourage stable separation of exhaust flow through <span class="hlt">shock</span>-boundary <span class="hlt">layer</span> interaction control offers tremendous off-design performance benefits for fixed-geometry nozzle installations. In addition, the ability to encourage separation on one divergent flap while alleviating it on the other makes it possible to generate thrust vectoring using a fixed-geometry nozzle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19770054185&hterms=wall+shear+stress&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dwall%2Bshear%2Bstress','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19770054185&hterms=wall+shear+stress&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dwall%2Bshear%2Bstress"><span id="translatedtitle">Direct measurements of wall shear stress by buried wire gages in a <span class="hlt">shock</span>-wave boundary-<span class="hlt">layer</span> interaction region</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Murthy, V. S.; Rose, W. C.</p> <p>1977-01-01</p> <p>Detailed measurements of wall shear stress (skin friction) were made with specially developed buried wire gages in the interaction regions of a Mach 2.9 turbulent boundary <span class="hlt">layer</span> with externally generated <span class="hlt">shocks</span>. Separation and reattachment points inferred by these measurements support the findings of earlier experiments which used a surface oil flow technique and pitot profile measurements. The measurements further indicate that the boundary <span class="hlt">layer</span> tends to attain significantly higher skin-friction values downstream of the interaction region as compared to upstream. Comparisons between measured wall shear stress and published results of some theoretical calculation schemes show that the general, but not detailed, behavior is predicted well by such schemes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993PhDT........20W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993PhDT........20W"><span id="translatedtitle">Skin-friction measurements in a 3-D, supersonic <span class="hlt">shock-wave/boundary-layer</span> interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wideman, Jeffrey Kenneth</p> <p></p> <p>An experimental study has been conducted in a three-dimensional, supersonic shockwave/boundary-<span class="hlt">layer</span> interaction (3-D SW/BLI) with the intent of providing accurate experimental data for turbulence modeling and computational fluid dynamics (CFD) code validation. The experiment was performed in the High Reynolds Channel 1 (HRCI) wind tunnel at NASA Ames Research Center. The test was conducted at a Mach number of M(sub infinity) = 2.89 and at a Reynolds number of Re = 15 x 106/m. The model consisted of a sting-supported cylinder aligned with the tunnel axis and a 20 deg half-angle conical flare offset 1.27 cm from the cylinder centerline. The generated <span class="hlt">shock</span> system was verified to be steady by schlieren visualization. The highlight of the study was the acquisition of 3-D skin-friction data by a laser interferometric skin friction (LISF) meter. Surface pressure measurements were obtained in 15 deg intervals around the cylinder and flare. Additional measurements included surface oil flow and laser light sheet illumination which were used to document the flow topology. Skin-friction measurements are proving to be a very challenging test of a CFD code predictive capability. However, at the present time there is a very limited amount of accurate skin-friction data in complex flows such as in 3-D SW/BLI. The LISF technique is advantageous as compared to other skin-friction measurement techniques for application in complex flows like the present since it is non-intrusive and is capable of performing measurements in flows with large shear and pressure gradients where the reliability of other techniques is questionable. Thus, the prevent skin-friction data will prove valuable to turbulence modeling and CFD code validation efforts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JSASS..58...68O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JSASS..58...68O"><span id="translatedtitle">Effects of Crack on Heat Flux in Hypersonic <span class="hlt">Shock/Boundary-Layer</span> Interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ozawa, Hiroshi; Hanai, Katsuhisa; Kitamura, Keiichi; Mori, Koichi; Nakamura, Yoshiaki</p> <p></p> <p>A small crack on body surface led to a tragic accident in 2003, which is the Columbia accident. During the shuttle's re-entry, high temperature gas penetrated crack on leading-edge of the left wing and melted the aluminum structure, finally the Columbia blew up. Since early times, there are many fundamental studies about simple cavity-flow formed on body surface in hypersonic speeds. However, an investigation of <span class="hlt">Shock/Boundary-Layer</span> Interaction (SBLI) on crack has not been researched. For multistage space transportation vehicle such as TSTO, SBLI is an inevitable problem, and then SBLI on crack becomes a critical issue for TSTO development. In this study, the effects of crack, where SBLI occurs, were investigated for TSTO hypersonic speed (M∞ = 8.1). A square crack locates at SBLI point on the TSTO booster. Results show that a crack and its depth strongly effect on peak heat flux and aerodynamic interaction flow-field. In the cases of shallow crack (d/C ≤ 0.10), there exist two high heat flux regions on crack floor, which locates at a flow reattachment region and a back end wall of crack. In this case, a peak heat flux at flow reattachment region becomes about 2 times as large as the stagnation point heat flux, which value becomes larger compared with a peak heat flux in the case of No-Crack TSTO. While in the case of deep crack (d/C = 0.20), overall heat flux on crack floor decreases to below the stagnation point heat flux. These results provide useful data for a development of TSTO thermal protection system (TPS) such as thermal protection tile.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110011889','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110011889"><span id="translatedtitle">Control Volume Analysis of Boundary <span class="hlt">Layer</span> Ingesting Propulsion Systems With or Without <span class="hlt">Shock</span> Wave Ahead of the Inlet</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kim, Hyun Dae; Felder, James L.</p> <p>2011-01-01</p> <p>The performance benefit of boundary <span class="hlt">layer</span> or wake ingestion on marine and air vehicles has been well documented and explored. In this article, a quasi-one-dimensional boundary <span class="hlt">layer</span> ingestion (BLI) benefit analysis for subsonic and transonic propulsion systems is performed using a control volume of a ducted propulsion system that ingests the boundary <span class="hlt">layer</span> developed by the external airframe surface. To illustrate the BLI benefit, a relationship between the amount of BLI and the net thrust is established and analyzed for two propulsor types. One propulsor is an electric fan, and the other is a pure turbojet. These engines can be modeled as a turbofan with an infinite bypass ratio for the electric fan, and with a zero bypass ratio for the pure turbojet. The analysis considers two flow processes: a boundary <span class="hlt">layer</span> being ingested by an aircraft inlet and a <span class="hlt">shock</span> wave sitting in front of the inlet. Though the two processes are completely unrelated, both represent a loss of total pressure and velocity. In real applications, it is possible to have both processes occurring in front of the inlet of a transonic vehicle. Preliminary analysis indicates that the electrically driven propulsion system benefits most from the boundary <span class="hlt">layer</span> ingestion and the presence of transonic <span class="hlt">shock</span> waves, whereas the benefit for the turbojet engine is near zero or negative depending on the amount of total temperature rise across the engine.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997JFM...351..139P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997JFM...351..139P"><span id="translatedtitle">Instability of two-<span class="hlt">layer</span> creeping flow in a channel with <span class="hlt">parallel</span>-sided walls</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pozrikidis, C.</p> <p>1997-11-01</p> <p>The evolution of the interface between two viscous fluid <span class="hlt">layers</span> in a two-dimensional horizontal channel confined between two <span class="hlt">parallel</span> walls is considered in the limit of Stokes flow. The motion is generated either by the translation of the walls, in a shear-driven or plane-Couette mode, or by an axial pressure gradient, in a plane-Poiseuille mode. Linear stability analysis for infinitesimal perturbations and fluids with matched densities shows that when the viscosities of the fluids are different and the Reynolds number is sufficiently high, the flow is unstable. At vanishing Reynolds number, the flow is stable when the surface tension has a non-zero value, and neutrally stable when the surface tension vanishes. We investigate the behaviour of the interface subject to finite-amplitude two-dimensional perturbations by solving the equations of Stokes flow using a boundary-integral method. Integral equations for the interfacial velocity are formulated for the three modular cases of shear-driven, pressure-driven, and gravity-driven flow, and numerical computations are performed for the first two modes. The results show that disturbances of sufficiently large amplitude may cause permanent interfacial deformation in which the interface folds, develops elongated fingers, or supports slowly evolving travelling waves. Smaller amplitude disturbances decay, sometimes after a transient period of interfacial folding. The ratio of the viscosities of the two fluids plays an important role in determining the morphology of the emerging interfacial patterns, but the parabolicity of the unperturbed velocity profile does not affect the character of the motion. Increasing the contrast in the viscosities of the two fluids, while keeping the channel capillary number fixed, destabilizes the interfaces; re-examining the flow in terms of an alternative capillary number that is defined with respect to the velocity drop across the more-viscous <span class="hlt">layer</span> shows that this is a reasonable behaviour</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992shwa.conf..671P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992shwa.conf..671P"><span id="translatedtitle">Studies of radiative emission from the simulated <span class="hlt">shock</span> <span class="hlt">layer</span> of the Huygens probe</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Park, C. S.; Bershader, D.</p> <p></p> <p>An investigation has been conducted to determine the radiative heating of the Huygens probe. The <span class="hlt">shock</span> tube facility at Stanford University was used to generate plasma behind strong <span class="hlt">shocks</span>, which simulates the flow field around the probe. Spectroscopic techniques have been used to measure thermophysical quantities of the plasma in the <span class="hlt">shock</span> tube. A numerical code has been developed using a three temperature model in order to generate one dimensional flow field solutions for comparison with these experimental data. Based on this analysis, the radiative heat transfer at the stagnation point of the prove was approximated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19810035936&hterms=shock+initiation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dshock%2Binitiation','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19810035936&hterms=shock+initiation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dshock%2Binitiation"><span id="translatedtitle">Interstellar <span class="hlt">shock</span> waves</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mckee, C. F.; Hollenbach, D. J.</p> <p>1980-01-01</p> <p>The structure of interstellar <span class="hlt">shocks</span> driven by supernova remnants and by expanding H II regions around early-type stars is discussed. Jump conditions are examined, along with <span class="hlt">shock</span> fronts, post-<span class="hlt">shock</span> relaxation <span class="hlt">layers</span>, collisional <span class="hlt">shocks</span>, collisionless <span class="hlt">shocks</span>, nonradiative <span class="hlt">shocks</span>, radiative atomic <span class="hlt">shocks</span>, and <span class="hlt">shock</span> models of observed nebulae. Effects of <span class="hlt">shock</span> waves on interstellar molecules are examined, with reference to the chemistry behind <span class="hlt">shock</span> fronts, infrared and vibrational-rotational cooling by molecules, and observations of <span class="hlt">shocked</span> molecules. Some current problems and applications of the study of interstellar <span class="hlt">shocks</span> are summarized, including the initiation of star formation by radiative <span class="hlt">shock</span> waves, interstellar masers, the stability of <span class="hlt">shocks</span>, particle acceleration in <span class="hlt">shocks</span>, and <span class="hlt">shocks</span> in galactic nuclei.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930064302&hterms=enthalpy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Denthalpy','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930064302&hterms=enthalpy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Denthalpy"><span id="translatedtitle">Aerothermodynamic heating due to <span class="hlt">shock</span> wave/laminar boundary-<span class="hlt">layer</span> interactions in high-enthalpy hypersonic flow</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hackett, Charles M.</p> <p>1993-01-01</p> <p>The interaction between a swept <span class="hlt">shock</span> wave and a laminar boundary <span class="hlt">layer</span> was investigated experimentally in high-enthalpy hypersonic flow. The effect of high-temperature, real gas physics on the interaction was examined by conducting tests in air and helium. Heat transfer measurements were made on the surface of a flat plate and a <span class="hlt">shock</span>-generating fin using thin-film resistance sensors for fin incidence angles of 0, 5, and 10 deg at Mach numbers of 6.9 in air and 7.2 in helium. The experiments were conducted in the NASA HYPULSE expansion tube, an impulse-type facility capable of generating high-enthalpy, high-velocity flow with freestream levels of dissociated species that are particularly low. The measurements indicate that the swept <span class="hlt">shock</span> wave creates high local heat transfer levels in the interaction region, with the highest heating found in the strongest interaction. The maximum measured heating rates in the interaction are order of magnitude greater than laminar flat plate boundary <span class="hlt">layer</span> heating levels at the same location.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhFl...26i6103O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhFl...26i6103O"><span id="translatedtitle">Laser energy deposition effectiveness on <span class="hlt">shock</span>-wave boundary-<span class="hlt">layer</span> interactions over cylinder-flare combinations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Osuka, T.; Erdem, E.; Hasegawa, N.; Majima, R.; Tamba, T.; Yokota, S.; Sasoh, A.; Kontis, K.</p> <p>2014-09-01</p> <p>The effects of repetitive laser-pulse energy depositions (5.5 mJ/pulse) onto a <span class="hlt">shock</span> wave-boundary <span class="hlt">layer</span> interaction region over cylinder-flare model in a Mach 1.92 flow are experimentally investigated. Depending on the nose shape and the flare angle, the flow patterns are subdivided to two; separated flow in which a slip line and a strong separation <span class="hlt">shock</span> wave originated in the nose-cylinder junction appears, and a non-separated flow in which a slip line is not observed and the re-attachment <span class="hlt">shock</span> wave is much weaker. At flare angles around 30°, the separation can be suppressed by laser energy deposition even of down to 5 kHz. The Schlieren-visualized flow patterns are well correlated to the drag characteristics, in which a larger drag is obtained without separation. A possible scenario of the separation control is that the disturbance introduced by the baroclinic vortex ring induced the boundary <span class="hlt">layer</span> transition so that it became robust against the adverse pressure gradient. Under marginal conditions, dual mode flow patterns, that is, a partial and full suppression modes are obtained under the same operation conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23927185','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23927185"><span id="translatedtitle">Model for the dynamics of a spherical bubble undergoing small shape oscillations between <span class="hlt">parallel</span> soft elastic <span class="hlt">layers</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hay, Todd A; Ilinskii, Yurii A; Zabolotskaya, Evgenia A; Hamilton, Mark F</p> <p>2013-08-01</p> <p>A model is developed for a pulsating and translating gas bubble immersed in liquid in a channel formed by two soft, thin elastic <span class="hlt">parallel</span> <span class="hlt">layers</span> having densities equal to that of the surrounding liquid and small, but finite, shear moduli. The bubble is nominally spherical but free to undergo small shape deformations. Shear strain in the elastic <span class="hlt">layers</span> is estimated in a way which is valid for short, transient excitations of the system. Coupled nonlinear second-order differential equations are obtained for the shape and position of the bubble, and numerical integration of an expression for the liquid velocity at the <span class="hlt">layer</span> interfaces yields an estimate of the elastic <span class="hlt">layer</span> displacement. Numerical integration of the dynamical equations reveals behavior consistent with laboratory observations of acoustically excited bubbles in ex vivo vessels reported by Chen et al. [Phys. Rev. Lett. 106, 034301 (2011) and Ultrasound Med. Biol. 37, 2139-2148 (2011)]. PMID:23927185</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004EJASP2004...20X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004EJASP2004...20X"><span id="translatedtitle"><span class="hlt">Parallel</span> Multistage Decision Feedback Equalizer for Single-Carrier <span class="hlt">Layered</span> Space-Time Systems in Frequency-Selective Channels</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xu, Jing; Wang, Haifeng; Cheng, Shixin; Chen, Ming</p> <p>2004-12-01</p> <p>Space-time transmission techniques can greatly increase the spectral efficiency. In this paper, a <span class="hlt">parallel</span> multistage decision feedback equalizer (PMDFE) is proposed for single-carrier <span class="hlt">layered</span> space-time systems with a fixed cyclic prefix over frequency-selective channels. It is composed of a <span class="hlt">parallel</span> interference canceller, a multiple-input single-output decision feedback equalizer (MISO-DFE), and a linear combiner. The soft output of the MISO-DFE is linearly combined with the previous tentative soft decision. In addition, an algorithm is proposed to obtain tentative soft and hard decisions for initializing the equalizer. The initializing complexity of the PMDFE is lower than that of MIMO-OFDM. Simulation results show that the PMDFE outperforms MIMO-OFDM and previously existing equalizers for single-carrier <span class="hlt">layered</span> space-time systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19900035154&hterms=skin+layers&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dskin%2Blayers','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19900035154&hterms=skin+layers&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dskin%2Blayers"><span id="translatedtitle">Laser skin friction measurements and CFD comparison of weak-to-strong swept <span class="hlt">shock/boundary-layer</span> interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kim, K.-S.; Lee, Y.; Alvi, F. S.; Settles, G. S.; Horstman, C. C.</p> <p>1990-01-01</p> <p>A joint experimental and computational study of skin friction in weak-to-strong swept <span class="hlt">shock</span> wave/turbulent boundary-<span class="hlt">layer</span> interactions has been carried out. A planar <span class="hlt">shock</span> wave is generated by a sharp fin at angles of attack alpha = 10 deg and 16 deg at M(infinity) = 3 and 16 and 20 deg at M(infinity) = 4. Measurements are made using the Laser Interferometer Skin Friction meter, which optically detects the rate of thinning of an oil film applied to the test surface. The results show a systematic rise in the peak c(f) at the rear part of the interaction, where the separated flow atttaches. For the stronget case studied, this peak is an order of magnitude higher than the incoming freestream c(f)level.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760002931','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760002931"><span id="translatedtitle">An experimental and numerical investigation of <span class="hlt">shock</span>-wave induced turbulent boundary-<span class="hlt">layer</span> separation at hypersonic speeds</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Marvin, J. G.; Horstman, C. C.; Rubesin, M. W.; Coakley, T. J.; Kussoy, M. I.</p> <p>1975-01-01</p> <p>An experiment designed to test and guide computations of the interaction of an impinging <span class="hlt">shock</span> wave with a turbulent boundary <span class="hlt">layer</span> is described. Detailed mean flow-field and surface data are presented for two <span class="hlt">shock</span> strengths which resulted in attached and separated flows, respectively. Numerical computations, employing the complete time-averaged Navier-Stokes equations along with algebraic eddy-viscosity and turbulent Prandtl number models to describe shear stress and heat flux, are used to illustrate the dependence of the computations on the particulars of the turbulence models. Models appropriate for zero-pressure-gradient flows predicted the overall features of the flow fields, but were deficient in predicting many of the details of the interaction regions. Improvements to the turbulence model parameters were sought through a combination of detailed data analysis and computer simulations which tested the sensitivity of the solutions to model parameter changes. Computer simulations using these improvements are presented and discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007SPIE.6422E..0UG&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007SPIE.6422E..0UG&link_type=ABSTRACT"><span id="translatedtitle">Laser <span class="hlt">shock</span> processing to improve residual stresses with and without paint <span class="hlt">layer</span> on 6061-T6 aluminum alloy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gomez-Rosas, G.; Rubio-Gonzalez, C.; Ocaña, J. L.; Molpeceres, C.; Porro, J. A.; Morales, M.; Casillas, F. J.; Mora-Gonzalez, M.; Chi-Moreno, W.</p> <p>2007-03-01</p> <p>Laser <span class="hlt">shock</span> processing (LSP) or laser <span class="hlt">shock</span> peening has been proposed as a competitive alternative technology to classical treatments for improving fatigue and wear resistance of metals. This process induces a compressive residual stress field which increases fatigue crack initiation life and reduce fatigue crack growth rate. We present a configuration and results in the LSP concept for metal surface treatments in underwater laser irradiation at 1064 nm with and without a thin surface paint <span class="hlt">layer</span>. A convergent lens is used to deliver 1, 2 J/cm2 with a 8 ns laser FWHM pulse produced by a 10 Hz, Q-switched Nd:YAG laser with a spot diameter of a 1,5 mm moving forward along the workpiece. A LSP configuration with experimental results using a pulse density of 5000 pulses/cm2 in 6061-T6 aluminum samples are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740011794','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740011794"><span id="translatedtitle">Experimental study of sharp and blunt nose streamwise corners at Mach 20. [hypersonic <span class="hlt">shock</span>-boundary <span class="hlt">layer</span> interaction parameters</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Watson, R. D.</p> <p>1974-01-01</p> <p>Extensive heat transfer and pressure distribution data and oil flow studies on sharp and blunt-nose streamwise corners at Mach 20 in helium are presented. The far corner boundary <span class="hlt">layers</span> on the wedge surfaces forming the corners are laminar for most test conditions. Analysis of the data indicates that the corner flow field geometry can be described in terms of the inviscid <span class="hlt">shock</span> pattern on the two dimensional surfaces forming the corner. Parameters used to correlate blunt <span class="hlt">shock</span> growth can be used to correlate features of the flow field observed in oil flow photographs in addition to the measured pressure and heat transfer distributions on the models. The flow field structure is described from available experimental data. Regions of the flow in which the structure still is not known are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ShWav..24..157C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ShWav..24..157C"><span id="translatedtitle">Influence of shear <span class="hlt">layers</span> on the structure of <span class="hlt">shocks</span> formed by rectangular and parabolic blockages placed in a subsonic flow-field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cheeda, V. K.; Kumar, A.; Ramamurthi, K.</p> <p>2014-03-01</p> <p>Flow blockages are used to promote the transition of a flame to a detonation. The structure of <span class="hlt">shock</span> waves formed with different configurations of blockages was experimentally determined for subsonic incoming flow. High speed subsonic flows could develop ahead of a turbulent flame and the interaction of such flows with blockages could lead to the formation of interacting <span class="hlt">shock</span> waves, slipstreams, and expansion waves. A blow-down test setup was designed to study the interacting <span class="hlt">shock</span> pattern formed with different configurations of blockages. The flow was found to accelerate to low supersonic velocities during its passage over the blockages. The <span class="hlt">shock</span> structure downstream of the blockages was found to depend on the shape, size, and number of blockages as well as the spacing between them. While a parabolic-shaped blockage provided <span class="hlt">shocks</span> of maximum strength, large blockage ratio values did not permit the formation of <span class="hlt">shocks</span>. The shear <span class="hlt">layer</span>, formed in the flow downstream of the blockages, reflected the expansion fan as <span class="hlt">shock</span> waves and was found to be a major feature influencing the formation of the interacting structure of oblique <span class="hlt">shocks</span>. The structure and strength of the <span class="hlt">shock</span> waves are analyzed using hodograms. The formation of the interacting family of <span class="hlt">shock</span> waves using different configurations of blockages and the spacings between them are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhDT.......128Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT.......128Y"><span id="translatedtitle">Three-Dimensional <span class="hlt">Shock</span>-Boundary <span class="hlt">Layer</span> Interactions in Simulations of HIFiRE-1 and HIFiRE-2</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yentsch, Robert J.</p> <p></p> <p>A series of high-fidelity, three-dimensional simulations has been performed to investigate hypersonic phenomena encountered in the HIFiRE Flight 1 and Flight 2 experiments. The investigation of HIFiRE-1highlights the performance of turbulence modeling in realistic hypersonic flight vehicles subject to laminar-to-turbulent boundary <span class="hlt">layer</span> transition and geometry induced adverse pressure gradient separated <span class="hlt">shock</span> boundary <span class="hlt">layer</span> interactions (corner flows) influenced by three-dimensional effects. Comparisons with flight test data indicate that the performance of the turbulence model is dependent on the flow condition and the variable under examination. The surface pressure trends are reproduced in all cases, and predictions for the axial separation location is generally within 20% of the separated region length. For the lower Mach number cases, the surface pressure is predicted better at the lower Reynolds number case. Heat transfer predictions on the cone are good, although the use of empirically specified laminar-to-turbulent transition is necessary. The best comparison in heat transfer rates at the flare are observed at the highest Mach number. Overall, the results suggest that the K -- o turbulence model used in this study can be used for flight test prediction, though such uses must be done with care. The primary focus of this dissertation is on the HIFiRE-2 scramjet, specifically, the transient process of dual-to-scramjet mode-transition. For this geometry, the role of the primary fuel injectors in scramjet-mode operation is very important. The barrel <span class="hlt">shocks</span> from the jet-in-crossflow interaction serves as a flameholder, allowing upstream propagation of pressure rise from the combustion in the cavity into the isolator. It is also shown that the presence of inlet <span class="hlt">shocks</span> in the isolator can profoundly change the flow, a fact which must be considered in ground testing. A mode-transition event is present which demarcates dual-mode operation from scramjet-mode operation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016JApA...37...14B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016JApA...37...14B&link_type=ABSTRACT"><span id="translatedtitle">Large Scale Earth's Bow <span class="hlt">Shock</span> with Northern IMF as Simulated by PIC Code in <span class="hlt">Parallel</span> with MHD Model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baraka, Suleiman</p> <p>2016-06-01</p> <p>In this paper, we propose a 3D kinetic model (particle-in-cell, PIC) for the description of the large scale Earth's bow <span class="hlt">shock</span>. The proposed version is stable and does not require huge or extensive computer resources. Because PIC simulations work with scaled plasma and field parameters, we also propose to validate our code by comparing its results with the available MHD simulations under same scaled solar wind (SW) and (IMF) conditions. We report new results from the two models. In both codes the Earth's bow <span class="hlt">shock</span> position is found to be ≈14.8 R E along the Sun-Earth line, and ≈29 R E on the dusk side. Those findings are consistent with past in situ observations. Both simulations reproduce the theoretical jump conditions at the <span class="hlt">shock</span>. However, the PIC code density and temperature distributions are inflated and slightly shifted sunward when compared to the MHD results. Kinetic electron motions and reflected ions upstream may cause this sunward shift. Species distributions in the foreshock region are depicted within the transition of the <span class="hlt">shock</span> (measured ≈2 c/ ω pi for Θ Bn = 90° and M MS = 4.7) and in the downstream. The size of the foot jump in the magnetic field at the <span class="hlt">shock</span> is measured to be (1.7 c/ ω pi ). In the foreshocked region, the thermal velocity is found equal to 213 km s-1 at 15 R E and is equal to 63 km s -1 at 12 R E (magnetosheath region). Despite the large cell size of the current version of the PIC code, it is powerful to retain macrostructure of planets magnetospheres in very short time, thus it can be used for pedagogical test purposes. It is also likely complementary with MHD to deepen our understanding of the large scale magnetosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150002101','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150002101"><span id="translatedtitle">Experimental Study of Fillets to Reduce Corner Effects in an Oblique <span class="hlt">Shock</span>-Wave/Boundary <span class="hlt">Layer</span> Interaction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hirt, Stefanie M.</p> <p>2015-01-01</p> <p>A test was conducted in the 15 cm x 15 cm supersonic wind tunnel at NASA Glenn Research Center that focused on corner effects of an oblique <span class="hlt">shock-wave/boundary-layer</span> interaction. In an attempt to control the interaction in the corner region, eight corner fillet configurations were tested. Three parameters were considered for the fillet configurations: the radius, the fillet length, and the taper length from the square corner to the fillet radius. Fillets effectively reduced the boundary-<span class="hlt">layer</span> thickness in the corner; however, there was an associated penalty in the form of increased boundary-<span class="hlt">layer</span> thickness at the tunnel centerline. Larger fillet radii caused greater reductions in boundary-<span class="hlt">layer</span> thickness along the corner bisector. To a lesser, but measureable, extent, shorter fillet lengths resulted in thinner corner boundary <span class="hlt">layers</span>. Overall, of the configurations tested, the largest radius resulted in the best combination of control in the corner, evidenced by a reduction in boundary-<span class="hlt">layer</span> thickness, coupled with minimal impacts at the tunnel centerline.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110013216','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110013216"><span id="translatedtitle">Uncertainty Assessments of 2D and Axisymmetric Hypersonic <span class="hlt">Shock</span> Wave - Turbulent Boundary <span class="hlt">Layer</span> Interaction Simulations at Compression Corners</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gnoffo, Peter A.; Berry, Scott A.; VanNorman, John W.</p> <p>2011-01-01</p> <p>This paper is one of a series of five papers in a special session organized by the NASA Fundamental Aeronautics Program that addresses uncertainty assessments for CFD simulations in hypersonic flow. Simulations of a <span class="hlt">shock</span> emanating from a compression corner and interacting with a fully developed turbulent boundary <span class="hlt">layer</span> are evaluated herein. Mission relevant conditions at Mach 7 and Mach 14 are defined for a pre-compression ramp of a scramjet powered vehicle. Three compression angles are defined, the smallest to avoid separation losses and the largest to force a separated flow engaging more complicated flow physics. The Baldwin-Lomax and the Cebeci-Smith algebraic models, the one-equation Spalart-Allmaras model with the Catrix-Aupoix compressibility modification and two-equation models including Menter SST, Wilcox k-omega 98, and Wilcox k-omega 06 turbulence models are evaluated. Each model is fully defined herein to preclude any ambiguity regarding model implementation. Comparisons are made to existing experimental data and Van Driest theory to provide preliminary assessment of model form uncertainty. A set of coarse grained uncertainty metrics are defined to capture essential differences among turbulence models. Except for the inability of algebraic models to converge for some separated flows there is no clearly superior model as judged by these metrics. A preliminary metric for the numerical component of uncertainty in <span class="hlt">shock-turbulent-boundary-layer</span> interactions at compression corners sufficiently steep to cause separation is defined as 55%. This value is a median of differences with experimental data averaged for peak pressure and heating and for extent of separation captured in new, grid-converged solutions presented here. This value is consistent with existing results in a literature review of hypersonic <span class="hlt">shock-turbulent-boundary-layer</span> interactions by Roy and Blottner and with more recent computations of MacLean.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20020004023&hterms=RADIATION+THERMAL&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DRADIATION%2BTHERMAL','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20020004023&hterms=RADIATION+THERMAL&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DRADIATION%2BTHERMAL"><span id="translatedtitle">Diverse Studies in the Reactivated NASA/Ames Radiation Facility: From <span class="hlt">Shock</span> <span class="hlt">Layer</span> Spectroscopy to Thermal Protection System Impact</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Miller, Robert J.; Hartman, G. Joseph (Technical Monitor)</p> <p>1994-01-01</p> <p>NASA/Ames' Hypervelocity Free-Flight Radiation Facility has been reactivated after having been decommissioned for some 15 years, first tests beginning in early 1994. This paper discusses two widely different studies from the first series, one involving spectroscopic analysis of model <span class="hlt">shock-layer</span> radiation, and the other the production of representative impact damage in space shuttle thermal protection tiles for testing in the Ames arc-jet facilities. These studies emphasize the interorganizational and interdisciplinary value of the facility in the newly-developing structure of NASA.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920014300','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920014300"><span id="translatedtitle">Viscous-<span class="hlt">shock-layer</span> analysis of hypersonic flows over long slender vehicles. Ph.D. Thesis, 1988</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lee, Kam-Pui; Gupta, Roop N.</p> <p>1992-01-01</p> <p>An efficient and accurate method for solving the viscous <span class="hlt">shock</span> <span class="hlt">layer</span> equations for hypersonic flows over long slender bodies is presented. The two first order equations, continuity and normal momentum, are solved simultaneously as a coupled set. The flow conditions included are from high Reynolds numbers at low altitudes to low Reynolds numbers at high altitudes. For high Reynolds number flows, both chemical nonequilibrium and perfect gas cases are analyzed with surface catalytic effects and different turbulence models, respectively. At low Reynolds number flow conditions, corrected slip models are implemented with perfect gas case. Detailed comparisons are included with other predictions and experimental data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012SPIE.8314E..1HL','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012SPIE.8314E..1HL"><span id="translatedtitle"><span class="hlt">Parallel</span> graph search: application to intraretinal <span class="hlt">layer</span> segmentation of 3D macular OCT scans</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, Kyungmoo; Abràmoff, Michael D.; Garvin, Mona K.; Sonka, Milan</p> <p>2012-02-01</p> <p>Image segmentation is of paramount importance for quantitative analysis of medical image data. Recently, a 3-D graph search method which can detect globally optimal interacting surfaces with respect to the cost function of volumetric images has been introduced, and its utility demonstrated in several application areas. Although the method provides excellent segmentation accuracy, its limitation is a slow processing speed when many surfaces are simultaneously segmented in large volumetric datasets. Here, we propose a novel method of <span class="hlt">parallel</span> graph search, which overcomes the limitation and allows the quick detection of multiple surfaces. To demonstrate the obtained performance with respect to segmentation accuracy and processing speedup, the new approach was applied to retinal optical coherence tomography (OCT) image data and compared with the performance of the former non-<span class="hlt">parallel</span> method. Our <span class="hlt">parallel</span> graph search methods for single and double surface detection are approximately 267 and 181 times faster than the original graph search approach in 5 macular OCT volumes (200 x 5 x 1024 voxels) acquired from the right eyes of 5 normal subjects. The resulting segmentation differences were small as demonstrated by the mean unsigned differences between the non-<span class="hlt">parallel</span> and <span class="hlt">parallel</span> methods of 0.0 +/- 0.0 voxels (0.0 +/- 0.0 μm) and 0.27 +/- 0.34 voxels (0.53 +/- 0.66 μm) for the single- and dual-surface approaches, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AcMSn.tmp..101X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AcMSn.tmp..101X"><span id="translatedtitle">Impact toughness of a gradient hardened <span class="hlt">layer</span> of Cr5Mo1V steel treated by laser <span class="hlt">shock</span> peening</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xia, Weiguang; Li, Lei; Wei, Yanpeng; Zhao, Aimin; Guo, Yacong; Huang, Chenguang; Yin, Hongxiang; Zhang, Lingchen</p> <p>2015-09-01</p> <p>Laser <span class="hlt">shock</span> peening (LSP) is a widely used surface treatment technique that can effectively improve the fatigue life and impact toughness of metal parts. Cr5Mo1V steel exhibits a gradient hardened <span class="hlt">layer</span> after a LSP process. A new method is proposed to estimate the impact toughness that considers the changing mechanical properties in the gradient hardened <span class="hlt">layer</span>. Assuming a linearly gradient distribution of impact toughness, the parameters controlling the impact toughness of the gradient hardened <span class="hlt">layer</span> were given. The influences of laser power densities and the number of laser shots on the impact toughness were investigated. The impact toughness of the laser peened <span class="hlt">layer</span> improves compared with an untreated specimen, and the impact toughness increases with the laser power densities and decreases with the number of laser shots. Through the fracture morphology analysis by a scanning electron microscope, we established that the Cr5Mo1V steel was fractured by the cleavage fracture mechanism combined with a few dimples. The increase in the impact toughness of the material after LSP is observed because of the decreased dimension and increased fraction of the cleavage fracture in the gradient hardened <span class="hlt">layer</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AcMSn..32..301X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AcMSn..32..301X"><span id="translatedtitle">Impact toughness of a gradient hardened <span class="hlt">layer</span> of Cr5Mo1V steel treated by laser <span class="hlt">shock</span> peening</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xia, Weiguang; Li, Lei; Wei, Yanpeng; Zhao, Aimin; Guo, Yacong; Huang, Chenguang; Yin, Hongxiang; Zhang, Lingchen</p> <p>2016-04-01</p> <p>Laser <span class="hlt">shock</span> peening (LSP) is a widely used surface treatment technique that can effectively improve the fatigue life and impact toughness of metal parts. Cr5Mo1V steel exhibits a gradient hardened <span class="hlt">layer</span> after a LSP process. A new method is proposed to estimate the impact toughness that considers the changing mechanical properties in the gradient hardened <span class="hlt">layer</span>. Assuming a linearly gradient distribution of impact toughness, the parameters controlling the impact toughness of the gradient hardened <span class="hlt">layer</span> were given. The influences of laser power densities and the number of laser shots on the impact toughness were investigated. The impact toughness of the laser peened <span class="hlt">layer</span> improves compared with an untreated specimen, and the impact toughness increases with the laser power densities and decreases with the number of laser shots. Through the fracture morphology analysis by a scanning electron microscope, we established that the Cr5Mo1V steel was fractured by the cleavage fracture mechanism combined with a few dimples. The increase in the impact toughness of the material after LSP is observed because of the decreased dimension and increased fraction of the cleavage fracture in the gradient hardened <span class="hlt">layer</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19730032110&hterms=adverse+pressure+gradient&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dadverse%2Bpressure%2Bgradient','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19730032110&hterms=adverse+pressure+gradient&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dadverse%2Bpressure%2Bgradient"><span id="translatedtitle">Turbulence measurements in a compressible boundary <span class="hlt">layer</span> subjected to a <span class="hlt">shock</span>-wave-induced adverse pressure gradient.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rose, W. C.</p> <p>1973-01-01</p> <p>The rms intensities of fluctuating mass flux and total temperature and their correlation coefficients are given for the case of an adiabatic, Mach 4, axisymmetric <span class="hlt">shock</span>-wave boundary-<span class="hlt">layer</span> interaction. Data were obtained upstream, within, and downstream of the interaction by the use of constant temperature hot-wire anemometer. Turbulence spectra and quantitative behavior from oscilloscope traces are shown at selected locations. The measurements indicate that certain frequencies of the turbulence are increased as a result of the interaction and that the mass flux and total temperature fluctuations remain highly correlated over most of the boundary <span class="hlt">layer</span> throughout the interaction. The present data are also transformed to rms intensities of fluctuating static temperature and velocity and compared with existing data obtained in adiabatic flows.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930016077','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930016077"><span id="translatedtitle">An experimental study of the sources of fluctuating pressure loads beneath swept <span class="hlt">shock/boundary-layer</span> interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Settles, G. S.; Garg, S.</p> <p>1993-01-01</p> <p>An experimental research program providing basic knowledge and establishing a database on the fluctuating pressure loads produced on aerodynamic surfaces beneath three dimensional <span class="hlt">shock</span> wave/boundary <span class="hlt">layer</span> interactions is described. Such loads constitute a fundamental problem of critical concern to future supersonic and hypersonic flight vehicles. A turbulent boundary <span class="hlt">layer</span> on a flat plate is subjected to interactions with swept planar <span class="hlt">shock</span> waves generated by sharp fins at angle of attack. Fin angles from 10 to 20 deg at freestream Mach numbers of 3 and 4 produce a variety of interaction strengths from weak to very strong. Miniature Kulite pressure transducers flush-mounted in the flat plate are used to measure interaction-induced wall pressure fluctuations. The distributions of properties of the pressure fluctuations, such as their ring levels, amplitude distributions, and power spectra, are also determined. Measurements were made for the first time in the aft regions of these interactions, revealing fluctuating pressure levels as high as 160 dB. These fluctuations are dominated by low frequency (0-5 kHz) signals. The maximum ring levels in the interactions show an increasing trend with increasing interaction strength. On the other hand, the maximum ring levels in the forward portion of the interactions decrease linearly with increasing interaction sweep back. These ring pressure distributions and spectra are correlated with the features of the interaction flowfield. The unsteadiness of the off-surface flowfield is studied using a new, non-intrusive technique based on the shadow graph method. The results indicate that the entire lambda-<span class="hlt">shock</span> structure generated by the interaction undergoes relatively low-frequency oscillations. Some regions where particularly strong fluctuations are generated were identified. Fluctuating pressure measurements are also made along the line of symmetry of an axisymmetric jet impinging upon a flat plate at an angle. This flow was</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFMSM31C0569W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFMSM31C0569W"><span id="translatedtitle">The Fine Structure of Ion-sound Turbulence Observed in the Terrestrial Bow <span class="hlt">Shock</span> Transition <span class="hlt">Layer</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Walker, S. N.; Baldacchino, T. S.; Alleyne, H.; Balikhin, M. A.; Andre, M.</p> <p>2007-12-01</p> <p>High time resolution observations the quasiperpendicular regime of the terrestrial bow <span class="hlt">shock</span> by Cluster are used to investigate ion sound turbulence in the ramp and foot regions. The four independent probe potential measurements onboard a single satellite are used to distinguish between ion-sound and whistler turbulence. The joint wavevector-frequency spectra are calculated and the waves propagation characteristics are determined. These wave characteristics are use to argue that at least some of observed wave packets have been generated by local currents in the foot region. The amplitude of the ion sound turbulence is used to assess the importance of ion sound based anomalous processes on the energy redistribution at the <span class="hlt">shock</span> front.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900007796','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900007796"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">layer</span> vacuum UV spectroscopy in an arc-jet wind tunnel</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Palumbo, G.</p> <p>1990-01-01</p> <p>An experimental program is being developed to obtain measurements of the incident surface radiation in the 1000 A to 2000 A range from the <span class="hlt">shock</span> stagnation region of a blunt model in the Ames 20 MW Arc-Jet Wind Tunnel. The setup consists of a water-cooled blunt model, with a magnesium fluoride forward-viewing window. Radiation incident on the window is optically imaged via an evacuated system and reflective optical elements onto the entrance slit of a spectrograph. The model will be exposed to the supersonic plasma stream from the exit nozzle of the arc-jet tunnel. The resulting bow <span class="hlt">shock</span> radiation will be measured. It is expected that this experiment will help evaluate the importance of atomic N and O lines to the radiative heating of future Aeroassist Space Transfer Vehicles (ASTVs).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1981STIN...8127453D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1981STIN...8127453D"><span id="translatedtitle">Kinetic heating due to a skewed <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span> interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Degrez, G.</p> <p>1981-01-01</p> <p>A flat/finned plate arrangement test configuration with both a sharp and a blunt fin was studied. The plate was set at angles of incidence of 7,4, and 0 degrees relative to the wind tunnel axis providing three different Mach numbers for the undisturbed flow over the flat plate (5.00, 5.53, and 6.07). Experimental data were obtained for three different <span class="hlt">shock</span> generator angles of incidence 5,10, and 15 degrees and for three Mach numbers. Very satisfactory pressure and heat distributions were predicted by Schuderi's method. The blunting of the fin's heading edge resulted is an outward displacement of the pressure and heat transfer distribution caused by the outward displacement of the inviscid <span class="hlt">shock</span> wave. The peak pressure was considerably reduced and the peak pressure and peak heating positions coincided.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhDT.......272S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhDT.......272S"><span id="translatedtitle">Experimental study of separated ramp-induced <span class="hlt">shock/boundary-layer</span> interaction with upstream micro-vortex generator at Mach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shih, Yusi</p> <p></p> <p><span class="hlt">Shock</span> wave/boundary <span class="hlt">layer</span> interactions (SBLIs) are important issues for high-speed vehicles. SBLIs reduce the performance of aerodynamic surfaces and engine inlets, amongst a number of adverse effects. Micro-vortex generators (MVGs) are a flow control method with strong potential to mitigate the effects of SBLI by energizing the boundary <span class="hlt">layer</span> through momentum transfers from the freestream. They have been implemented in actual configurations at low speeds. The present research includes a combined experimental and theoretical analysis of the evolution of the perturbation downstream the MVG, the formation of vortices, and their interaction with the <span class="hlt">shock</span> front. Experiments were performed with a baseline MVG configuration of 90° trailing edge on flat plate, ramp alone, and also with MVG mounted ahead of a 20° ramp. The surface flow visualization and particle image velocimetry (PIV) results are presented; the surface flow visualization shows a substantial suppression of SBLIs. A new method to quantify the effectiveness of the MVG on the <span class="hlt">shock</span> recompression is presented. Moreover, the PIV results were used as the initial input values for the simulation work. A theoretical analysis of the interaction of the MVG perturbation with the boundary <span class="hlt">layer</span> is performed by assuming linear dynamics of the perturbation. The major assumption is that the interaction between MVG perturbation and the shear flow is affected by transient growth as a result of the non-orthogonality of the linearized Navier-Stokes equations. A new method to perform the projection of the measured perturbation on the continuous modes of the boundary <span class="hlt">layer</span> is presented. The method takes advantage of the biorthogonality of the direct and adjoint modes. The implementation of such a method using both the Chebyshev polynomials and a shooting algorithm is discussed. The results of the theoretical analysis are encouraging and display a similar trend as the experiments. Both experimental and theoretical results</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PPCF...55e5009O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PPCF...55e5009O"><span id="translatedtitle">Non-local approach to kinetic effects on <span class="hlt">parallel</span> transport in fluid models of the scrape-off <span class="hlt">layer</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Omotani, J. T.; Dudson, B. D.</p> <p>2013-05-01</p> <p>Using a non-local model, fluid simulations can capture kinetic effects in the <span class="hlt">parallel</span> electron heat-flux better than is possible using flux limiters in the usual diffusive models. Non-local and diffusive models are compared using a test case representative of an edge-localized mode crash in the JET scrape-off <span class="hlt">layer</span> (SOL), simulated in one dimension. The non-local model shows substantially enhanced electron temperature gradients, which cannot be achieved using a flux limiter. The performance of the implementation, in the BOUT++ framework, is also analysed to demonstrate its suitability for application in three-dimensional simulations of turbulent transport in the SOL.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140005957','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140005957"><span id="translatedtitle">Aeroheating Measurement of Apollo Shaped Capsule with Boundary <span class="hlt">Layer</span> Trip in the Free-piston <span class="hlt">Shock</span> Tunnel HIEST</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hideyuki, TANNO; Tomoyuki, KOMURO; Kazuo, SATO; Katsuhiro, ITOH; Lillard, Randolph P.; Olejniczak, Joseph</p> <p>2013-01-01</p> <p>An aeroheating measurement test campaign of an Apollo capsule model with laminar and turbulent boundary <span class="hlt">layer</span> was performed in the free-piston <span class="hlt">shock</span> tunnel HIEST at JAXA Kakuda Space Center. A 250mm-diameter 6.4%-scaled Apollo CM capsule model made of SUS-304 stainless steel was applied in this study. To measure heat flux distribution, the model was equipped with 88 miniature co-axial Chromel-Constantan thermocouples on the heat shield surface of the model. In order to promote boundary <span class="hlt">layer</span> transition, a boundary <span class="hlt">layer</span> trip insert with 13 "pizza-box" isolated roughness elements, which have 1.27mm square, were placed at 17mm below of the model geometric center. Three boundary <span class="hlt">layer</span> trip inserts with roughness height of k=0.3mm, 0.6mm and 0.8mm were used to identify the appropriate height to induce transition. Heat flux records with or without roughness elements were obtained for model angles of attack 28º under stagnation enthalpy between H(sub 0)=3.5MJ/kg to 21MJ/kg and stagnation pressure between P(sub 0)=14MPa to 60MPa. Under the condition above, Reynolds number based on the model diameter was varied from 0.2 to 1.3 million. With roughness elements, boundary <span class="hlt">layer</span> became fully turbulent less than H(sub 0)=9MJ/kg condition. However, boundary <span class="hlt">layer</span> was still laminar over H(sub 0)=13MJ/kg condition even with the highest roughness elements. An additional experiment was also performed to correct unexpected heat flux augmentation observed over H(sub 0)=9MJ/kg condition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930036194&hterms=wavefront+curvature&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dwavefront%2Bcurvature','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930036194&hterms=wavefront+curvature&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dwavefront%2Bcurvature"><span id="translatedtitle">Linear stability of three-dimensional boundary <span class="hlt">layers</span> - Effects of curvature and non-<span class="hlt">parallelism</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Malik, M. R.; Balakumar, P.</p> <p>1993-01-01</p> <p>In this paper we study the effect of in-plane (wavefront) curvature on the stability of three-dimensional boundary <span class="hlt">layers</span>. It is found that this effect is stabilizing or destabilizing depending upon the sign of the crossflow velocity profile. We also investigate the effects of surface curvature and nonparallelism on crossflow instability. Computations performed for an infinite-swept cylinder show that while convex curvature stabilizes the three-dimensional boundary <span class="hlt">layer</span>, nonparallelism is, in general, destabilizing and the net effect of the two depends upon meanflow and disturbance parameters. It is also found that concave surface curvature further destabilizes the crossflow instability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19820054812&hterms=magnetic+separation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dmagnetic%2Bseparation','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19820054812&hterms=magnetic+separation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dmagnetic%2Bseparation"><span id="translatedtitle">Large-amplitude magnetic variations in quasi-<span class="hlt">parallel</span> <span class="hlt">shocks</span> - Correlation lengths measured by ISEE 1 and 2</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Greenstadt, E. W.; Hoppe, M. M.; Russell, C. T.</p> <p>1982-01-01</p> <p>Wide separations up to more than 1 earth radius between ISEE 1 and 2 during the second half of 1978 have been used to measure the correlation length of magnetic pulsations in quasiparallel <span class="hlt">shocks</span>. When the two spacecraft were less than a few hundred km apart, magnetic oscillations measured by magnetometers on both spacecraft exhibited virtually identical waveforms, but at distances of several thousand km, the two time series of field variation showed no detailed similarily at all. The correlation coefficients of the pulsations dropped from close to 1.0 for spacecraft separations of less than 100 km to 0.2 for separations of greater than 800 km. A correlation length of several hundred km may be related to the gyroradius of return protons with energy typical of the peaks of diffuse and beam ion distributions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19810018889','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19810018889"><span id="translatedtitle">Computation of the <span class="hlt">shock</span>-wave boundary <span class="hlt">layer</span> interaction with flow separation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ardonceau, P.; Alziary, T.; Aymer, D.</p> <p>1980-01-01</p> <p>The boundary <span class="hlt">layer</span> concept is used to describe the flow near the wall. The external flow is approximated by a pressure displacement relationship (tangent wedge in linearized supersonic flow). The boundary <span class="hlt">layer</span> equations are solved in finite difference form and the question of the presence and unicity of the solution is considered for the direct problem (assumed pressure) or converse problem (assumed displacement thickness, friction ratio). The coupling algorithm presented implicitly processes the downstream boundary condition necessary to correctly define the interacting boundary <span class="hlt">layer</span> problem. The algorithm uses a Newton linearization technique to provide a fast convergence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ApSS..339...75Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ApSS..339...75Y"><span id="translatedtitle">Investigation of the crater-like microdefects induced by laser <span class="hlt">shock</span> processing with aluminum foil as absorbent <span class="hlt">layer</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ye, Y. X.; Xuan, T.; Lian, Z. C.; Feng, Y. Y.; Hua, X. J.</p> <p>2015-06-01</p> <p>This paper reports that 3D crater-like microdefects form on the metal surface when laser <span class="hlt">shock</span> processing (LSP) is applied. LSP was conducted on pure copper block using the aluminum foil as the absorbent material and water as the confining <span class="hlt">layer</span>. There existed the bonding material to attach the aluminum foil on the metal target closely. The surface morphologies and metallographs of copper surfaces were characterized with 3D profiler, the optical microscopy (OM) or the scanning electron microscopy (SEM). Temperature increases of metal surface due to LSP were evaluated theoretically. It was found that, when aluminum foil was used as the absorbent material, and if there existed air bubbles in the bonding material, the air temperatures within the bubbles rose rapidly because of the adiabatic compression. So at the locations of the air bubbles, the metal materials melted and micromelting pool formed. Then under the subsequent expanding of the air bubbles, a secondary <span class="hlt">shock</span> wave was launched against the micromelting pool and produced the crater-like microdefects on the metal surface. The temperature increases due to <span class="hlt">shock</span> heat and high-speed deformation were not enough to melt the metal target. The temperature increase induced by the adiabatic compression of the air bubbles may also cause the gasification of the metal target. This will also help form the crater-like microdefects. The results of this paper can help to improve the surface quality of a metal target during the application of LSP. In addition, the results provide another method to fabricate 3D crater-like dents on metal surface. This has a potential application in mechanical engineering.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/21517593','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/21517593"><span id="translatedtitle">Parametric study on instabilities in a two-<span class="hlt">layer</span> electromagnetohydrodynamic channel flow confined between two <span class="hlt">parallel</span> electrodes.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Reddy, P Dinesh Sankar; Bandyopadhyay, Dipankar; Joo, Sang Woo; Sharma, Ashutosh; Qian, Shizhi</p> <p>2011-03-01</p> <p>Instabilities in a two-phase electromagnetohydrodynamic (EMHD) flow between a pair of <span class="hlt">parallel</span> electrodes are explored. A linear stability analysis has been performed based on a coupled Orr-Sommerfeld system generated from the conservation laws. The study shows the presence of a finite-wave-number EMHD mode of instability in addition to the two commonly observed instability modes in the pressure-driven two-<span class="hlt">layer</span> flows, namely, the long-wave interfacial mode arising from the viscosity or density stratification and the finite-wave-number shear flow mode engendered by the Reynolds stresses. This extra EMHD mode originates from the additional stresses generated by the Lorenz force acting at the liquid <span class="hlt">layers</span> and is found to exist under all conditions beyond a critical strength of the externally applied magnetic field. The EMHD mode either can exist as a singular dominant mode or can coexist as a dominant or subdominant mode with the conventional interfacial mode or shear flow instabilities in the two-<span class="hlt">layer</span> flows. The EMHD flow studied here has numerous potential applications in fluid transport, enhanced heat and mass transfer, mixing, and emulsification because of the low energy requirement, flow reversibility, absence of moving parts, and facile control over flow rate. The parametric study presented here on the instabilities in the two-<span class="hlt">layer</span> EMHD flow will thus be of great practical use. PMID:21517593</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993A%26A...272..571S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993A%26A...272..571S"><span id="translatedtitle">Compression in radiative <span class="hlt">shocks</span>: switch and intermediate properties</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, M. D.</p> <p>1993-05-01</p> <p>The degree of compression in radiative <span class="hlt">shocks</span> (discontinuous jump followed by strong cooling) is crucial to the distribution of the phases of interstellar gas. The influence of the magnetic field, especially its direction, is studied here. In fact plane-<span class="hlt">parallel</span> radiative <span class="hlt">shocks</span> are switch type for a wide range of conditions. In such <span class="hlt">shocks</span>, the magnetic field is turned through a large angle from being quasi-<span class="hlt">parallel</span>. It is shown here that plane-<span class="hlt">parallel</span> isothermal <span class="hlt">shocks</span> are switch type for magnetic fields within an angle 1/A of the <span class="hlt">shock</span> normal where A is the Alfvén number, with the stringent condition that the Alfvén speed exceeds the sound speed. The switch is usually located within the dense cooling <span class="hlt">layer</span> rather than the <span class="hlt">shock</span> front. Super-cooling, in which the downstream temperature drops below the pre-<span class="hlt">shock</span> value, is often encountered. A super-cooling <span class="hlt">layer</span> can be switch type even if the Alfvén speed is much less than the sound speed. The degree of compression is then still limited by the magnetic pressure rather than thermal pressure. Applications and predictions pertaining mainly to the interstellar medium are presented. Switch off and intermediate <span class="hlt">shocks</span> are also studied. Supernova and super-bubble shell structures may then provide evidence for interstellar gas properties. The switch-off <span class="hlt">shock</span> can be recognised by synchrotron radiation signatures. Also the switch-off temperature jump is shown to be closely related to the value of the ratio of Alfvén to sound speeds. Super-cooled intermediate <span class="hlt">shocks</span>, existing when the plane-<span class="hlt">parallel</span> assumption is relaxed, can also occur under an extended range of pre-<span class="hlt">shock</span> states. Hence the "dimple" shell structures of some remnants do not provide evidence for high Alfvén speeds. Finally, torsional switches are presented as an alternative to intermediate waves in interpreting shell structures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.T21B0420M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.T21B0420M"><span id="translatedtitle">Recognition and implication for two stage <span class="hlt">layer-parallel</span> faults in accretionary prisms onland and under the sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Michiguchi, Y.; Ogawa, Y.</p> <p>2006-12-01</p> <p>The Nishizaki Formation of the Miura Group in the southernmost Boso Peninsula, southeast of Tokyo, close to the only trench-trench-trench (TTT)-type triple junction, is thought to be an accretionary prism from the late Miocene to early Pliocene, having many initial deformation structures without strong metamorphism. <span class="hlt">Layer</span>- <span class="hlt">parallel</span> faults composed of black seams of a few mm thick in the upper alternating beds of sandstone and siltstone are developed ubiquitously in the Nishizaki Formation, crosscutting late faults of both normal and thrust senses, suggesting to form before lithification. By SEM and thin section observation the black seam is characterized not by grain-crushing but by rearrangement of mica-clay minerals. In additon, the mica-clay minerals array at least 2 directions. Such features are similar to the black seam was commonly observed in the samples from the Nankai Trough prism collected by Sinkai 6500 of JAMSTEC. XRD analysis indicates the mica-clay minerals in black seams for both the Nishizaki and Nankai are composed of smectite and illite. Some black seams occurred <span class="hlt">parallel</span> to bedding plane immediately after sedimentation, because they are cut by vein structure and the grains on the boundary flow ductility, probably during submarine sliding. This kind of faults is transitional to either normal or thrust faults laterally, most probably similar to the based slip plane of land sliding. However, there are at least two stages <span class="hlt">layer-parallel</span> faults. One is submarine sliding stage before accretion, that is gravitation, another is thrust fault stage during accretion, that is tectonic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016ThCFD.tmp....6S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016ThCFD.tmp....6S&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Parallel</span> data-driven decomposition algorithm for large-scale datasets: with application to transitional boundary <span class="hlt">layers</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sayadi, Taraneh; Schmid, Peter J.</p> <p>2016-03-01</p> <p>Many fluid flows of engineering interest, though very complex in appearance, can be approximated by low-order models governed by a few modes, able to capture the dominant behavior (dynamics) of the system. This feature has fueled the development of various methodologies aimed at extracting dominant coherent structures from the flow. Some of the more general techniques are based on data-driven decompositions, most of which rely on performing a singular value decomposition (SVD) on a formulated snapshot (data) matrix. The amount of experimentally or numerically generated data expands as more detailed experimental measurements and increased computational resources become readily available. Consequently, the data matrix to be processed will consist of far more rows than columns, resulting in a so-called tall-and-skinny (TS) matrix. Ultimately, the SVD of such a TS data matrix can no longer be performed on a single processor, and <span class="hlt">parallel</span> algorithms are necessary. The present study employs the <span class="hlt">parallel</span> TSQR algorithm of (Demmel et al. in SIAM J Sci Comput 34(1):206-239, 2012), which is further used as a basis of the underlying <span class="hlt">parallel</span> SVD. This algorithm is shown to scale well on machines with a large number of processors and, therefore, allows the decomposition of very large datasets. In addition, the simplicity of its implementation and the minimum required communication makes it suitable for integration in existing numerical solvers and data decomposition techniques. Examples that demonstrate the capabilities of highly <span class="hlt">parallel</span> data decomposition algorithms include transitional processes in compressible boundary <span class="hlt">layers</span> without and with induced flow separation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930062803&hterms=chimera&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dchimera','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930062803&hterms=chimera&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dchimera"><span id="translatedtitle">Effects of bleed-hole geometry and plenum pressure on three-dimensional <span class="hlt">shock-wave/boundary-layer</span>/bleed interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chyu, Wei J.; Rimlinger, Mark J.; Shih, Tom I.-P.</p> <p>1993-01-01</p> <p>A numerical study was performed to investigate 3D <span class="hlt">shock-wave/boundary-layer</span> interactions on a flat plate with bleed through one or more circular holes that vent into a plenum. This study was focused on how bleed-hole geometry and pressure ratio across bleed holes affect the bleed rate and the physics of the flow in the vicinity of the holes. The aspects of the bleed-hole geometry investigated include angle of bleed hole and the number of bleed holes. The plenum/freestream pressure ratios investigated range from 0.3 to 1.7. This study is based on the ensemble-averaged, 'full compressible' Navier-Stokes (N-S) equations closed by the Baldwin-Lomax algebraic turbulence model. Solutions to the ensemble-averaged N-S equations were obtained by an implicit finite-volume method using the partially-split, two-factored algorithm of Steger on an overlapping Chimera grid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910059009&hterms=dia&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddia','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910059009&hterms=dia&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddia"><span id="translatedtitle">On the quasi-conical flowfield structure of the swept <span class="hlt">shock</span> wave-turbulent boundary <span class="hlt">layer</span> interaction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Knight, Doyle D.; Badekas, Dias</p> <p>1991-01-01</p> <p>The swept oblique <span class="hlt">shock-wave/turbulent-boundary-layer</span> interaction generated by a 20-deg sharp fin at Mach 4 and Reynolds number 21,000 is investigated via a series of computations using both conical and three-dimensional Reynolds-averaged Navier-Stokes equations with turbulence incorporated through the algebraic turbulent eddy viscosity model of Baldwin-Lomax. Results are compared with known experimental data, and it is concluded that the computed three-dimensional flowfield is quasi-conical (in agreement with the experimental data), the computed three-dimensional and conical surface pressure and surface flow direction are in good agreement with the experiment, and the three-dimensional and conical flows significantly underpredict the peak experimental skin friction. It is pointed out that most of the features of the conical flowfield model in the experiment are observed in the conical computation which also describes the complete conical streamline pattern not included in the model of the experiment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JEMat..43..567S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JEMat..43..567S"><span id="translatedtitle">Fracture Behaviors of Sn-Cu Intermetallic Compound <span class="hlt">Layer</span> in Ball Grid Array Induced by Thermal <span class="hlt">Shock</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shen, Jun; Zhai, Dajun; Cao, Zhongming; Zhao, Mali; Pu, Yayun</p> <p>2014-02-01</p> <p>In this work, thermal <span class="hlt">shock</span> reliability testing and finite-element analysis (FEA) of solder joints between ball grid array components and printed circuit boards with Cu pads were used to investigate the failure mechanism of solder interconnections. The morphologies, composition, and thickness of Sn-Cu intermetallic compounds (IMC) at the interface of Sn-3.0Ag-0.5Cu lead-free solder alloy and Cu substrates were investigated by scanning electron microscopy and transmission electron microscopy. Based on the experimental observations and FEA results, it can be recognized that the origin and propagation of cracks are caused primarily by the difference between the coefficient of thermal expansion of different parts of the packaged products, the growth behaviors and roughness of the IMC <span class="hlt">layer</span>, and the grain size of the solder balls.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950007307','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950007307"><span id="translatedtitle">Measured and calculated spectral radiation from a blunt body <span class="hlt">shock</span> <span class="hlt">layer</span> in an arc-jet wind tunnel</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Babikian, Dikran S.; Palumbo, Giuseppe; Craig, Roger A.; Park, Chul; Palmer, Grant; Sharma, Surendra P.</p> <p>1994-01-01</p> <p>Spectra of the <span class="hlt">shock</span> <span class="hlt">layer</span> radiation incident on the stagnation point of a blunt body placed in an arc-jet wind tunnel were measured over the wavelength range from 600 nm to 880 nm. The test gas was a mixture of 80 percent air and 20 percent argon by mass, and the run was made in a highly nonequilibrium environment. The observed spectra contained contributions from atomic lines of nitrogen, oxygen, and argon, of bound-free and free-free continua, and band systems of N2 and N2(+). The measured spectra were compared with the synthetic spectra, which were obtained through four steps: the calculation of the arc-heater characteristics, of the nozzle flow, of the blunt-body flow, and the nonequilibrium radiation processes. The results show that the atomic lines are predicted approximately correctly, but all other sources are underpredicted by orders of magnitude. A possible explanation for the discrepancy is presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016PhRvB..94h5302C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016PhRvB..94h5302C&link_type=ABSTRACT"><span id="translatedtitle">Magnetotransport in single-<span class="hlt">layer</span> graphene in a large <span class="hlt">parallel</span> magnetic field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chiappini, F.; Wiedmann, S.; Titov, M.; Geim, A. K.; Gorbachev, R. V.; Khestanova, E.; Mishchenko, A.; Novoselov, K. S.; Maan, J. C.; Zeitler, U.</p> <p>2016-08-01</p> <p>Graphene on hexagonal boron nitride (h-BN) is an atomically flat conducting system that is ideally suited for probing the effect of Zeeman splitting on electron transport. We demonstrate by magnetotransport measurements that a <span class="hlt">parallel</span> magnetic field up to 30 Tesla does not affect the transport properties of graphene on h-BN even at charge neutrality where such an effect is expected to be maximal. The only magnetoresistance detected at low carrier concentrations is shown to be associated with a small perpendicular component of the field which cannot be fully eliminated in the experiment. Despite the high mobility of charge carriers at low temperatures, we argue that the effects of Zeeman splitting are fully masked by electrostatic potential fluctuations at charge neutrality.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150007505','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150007505"><span id="translatedtitle">Effects of Hybrid Flow Control on a Normal <span class="hlt">Shock</span> Boundary-<span class="hlt">Layer</span> Interaction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hirt, Stefanie M.; Vyas, Manan A.</p> <p>2013-01-01</p> <p>Hybrid flow control, a combination of micro-ramps and steady micro-jets, was experimentally investigated in the 15x15 cm Supersonic Wind Tunnel at the NASA Glenn Research Center. A central composite design of experiments method, was used to develop response surfaces for boundary-<span class="hlt">layer</span> thickness and reversed-flow thickness, with factor variables of inter-ramp spacing, ramp height and chord length, and flow injection ratio. Boundary-<span class="hlt">layer</span> measurements and wall static pressure data were used to understand flow separation characteristics. A limited number of profiles were measured in the corners of the tunnel to aid in understanding the three-dimensional characteristics of the flowfield.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730015974','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730015974"><span id="translatedtitle">Ion streaming instabilities with application to collisionless <span class="hlt">shock</span> wave structure</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Golden, K. I.; Linson, L. M.; Mani, S. A.</p> <p>1973-01-01</p> <p>The electromagnetic dispersion relation for two counterstreaming ion beams of arbitrary relative strength flowing <span class="hlt">parallel</span> to a dc magnetic field is derived. The beams flow through a stationary electron background and the dispersion relation in the fluid approximation is unaffected by the electron thermal pressure. The dispersion relation is solved with a zero net current condition applied and the regions of instability in the k-U space (U is the relative velocity between the two ion beams) are presented. The parameters are then chosen to be applicable for <span class="hlt">parallel</span> <span class="hlt">shocks</span>. It was found that unstable waves with zero group velocity in the <span class="hlt">shock</span> frame can exist near the leading edge of the <span class="hlt">shock</span> for upstream Alfven Mach numbers greater than 5.5. It is suggested that this mechanism could generate sufficient turbulence within the <span class="hlt">shock</span> <span class="hlt">layer</span> to scatter the incoming ions and create the required dissipation for intermediate strength <span class="hlt">shocks</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730012553','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730012553"><span id="translatedtitle">The behavior of a compressible turbulent boundary <span class="hlt">layer</span> in a <span class="hlt">shock</span>-wave-induced adverse pressure gradient. Ph.D. Thesis - Washington Univ., Seattle, Aug. 1972</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rose, W. C.</p> <p>1973-01-01</p> <p>The results of an experimental investigation of the mean- and fluctuating-flow properties of a compressible turbulent boundary <span class="hlt">layer</span> in a <span class="hlt">shock</span>-wave-induced adverse pressure gradient are presented. The turbulent boundary <span class="hlt">layer</span> developed on the wall of an axially symmetric nozzle and test section whose nominal free-stream Mach number and boundary-<span class="hlt">layer</span> thickness Reynolds number were 4 and 100,000, respectively. The adverse pressure gradient was induced by an externally generated conical <span class="hlt">shock</span> wave. Mean and time-averaged fluctuating-flow data, including the complete experimental Reynolds stress tensor and experimental turbulent mass- and heat-transfer rates are presented for the boundary <span class="hlt">layer</span> and external flow, upstream, within and downstream of the pressure gradient. The mean-flow data include distributions of total temperature throughout the region of interest. The turbulent mixing properties of the flow were determined experimentally with a hot-wire anemometer. The calibration of the wires and the interpretation of the data are discussed. From the results of the investigation, it is concluded that the <span class="hlt">shock</span>-wave - boundary-<span class="hlt">layer</span> interaction significantly alters the turbulent mixing characteristics of the boundary <span class="hlt">layer</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19820048416&hterms=OM&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DOM','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19820048416&hterms=OM&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DOM"><span id="translatedtitle">An experimental investigation and a numerical prediction of a transonic normal <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span> interaction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Om, D.; Childs, M. E.; Viegas, J. R.</p> <p>1982-01-01</p> <p>Detailed pitot, static and wall pressure measurements have been obtained for a transonic normal <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span> interaction at free-stream Mach numbers of 1.28, 1.37 and 1.48 and at a constant unit Reynolds number of 4.92 x 10 to the 6th per meter in an axisymmetric, internal flow. Measurements have also been obtained at a unit Reynolds number of 9.84 x 10 to the 6th per meter at a free-stream Mach number of 1.29. The interaction depends very strongly on the Mach number. The effect of Reynolds number under study is small. Flow confinement due to the wind-tunnel wall boundary <span class="hlt">layer</span> produces a weaker interaction and a much larger supersonic tongue than is observed for planar flows. Comparisons are made with solutions to the time-dependent, mass-averaged, Navier-Stokes equations incorporating a two-equation, Wilcox-Rubesin turbulence model (1980). The computations are in agreement with the experimental results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3912118','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3912118"><span id="translatedtitle">Gibberellic Acid-Induced Aleurone <span class="hlt">Layers</span> Responding to Heat <span class="hlt">Shock</span> or Tunicamycin Provide Insight into the N-Glycoproteome, Protein Secretion, and Endoplasmic Reticulum Stress1[W</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Barba-Espín, Gregorio; Dedvisitsakul, Plaipol; Hägglund, Per; Svensson, Birte; Finnie, Christine</p> <p>2014-01-01</p> <p>The growing relevance of plants for the production of recombinant proteins makes understanding the secretory machinery, including the identification of glycosylation sites in secreted proteins, an important goal of plant proteomics. Barley (Hordeum vulgare) aleurone <span class="hlt">layers</span> maintained in vitro respond to gibberellic acid by secreting an array of proteins and provide a unique system for the analysis of plant protein secretion. Perturbation of protein secretion in gibberellic acid-induced aleurone <span class="hlt">layers</span> by two independent mechanisms, heat <span class="hlt">shock</span> and tunicamycin treatment, demonstrated overlapping effects on both the intracellular and secreted proteomes. Proteins in a total of 22 and 178 two-dimensional gel spots changing in intensity in extracellular and intracellular fractions, respectively, were identified by mass spectrometry. Among these are proteins with key roles in protein processing and secretion, such as calreticulin, protein disulfide isomerase, proteasome subunits, and isopentenyl diphosphate isomerase. Sixteen heat <span class="hlt">shock</span> proteins in 29 spots showed diverse responses to the treatments, with only a minority increasing in response to heat <span class="hlt">shock</span>. The majority, all of which were small heat <span class="hlt">shock</span> proteins, decreased in heat-<span class="hlt">shocked</span> aleurone <span class="hlt">layers</span>. Additionally, glycopeptide enrichment and N-glycosylation analysis identified 73 glycosylation sites in 65 aleurone <span class="hlt">layer</span> proteins, with 53 of the glycoproteins found in extracellular fractions and 36 found in intracellular fractions. This represents major progress in characterization of the barley N-glycoproteome, since only four of these sites were previously described. Overall, these findings considerably advance knowledge of the plant protein secretion system in general and emphasize the versatility of the aleurone <span class="hlt">layer</span> as a model system for studying plant protein secretion. PMID:24344171</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/919445','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/919445"><span id="translatedtitle">A <span class="hlt">Parallel</span> Controls Software Approach for PEP II: AIDA & Matlab Middle <span class="hlt">Layer</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wittmer, W.; Colocho, W.; White, G.; /SLAC</p> <p>2007-11-06</p> <p>The controls software in use at PEP II (Stanford Control Program - SCP) had originally been developed in the eighties. It is very successful in routine operation but due to its internal structure it is difficult and time consuming to extend its functionality. This is problematic during machine development and when solving operational issues. Routinely, data has to be exported from the system, analyzed offline, and calculated settings have to be reimported. Since this is a manual process, it is time consuming and error-prone. Setting up automated processes, as is done for MIA (Model Independent Analysis), is also time consuming and specific to each application. Recently, there has been a trend at light sources to use MATLAB as the platform to control accelerators using a 'MATLAB Middle <span class="hlt">Layer</span>' (MML), and so called channel access (CA) programs to communicate with the low level control system (LLCS). This has proven very successful, especially during machine development time and trouble shooting. A special CA code, named AIDA (Accelerator Independent Data Access), was developed to handle the communication between MATLAB, modern software frameworks, and the SCP. The MML had to be adapted for implementation at PEP II. Colliders differ significantly in their designs compared to light sources, which poses a challenge. PEP II is the first collider at which this implementation is being done. We will report on this effort, which is still ongoing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19880020700&hterms=effect+pH&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Deffect%2BpH','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19880020700&hterms=effect+pH&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Deffect%2BpH"><span id="translatedtitle">Experimental and numerical investigation of the effect of distributed suction on oblique <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span> interaction. Ph.D. Thesis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Benhachmi, Driss; Greber, Isaac; Hingst, Warren R.</p> <p>1988-01-01</p> <p>A combined experimental and numerical study of the interaction of an incident oblique <span class="hlt">shock</span> wave with a turbulent boundary <span class="hlt">layer</span> on a rough plate and on a porous plate with suction is presented. The experimental phase involved the acquisition of mean data upstream of, within, and downstream of the interaction region at Mach numbers 2.5 and 3.0. Data were taken at unit Reynolds numbers of 1.66 E7 and 1.85 E7 m respectively, and for flow deflection angles of 0, 4, 6 and 8 degs. Measured data include wall static pressure, pitot pressure profiles, and local bleed distributions on the porous plate. On the rough plate, with no suction, the boundary <span class="hlt">layer</span> profiles were modified near the wall, but not separated for the 4 deg flow deflection angle. For the higher deflection angles of 6 and 8 degs, the boundary <span class="hlt">layer</span> was separated. Suction increases the strength of the incident <span class="hlt">shock</span> required to separate the turbulent boundary <span class="hlt">layer</span>; for all <span class="hlt">shock</span> strengths tested, separation is completely eliminated. The pitot pressure profiles are affected throughout the whole boundary <span class="hlt">layer</span>; they are fuller than the ones obtained on the rough plate. It is also found that the combination of suction and roughness introduces spatial perturbations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980223593','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980223593"><span id="translatedtitle">A Nonlinear Theory for Predicting the Effects of Unsteady Laminar, Turbulent, or Transitional Boundary <span class="hlt">Layers</span> on the Attenuation of <span class="hlt">Shock</span> Waves in a <span class="hlt">Shock</span> Tube with Experimental Comparison</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Trimpi, Robert L.; Cohen, Nathaniel B.</p> <p>1961-01-01</p> <p>The linearized attenuation theory of NACA Technical Note 3375 is modified in the following manner: (a) an unsteady compressible local skin-friction coefficient is employed rather than the equivalent steady-flow incompressible coefficient; (b) a nonlinear approach is used to permit application of the theory to large attenuations; and (c) transition effects are considered. Curves are presented for predicting attenuation for a <span class="hlt">shock</span> pressure ratio up to 20 and a range of <span class="hlt">shock</span>-tube Reynolds numbers. Comparison of theory and experimental data for <span class="hlt">shock</span>-wave strengths between 1.5 and 10 over a wide range of Reynolds numbers shows good agreement with the nonlinear theory evaluated for a transition Reynolds number of 2.5 X 10(exp 5).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22490023','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22490023"><span id="translatedtitle">First results of radiation-driven, <span class="hlt">layered</span> deuterium-tritium implosions with a 3-<span class="hlt">shock</span> adiabat-shaped drive at the National Ignition Facility</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Smalyuk, V. A.; Robey, H. F.; Döppner, T.; Jones, O. S.; Milovich, J. L.; Bachmann, B.; Baker, K. L.; Berzak Hopkins, L. F.; Bond, E.; Callahan, D. A.; Casey, D. T.; Celliers, P. M.; Cerjan, C.; Clark, D. S.; Dixit, S. N.; Edwards, M. J.; Haan, S. W.; Hamza, A. V.; Hurricane, O. A.; Jancaitis, K. S.; and others</p> <p>2015-08-15</p> <p>Radiation-driven, <span class="hlt">layered</span> deuterium-tritium plastic capsule implosions were carried out using a new, 3-<span class="hlt">shock</span> “adiabat-shaped” drive on the National Ignition Facility. The purpose of adiabat shaping is to use a stronger first <span class="hlt">shock</span>, reducing hydrodynamic instability growth in the ablator. The <span class="hlt">shock</span> can decay before reaching the deuterium-tritium fuel leaving it on a low adiabat and allowing higher fuel compression. The fuel areal density was improved by ∼25% with this new drive compared to similar “high-foot” implosions, while neutron yield was improved by more than 4 times, compared to “low-foot” implosions driven at the same compression and implosion velocity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140010683','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140010683"><span id="translatedtitle">Experimental Database with Baseline CFD Solutions: 2-D and Axisymmetric Hypersonic <span class="hlt">Shock-Wave/Turbulent-Boundary-Layer</span> Interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Marvin, Joseph G.; Brown, James L.; Gnoffo, Peter A.</p> <p>2013-01-01</p> <p>A database compilation of hypersonic <span class="hlt">shock</span>-wave/turbulent boundary <span class="hlt">layer</span> experiments is provided. The experiments selected for the database are either 2D or axisymmetric, and include both compression corner and impinging type SWTBL interactions. The strength of the interactions range from attached to incipient separation to fully separated flows. The experiments were chosen based on criterion to ensure quality of the datasets, to be relevant to NASA's missions and to be useful for validation and uncertainty assessment of CFD Navier-Stokes predictive methods, both now and in the future. An emphasis on datasets selected was on surface pressures and surface heating throughout the interaction, but include some wall shear stress distributions and flowfield profiles. Included, for selected cases, are example CFD grids and setup information, along with surface pressure and wall heating results from simulations using current NASA real-gas Navier-Stokes codes by which future CFD investigators can compare and evaluate physics modeling improvements and validation and uncertainty assessments of future CFD code developments. The experimental database is presented tabulated in the Appendices describing each experiment. The database is also provided in computer-readable ASCII files located on a companion DVD.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015CoPhC.194...64C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015CoPhC.194...64C&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Parallel</span> implementation of inverse adding-doubling and Monte Carlo multi-<span class="hlt">layered</span> programs for high performance computing systems with shared and distributed memory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chugunov, Svyatoslav; Li, Changying</p> <p>2015-09-01</p> <p><span class="hlt">Parallel</span> implementation of two numerical tools popular in optical studies of biological materials-Inverse Adding-Doubling (IAD) program and Monte Carlo Multi-<span class="hlt">Layered</span> (MCML) program-was developed and tested in this study. The implementation was based on Message Passing Interface (MPI) and standard C-language. <span class="hlt">Parallel</span> versions of IAD and MCML programs were compared to their sequential counterparts in validation and performance tests. Additionally, the portability of the programs was tested using a local high performance computing (HPC) cluster, Penguin-On-Demand HPC cluster, and Amazon EC2 cluster. <span class="hlt">Parallel</span> IAD was tested with up to 150 <span class="hlt">parallel</span> cores using 1223 input datasets. It demonstrated linear scalability and the speedup was proportional to the number of <span class="hlt">parallel</span> cores (up to 150x). <span class="hlt">Parallel</span> MCML was tested with up to 1001 <span class="hlt">parallel</span> cores using problem sizes of 104-109 photon packets. It demonstrated classical performance curves featuring communication overhead and performance saturation point. Optimal performance curve was derived for <span class="hlt">parallel</span> MCML as a function of problem size. Typical speedup achieved for <span class="hlt">parallel</span> MCML (up to 326x) demonstrated linear increase with problem size. Precision of MCML results was estimated in a series of tests - problem size of 106 photon packets was found optimal for calculations of total optical response and 108 photon packets for spatially-resolved results. The presented <span class="hlt">parallel</span> versions of MCML and IAD programs are portable on multiple computing platforms. The <span class="hlt">parallel</span> programs could significantly speed up the simulation for scientists and be utilized to their full potential in computing systems that are readily available without additional costs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19870032771&hterms=electrodynamics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Delectrodynamics','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19870032771&hterms=electrodynamics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Delectrodynamics"><span id="translatedtitle">The resolved <span class="hlt">layer</span> of a collisionless, high beta, supercritical, quasi-perpendicular <span class="hlt">shock</span> wave. II - Dissipative fluid electrodynamics</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Scudder, J. D.; Aggson, T. L.; Mangeney, A.; Lacombe, C.; Harvey, C. C.</p> <p>1986-01-01</p> <p>Using the results of Scudder et al. (1986) on the bow <span class="hlt">shock</span> wave observed by ISEE satellites, a quantitative description is presented of the electrodynamics of ion and electron fluids, and phase-standing wave interaction which manifests itself as a supercritical MHD <span class="hlt">shock</span>. The cross-<span class="hlt">shock</span> electrical profile was determined in both the normal incidence frame and in the deHoffman-Teller frame by two different methods, and the results were compared with dc electric field measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910011772','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910011772"><span id="translatedtitle">Heat transfer, velocity-temperature correlation, and turbulent shear stress from Navier-Stokes computations of <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span> interaction flows</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wang, C. R.; Hingst, W. R.; Porro, A. R.</p> <p>1991-01-01</p> <p>The properties of 2-D <span class="hlt">shock</span> wave/turbulent boundary <span class="hlt">layer</span> interaction flows were calculated by using a compressible turbulent Navier-Stokes numerical computational code. Interaction flows caused by oblique <span class="hlt">shock</span> wave impingement on the turbulent boundary <span class="hlt">layer</span> flow were considered. The oblique <span class="hlt">shock</span> waves were induced with <span class="hlt">shock</span> generators at angles of attack less than 10 degs in supersonic flows. The surface temperatures were kept at near-adiabatic (ratio of wall static temperature to free stream total temperature) and cold wall (ratio of wall static temperature to free stream total temperature) conditions. The computational results were studied for the surface heat transfer, velocity temperature correlation, and turbulent shear stress in the interaction flow fields. Comparisons of the computational results with existing measurements indicated that (1) the surface heat transfer rates and surface pressures could be correlated with Holden's relationship, (2) the mean flow streamwise velocity components and static temperatures could be correlated with Crocco's relationship if flow separation did not occur, and (3) the Baldwin-Lomax turbulence model should be modified for turbulent shear stress computations in the interaction flows.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DPPB12029O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DPPB12029O"><span id="translatedtitle">Electron Beam-Blip Spectroscopic Diagnostics of the Scrape-off-<span class="hlt">Layer</span> <span class="hlt">Parallel</span> Transport in C-2</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Osin, Dmitry; Thompson, Matthew; Garate, Eusebio; TAE Team</p> <p>2015-11-01</p> <p>C-2 is a microscopically stable, high-performance field-reversed configuration (FRC), where high plasma temperatures with significant fast ion population and record lifetimes were achieved by a combination of tangential neutral beam injection, electrically biased plasma guns at the ends and wall conditioning. FRC confinement depends on the properties of both the open and closed field lines, therefore, understanding the electron transport in the scrape-of-<span class="hlt">layer</span> (SOL) is critical. To study <span class="hlt">parallel</span> heat conduction in SOL, a high-energy pulsed electron beam (e-beam) was injected on-axis into C-2 to produce a heat pulse, which causes a fast rise and slower decay of the electron temperature, Te, in the SOL. The heat-blip was observed by means of He-jet spectroscopy. A small fraction of the total deposited e-beam energy is necessary to explain the measured Te increase. The electron thermal conductivity along the magnetic field lines can be inferred from the Te decay. Experiments suggest that a high energy e-beam pulse can serve as a direct diagnostic of heat transport in the SOL.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22399334','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22399334"><span id="translatedtitle">Néel walls between tailored <span class="hlt">parallel</span>-stripe domains in IrMn/CoFe exchange bias <span class="hlt">layers</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ueltzhöffer, Timo Schmidt, Christoph; Ehresmann, Arno; Krug, Ingo; Nickel, Florian; Gottlob, Daniel</p> <p>2015-03-28</p> <p>Tailored <span class="hlt">parallel</span>-stripe magnetic domains with antiparallel magnetizations in adjacent domains along the long stripe axis have been fabricated in an IrMn/CoFe Exchange Bias thin film system by 10 keV He{sup +}-ion bombardment induced magnetic patterning. Domain walls between these domains are of Néel type and asymmetric as they separate domains of different anisotropies. X-ray magnetic circular dichroism asymmetry images were obtained by x-ray photoelectron emission microscopy at the Co/Fe L{sub 3} edges at the synchrotron radiation source BESSY II. They revealed Néel-wall tail widths of 1 μm in agreement with the results of a model that was modified in order to describe such walls. Similarly obtained domain core widths show a discrepancy to values estimated from the model, but could be explained by experimental broadening. The rotation senses in adjacent walls were determined, yielding unwinding domain walls with non-interacting walls in this <span class="hlt">layer</span> system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19870032770&hterms=fluids+supercritical&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dfluids%2Bsupercritical','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19870032770&hterms=fluids+supercritical&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dfluids%2Bsupercritical"><span id="translatedtitle">The resolved <span class="hlt">layer</span> of a collisionless, high beta, supercritical, quasi-perpendicular <span class="hlt">shock</span> wave. I - Rankine-Hugoniot geometry, currents, and stationarity</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Scudder, J. D.; Aggson, T. L.; Mangeney, A.; Lacombe, C.; Harvey, C. C.</p> <p>1986-01-01</p> <p>Data collected by the ISEE dual-spacecraft mission (on November 7, 1977) on a slowly moving, supercritical, high-beta, quasi-perpendicular bow <span class="hlt">shock</span> are presented, and the local geometry, spatial scales, and stationarity of this <span class="hlt">shock</span> wave are assessed in a self-consistent Rankine-Hugoniot-constrained frame of reference. Included are spatial profiles of the ac and dc magnetic and electric fields, electron and proton fluid velocities, current densities, electron and proton number densities, temperatures, pressures, and partial densities of the reflected protons. The observed <span class="hlt">layer</span> profile is shown to be nearly phase standing and one-dimensional in a Rankine-Hugoniot frame, empirically determined by the magnetofluid parameters outside the <span class="hlt">layer</span> proper.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013CPL...582..105V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013CPL...582..105V"><span id="translatedtitle">Effect of high-temperature <span class="hlt">shock</span>-wave compression on few-<span class="hlt">layer</span> MoS2, WS2 and MoSe2</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vasu, K.; Matte, H. S. S. R.; Shirodkar, Sharmila N.; Jayaram, V.; Reddy, K. P. J.; Waghmare, Umesh V.; Rao, C. N. R.</p> <p>2013-09-01</p> <p>Exposure of few-<span class="hlt">layer</span> MoS2, WS2 and MoSe2 to high-temperature <span class="hlt">shock</span> waves causes morphological changes and a significant decrease in the interlayer separation between the (0 0 2) planes, the decrease being greatest in MoSe2. Raman spectra show softening of both the A1g and the E2g1 modes initially, followed by a slightly stiffening. Using first-principles density functional theoretical analysis of the response of few-<span class="hlt">layer</span> MoS2 to <span class="hlt">shock</span> waves, we propose that a combination of shear and uniaxial compressive deformation leads to flattening of MoS2 sheets which is responsible for the changes in the vibrational spectra.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840021091','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840021091"><span id="translatedtitle">Numerical solution for the interaction of <span class="hlt">shock</span> wave with laminar boundary <span class="hlt">layer</span> in two-dimensional flow on a flat plate. Ph.D. Thesis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Landau, U.</p> <p>1984-01-01</p> <p>The finite difference computation method was investigated for solving problems of interaction between a <span class="hlt">shock</span> wave and a laminar boundary <span class="hlt">layer</span>, through solution of the complete Navier-Stokes equations. This method provided excellent solutions, was simple to perform and needed a relatively short solution time. A large number of runs for various flow conditions could be carried out from which the interaction characteristics and principal factors that influence interaction could be studied.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19810017517&hterms=boundary+descriptions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dboundary%2Bdescriptions','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19810017517&hterms=boundary+descriptions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dboundary%2Bdescriptions"><span id="translatedtitle">Simple approximations for the asymptotic description of the interaction between a normal <span class="hlt">shock</span> wave and a turbulent boundary <span class="hlt">layer</span> at transonic speeds</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Adamson, T. C., Jr.; Messiter, A. F.</p> <p>1981-01-01</p> <p>The asymptotic description of the interaction between a normal <span class="hlt">shock</span> wave and a turbulent boundary <span class="hlt">layer</span> is reviewed. The <span class="hlt">layers</span> necessary in a rational analysis of the interaction are discussed with emphasis on the differences from an interaction with a laminar boundary <span class="hlt">layer</span>, the uncoupling of solutions for the distribution of pressure and skin friction at the wall, and the role of the Reynolds shear stress in these solutions. The accuracy of asymptotic solutions in flows at Reynolds numbers of technical interest is discussed. Solutions for the distribution of pressure and skin friction at the wall and the shape of the <span class="hlt">shock</span> are considered for the case where the flow is near separation. For the pressure and skin friction, it is possible to write two simplified partial solutions, one valid at the beginning of the interaction and one valid somewhat downstream of the <span class="hlt">shock</span> wave. A solution composed of these two parts and a linear interpolation between them appears to give good comparison with experiment; one unknown constant, independent of the parameters of the interaction, must be found from experiment. The simplified relations are presented. Comparison of numerical computations with experimental data indicates a possible value for the constant and shows quite satisfactory results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750008700','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750008700"><span id="translatedtitle">Numerical solution of the hypersonic viscous-<span class="hlt">shock-layer</span> equations for laminar, transitional, and turbulent flows of a perfect gas over blunt axially symmetric bodies</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Anderson, E. C.; Moss, J. N.</p> <p>1975-01-01</p> <p>The viscous <span class="hlt">shock</span> <span class="hlt">layer</span> equations applicable to hypersonic laminar, transitional, and turbulent flows of a perfect gas over two-dimensional plane or axially symmetric blunt bodies are presented. The equations are solved by means of an implicit finite difference scheme, and the results are compared with a turbulent boundary <span class="hlt">layer</span> analysis. The agreement between the two solution procedures is satisfactory for the region of flow where streamline swallowing effects are negligible. For the downstream regions, where streamline swallowing effects are present, the expected differences in the two solution procedures are evident.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140017025','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140017025"><span id="translatedtitle">Boundary <span class="hlt">Layer</span> Transition and Trip Effectiveness on an Apollo Capsule in the JAXA High Enthalpy <span class="hlt">Shock</span> Tunnel (HIEST) Facility</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kirk, Lindsay C.; Lillard, Randolph P.; Olejniczak, Joseph; Tanno, Hideyuki</p> <p>2015-01-01</p> <p>Computational assessments were performed to size boundary <span class="hlt">layer</span> trips for a scaled Apollo capsule model in the High Enthalpy <span class="hlt">Shock</span> Tunnel (HIEST) facility at the JAXA Kakuda Space Center in Japan. For stagnation conditions between 2 MJ/kg and 20 MJ/kg and between 10 MPa and 60 MPa, the appropriate trips were determined to be between 0.2 mm and 1.3 mm high, which provided kappa/delta values on the heatshield from 0.15 to 2.25. The tripped configuration consisted of an insert with a series of diamond shaped trips along the heatshield downstream of the stagnation point. Surface heat flux measurements were obtained on a capsule with a 250 mm diameter, 6.4% scale model, and pressure measurements were taken at axial stations along the nozzle walls. At low enthalpy conditions, the computational predictions agree favorably to the test data along the heatshield centerline. However, agreement becomes less favorable as the enthalpy increases conditions. The measured surface heat flux on the heatshield from the HIEST facility was under-predicted by the computations in these cases. Both smooth and tripped configurations were tested for comparison, and a post-test computational analysis showed that kappa/delta values based on the as-measured stagnation conditions ranged between 0.5 and 1.2. Tripped configurations for both 0.6 mm and 0.8 mm trip heights were able to effectively trip the flow to fully turbulent for a range of freestream conditions.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JSASS..58..226I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JSASS..58..226I"><span id="translatedtitle">A Simple Technique for Controlling the Görtler Vortex Wavelength in Hypersonic <span class="hlt">Shock-Wave/Boundary-Layer</span> Interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Itoh, Hajime; Honda, Hirokazu</p> <p></p> <p>This paper describes results of an exploratory study to investigate the capability of a passive approach for controlling the characteristic spanwise length of Görtler vortices generated in hypersonic flows: a serrated leading edge. Heat transfer, pressure measurements, encapsulated thermochromic liquid crystal, schlieren and glow spark visualizations were conducted with a flat plate/ramp model whose leading edge had a triangular wave shape in a gun tunnel at Mach number 10. Effect of wavelength Λ of the triangular waves on downstream flows was studied. Aerodynamic heating patterns observed with the liquid crystal confirmed that the vortex wavelength was equal to Λ. This was also supported by the spark results that filamentary bright lines perpendicular to an installed line-anode <span class="hlt">parallel</span> to the spanwise direction at the ramp surface emerged at intervals of Λ. Phase lag was observed only between heat transfer data measured in the spanwise direction, which suggests that the vortex structure existed in the reattaching boundary <span class="hlt">layers</span>. Pressure distribution in the streamwise direction was similar among all of the Λ tested. In contrast, the heat transfer data points exhibited a large scatter and the peak heating value for the finite Λ was somewhat larger than that for the infinite Λ. Schlieren results indicated that the appropriate Λ can mitigate flow separation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015CoPhC.188...21J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015CoPhC.188...21J"><span id="translatedtitle">Numerical approach to the <span class="hlt">parallel</span> gradient operator in tokamak scrape-off <span class="hlt">layer</span> turbulence simulations and application to the GBS code</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jolliet, S.; Halpern, F. D.; Loizu, J.; Mosetto, A.; Riva, F.; Ricci, P.</p> <p>2015-03-01</p> <p>This paper presents two discretisation schemes for the <span class="hlt">parallel</span> gradient operator used in scrape-off <span class="hlt">layer</span> plasma turbulence simulations. First, a simple model describing the propagation of electrostatic shear-Alfvén waves, and retaining the key elements of the <span class="hlt">parallel</span> dynamics, is used to test the accuracy of the different schemes against analytical predictions. The most promising scheme is then tested in simulations of limited scrape-off <span class="hlt">layer</span> turbulence with the flux-driven 3D fluid code GBS (Ricci et al., 2012): the new approach is successfully benchmarked against the original <span class="hlt">parallel</span> gradient discretisation implemented in GBS. Finally, GBS simulations using a radially varying safety profile, which were inapplicable with the original scheme are carried out for the first time: the well-known stabilisation of resistive ballooning modes at negative magnetic shear is recovered. The main conclusion of this paper is that a simple approach to the <span class="hlt">parallel</span> gradient, namely centred finite differences in the poloidal and toroidal direction, is able to simulate scrape-off <span class="hlt">layer</span> turbulence provided that a higher resolution and higher convergence order are used.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19960047570','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19960047570"><span id="translatedtitle">Three-Dimensional Navier-Stokes Simulations with Two-Equation Turbulence Models of Intersecting <span class="hlt">Shock</span>-Waves/Turbulent Boundary <span class="hlt">Layer</span> at Mach 8.3</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bardina, J. E.; Coakley, T. J.</p> <p>1994-01-01</p> <p>An investigation of the numerical simulation with two-equation turbulence models of a three-dimensional hypersonic intersecting (SWTBL) <span class="hlt">shock</span>-wave/turbulent boundary <span class="hlt">layer</span> interaction flow is presented. The flows are solved with an efficient implicit upwind flux-difference split Reynolds-averaged Navier-Stokes code. Numerical results are compared with experimental data for a flow at Mach 8.28 and Reynolds number 5.3x10(exp 6) with crossing <span class="hlt">shock</span>-waves and expansion fans generated by two lateral 15 fins located on top of a cold-wall plate. This experiment belongs to the hypersonic database for modeling validation. Simulations show the development of two primary counter-rotating cross-flow vortices and secondary turbulent structures under the main vortices and in each corner singularity inside the turbulent boundary <span class="hlt">layer</span>. A significant loss of total pressure is produced by the complex interaction between the main vortices and the uplifted jet stream of the boundary <span class="hlt">layer</span>. The overall agreement between computational and experimental data is generally good. The turbulence modeling corrections show improvements in the predictions of surface heat transfer distribution and an increase in the strength of the cross-flow vortices. Accurate predictions of the outflow flowfield is found to require accurate modeling of the laminar/turbulent boundary <span class="hlt">layers</span> on the fin walls.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140011158','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140011158"><span id="translatedtitle">On Parametric Sensitivity of Reynolds-Averaged Navier-Stokes SST Turbulence Model: 2D Hypersonic <span class="hlt">Shock</span>-Wave Boundary <span class="hlt">Layer</span> Interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Brown, James L.</p> <p>2014-01-01</p> <p>Examined is sensitivity of separation extent, wall pressure and heating to variation of primary input flow parameters, such as Mach and Reynolds numbers and <span class="hlt">shock</span> strength, for 2D and Axisymmetric Hypersonic <span class="hlt">Shock</span> Wave Turbulent Boundary <span class="hlt">Layer</span> interactions obtained by Navier-Stokes methods using the SST turbulence model. Baseline parametric sensitivity response is provided in part by comparison with vetted experiments, and in part through updated correlations based on free interaction theory concepts. A recent database compilation of hypersonic 2D <span class="hlt">shock</span>-wave/turbulent boundary <span class="hlt">layer</span> experiments extensively used in a prior related uncertainty analysis provides the foundation for this updated correlation approach, as well as for more conventional validation. The primary CFD method for this work is DPLR, one of NASA's real-gas aerothermodynamic production RANS codes. Comparisons are also made with CFL3D, one of NASA's mature perfect-gas RANS codes. Deficiencies in predicted separation response of RANS/SST solutions to parametric variations of test conditions are summarized, along with recommendations as to future turbulence approach.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720015593','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720015593"><span id="translatedtitle">Solutions for Reacting and Nonreacting Viscous <span class="hlt">Shock</span> <span class="hlt">Layers</span> with Multicomponent Diffusion and Mass Injection. Ph.D. Thesis - Virginia Polytechnic Inst. and State Univ.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Moss, J. N.</p> <p>1971-01-01</p> <p>Numerical solutions are presented for the viscous shocklayer equations where the chemistry is treated as being either frozen, equilibrium, or nonequilibrium. Also the effects of the diffusion model, surface catalyticity, and mass injection on surface transport and flow parameters are considered. The equilibrium calculations for air species using multicomponent: diffusion provide solutions previously unavailable. The viscous <span class="hlt">shock-layer</span> equations are solved by using an implicit finite-difference scheme. The flow is treated as a mixture of inert and thermally perfect species. Also the flow is assumed to be in vibrational equilibrium. All calculations are for a 45 deg hyperboloid. The flight conditions are those for various altitudes and velocities in the earth's atmosphere. Data are presented showing the effects of the chemical models; diffusion models; surface catalyticity; and mass injection of air, water, and ablation products on heat transfer; skin friction; <span class="hlt">shock</span> stand-off distance; wall pressure distribution; and tangential velocity, temperature, and species profiles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014BrJPh..44..703H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014BrJPh..44..703H"><span id="translatedtitle">Modified Ion-Acoustic <span class="hlt">Shock</span> Waves and Double <span class="hlt">Layers</span> in a Degenerate Electron-Positron-Ion Plasma in Presence of Heavy Negative Ions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hossen, M. A.; Hossen, M. R.; Mamun, A. A.</p> <p>2014-12-01</p> <p>A general theory for nonlinear propagation of one dimensional modified ion-acoustic waves in an unmagnetized electron-positron-ion (e-p-i) degenerate plasma is investigated. This plasma system is assumed to contain relativistic electron and positron fluids, non-degenerate viscous positive ions, and negatively charged static heavy ions. The modified Burgers and Gardner equations have been derived by employing the reductive perturbation method and analyzed in order to identify the basic features (polarity, width, speed, etc.) of <span class="hlt">shock</span> and double <span class="hlt">layer</span> (DL) structures. It is observed that the basic features of these <span class="hlt">shock</span> and DL structures obtained from this analysis are significantly different from those obtained from the analysis of standard Gardner or Burgers equations. The implications of these results in space and interstellar compact objects (viz. non-rotating white dwarfs, neutron stars, etc.) are also briefly mentioned.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011AAS...21813405D&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011AAS...21813405D&link_type=ABSTRACT"><span id="translatedtitle">Radiative <span class="hlt">Shock</span> Waves In Emerging <span class="hlt">Shocks</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Drake, R. Paul; Doss, F.; Visco, A.</p> <p>2011-05-01</p> <p>In laboratory experiments we produce radiative <span class="hlt">shock</span> waves having dense, thin shells. These <span class="hlt">shocks</span> are similar to <span class="hlt">shocks</span> emerging from optically thick environments in astrophysics in that they are strongly radiative with optically thick <span class="hlt">shocked</span> <span class="hlt">layers</span> and optically thin or intermediate downstream <span class="hlt">layers</span> through which radiation readily escapes. Examples include <span class="hlt">shocks</span> breaking out of a Type II supernova (SN) and the radiative reverse <span class="hlt">shock</span> during the early phases of the SN remnant produced by a red supergiant star. We produce these <span class="hlt">shocks</span> by driving a low-Z plasma piston (Be) at > 100 km/s into Xe gas at 1.1 atm. pressure. The <span class="hlt">shocked</span> Xe collapses to > 20 times its initial density. Measurements of structure by radiography and temperature by several methods confirm that the <span class="hlt">shock</span> wave is strongly radiative. We observe small-scale perturbations in the post-<span class="hlt">shock</span> <span class="hlt">layer</span>, modulating the <span class="hlt">shock</span> and material interfaces. We describe a variation of the Vishniac instability theory of decelerating <span class="hlt">shocks</span> and an analysis of associated scaling relations to account for the growth of these perturbations, identify how they scale to astrophysical systems such as SN 1993J, and consider possible future experiments. Collaborators in this work have included H.F. Robey, J.P. Hughes, C.C. Kuranz, C.M. Huntington, S.H. Glenzer, T. Doeppner, D.H. Froula, M.J. Grosskopf, and D.C. Marion ________________________________ * Supported by the US DOE NNSA under the Predictive Sci. Academic Alliance Program by grant DE-FC52-08NA28616, the Stewardship Sci. Academic Alliances program by grant DE-FG52-04NA00064, and the Nat. Laser User Facility by grant DE-FG03-00SF22021.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27586773','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27586773"><span id="translatedtitle">Seafloor sound-speed profile characterization with non-<span class="hlt">parallel</span> <span class="hlt">layering</span> by the image source method: Application to CLUTTER'09 campaign data.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pinson, Samuel; Holland, Charles W</p> <p>2016-08-01</p> <p>The image source method was originally developed to estimate sediment sound speed as a function of depth assuming plane-<span class="hlt">layered</span> sediments. Recently, the technique was extended to treat dipping, i.e., non-<span class="hlt">parallel</span> <span class="hlt">layers</span> and was tested using synthetic data. Here, the technique is applied to measured reflection data with dipping <span class="hlt">layers</span> and mud volcanoes. The data were collected with an autonomous underwater vehicle towing a source (1600-3500 Hz) and a horizontal array of hydrophones. Data were collected every 3 m criss-crossing an area about 1 km(2). The results provide a combination of two-dimensional sections of the sediment sound-speeds plotted in a three-dimensional picture. PMID:27586773</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19750036179&hterms=boundary+descriptions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dboundary%2Bdescriptions','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19750036179&hterms=boundary+descriptions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dboundary%2Bdescriptions"><span id="translatedtitle">A numerical method for solving the Navier-Stokes equations with application to <span class="hlt">shock</span>-boundary <span class="hlt">layer</span> interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Maccormack, R. W.; Baldwin, B. S.</p> <p>1975-01-01</p> <p>A numerical method for solving the compressible form of the unsteady Navier-Stokes equations is described. This method was originally presented in 1970 and has since been modified during the development of computer programs at Ames for implementing models that account for the effects of turbulence in <span class="hlt">shock</span>-induced separated flows. Although this paper does not describe the turbulence models themselves, a complete description of the basic numerical method is given with emphasis on the choice of a computational mesh for high Reynolds number flows, finite-difference approximations for mixed partial derivatives, extension of the Courant-Friedrichs-Lewy stability condition for viscous flows, mesh boundary conditions, and numerical smoothing for strong <span class="hlt">shock</span>-wave calculations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014APS..DFDL26012A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APS..DFDL26012A"><span id="translatedtitle">Thermo-fluid-dynamics of turbulent boundary <span class="hlt">layer</span> over a moving continuous flat sheet in a <span class="hlt">parallel</span> free stream</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Afzal, Bushra; Noor Afzal Team; Bushra Afzal Team</p> <p>2014-11-01</p> <p>The momentum and thermal turbulent boundary <span class="hlt">layers</span> over a continuous moving sheet subjected to a free stream have been analyzed in two <span class="hlt">layers</span> (inner wall and outer wake) theory at large Reynolds number. The present work is based on open Reynolds equations of momentum and heat transfer without any closure model say, like eddy viscosity or mixing length etc. The matching of inner and outer <span class="hlt">layers</span> has been carried out by Izakson-Millikan-Kolmogorov hypothesis. The matching for velocity and temperature profiles yields the logarithmic laws and power laws in overlap region of inner and outer <span class="hlt">layers</span>, along with friction factor and heat transfer laws. The uniformly valid solution for velocity, Reynolds shear stress, temperature and thermal Reynolds heat flux have been proposed by introducing the outer wake functions due to momentum and thermal boundary <span class="hlt">layers</span>. The comparison with experimental data for velocity profile, temperature profile, skin friction and heat transfer are presented. In outer non-linear <span class="hlt">layers</span>, the lowest order momentum and thermal boundary <span class="hlt">layer</span> equations have also been analyses by using eddy viscosity closure model, and results are compared with experimental data. Retired Professor, Embassy Hotel, Rasal Ganj, Aligarh 202001 India.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26395729','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26395729"><span id="translatedtitle">Hydrogen bond network in the hydration <span class="hlt">layer</span> of the water confined in nanotubes increasing the dielectric constant <span class="hlt">parallel</span> along the nanotube axis.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Qi, Wenpeng; Zhao, Hongwei</p> <p>2015-09-21</p> <p>The water confined in nanotubes has been extensively studied, because of the potential usages in drug delivery and desalination. The radial distribution of the dielectric constant <span class="hlt">parallel</span> along the nanotube axis was obtained by molecular dynamics simulations in a carbon nanotube and a nanotube with a very small van der Waals potential. The confined water was divided into two parts, the middle part water and the hydration water. In both cases, the hydrogen bond orientation of the middle water is isotropic, while the hydrogen bonds in hydration <span class="hlt">layers</span> are apt to <span class="hlt">parallel</span> along the nanotube axis. Therefore, the hydration water has higher dipole correlations increasing the dielectric constant along the nanotube axis. PMID:26395729</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19790014839','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19790014839"><span id="translatedtitle">Interaction between a normal <span class="hlt">shock</span> wave and a turbulent boundary <span class="hlt">layer</span> at high transonic speeds. Part 2: Wall shear stress</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Liou, M. S.; Adamson, T. C., Jr.</p> <p>1979-01-01</p> <p>An analysis is presented of the flow in the two inner <span class="hlt">layers</span>, the Reynolds stress sublayer and the wall <span class="hlt">layer</span>. Included is the calculation of the shear stress at the wall in the interaction region. The limit processes considered are those used for an inviscid flow.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014SPIE.9295E..0YY','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014SPIE.9295E..0YY"><span id="translatedtitle">Laser <span class="hlt">shock</span> microforming of aluminum foil with fs laser</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ye, Yunxia; Feng, Yayun; Xuan, Ting; Hua, Xijun; Hua, Yinqun</p> <p>2014-12-01</p> <p>Laser <span class="hlt">shock</span> microforming of Aluminum(Al) foil through fs laser has been researched in this paper. The influences of confining <span class="hlt">layer</span>, clamping method and impact times on induced dent depths were investigated experimentally. Microstructure of fs laser <span class="hlt">shock</span> forming Al foil was observed through Transmission electron microscopy (TEM). Under the condition of tightly clamping, the dent depths increase with impact times and finally tend to saturating. Another new confining <span class="hlt">layer</span>, the main component of which is polypropylene, was applied and the confining effect of it is better because of its higher impedance. TEM results show that dislocation is one of the main deformation mechanisms of fs laser <span class="hlt">shock</span> forming Al foil. Specially, most of dislocations exist in the form of short and discrete dislocation lines. <span class="hlt">Parallel</span> straight dislocation slip line also were observed. We analyzed that these unique dislocation arrangements are due to fs laser-induced ultra high strain rate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950006645','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950006645"><span id="translatedtitle">Validation of the RPLUS3D Code for Supersonic Inlet Applications Involving Three-Dimensional <span class="hlt">Shock</span> Wave-Boundary <span class="hlt">Layer</span> Interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kapoor, Kamlesh; Anderson, Bernhard H.; Shaw, Robert J.</p> <p>1994-01-01</p> <p>A three-dimensional computational fluid dynamics code, RPLUS3D, which was developed for the reactive propulsive flows of ramjets and scramjets, was validated for glancing <span class="hlt">shock</span> wave-boundary <span class="hlt">layer</span> interactions. Both laminar and turbulent flows were studied. A supersonic flow over a wedge mounted on a flat plate was numerically simulated. For the laminar case, the static pressure distribution, velocity vectors, and particle traces on the flat plate were obtained. For turbulent flow, both the Baldwin-Lomax and Chien two-equation turbulent models were used. The static pressure distributions, pitot pressure, and yaw angle profiles were computed. In addition, the velocity vectors and particle traces on the flat plate were also obtained from the computed solution. Overall, the computed results for both laminar and turbulent cases compared very well with the experimentally obtained data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890011821','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890011821"><span id="translatedtitle">Numerical computation of <span class="hlt">shock</span> wave-turbulent boundary <span class="hlt">layer</span> interaction in transonic flow over an axisymmetric curved hill</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kim, S.-W.</p> <p>1989-01-01</p> <p>A control-volume based finite difference computation of a turbulent transonic flow over an axisymmetric curved hill is presented. The numerical method is based on the SIMPLE algorithm, and hence the conservation of mass equation is replaced by a pressure correction equation for compressible flows. The turbulence is described by a k-epsilon turbulence model supplemented by a near-wall turbulence model. In the method, the dissipation rate in the region very close to the wall is obtained from an algebraic equation and that for the rest of the flow domain is obtained by solving a partial differential equation for the dissipation rate. The other flow equations are integrated up to the wall. It is shown that the present turbulence model yields the correct location of the compression <span class="hlt">shock</span>. The other computational results are also in good agreement with experimental data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009GeCoA..73.1180S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009GeCoA..73.1180S"><span id="translatedtitle">A dual-<span class="hlt">layer</span> Chicxulub ejecta sequence with <span class="hlt">shocked</span> carbonates from the Cretaceous Paleogene (K Pg) boundary, Demerara Rise, western Atlantic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schulte, P.; Deutsch, A.; Salge, T.; Berndt, J.; Kontny, A.; MacLeod, K. G.; Neuser, R. D.; Krumm, S.</p> <p>2009-02-01</p> <p>An up to ˜2-cm thick Chicxulub ejecta deposit marking the Cretaceous-Paleogene (K-Pg) boundary (the "K-T" boundary) was recovered in six holes drilled during ODP Leg 207 (Demerara Rise, tropical western Atlantic). Stunning features of this deposit are its uniformity over an area of 30 km 2 and the total absence of bioturbation, allowing documentation of the original sedimentary sequence. High-resolution mineralogical, petrological, elemental, isotopic (Sr-Nd), and rock magnetic data reveal a distinct microstratigraphy and a range of ejecta components. The deposit is normally graded and composed predominantly of rounded, 0.1- to max. 1-mm sized spherules. Spherules are altered to dioctahedral aluminous smectite, though occasionally relict Si-Al-rich hydrated glass is also present, suggesting acidic precursor lithologies. Spherule textures vary from hollow to vesicle-rich to massive; some show in situ collapse, others include distinct Fe-Mg-Ca-Ti-rich melt globules and lath-shaped Al-rich quench crystals. Both altered glass spherules and the clay matrix (Site 1259B) display strongly negative ɛNdT=65Ma values (-17) indicating uptake of Nd from contemporaneous ocean water during alteration. Finally, Fe-Mg-rich spherules, <span class="hlt">shocked</span> quartz and feldspar grains, few lithic clasts, as well as abundant accretionary and porous carbonate clasts are concentrated in the uppermost 0.5-0.7 mm of the deposit. The carbonate clasts display in part very unusual textures, which are interpreted to be of <span class="hlt">shock</span>-metamorphic origin. The preservation of delicate spherule textures, normal grading with lack of evidence for traction transport, and sub-millimeter scale compositional trends provide evidence for this spherule deposit representing a primary air-fall deposit not affected by significant reworking. The ODP Leg 207 spherule deposit is the first known dual-<span class="hlt">layer</span> K-Pg boundary in marine settings; it incorporates compositional and stratigraphic aspects of both proximal and distal marine</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMSM13C2091H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMSM13C2091H"><span id="translatedtitle">Slow <span class="hlt">shock</span> formation and temperature anisotropy in collisionless magnetic reconnection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Higashimori, K.; Hoshino, M.</p> <p>2011-12-01</p> <p>We perform a two-dimensional simulation by using an electromagnetic hybrid code to study the formation of slow-mode <span class="hlt">shocks</span> in collisionless magnetic reconnection in low beta plasmas, and we argue that one of important agents of the formation of slow <span class="hlt">shocks</span> is the ion temperature anisotropy enhanced at the <span class="hlt">shock</span> downstream region. As magnetic reconnection develops, it is known that the <span class="hlt">parallel</span> temperature along the magnetic field becomes large in association with the anisotropic PSBL ion beams, and this temperature anisotropy has a tendency to suppress the formation of slow <span class="hlt">shock</span>. Although preceding studies on magnetic reconnection with kinetic codes have shown such ion temperature anisotropy along the reconnection <span class="hlt">layer</span>, the direct relation between formation of slow <span class="hlt">shocks</span> and the ion temperature anisotropy has not been investigated. Based on our simulation result, we found that the slow <span class="hlt">shock</span> formation is suppressed due to the large temperature anisotropy near the X-type region, but the downstream ion temperature anisotropy relaxes with increasing the distance from the magnetic neutral point. As a result, two pairs of current structures, which are the strong evidence of dissipation of magnetic field in slow <span class="hlt">shocks</span>, are formed at the distance |x| > 115 λ i from the neutral point.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016PhRvB..93r4513K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016PhRvB..93r4513K&link_type=ABSTRACT"><span id="translatedtitle">Superconducting subphase in the <span class="hlt">layered</span> perovskite ruthenate Sr2RuO4 in a <span class="hlt">parallel</span> magnetic field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kikugawa, Naoki; Terashima, Taichi; Uji, Shinya; Sugii, Kaori; Maeno, Yoshiteru; Graf, David; Baumbach, Ryan; Brooks, James</p> <p>2016-05-01</p> <p>Magnetic torque measurements using a microcantilever have been performed to investigate the superconducting phase of Sr2RuO4 down to 40 mK. For high-quality single crystals with the transition temperature (Tc) of 1.48-1.49 K, an abrupt jump of the torque signal is found near 1.5 T in field <span class="hlt">parallel</span> to the conducting RuO2 planes below ˜0.8 K . The jump corresponds to the first order transition recently revealed by magnetocaloric and magnetization measurements [Yonezawa et al., Phys. Rev. Lett. 110, 077003 (2013), 10.1103/PhysRevLett.110.077003; Kittaka et al., Phys. Rev. B 90, 220502(R) (2014), 10.1103/PhysRevB.90.220502]. Furthermore, weak diamagnetic and irreversible signals are found to persist above the first order transition up to 1.85 T. The result indicates the presence of a subphase boundary separating low- and high-field phases in the superconducting phase. The high-field subphase disappears when the field is tilted from the conducting planes only by a few degrees. Quantum oscillation measurements are also reported to clarify the strong sample-quality dependence of the high-field subphase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20060009012','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20060009012"><span id="translatedtitle">Flexible Multi-<span class="hlt">Shock</span> Shield</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Christiansen, Eric L. (Inventor); Crews, Jeanne L. (Inventor)</p> <p>2005-01-01</p> <p>Flexible multi-<span class="hlt">shock</span> shield system and method are disclosed for defending against hypervelocity particles. The flexible multi-<span class="hlt">shock</span> shield system and method may include a number of flexible bumpers or shield <span class="hlt">layers</span> spaced apart by one or more resilient support <span class="hlt">layers</span>, all of which may be encapsulated in a protective cover. Fasteners associated with the protective cover allow the flexible multi-<span class="hlt">shock</span> shield to be secured to the surface of a structure to be protected.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012ApPhL.100m3302C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012ApPhL.100m3302C"><span id="translatedtitle">Efficient broad-spectrum <span class="hlt">parallel</span> tandem organic solar cells based on the highly crystalline chloroaluminum phthalocyanine films as the planar <span class="hlt">layer</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Weichao; Qiao, Xiaolan; Yang, Jianbing; Yu, Bo; Yan, Donghang</p> <p>2012-03-01</p> <p>Efficient <span class="hlt">parallel</span> tandem organic solar cells are demonstrated by using the highly crystalline chloroaluminum phthalocyanine (AlClPc) films as the planar <span class="hlt">layer</span>. Their broad photoresponse from 400-900 nm is contributed to the strong near-infrared absorption of the AlClPc films and the good complementarity between AlClPc and zinc phthalocyanine. Importantly, the high external quantum efficiency is obtained in the entire response range with the peak value 65% due to the high carrier mobility of the AlClPc films, and correspondingly the high power conversion efficiency of 3.5% is attributed to the large short circuit current density of 12.15 mA/cm2.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012RScI...83c3505N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012RScI...83c3505N"><span id="translatedtitle">Simultaneous measurements of the <span class="hlt">parallel</span> and perpendicular ion temperature with a pinhole probe in the scrape-off-<span class="hlt">layer</span> of the tokamak ISTTOK</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nedzelskiy, I. S.; Silva, C.; Duarte, P.; Fernandes, H.</p> <p>2012-03-01</p> <p>A pinhole probe (PHP) for the simultaneous measurement of the <span class="hlt">parallel</span>, T∥, and perpendicular, T⊥, ion temperature has been designed and tested in the scrape-off-<span class="hlt">layer</span> (SOL) plasma of the tokamak ISTTOK. The PHP consists of a tunnel immersed into the plasma <span class="hlt">parallel</span> to magnetic field and an ion collector. One end of the tunnel is covered with a thin foil that has a pinhole sampling ions from the plasma. The other end of the tunnel (close to the negatively biased collector) is covered with a fine-mesh screen. The possibility of performing an analytical description of the PHP current-to-voltage characteristics obtained on the collector when biasing the tunnel simplifies the interpretation of the results. The PHP operation has been previously tested in T∥, T⊥ measurements in low temperature weekly magnetized plasma [H. Mase, T. Honzava, and G. Miyamoto, J. Appl. Phys. 49(10), 5171 (1978)], 10.1063/1.324412. In this paper, the PHP operation in the SOL of the tokamak ISTTOK is described, and the first results of T∥ and T⊥ measurements are presented. The obtained results demonstrate strong (˜30%) variation of T∥ and T⊥ on a time scale of 0.5 ms, and general predominance of T∥ > T⊥ anisotropy (T∥mean/T⊥mean ˜ 1.5) during plasma shot.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25989935','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25989935"><span id="translatedtitle">In vitro apatite formation on nano-crystalline titania <span class="hlt">layer</span> aligned <span class="hlt">parallel</span> to Ti6Al4V alloy substrates with sub-millimeter gap.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hayakawa, Satoshi; Matsumoto, Yuko; Uetsuki, Keita; Shirosaki, Yuki; Osaka, Akiyoshi</p> <p>2015-06-01</p> <p>Pure titanium substrates were chemically oxidized with H2O2 and subsequent thermally oxidized at 400 °C in air to form anatase-type titania <span class="hlt">layer</span> on their surface. The chemically and thermally oxidized titanium substrate (CHT) was aligned <span class="hlt">parallel</span> to the counter specimen such as commercially pure titanium (cpTi), titanium alloy (Ti6Al4V) popularly used as implant materials or Al substrate with 0.3-mm gap. Then, they were soaked in Kokubo's simulated body fluid (SBF, pH 7.4, 36.5 °C) for 7 days. XRD and SEM analysis showed that the in vitro apatite-forming ability of the contact surface of the CHT specimen decreased in the order: cpTi > Ti6Al4V > Al. EDX and XPS surface analysis showed that aluminum species were present on the contact surface of the CHT specimen aligned <span class="hlt">parallel</span> to the counter specimen such as Ti6Al4V and Al. This result indicated that Ti6Al4V or Al specimens released the aluminum species into the SBF under the spatial gap. The released aluminum species might be positively or negatively charged in the SBF and thus can interact with calcium or phosphate species as well as titania <span class="hlt">layer</span>, causing the suppression of the primary heterogeneous nucleation and growth of apatite on the contact surface of the CHT specimen under the spatial gap. The diffusion and adsorption of aluminum species derived from the half-sized counter specimen under the spatial gap resulted in two dimensionally area-selective deposition of apatite particles on the contact surfaces of the CHT specimen. PMID:25989935</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21259656','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21259656"><span id="translatedtitle">Effects of the <span class="hlt">parallel</span> electron dynamics and finite ion temperature on the plasma blob propagation in the scrape-off <span class="hlt">layer</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jovanovic, D.; Shukla, P. K.; Pegoraro, F.</p> <p>2008-11-15</p> <p>A new three-dimensional model for the warm-ion turbulence at the tokamak edge plasma and in the scrape-off <span class="hlt">layer</span> is proposed, and used to study the dynamics of plasma blobs in the scrape-off <span class="hlt">layer</span>. The model is based on the nonlinear interchange mode, coupled with the nonlinear resistive drift mode, in the presence of the magnetic curvature drive, the density inhomogeneity, the electron dynamics along the open magnetic field lines, and the electron-ion and electron-neutral collisions. Within the present model, the effect of the sheath resistivity decreases with the distance from the wall, resulting in the bending and the break up of the plasma blob structure. Numerical solutions exhibit the coupling of interchange modes with nonlinear drift modes, causing the collapse of the blob in the lateral direction, followed by a clockwise rotation and radial propagation. The symmetry breaking, caused both by the <span class="hlt">parallel</span> resistivity and the finite ion temperature, introduces a poloidal component in the plasma blob propagation, while the overall stability properties and the speed are not affected qualitatively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830003774','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830003774"><span id="translatedtitle">Experimental investigation of tangential blowing for control of the strong <span class="hlt">shock</span> boundary <span class="hlt">layer</span> interaction on inlet ramps</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schwendemann, M. F.</p> <p>1981-01-01</p> <p>A 0.165-scale isolated inlet model was tested in the NASA Lewis Research Center 8-ft by 6-ft Supersonic Wind Tunnel. Ramp boundary <span class="hlt">layer</span> control was provided by tangential blowing from a row of holes in an aft-facing step set into the ramp surface. Testing was performed at Mach numbers from 1.36 to 1.96 using both cold and heated air in the blowing system. Stable inlet flow was achieved at all Mach numbers. Blowing hole geometry was found to be significant at 1.96M. Blowing air temperature was found to have only a small effect on system performance. High blowing levels were required at the most severe test conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22118610','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22118610"><span id="translatedtitle">STEREO interplanetary <span class="hlt">shocks</span> and foreshocks</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Blanco-Cano, X.; Kajdic, P.; Aguilar-Rodriguez, E.; Russell, C. T.; Jian, L. K.; Luhmann, J. G.</p> <p>2013-06-13</p> <p>We use STEREO data to study <span class="hlt">shocks</span> driven by stream interactions and the waves associated with them. During the years of the extended solar minimum 2007-2010, stream interaction <span class="hlt">shocks</span> have Mach numbers between 1.1-3.8 and {theta}{sub Bn}{approx}20-86 Degree-Sign . We find a variety of waves, including whistlers and low frequency fluctuations. Upstream whistler waves may be generated at the <span class="hlt">shock</span> and upstream ultra low frequency (ULF) waves can be driven locally by ion instabilities. The downstream wave spectra can be formed by both, locally generated perturbations, and <span class="hlt">shock</span> transmitted waves. We find that many quasiperpendicular <span class="hlt">shocks</span> can be accompanied by ULF wave and ion foreshocks, which is in contrast to Earth's bow <span class="hlt">shock</span>. Fluctuations downstream of quasi-<span class="hlt">parallel</span> <span class="hlt">shocks</span> tend to have larger amplitudes than waves downstream of quasi-perpendicular <span class="hlt">shocks</span>. Proton foreshocks of <span class="hlt">shocks</span> driven by stream interactions have extensions dr {<=}0.05 AU. This is smaller than foreshock extensions for ICME driven <span class="hlt">shocks</span>. The difference in foreshock extensions is related to the fact that ICME driven <span class="hlt">shocks</span> are formed closer to the Sun and therefore begin to accelerate particles very early in their existence, while stream interaction <span class="hlt">shocks</span> form at {approx}1 AU and have been producing suprathermal particles for a shorter time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750024905','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750024905"><span id="translatedtitle">Bow <span class="hlt">shock</span> and magnetosheath waves at Mercury</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fairfield, D. H.; Behannon, K. W.</p> <p>1975-01-01</p> <p>Mariner 10 measurements at the Mercury bow <span class="hlt">shock</span> provide examples where the magnetic field is approximately <span class="hlt">parallel</span> or perpendicular to the bow <span class="hlt">shock</span> normal. Upstream of a broad irregular <span class="hlt">parallel</span> <span class="hlt">shock</span>, left hand circularly polarized waves are observed which cut off very sharply at approximately 4 Hz. Upstream of a perpendicular <span class="hlt">shock</span>, right hand circularly polarized waves are observed which persist up to the Nyquist frequency of 12 Ha. Determination of the wave propagation vector as a function of frequency helps conclusively identify the waves as whistler mode waves propagating from the <span class="hlt">shock</span>. The magnetosheath downstream of the <span class="hlt">parallel</span> <span class="hlt">shock</span> is disturbed more than that downstream of the perpendicular <span class="hlt">shock</span> particularly below 1 Hz. In the latter case regular left hand polarized waves observed slightly above the proton gyrofrequency are identified as ion cyclotron waves with wavelength approximately 300 km which are Doppler shifted up to their observed frequency.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930064250&hterms=skin+layers&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dskin%2Blayers','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930064250&hterms=skin+layers&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dskin%2Blayers"><span id="translatedtitle">Laser Interferometer Skin-Friction measurements of crossing-<span class="hlt">shock</span> wave/turbulent boundary-<span class="hlt">layer</span> interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Garrison, T. J.; Settles, G. S.</p> <p>1993-01-01</p> <p>Wall shear stress measurements beneath crossingshock wave/turbulent boundary-<span class="hlt">layer</span> interactions have been made for three interactions of different strengths. The interactions are generated by two sharp fins at symmetric angles of attack mounted on a flat plate. The shear stress measurements were made for fin angles of 7 and 11 degrees at Mach 3 and 15 degrees at Mach 4. The measurements were made using a Laser Interferometer Skin Friction (LISF) meter; a device which determines the wail shear by optically measuring the time rate of thinning of an oil film placed on the test model surface. Results of the measurements reveal high skin friction coefficients in the vicinity of the fin/plate junction and the presence of quasi-two-dimensional flow separation on the interaction centerline. Additionally, two Navier-Stokes computations, one using a Baldwin-Lomax turbulence model and one using a k- model, are compared to the experimental results for the Mach 4, 15 degree interaction case. While the k- model did a reasonable job of predicting the overall trend in portions of the skin friction distribution, neither computation fully captured the physics of the near surface flow in this complex interaction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016IJAME..21..423L&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016IJAME..21..423L&link_type=ABSTRACT"><span id="translatedtitle">Unsteady two-<span class="hlt">layered</span> fluid flow of conducting fluids in a channel between <span class="hlt">parallel</span> porous plates under transverse magnetic field in a rotating system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Linga Raju, T.; Neela Rao, B.</p> <p>2016-05-01</p> <p>An unsteady MHD two-<span class="hlt">layered</span> fluid flow of electrically conducting fluids in a horizontal channel bounded by two <span class="hlt">parallel</span> porous plates under the influence of a transversely applied uniform strong magnetic field in a rotating system is analyzed. The flow is driven by a common constant pressure gradient in a channel bounded by two <span class="hlt">parallel</span> porous plates, one being stationary and the other oscillatory. The two fluids are assumed to be incompressible, electrically conducting with different viscosities and electrical conductivities. The governing partial differential equations are reduced to the linear ordinary differential equations using two-term series. The resulting equations are solved analytically to obtain exact solutions for the velocity distributions (primary and secondary) in the two regions respectively, by assuming their solutions as a combination of both the steady state and time dependent components of the solutions. Numerical values of the velocity distributions are computed for different sets of values of the governing parameters involved in the study and their corresponding profiles are also plotted. The details of the flow characteristics and their dependence on the governing parameters involved, such as the Hartmann number, Taylor number, porous parameter, ratio of the viscosities, electrical conductivities and heights are discussed. Also an observation is made how the velocity distributions vary with the rotating hydromagnetic interaction in the case of steady and unsteady flow motions. The primary velocity distributions in the two regions are seen to decrease with an increase in the Taylor number, but an increase in the Taylor number causes a rise in secondary velocity distributions. It is found that an increase in the porous parameter decreases both the primary and secondary velocity distributions in the two regions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016PhPl...23e0701B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016PhPl...23e0701B&link_type=ABSTRACT"><span id="translatedtitle">Measurements of the <span class="hlt">parallel</span> wavenumber of lower hybrid waves in the scrape-off <span class="hlt">layer</span> of a high-density tokamak</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baek, S. G.; Wallace, G. M.; Shinya, T.; Parker, R. R.; Shiraiwa, S.; Bonoli, P. T.; Brunner, D.; Faust, I.; LaBombard, B. L.; Takase, Y.; Wukitch, S.</p> <p>2016-05-01</p> <p>In lower hybrid current drive (LHCD) experiments on tokamaks, the <span class="hlt">parallel</span> wavenumber of lower hybrid waves is an important physics parameter that governs the wave propagation and absorption physics. However, this parameter has not been experimentally well-characterized in the present-day high density tokamaks, despite the advances in the wave physics modeling. In this paper, we present the first measurement of the dominant <span class="hlt">parallel</span> wavenumber of lower hybrid waves in the scrape-off <span class="hlt">layer</span> (SOL) of the Alcator C-Mod tokamak with an array of magnetic loop probes. The electric field strength measured with the probe in typical C-Mod plasmas is about one-fifth of that of the electric field at the mouth of the grill antenna. The amplitude and phase responses of the measured signals on the applied power spectrum are consistent with the expected wave energy propagation. At higher density, the observed k|| increases for the fixed launched k||, and the wave amplitude decreases rapidly. This decrease is correlated with the loss of LHCD efficiency at high density, suggesting the presence of loss mechanisms. Evidence of the spectral broadening mechanisms is observed in the frequency spectra. However, no clear modifications in the dominant k|| are observed in the spectrally broadened wave components, as compared to the measured k|| at the applied frequency. It could be due to (1) the probe being in the SOL and (2) the limited k|| resolution of the diagnostic. Future experiments are planned to investigate the roles of the observed spectral broadening mechanisms on the LH density limit problem in the strong single pass damping regime.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1196173','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1196173"><span id="translatedtitle">Kinetic Simulations of Particle Acceleration at <span class="hlt">Shocks</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Caprioli, Damiano; Guo, Fan</p> <p>2015-07-16</p> <p>Collisionless <span class="hlt">shocks</span> are mediated by collective electromagnetic interactions and are sources of non-thermal particles and emission. The full particle-in-cell approach and a hybrid approach are sketched, simulations of collisionless <span class="hlt">shocks</span> are shown using a multicolor presentation. Results for SN 1006, a case involving ion acceleration and B field amplification where the <span class="hlt">shock</span> is <span class="hlt">parallel</span>, are shown. Electron acceleration takes place in planetary bow <span class="hlt">shocks</span> and galaxy clusters. It is concluded that acceleration at <span class="hlt">shocks</span> can be efficient: >15%; CRs amplify B field via streaming instability; ion DSA is efficient at <span class="hlt">parallel</span>, strong <span class="hlt">shocks</span>; ions are injected via reflection and <span class="hlt">shock</span> drift acceleration; and electron DSA is efficient at oblique <span class="hlt">shocks</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6910851','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6910851"><span id="translatedtitle"><span class="hlt">Shock</span> wave interaction with turbulence: Pseudospectral simulations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Buckingham, A.C.</p> <p>1986-12-30</p> <p><span class="hlt">Shock</span> waves amplify pre-existing turbulence. <span class="hlt">Shock</span> tube and <span class="hlt">shock</span> wave boundary <span class="hlt">layer</span> interaction experiments provide qualitative confirmation. However, <span class="hlt">shock</span> pressure, temperature, and rapid transit complicate direct measurement. Computational simulations supplement the experimental data base and help isolate the mechanisms responsible. Simulations and experiments, particularly under reflected <span class="hlt">shock</span> wave conditions, significantly influence material mixing. In these pseudospectral Navier-Stokes simulations the <span class="hlt">shock</span> wave is treated as either a moving (tracked or fitted) domain boundary. The simulations assist development of code mix models. <span class="hlt">Shock</span> Mach number and pre-existing turbulence intensity initially emerge as key parameters. 20 refs., 8 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://medlineplus.gov/ency/article/000185.htm','NIH-MEDLINEPLUS'); return false;" href="https://medlineplus.gov/ency/article/000185.htm"><span id="translatedtitle">Cardiogenic <span class="hlt">shock</span></span></a></p> <p><a target="_blank" href="http://medlineplus.gov/">MedlinePlus</a></p> <p></p> <p></p> <p>... this page: //medlineplus.gov/ency/article/000185.htm Cardiogenic <span class="hlt">shock</span> To use the sharing features on this page, please enable JavaScript. Cardiogenic <span class="hlt">shock</span> is when the heart has been damaged so ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.nlm.nih.gov/medlineplus/ency/article/000668.htm','NIH-MEDLINEPLUS'); return false;" href="https://www.nlm.nih.gov/medlineplus/ency/article/000668.htm"><span id="translatedtitle">Septic <span class="hlt">shock</span></span></a></p> <p><a target="_blank" href="http://medlineplus.gov/">MedlinePlus</a></p> <p></p> <p></p> <p>Septic <span class="hlt">shock</span> is a serious condition that occurs when a body-wide infection leads to dangerously low blood ... Septic <span class="hlt">shock</span> occurs most often in the very old and the very young. It may also occur in ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22261781','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22261781"><span id="translatedtitle">Depletion of <span class="hlt">parallel</span> conducting <span class="hlt">layers</span> in high mobility In{sub 0.53}Ga{sub 0.47}As/In{sub 0.52}Al{sub 0.48}As modulation doped field effect transistors</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Skuras, E. Gavalas, A. Spathara, D. Makris, Th. Anagnostopoulos, D.; Stanley, C. R.; Long, A. R.</p> <p>2013-12-04</p> <p>Self-consistent calculations for solving the Poisson and Schrödinger equations were performed in order to study <span class="hlt">parallel</span> conduction in the In{sub 0.52}Al{sub 0.48}As barrier <span class="hlt">layer</span> in In{sub 0.53}Ga{sub 0.47}As/In{sub 0.52}Al{sub 0.48}As Modulation Doped Field Effect Transistors. It is shown that the <span class="hlt">parallel</span> conducting <span class="hlt">layer</span> occupied sub-bands can be entirely depleted by wet chemical etching of the upper part of the un-doped In{sub 0.52}Al{sub 0.48}As Schottky <span class="hlt">layer</span> without affecting the total carrier concentration at the In{sub 0.53}Ga{sub 0.47}As quantum well.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850026578','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850026578"><span id="translatedtitle">The cosmic-ray <span class="hlt">shock</span> structure problem for relativistic <span class="hlt">shocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Webb, G. M.</p> <p>1985-01-01</p> <p>The time asymptotic behaviour of a relativistic (<span class="hlt">parallel</span>) <span class="hlt">shock</span> wave significantly modified by the diffusive acceleration of cosmic-rays is investigated by means of relativistic hydrodynamical equations for both the cosmic-rays and thermal gas. The form of the <span class="hlt">shock</span> structure equation and the dispersion relation for both long and short wavelength waves in the system are obtained. The dependence of the <span class="hlt">shock</span> acceleration efficiency on the upstream fluid spped, long wavelength Mach number and the ratio N = P sub co/cP sub co+P sub go)(Psub co and P sub go are the upstream cosmic-ray and thermal gas pressures respectively) are studied.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19800023816','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19800023816"><span id="translatedtitle">Interaction between a normal <span class="hlt">shock</span> wave and a turbulent boundary <span class="hlt">layer</span> at high transonic speeds. Part 1: Pressure distribution. Part 2: Wall shear stress. Part 3: Simplified formulas for the prediction of surface pressures and skin friction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Adamson, T. C., Jr.; Liou, M. S.; Messiter, A. F.</p> <p>1980-01-01</p> <p>An asymptotic description is derived for the interaction between a <span class="hlt">shock</span> wave and a turbulent boundary <span class="hlt">layer</span> in transonic flow, for a particular limiting case. The dimensionless difference between the external flow velocity and critical sound speed is taken to be much smaller than one, but large in comparison with the dimensionless friction velocity. The basic results are derived for a flat plate, and corrections for longitudinal wall curvature and for flow in a circular pipe are also shown. Solutions are given for the wall pressure distribution and the shape of the <span class="hlt">shock</span> wave. Solutions for the wall shear stress are obtained, and a criterion for incipient separation is derived. Simplified solutions for both the wall pressure and skin friction distributions in the interaction region are given. These results are presented in a form suitable for use in computer programs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920033175&hterms=plasma+physics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dplasma%2Bphysics','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920033175&hterms=plasma+physics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dplasma%2Bphysics"><span id="translatedtitle">The plasma physics of <span class="hlt">shock</span> acceleration</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jones, Frank C.; Ellison, Donald C.</p> <p>1991-01-01</p> <p>The history and theory of <span class="hlt">shock</span> acceleration is reviewed, paying particular attention to theories of <span class="hlt">parallel</span> <span class="hlt">shocks</span> which include the backreaction of accelerated particles on the <span class="hlt">shock</span> structure. The work that computer simulations, both plasma and Monte Carlo, are playing in revealing how thermal ions interact with <span class="hlt">shocks</span> and how particle acceleration appears to be an inevitable and necessary part of the basic plasma physics that governs collisionless <span class="hlt">shocks</span> is discussed. Some of the outstanding problems that still confront theorists and observers in this field are described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/639812','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/639812"><span id="translatedtitle"><span class="hlt">Shock</span> transmissibility of threaded joints</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hansen, N.R.; Bateman, V.I.; Brown, F.A.</p> <p>1996-12-31</p> <p>Sandia National Laboratories (SNL) designs mechanical systems with threaded joints that must survive high <span class="hlt">shock</span> environments. These mechanical systems include penetrators that must survive soil and rock penetration; drilling pipe strings that must survive rock-cutting, <span class="hlt">shock</span> environments; and laydown weapons that must survive delivery impact <span class="hlt">shock</span>. This paper summarizes an analytical study and an experimental evaluation of compressive, one-dimensional, <span class="hlt">shock</span> transmission through a threaded joint in a split Hopkinson bar configuration. Thread geometries were scaled to simulate large diameter threaded joints with loadings <span class="hlt">parallel</span> to the axis of the threads. Both strain and acceleration were evaluated with experimental measurements and analysis. Analytical results confirm the experimental conclusions that in this split Hopkinson bar configuration, the change in the one-dimensional <span class="hlt">shock</span> wave by the threaded joint is localized to a length equal to a few diameters` length beyond the threaded joint.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19820061328&hterms=1084&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3D%2526%25231084','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19820061328&hterms=1084&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3D%2526%25231084"><span id="translatedtitle">Slow <span class="hlt">shocks</span> around the sun</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Whang, Y. C.</p> <p>1982-01-01</p> <p>It is inferred from this study that magnetohydrodynamic slow <span class="hlt">shocks</span> can exist in the vicinity of the sun. The study uses a two-hole corona model, the sub-Alfvenic streams originating from the edge of the polar open-field regions are forced to turn towards equator in coronal space following the curved boundary of the closed field region. When the streamlines from the opposite poles merge at a neutral point, their directions become <span class="hlt">parallel</span> to the neutral sheet. An oblique slow <span class="hlt">shock</span> can develop near or at the neutral point, the <span class="hlt">shock</span> extends polewards to form a surface of discontinuity around the sun.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1811389L&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1811389L&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Shocked</span> cobbles in Lower Cretaceous Duwon Formation, South Korea: their classification and possible formation mechanisms</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lim, Hyoun Soo; Chae, Yong-Un; Kim, Kyung Soo; Kim, Cheng-Bin; Huh, Min</p> <p>2016-04-01</p> <p><span class="hlt">Shocked</span> cobbles are the cobbles having <span class="hlt">shock</span>-induced deformation structures on the surfaces. The most distinctive macroscopic features are the subparallel fractures and the pervasive surface craters, with or without radial fractures. Until now, these <span class="hlt">shocked</span> cobbles have been reported mainly in Europe, America, and Africa, but never been found or reported in Korea. <span class="hlt">Shocked</span> cobbles have recently found in the Lower Cretaceous Duwon Formation in South Korea, which was the second report in Asia. The Duwon Formation consists mainly of conglomerates, gravelly sandstones and intercalated mudstone and shale <span class="hlt">layers</span>. The <span class="hlt">shocked</span> cobbles are commonly found in the lowermost clast-supported conglomerate <span class="hlt">layers</span>, and they show various deformation features, such as pockmarked (circular or elliptical) cobbles, cratered (Hertzian or bowl-shaped) cobbles with or without radial fractures, cobbles showing subparallel fractures, and strongly squashed or heavily dissected cobbles. In general, these deformation structures are considered to have resulted from pressure dissolution by overburden, tectonic compression, and seismic or meteorite impacts. However, the exact formation mechanism is not clearly understood, and still in debate. The <span class="hlt">shocked</span> cobbles found in the Duwon Formation have similar features to those of previously reported <span class="hlt">shocked</span> cobbles, especially to Triassic Buntsandstein conglomerates in northeastern Spain. Based on the degree of deformation, the Duwon <span class="hlt">shocked</span> cobbles can be divided into four types, which are (1) faint contact marks, (2) pitted marks without any fractures, (3) pitted marks with radial or sub-<span class="hlt">parallel</span> fractures affected by pits, and (4) intensive fractures and heavily dissected fragments. The possible mechanisms for the Duwon <span class="hlt">shocked</span> cobbles are thought to be crushing process by shear stress and pressure solution.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950017176','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950017176"><span id="translatedtitle">Entropy jump across an inviscid <span class="hlt">shock</span> wave</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Salas, Manuel D.; Iollo, Angelo</p> <p>1995-01-01</p> <p>The <span class="hlt">shock</span> jump conditions for the Euler equations in their primitive form are derived by using generalized functions. The <span class="hlt">shock</span> profiles for specific volume, speed, and pressure are shown to be the same, however density has a different <span class="hlt">shock</span> profile. Careful study of the equations that govern the entropy shows that the inviscid entropy profile has a local maximum within the <span class="hlt">shock</span> <span class="hlt">layer</span>. We demonstrate that because of this phenomenon, the entropy, propagation equation cannot be used as a conservation law.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19880044698&hterms=conduction&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dconduction','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19880044698&hterms=conduction&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dconduction"><span id="translatedtitle">The structure of <span class="hlt">shocks</span> with thermal conduction and radiative cooling. [in astrophysical plasmas</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lacey, Cedric G.</p> <p>1988-01-01</p> <p>A general analysis is presented of the structure of a steady state, plane-<span class="hlt">parallel</span> <span class="hlt">shock</span> wave in which both thermal conduction and radiative cooling are important. The fluid is assumed to have a perfect-gas equation of state, with radiative cooling a function only of its temperature and density. Conduction in both diffusive and saturated regimes is treated. For the case of a strong <span class="hlt">shock</span>, with conductivity and cooling function varying as power laws in temperature, approximate analytic solutions describing the <span class="hlt">shock</span> wave are derived. For a plasma of solar composition, conduction is found to have a significant effect on the <span class="hlt">shock</span> temperature and overall thickness of the postshock <span class="hlt">layer</span> only for <span class="hlt">shock</span> velocities greater than about 30,000 km/s, corresponding to <span class="hlt">shock</span> temperatures greater than about 10 to the 10th K, but it affects the local structure of parts of the <span class="hlt">shock</span> wave at much lower velocities. The effects of conduction are greatly enhanced if the heavy-element abundance is increased.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1019055','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1019055"><span id="translatedtitle">The role of <span class="hlt">parallel</span> heat transport in the relation between upstream scrape-off <span class="hlt">layer</span> widths and target heat flux width in H-mode plasmas of NSTX.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ahn, J W; Boedo, J A; Maingi, R; Soukhanovskii, V A</p> <p>2009-01-05</p> <p>The physics of <span class="hlt">parallel</span> heat transport was tested in the Scrape-off <span class="hlt">Layer</span> (SOL) plasma of the National Spherical Torus Experiment (NSTX) [M. Ono, et al., Nucl. Fusion 40, 557 (2000) and S. M. Kaye, et al., Nucl. Fusion 45, S168 (2005)] tokamak by comparing the upstream electron temperature (T{sub e}) and density (n{sub e}) profiles measured by the mid-plane reciprocating probe to the heat flux (q{sub {perpendicular}}) profile at the divertor plate measured by an infrared (IR) camera. It is found that electron conduction explains the near SOL width data reasonably well while the far SOL, which is in the sheath limited regime, requires an ion heat flux profile broader than the electron one to be consistent with the experimental data. The measured plasma parameters indicate that the SOL energy transport should be in the conduction-limited regime for R-R{sub sep} (radial distance from the separatrix location) < 2-3 cm. The SOL energy transport should transition to the sheath-limited regime for R-R{sub sep} > 2-3cm. The T{sub e}, n{sub e}, and q{sub {perpendicular}} profiles are better described by an offset exponential function instead of a simple exponential. The conventional relation between mid plane electron temperature decay length ({lambda}{sub Te}) and target heat flux decay length ({lambda}{sub q}) is {lambda}{sub Te} = 7/2{lambda}{sub q}, whereas the newly-derived relation, assuming offset exponential functional forms, implies {lambda}{sub Te} = (2-2.5){lambda}{sub q}. The measured values of {lambda}{sub Te}/{lambda}{sub q} differ from the new prediction by 25-30%. The measured {lambda}{sub q} values in the far SOL (R-R{sub sep} > 2-3cm) are 9-10cm, while the expected values are 2.7 < {lambda}{sub q} < 4.9 cm (for sheath-limited regime). We propose that the ion heat flux profile is substantially broader than the electron heat flux profile as an explanation for this discrepancy in the far SOL.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5027293','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5027293"><span id="translatedtitle">The earth's foreshock, bow <span class="hlt">shock</span>, and magnetosheath</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Onsager, T.G.; Thomsen, M.F. )</p> <p>1991-01-01</p> <p>Studies directly pertaining to the earth's foreshock, bow <span class="hlt">shock</span>, and magnetosheath are reviewed, and some comparisons are made with data on other planets. Topics considered in detail include the electron foreshock, the ion foreshock, the quasi-<span class="hlt">parallel</span> <span class="hlt">shock</span>, the quasi-perpendicular <span class="hlt">shock</span>, and the magnetosheath. Information discussed spans a broad range of disciplines, from large-scale macroscopic plasma phenomena to small-scale microphysical interactions. 184 refs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950023885','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950023885"><span id="translatedtitle"><span class="hlt">Parallel</span> rendering</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Crockett, Thomas W.</p> <p>1995-01-01</p> <p>This article provides a broad introduction to the subject of <span class="hlt">parallel</span> rendering, encompassing both hardware and software systems. The focus is on the underlying concepts and the issues which arise in the design of <span class="hlt">parallel</span> rendering algorithms and systems. We examine the different types of <span class="hlt">parallelism</span> and how they can be applied in rendering applications. Concepts from <span class="hlt">parallel</span> computing, such as data decomposition, task granularity, scalability, and load balancing, are considered in relation to the rendering problem. We also explore concepts from computer graphics, such as coherence and projection, which have a significant impact on the structure of <span class="hlt">parallel</span> rendering algorithms. Our survey covers a number of practical considerations as well, including the choice of architectural platform, communication and memory requirements, and the problem of image assembly and display. We illustrate the discussion with numerous examples from the <span class="hlt">parallel</span> rendering literature, representing most of the principal rendering methods currently used in computer graphics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1179171','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1179171"><span id="translatedtitle">An Overview of High-performance <span class="hlt">Parallel</span> Big Data transfers over multiple network channels with Transport <span class="hlt">Layer</span> Security (TLS) and TLS plus Perfect Forward Secrecy (PFS)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fang, Chin; Corttrell, R. A.</p> <p>2015-05-06</p> <p>This Technical Note provides an overview of high-performance <span class="hlt">parallel</span> Big Data transfers with and without encryption for data in-transit over multiple network channels. It shows that with the <span class="hlt">parallel</span> approach, it is feasible to carry out high-performance <span class="hlt">parallel</span> "encrypted" Big Data transfers without serious impact to throughput. But other impacts, e.g. the energy-consumption part should be investigated. It also explains our rationales of using a statistics-based approach for gaining understanding from test results and for improving the system. The presentation is of high-level nature. Nevertheless, at the end we will pose some questions and identify potentially fruitful directions for future work.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5008311','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5008311"><span id="translatedtitle">Current topics in <span class="hlt">shock</span> waves; Proceedings of the International Symposium on <span class="hlt">Shock</span> Waves and <span class="hlt">Shock</span> Tubes, 17th, Lehigh University, Bethlehem, PA, July 17-21, 1989</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kim, Y.W.</p> <p>1990-01-01</p> <p>Various papers on <span class="hlt">shock</span> waves are presented. The general topics addressed include: <span class="hlt">shock</span> formation, focusing, and implosion; <span class="hlt">shock</span> reflection and diffraction; turbulence; laser-produced plasmas and waves; ionization and <span class="hlt">shock</span>-plasma interaction; chemical kinetics, pyrolysis, and soot formation; experimental facilities, techniques, and applications; ignition of detonation and combustion; particle entrainment and <span class="hlt">shock</span> propagation through particle suspension; boundary <span class="hlt">layers</span> and blast simulation; computational methods and numerical simulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015RuPhJ..57.1615A&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015RuPhJ..57.1615A&link_type=ABSTRACT"><span id="translatedtitle">Formation of a Refracted Electromagnetic Wave at the Output from a Plane-<span class="hlt">Parallel</span> Dielectric <span class="hlt">Layer</span> and Interference Nature of Fermat's Principle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Averbukh, B. B.; Averbukh, I. B.</p> <p>2015-04-01</p> <p>It is shown that a transition <span class="hlt">layer</span> representing a spatial region in which field propagation is analogous to refraction in an inhomogeneous medium exists after a dielectric <span class="hlt">layer</span>. In this region located within the near field zone the direction of the wave vector of the transmitted field varies smoothly, and with increasing distance from the <span class="hlt">layer</span>, approaches to that of the wave incident on the <span class="hlt">layer</span>. It is shown that such behavior of the field and occurrence of the transition <span class="hlt">layer</span> are caused by the interference of the incident wave field and the fields of secondary sources excited in the dielectric by the incident wave field. It is shown that the refraction of the field in a homogeneous medium after the dielectric corresponds to Fermat's principle, and the interference nature of Fermat's principle is justified.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PhDT.......145A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PhDT.......145A"><span id="translatedtitle">Noise transmission along <span class="hlt">shock</span>-waves</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Amur Varadarajan, Prasanna</p> <p></p> <p><span class="hlt">Shocks</span> at the inlet of scramjet engines are subject to perturbations from their interaction with turbulent boundary <span class="hlt">layer</span>. DNS results for this interaction indicate the presence of discrete vortices that interact with the <span class="hlt">shock</span> at its foot. These studies reveal that the vortices cause oscillations of the <span class="hlt">shock</span>. In this work we examine the propagation of disturbances along a stationary oblique <span class="hlt">shock</span> following interaction with a two-dimensional vortex. We study the decay of disturbances along a normal <span class="hlt">shock</span> as measured from Euler computations and compare these with the predictions of Geometrical <span class="hlt">Shock</span> Dynamics (GSD) for long range propagation. We have incorporated two improvements into the GSD model to tackle the <span class="hlt">shock</span>-vortex interaction problem. The wave structure of the disturbance resembles N waves, the decay of which follows a power law profile. An extension of the GSD model to predict <span class="hlt">shock</span> surface propagation in 3-D flows is presented along with the numerical implementation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://medlineplus.gov/ency/article/000167.htm','NIH-MEDLINEPLUS'); return false;" href="https://medlineplus.gov/ency/article/000167.htm"><span id="translatedtitle">Hypovolemic <span class="hlt">shock</span></span></a></p> <p><a target="_blank" href="http://medlineplus.gov/">MedlinePlus</a></p> <p></p> <p></p> <p>... clammy skin Confusion Decreased or no urine output General weakness Pale skin color (pallor) Rapid breathing Sweating , moist skin Unconsciousness The greater and more rapid the blood loss, the more severe the symptoms of <span class="hlt">shock</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/220739','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/220739"><span id="translatedtitle">Optical measurements of the mutual reflection of two-plane <span class="hlt">shock</span> waves</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Barbosa, F.J.; Skews, B.W.</p> <p>1995-12-31</p> <p>A bifurcated <span class="hlt">shock</span> tube is used to create two synchronized waves of equal strength. Essentially a single <span class="hlt">shock</span> wave is split symmetrically in two, the two waves then are later brought back together at a trailing edge of a wedge to interact, the plane of symmetry acting as an ideal rigid wall. The normal method of studying mach reflections is to allow a plane <span class="hlt">shock</span> wave to impinge on a wedge, however the boundary <span class="hlt">layer</span> growth on the wedge surface effectively ensures that the flow direction behind the Mach stem does not have to satisfy the boundary condition of being <span class="hlt">parallel</span> to the surface of the wedge. Thus the transition from regular to Mach reflection occurs at higher angles of incidence than theory allows. The present experiment was initiated to generate data on the ideal cause of reflection off a plane wall. The advantage of the new system is that like classical theory and computational solutions of the inviscid Euler equations, the boundary <span class="hlt">layer</span> no slip condition is not imposed at the plane of reflection. Optical methods are used to investigate the post-<span class="hlt">shock</span> flow, as well as to help explain the complex interactions which occur when the two <span class="hlt">shock</span> waves are not synchronized. These interactions show many very interesting features and clearly indicate the need for higher resolution measurements such as are obtained using holographic interferometry, and also to extend the work to different wedge angles and Mach numbers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4910073','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4910073"><span id="translatedtitle">Dendrite Suppression by <span class="hlt">Shock</span> Electrodeposition in Charged Porous Media</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Han, Ji-Hyung; Wang, Miao; Bai, Peng; Brushett, Fikile R.; Bazant, Martin Z.</p> <p>2016-01-01</p> <p>It is shown that surface conduction can stabilize electrodeposition in random, charged porous media at high rates, above the diffusion-limited current. After linear sweep voltammetry and impedance spectroscopy, copper electrodeposits are visualized by scanning electron microscopy and energy dispersive spectroscopy in two different porous separators (cellulose nitrate, polyethylene), whose surfaces are modified by <span class="hlt">layer-by-layer</span> deposition of positive or negative charged polyelectrolytes. Above the limiting current, surface conduction inhibits growth in the positive separators and produces irregular dendrites, while it enhances growth and suppresses dendrites behind a deionization <span class="hlt">shock</span> in the negative separators, also leading to improved cycle life. The discovery of stable uniform growth in the random media differs from the non-uniform growth observed in <span class="hlt">parallel</span> nanopores and cannot be explained by classic quasi-steady “leaky membrane” models, which always predict instability and dendritic growth. Instead, the experimental results suggest that transient electro-diffusion in random porous media imparts the stability of a deionization <span class="hlt">shock</span> to the growing metal interface behind it. <span class="hlt">Shock</span> electrodeposition could be exploited to enhance the cycle life and recharging rate of metal batteries or to accelerate the fabrication of metal matrix composite coatings. PMID:27307136</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016NatSR...628054H&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016NatSR...628054H&link_type=ABSTRACT"><span id="translatedtitle">Dendrite Suppression by <span class="hlt">Shock</span> Electrodeposition in Charged Porous Media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Han, Ji-Hyung; Wang, Miao; Bai, Peng; Brushett, Fikile R.; Bazant, Martin Z.</p> <p>2016-06-01</p> <p>It is shown that surface conduction can stabilize electrodeposition in random, charged porous media at high rates, above the diffusion-limited current. After linear sweep voltammetry and impedance spectroscopy, copper electrodeposits are visualized by scanning electron microscopy and energy dispersive spectroscopy in two different porous separators (cellulose nitrate, polyethylene), whose surfaces are modified by <span class="hlt">layer-by-layer</span> deposition of positive or negative charged polyelectrolytes. Above the limiting current, surface conduction inhibits growth in the positive separators and produces irregular dendrites, while it enhances growth and suppresses dendrites behind a deionization <span class="hlt">shock</span> in the negative separators, also leading to improved cycle life. The discovery of stable uniform growth in the random media differs from the non-uniform growth observed in <span class="hlt">parallel</span> nanopores and cannot be explained by classic quasi-steady “leaky membrane” models, which always predict instability and dendritic growth. Instead, the experimental results suggest that transient electro-diffusion in random porous media imparts the stability of a deionization <span class="hlt">shock</span> to the growing metal interface behind it. <span class="hlt">Shock</span> electrodeposition could be exploited to enhance the cycle life and recharging rate of metal batteries or to accelerate the fabrication of metal matrix composite coatings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27307136','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27307136"><span id="translatedtitle">Dendrite Suppression by <span class="hlt">Shock</span> Electrodeposition in Charged Porous Media.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Han, Ji-Hyung; Wang, Miao; Bai, Peng; Brushett, Fikile R; Bazant, Martin Z</p> <p>2016-01-01</p> <p>It is shown that surface conduction can stabilize electrodeposition in random, charged porous media at high rates, above the diffusion-limited current. After linear sweep voltammetry and impedance spectroscopy, copper electrodeposits are visualized by scanning electron microscopy and energy dispersive spectroscopy in two different porous separators (cellulose nitrate, polyethylene), whose surfaces are modified by <span class="hlt">layer-by-layer</span> deposition of positive or negative charged polyelectrolytes. Above the limiting current, surface conduction inhibits growth in the positive separators and produces irregular dendrites, while it enhances growth and suppresses dendrites behind a deionization <span class="hlt">shock</span> in the negative separators, also leading to improved cycle life. The discovery of stable uniform growth in the random media differs from the non-uniform growth observed in <span class="hlt">parallel</span> nanopores and cannot be explained by classic quasi-steady "leaky membrane" models, which always predict instability and dendritic growth. Instead, the experimental results suggest that transient electro-diffusion in random porous media imparts the stability of a deionization <span class="hlt">shock</span> to the growing metal interface behind it. <span class="hlt">Shock</span> electrodeposition could be exploited to enhance the cycle life and recharging rate of metal batteries or to accelerate the fabrication of metal matrix composite coatings. PMID:27307136</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22011755','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22011755"><span id="translatedtitle">A FOCUSED TRANSPORT APPROACH TO THE TIME-DEPENDENT <span class="hlt">SHOCK</span> ACCELERATION OF SOLAR ENERGETIC PARTICLES AT A FAST TRAVELING <span class="hlt">SHOCK</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Le Roux, J. A.; Webb, G. M.</p> <p>2012-02-10</p> <p>Some of the most sophisticated models for solar energetic particle (SEP) acceleration at coronal mass ejection driven <span class="hlt">shocks</span> are based on standard diffusive <span class="hlt">shock</span> acceleration theory. However, this theory, which only applies when SEP pitch-angle anisotropies are small, might have difficulty in describing first-order Fermi acceleration or the <span class="hlt">shock</span> pre-heating and injection of SEPs into first-order Fermi acceleration accurately at lower SEP speeds where SEP pitch-angle anisotropies upstream near the <span class="hlt">shock</span> can be large. To avoid this problem, we use a time-dependent focused transport model to reinvestigate first-order Fermi acceleration at planar <span class="hlt">parallel</span> and quasi-<span class="hlt">parallel</span> spherical traveling <span class="hlt">shocks</span> between the Sun and Earth with high <span class="hlt">shock</span> speeds associated with rare extreme gradual SEP events. The focused transport model is also used to investigate and compare three different <span class="hlt">shock</span> pre-heating mechanisms associated with different aspects of the nonuniform cross-<span class="hlt">shock</span> solar wind flow, namely, the convergence of the flow (adiabatic compression), the shear tensor of the flow, and the acceleration of the flow, and a fourth <span class="hlt">shock</span> pre-heating mechanism associated with the cross-<span class="hlt">shock</span> electric field, to determine which pre-heating mechanism contributes the most to injecting <span class="hlt">shock</span> pre-heated source particles into the first-order Fermi acceleration process. The effects of variations in traveling <span class="hlt">shock</span> conditions, such as increasing <span class="hlt">shock</span> obliquity and <span class="hlt">shock</span> slowdown, and variations in the SEP source with increasing <span class="hlt">shock</span> distance from the Sun on the coupled processes of <span class="hlt">shock</span> pre-heating, injection, and first-order Fermi acceleration are analyzed. Besides the finding that the cross-<span class="hlt">shock</span> acceleration of the solar wind flow yields the dominant <span class="hlt">shock</span> pre-heating mechanism at high <span class="hlt">shock</span> speeds, we find that first-order Fermi acceleration at fast traveling <span class="hlt">shocks</span> differs in a number of respects from the predictions and assumptions of standard steady-state diffusive <span class="hlt">shock</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JGRA..117.1220H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JGRA..117.1220H"><span id="translatedtitle">The relation between ion temperature anisotropy and formation of slow <span class="hlt">shocks</span> in collisionless magnetic reconnection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Higashimori, K.; Hoshino, M.</p> <p>2012-01-01</p> <p>We perform a two-dimensional simulation by using an electromagnetic hybrid code to study the formation of slow-mode <span class="hlt">shocks</span> in collisionless magnetic reconnection in low beta plasmas, and we focus on the relation between the formation of slow <span class="hlt">shocks</span> and the ion temperature anisotropy enhanced at the <span class="hlt">shock</span> downstream region. It is known that as magnetic reconnection develops, the <span class="hlt">parallel</span> temperature along the magnetic field becomes large in association with the anisotropic plasma sheet boundary <span class="hlt">layer</span> ion beams, and this temperature anisotropy has a tendency to suppress the formation of slow <span class="hlt">shocks</span>. On the basis of our simulation result, we found that the slow <span class="hlt">shock</span> formation is suppressed due to the large temperature anisotropy near the X-type region, but the ion temperature anisotropy relaxes with increasing the distance from the magnetic neutral point. As a result, two pairs of current structures, which are the strong evidence of dissipation of magnetic field in slow <span class="hlt">shocks</span>, are formed at the distance ∣x∣ ≥ 115 λi from the neutral point.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5601344','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5601344"><span id="translatedtitle"><span class="hlt">Shock</span> temperature measurements in ammonia</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Radousky, H.B.; Mitchell, A.C.; Nellis, W.J.; Ross, M.</p> <p>1985-07-01</p> <p>Our first <span class="hlt">shock</span> temperature measurements on a cryogenic target are reported for NH/sub 3/. A new fast optical pyrometer and a cryogenic specimen holder for liquid NH/sub 3/ were developed to measure <span class="hlt">shock</span> temperatures of 4400 and 3600 K at pressures of 61 and 48 GPa. These conditions correspond to those in the ice <span class="hlt">layers</span> in Uranus and Neptune. The <span class="hlt">shock</span> temperature data are in reasonable agreement with an equation of state based on an intermolecular potential derived from NH/sub 3/ Hugoniot data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/125628','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/125628"><span id="translatedtitle">Massively <span class="hlt">parallel</span> visualization: <span class="hlt">Parallel</span> rendering</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hansen, C.D.; Krogh, M.; White, W.</p> <p>1995-12-01</p> <p>This paper presents rendering algorithms, developed for massively <span class="hlt">parallel</span> processors (MPPs), for polygonal, spheres, and volumetric data. The polygon algorithm uses a data <span class="hlt">parallel</span> approach whereas the sphere and volume renderer use a MIMD approach. Implementations for these algorithms are presented for the Thinking Machines Corporation CM-5 MPP.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003APS..MAR.R1284P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003APS..MAR.R1284P"><span id="translatedtitle">Multi-<span class="hlt">layer</span> <span class="hlt">Parallel</span> Beta-Sheet Structure of Amyloid Beta peptide (1-40) aggregate observed by discrete molecular dynamics simulations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Peng, Shouyong; Urbanc, Brigita; Ding, Feng; Cruz, Luis; Buldyrev, Sergey; Dokholyan, Nikolay; Stanley, H. E.</p> <p>2003-03-01</p> <p>New evidence shows that oligomeric forms of Amyloid-Beta are potent neurotoxins that play a major role in neurodegeneration of Alzheimer's disease. Detailed knowledge of the structure and assembly dynamics of Amyloid-Beta is important for the development of new therapeutic strategies. Here we apply a two-atom model with Go interactions to model aggregation of Amyloid-Beta (1-40) peptides using the discrete molecular dynamics simulation. At temperatures above the transition temperature from an alpha-helical to random coil, we obtain two types of <span class="hlt">parallel</span> beta-sheet structures, (a) a helical beta-sheet structure at a lower temperature and (b) a <span class="hlt">parallel</span> beta-sheet structure at a higher temperature, both with inter-sheet distance of 10 A and with free edges which possibly enable further fibrillar elongation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/21406807','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/21406807"><span id="translatedtitle">Vortex phase diagram of the <span class="hlt">layered</span> superconductor Cu0.03TaS2 for H is <span class="hlt">parallel</span> to c.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhu, X D; Lu, J C; Sun, Y P; Pi, L; Qu, Z; Ling, L S; Yang, Z R; Zhang, Y H</p> <p>2010-12-22</p> <p>The magnetization and anisotropic electrical transport properties have been measured in high quality Cu(0.03)TaS(2) single crystals. A pronounced peak effect has been observed, indicating that high quality and homogeneity are vital to the peak effect. A kink has been observed in the magnetic field, H, dependence of the in-plane resistivity ρ(ab) for H is <span class="hlt">parallel</span> to c, which corresponds to a transition from activated to diffusive behavior of the vortex liquid phase. In the diffusive regime of the vortex liquid phase, the in-plane resistivity ρ(ab) is proportional to H(0.3), which does not follow the Bardeen-Stephen law for free flux flow. Finally, a simplified vortex phase diagram of Cu(0.03)TaS(2) for H is <span class="hlt">parallel</span> to c is given. PMID:21406807</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760003990','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760003990"><span id="translatedtitle">High Reynolds number tests of a C-141A aircraft semispan model to investigate <span class="hlt">shock</span>-induced separation. [boundary <span class="hlt">layer</span> separation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Blackerby, W. T.; Cahill, J. F.</p> <p>1975-01-01</p> <p>Results from a high Reynolds number transonic wind tunnel investigation are presented. Wing chordwise pressure distributions were measured over a matrix of Mach numbers and angles-of-attack for which <span class="hlt">shock</span>-induced separations are known to exist. The range of Reynolds number covered by these data nearly spanned the gap between previously available wind tunnel and flight test data. The results are compared with both flight and low Reynolds number data, and show that use of the semispan test technique produced good correlation with the prior data at both ends of the Reynolds number range, but indicated strong sensitivity to details of the test setup.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5604072','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5604072"><span id="translatedtitle">Magnetic field overshoots in the Venus blow <span class="hlt">shock</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tatrallyay, M.; Luhmann, J.G.; Russell, C.T.</p> <p>1984-01-01</p> <p>An examination of Pioneer Venus Orbiter fluxgate magnetometer data has shown that magnetic field overshoots occur not only behind quasi-perpendicular bow <span class="hlt">shocks</span> but also behind quasi-<span class="hlt">parallel</span> <span class="hlt">shocks</span>. Overshoots are assocciated only with supercritical <span class="hlt">shocks</span>. Their amplitudes increase with increasing fast Mach number. Solar wind beta has a lesser effect. The thickness of the overshoot increases with decreasing Theta-BN. The thickness of apparent overshoots detected behind 4 strong fast interplanetary <span class="hlt">shocks</span> (M greater than M/crit) is about 3 orders of magnitude larger. Multiple crossings of the Venus bow <span class="hlt">shock</span> were observed mainly at turbulent <span class="hlt">shocks</span>. Their occurence is not influenced by Theta-BN. 15 references.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6417170','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6417170"><span id="translatedtitle"><span class="hlt">Parallel</span> machines: <span class="hlt">Parallel</span> machine languages</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Iannucci, R.A. )</p> <p>1990-01-01</p> <p>This book presents a framework for understanding the tradeoffs between the conventional view and the dataflow view with the objective of discovering the critical hardware structures which must be present in any scalable, general-purpose <span class="hlt">parallel</span> computer to effectively tolerate latency and synchronization costs. The author presents an approach to scalable general purpose <span class="hlt">parallel</span> computation. Linguistic Concerns, Compiling Issues, Intermediate Language Issues, and hardware/technological constraints are presented as a combined approach to architectural Develoement. This book presents the notion of a <span class="hlt">parallel</span> machine language.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25994928','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25994928"><span id="translatedtitle">[Obstructive <span class="hlt">shock</span>].</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pich, H; Heller, A R</p> <p>2015-05-01</p> <p>An acute obstruction of blood flow in central vessels of the systemic or pulmonary circulation causes the clinical symptoms of <span class="hlt">shock</span> accompanied by disturbances of consciousness, centralization, oliguria, hypotension and tachycardia. In the case of an acute pulmonary embolism an intravascular occlusion results in an acute increase of the right ventricular afterload. In the case of a tension pneumothorax, an obstruction of the blood vessels supplying the heart is caused by an increase in extravascular pressure. From a hemodynamic viewpoint circulatory <span class="hlt">shock</span> caused by obstruction is closely followed by cardiac deterioration; however, etiological and therapeutic options necessitate demarcation of cardiac from non-cardiac obstructive causes. The high dynamics of this potentially life-threatening condition is a hallmark of all types of obstructive <span class="hlt">shock</span>. This requires an expeditious and purposeful diagnosis and a rapid and well-aimed therapy. PMID:25994928</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25199226','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25199226"><span id="translatedtitle">[Neurogenic <span class="hlt">shock</span>].</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Meister, Rafael; Pasquier, Mathieu; Clerc, David; Carron, Pierre-Nicolas</p> <p>2014-08-13</p> <p>The neurogenic <span class="hlt">shock</span> is a common complication of spinal cord injury, especially when localized at the cervical level. Characterized by a vasoplegia (hypotension) and bradycardia, the neurogenic <span class="hlt">shock</span> is secondary to the damage of the sympathetic nervous system. The clinical presentation often includes tetraplegia, with or without respiratory failure. Early treatment aims to minimize the occurrence of secondary spinal cord lesions resulting from systemic ischemic injuries. Medical management consists in a standardized ABCDE approach, in order to stabilize vital functions and immobilize the spine. The hospital care includes performing imaging, further measures of neuro-resuscitation, and coordinated surgical assessment and treatment of any other injury. PMID:25199226</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013IJAME..18..699R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013IJAME..18..699R"><span id="translatedtitle">Unsteady Two-<span class="hlt">Layered</span> Fluid Flow and Heat Transfer of Conducting Fluids in a Channel Between <span class="hlt">Parallel</span> Porous Plates Under Transverse Magnetic Field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Raju, T. Linga; Nagavalli, M.</p> <p>2013-08-01</p> <p>The unsteady magnetohydrodynamic flow of two immiscible fluids in a horizontal channel bounded by two <span class="hlt">parallel</span> porous isothermal plates in the presence of an applied magnetic and electric field is investigated. The flow is driven by a constant uniform pressure gradient in the channel bounded by two <span class="hlt">parallel</span> insulating plates, one being stationary and the other oscillating, when both fluids are considered as electrically conducting. Also, both fluids are assumed to be incompressible with variable properties, viz. different viscosities, thermal and electrical conductivities. The transport properties of the two fluids are taken to be constant and the bounding plates are maintained at constant and equal temperatures. The governing equations are partial in nature, which are then reduced to the ordinary linear differential equations using two-term series. Closed form solutions for velocity and temperature distributions are obtained in both fluid regions of the channel. Profiles of these solutions are plotted to discuss the effect on the flow and heat transfer characteristics, and their dependence on the governing parameters involved, such as the Hartmann number, porous parameter, ratios of the viscosities, heights, electrical and thermal conductivities</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012ShWav..22..225C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012ShWav..22..225C"><span id="translatedtitle">Characteristics of unsteady type IV <span class="hlt">shock/shock</span> interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chu, Y.-B.; Lu, X.-Y.</p> <p>2012-05-01</p> <p>Characteristics of the unsteady type IV <span class="hlt">shock/shock</span> interaction of hypersonic blunt body flows are investigated by solving the Navier-Stokes equations with high-order numerical methods. The intrinsic relations of flow structures to shear, compression, and heating processes are studied and the physical mechanisms of the unsteady flow evolution are revealed. It is found that the instantaneous surface-heating peak is caused by the fluid in the "hot spot" generated by an oscillating and deforming jet bow <span class="hlt">shock</span> (JBS) just ahead of the body surface. The features of local <span class="hlt">shock</span>/boundary <span class="hlt">layer</span> interaction and vortex/boundary <span class="hlt">layer</span> interaction are clarified. Based on the analysis of flow evolution, it is identified that the upstream-propagating compression waves are associated with the interaction of the JBS and the shear <span class="hlt">layers</span> formed by a supersonic impinging jet, and then the interaction of the freestream bow <span class="hlt">shocks</span> and the compression waves results in entropy and vortical waves propagating to the body surface. Further, the feedback mechanism of the inherent unsteadiness of the flow field is revealed to be related to the impinging jet. A feedback model is proposed to reliably predict the dominant frequency of flow evolution. The results obtained in this study provide physical insight into the understanding of the mechanisms relevant to this complex flow.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013DSRI...82...10L&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013DSRI...82...10L&link_type=ABSTRACT"><span id="translatedtitle">Oxidative stress in deep scattering <span class="hlt">layers</span>: Heat <span class="hlt">shock</span> response and antioxidant enzymes activities of myctophid fishes thriving in oxygen minimum zones</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lopes, Ana Rita; Trübenbach, Katja; Teixeira, Tatiana; Lopes, Vanessa M.; Pires, Vanessa; Baptista, Miguel; Repolho, Tiago; Calado, Ricardo; Diniz, Mário; Rosa, Rui</p> <p>2013-12-01</p> <p>Diel vertical migrators, such as myctophid fishes, are known to encounter oxygen minimum zones (OMZ) during daytime in the Eastern Pacific Ocean and, therefore, have to cope with temperature and oxidative stress that arise while ascending to warmer, normoxic surface waters at night-time. The aim of this study was to investigate the antioxidant defense strategies and heat <span class="hlt">shock</span> response (HSR) in two myctophid species, namely Triphoturus mexicanus and Benthosema panamense, at shallow and warm surface waters (21 kPa, 20-25 °C) and at hypoxic, cold (≤1 kPa, 10 °C) mesopelagic depths. More specifically, we quantified (i) heat <span class="hlt">shock</span> protein concentrations (HSP70/HSC70) (ii) antioxidant enzyme activities [including superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST)], and (iii) lipid peroxidation [malondialdehyde (MDA) levels]. HSP70/HSC70 levels increased in both myctophid species at warmer, well-oxygenated surface waters probably to prevent cellular damage (oxidative stress) due to increased oxygen demand under elevated temperatures and reactive oxygen species (ROS) formation. On the other hand, CAT and GST activities were augmented under hypoxic conditions, probably as preparatory response to a burst of oxyradicals during the reoxygenation phase (while ascending). SOD activity decreased under hypoxia in B. panamense, but was kept unchanged in T. mexicanus. MDA levels in B. panamense did not change between the surface and deep-sea conditions, whereas T. mexicanus showed elevated MDA and HSP70/HSC70 concentrations at warmer surface waters. This indicated that T. mexicanus seems to be not so well tuned to temperature and oxidative stress associated to diel vertical migrations. The understanding of such physiological strategies that are linked to oxygen deprivation and reoxygenation phases may provide valuable information about how different species might respond to the impacts of environmental stressors (e.g. expanding mesopelagic hypoxia</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/118726','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/118726"><span id="translatedtitle"><span class="hlt">Parallel</span> pipelining</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Joseph, D.D.; Bai, R.; Liao, T.Y.; Huang, A.; Hu, H.H.</p> <p>1995-09-01</p> <p>In this paper the authors introduce the idea of <span class="hlt">parallel</span> pipelining for water lubricated transportation of oil (or other viscous material). A <span class="hlt">parallel</span> system can have major advantages over a single pipe with respect to the cost of maintenance and continuous operation of the system, to the pressure gradients required to restart a stopped system and to the reduction and even elimination of the fouling of pipe walls in continuous operation. The authors show that the action of capillarity in small pipes is more favorable for restart than in large pipes. In a <span class="hlt">parallel</span> pipeline system, they estimate the number of small pipes needed to deliver the same oil flux as in one larger pipe as N = (R/r){sup {alpha}}, where r and R are the radii of the small and large pipes, respectively, and {alpha} = 4 or 19/7 when the lubricating water flow is laminar or turbulent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6640647','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6640647"><span id="translatedtitle">Data <span class="hlt">parallelism</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gorda, B.C.</p> <p>1992-09-01</p> <p>Data locality is fundamental to performance on distributed memory <span class="hlt">parallel</span> architectures. Application programmers know this well and go to great pains to arrange data for optimal performance. Data <span class="hlt">Parallelism</span>, a model from the Single Instruction Multiple Data (SIMD) architecture, is finding a new home on the Multiple Instruction Multiple Data (MIMD) architectures. This style of programming, distinguished by taking the computation to the data, is what programmers have been doing by hand for a long time. Recent work in this area holds the promise of making the programmer's task easier.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/10141735','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/10141735"><span id="translatedtitle">Data <span class="hlt">parallelism</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gorda, B.C.</p> <p>1992-09-01</p> <p>Data locality is fundamental to performance on distributed memory <span class="hlt">parallel</span> architectures. Application programmers know this well and go to great pains to arrange data for optimal performance. Data <span class="hlt">Parallelism</span>, a model from the Single Instruction Multiple Data (SIMD) architecture, is finding a new home on the Multiple Instruction Multiple Data (MIMD) architectures. This style of programming, distinguished by taking the computation to the data, is what programmers have been doing by hand for a long time. Recent work in this area holds the promise of making the programmer`s task easier.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19900026019&hterms=doubling&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Ddoubling','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19900026019&hterms=doubling&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Ddoubling"><span id="translatedtitle">Resonance line transfer calculations by doubling thin <span class="hlt">layers</span>. I - Comparison with other techniques. II - The use of the R-<span class="hlt">parallel</span> redistribution function. [planetary atmospheres</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Yelle, Roger V.; Wallace, Lloyd</p> <p>1989-01-01</p> <p>A versatile and efficient technique for the solution of the resonance line scattering problem with frequency redistribution in planetary atmospheres is introduced. Similar to the doubling approach commonly used in monochromatic scattering problems, the technique has been extended to include the frequency dependence of the radiation field. Methods for solving problems with external or internal sources and coupled spectral lines are presented, along with comparison of some sample calculations with results from Monte Carlo and Feautrier techniques. The doubling technique has also been applied to the solution of resonance line scattering problems where the R-<span class="hlt">parallel</span> redistribution function is appropriate, both neglecting and including polarization as developed by Yelle and Wallace (1989). With the constraint that the atmosphere is illuminated from the zenith, the only difficulty of consequence is that of performing precise frequency integrations over the line profiles. With that problem solved, it is no longer necessary to use the Monte Carlo method to solve this class of problem.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920075515&hterms=high+jump&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dhigh%2Bjump','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920075515&hterms=high+jump&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dhigh%2Bjump"><span id="translatedtitle">Electron heating in a Monte Carlo model of a high Mach number, supercritical, collisionless <span class="hlt">shock</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ellison, Donald C.; Jones, Frank C.</p> <p>1987-01-01</p> <p>Preliminary work in the investigation of electron injection and acceleration at <span class="hlt">parallel</span> <span class="hlt">shocks</span> is presented. A simple model of electron heating that is derived from a unified <span class="hlt">shock</span> model which includes the effects of an electrostatic potential jump is described. The unified <span class="hlt">shock</span> model provides a kinetic description of the injection and acceleration of ions and a fluid description of electron heating at high Mach number, supercritical, and <span class="hlt">parallel</span> <span class="hlt">shocks</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMSH24A..05G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMSH24A..05G"><span id="translatedtitle">The Diffusive <span class="hlt">Shock</span> Acceleration Myth</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gloeckler, G.; Fisk, L. A.</p> <p>2012-12-01</p> <p>It is generally accepted that diffusive <span class="hlt">shock</span> acceleration (DSA) is the dominant mechanism for particle acceleration at <span class="hlt">shocks</span>. This is despite the overwhelming observational evidence that is contrary to predictions of DSA models. For example, our most recent survey of hourly-averaged, spin-averaged proton distribution functions around 61 locally observed <span class="hlt">shocks</span> in 2001 at 1 AU found that in 21 cases no particles were accelerated. Spectral indices (γ ) of suprathermal tails on the velocity distributions around the 40 <span class="hlt">shocks</span> that did accelerate particles, showed none of the DSA-predicted correlations of γ with the <span class="hlt">shock</span> compression ratio and the <span class="hlt">shock</span> normal to magnetic field angle. Here we will present ACE/SWICS observations of three sets of 72 consecutive one-hour averaged velocity distributions (in each of 8 SWICS spin sectors). Each set includes passage of one or more <span class="hlt">shocks</span> or strong compression regions. All spectra were properly transformed to the solar wind frame using the detailed, updated SWICS forward model, taking into account the hourly-averaged directions of the solar wind flow, the magnetic field and the ACE spin axis (http://www.srl.caltech.edu/ACE/ASC/). The suprathermal tails are observed to be a combination of locally accelerated and remote tails. The local tails are power laws. The remote tails are also power laws with rollovers at higher energies. When local tails are weak (as is the case especially upstream of strong <span class="hlt">shocks</span> or compression regions) the remote tails also have a rollover at low energies due to modulation (transport effects). Among our main findings are that (1) the spectral indices of both the local and remote tails are -5 within the uncertainties of the measurements, as predicted by our pump acceleration mechanism, and (2) the velocity distributions are anisotropic with the perpendicular (to the magnetic field) pressure greater than the <span class="hlt">parallel</span> pressure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080039626','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080039626"><span id="translatedtitle">Turbulence Evolution and <span class="hlt">Shock</span> Acceleration of Solar Energetic Particles</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chee, Ng K.</p> <p>2007-01-01</p> <p>We model the effects of self-excitation/damping and <span class="hlt">shock</span> transmission of Alfven waves on solar-energetic-particle (SEP) acceleration at a coronal-mass-ejection (CME) driven <span class="hlt">parallel</span> <span class="hlt">shock</span>. SEP-excited outward upstream waves speedily bootstrap acceleration. <span class="hlt">Shock</span> transmission further raises the SEP-excited wave intensities at high wavenumbers but lowers them at low wavenumbers through wavenumber shift. Downstream, SEP excitation of inward waves and damping of outward waves tend to slow acceleration. Nevertheless, > 2000 km/s <span class="hlt">parallel</span> <span class="hlt">shocks</span> at approx. 3.5 solar radii can accelerate SEPs to 100 MeV in < 5 minutes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011APS..DFDG26002M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011APS..DFDG26002M"><span id="translatedtitle">Deionization <span class="hlt">shocks</span> in cross flows</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mani, Ali</p> <p>2011-11-01</p> <p>Recent experimental and theoretical studies have shown that surface conduction in supported electrolytes, such as in micro/nanochannels or porous media, can lead to nonlinear modes of transport and formation of sharp concentration fronts analogous to <span class="hlt">shock</span> waves in gas dynamics. Propagation of these <span class="hlt">shocks</span> leaves behind a region of ultra pure fluid, acting to deionize the bulk solution. In this work we present the analysis of salt transport in a porous medium next to a membrane with an electric field applied normal to the interface and cross flow in tangential direction. We show that two distinct boundary <span class="hlt">layers</span> grow near the membrane: an inner (<span class="hlt">shocked</span>) region with almost deionized solution dominated by surface conduction, and an outer <span class="hlt">layer</span> with diffuse dynamics. Under certain conditions both regions collapse into a similarity solution with the same scaling. We will discuss advantages of such systems for desalination and water purification. Research performed in collaboration with Martin Bazant (MIT).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016OEng....6....4K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016OEng....6....4K&link_type=ABSTRACT"><span id="translatedtitle">Investigation of combined heat and mass transfer between vertical <span class="hlt">parallel</span> plates in a two-<span class="hlt">layer</span> flow of couple stress nanofluid</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khan, Najeeb Alam; Sultan, Faqiha; Riaz, Fatima; Jamil, Muhammad</p> <p>2016-02-01</p> <p>This study is an investigation of fully-developed laminar flow in a two-<span class="hlt">layer</span> vertical channel; one part filled with couple stress nanofluid and the other part with clear couple stress fluid. The flow is examined for combined heat and mass transfer using uniform wall temperature and concentration boundary conditions. Optimal homotopy analysis method (OHAM) is used to solve the nonlinear coupled ordinary differential equations (ODEs) governing the flow in each region. This method is based on the homotopy analysis method (HAM)which is an effective method to analytically approximate the solution of highly nonlinear problems. The influence of pertinent parameters is observed on velocity, temperature, and concentration distributions, specifically, the effect of Brownian parameter on couple stress fluid is mentioned.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013HEDP....9..315K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013HEDP....9..315K"><span id="translatedtitle">Early-time evolution of a radiative <span class="hlt">shock</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kuranz, C. C.; Drake, R. P.; Huntington, C. M.; Krauland, C. M.; Di Stefano, C. A.; Trantham, M.; Grosskopf, M. J.; Klein, S. R.; Marion, D. C.</p> <p>2013-06-01</p> <p>We have performed high-energy-density physics experiments with large radiative fluxes, relevant to radiative <span class="hlt">shocks</span> in our universe. These experiments were performed at the Omega Laser facility and used a laser irradiance of 7.2 × 1014 W cm-2 to launch a Be disk into low-density Xe gas. The radiative <span class="hlt">shocks</span> were observed early in time as the dense <span class="hlt">shocked</span> Xe <span class="hlt">layer</span> began to form. The average <span class="hlt">shock</span> position indicates that the <span class="hlt">shock</span> is moving over 130 km s-1. Data are compared to simulation output from the CRASH code, which was developed at the Center for Radiative <span class="hlt">Shock</span> Hydrodynamics at the University of Michigan.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AIPC..781...27O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AIPC..781...27O"><span id="translatedtitle">Global Hybrid Simulations of the Bow <span class="hlt">Shock</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Omidi, N.; Blanco-Cano, X.; Russell, C. T.</p> <p>2005-08-01</p> <p>This paper summarizes recent results from global hybrid (kinetic ions, fluid electrons) simulations of bow <span class="hlt">shocks</span> or waves associated with solar wind interaction with magnetic dipoles of various strength. By virtue of resolving ion temporal and spatial scales, global hybrid simulations account for collissionless dissipational processes at and upstream of the <span class="hlt">shock</span> and their effects on the macrostructure of the bow <span class="hlt">shock</span>, ion foreshock and the magnetosheath. The results demonstrate that as the level of magnetization increases and the dipole becomes a more effective obstacle, the quasi-perpendicular part of the bow <span class="hlt">shock</span> forms first and that formation of quasi-<span class="hlt">parallel</span> part of the bow <span class="hlt">shock</span> is tied to the generation of oblique magnetosonic waves which steepen to form shocklets in the upstream region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120002025','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120002025"><span id="translatedtitle">Entropy Generation Across Earth's Bow <span class="hlt">Shock</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Parks, George K.; McCarthy, Michael; Fu, Suiyan; Lee E. s; Cao, Jinbin; Goldstein, Melvyn L.; Canu, Patrick; Dandouras, Iannis S.; Reme, Henri; Fazakerley, Andrew; Lin, Naiguo; Wilber, Mark</p> <p>2011-01-01</p> <p>Earth's bow <span class="hlt">shock</span> is a transition <span class="hlt">layer</span> that causes an irreversible change in the state of plasma that is stationary in time. Theories predict entropy increases across the bow <span class="hlt">shock</span> but entropy has never been directly measured. Cluster and Double Star plasma experiments measure 3D plasma distributions upstream and downstream of the bow <span class="hlt">shock</span> that allow calculation of Boltzmann's entropy function H and his famous H-theorem, dH/dt O. We present the first direct measurements of entropy density changes across Earth's bow <span class="hlt">shock</span>. We will show that this entropy generation may be part of the processes that produce the non-thermal plasma distributions is consistent with a kinetic entropy flux model derived from the collisionless Boltzmann equation, giving strong support that solar wind's total entropy across the bow <span class="hlt">shock</span> remains unchanged. As far as we know, our results are not explained by any existing <span class="hlt">shock</span> models and should be of interests to theorists.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910059016&hterms=Theory+knowledge&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DTheory%2Bof%2Bknowledge','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910059016&hterms=Theory+knowledge&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DTheory%2Bof%2Bknowledge"><span id="translatedtitle"><span class="hlt">Shock</span> loading predictions from application of indicial theory to <span class="hlt">shock</span>-turbulence interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Keefe, Laurence R.; Nixon, David</p> <p>1991-01-01</p> <p>A sequence of steps that permits prediction of some of the characteristics of the pressure field beneath a fluctuating <span class="hlt">shock</span> wave from knowledge of the oncoming turbulent boundary <span class="hlt">layer</span> is presented. The theory first predicts the power spectrum and pdf of the position and velocity of the <span class="hlt">shock</span> wave, which are then used to obtain the <span class="hlt">shock</span> frequency distribution, and the pdf of the pressure field, as a function of position within the interaction region. To test the validity of the crucial assumption of linearity, the indicial response of a normal <span class="hlt">shock</span> is calculated from numerical simulation. This indicial response, after being fit by a simple relaxation model, is used to predict the <span class="hlt">shock</span> position and velocity spectra, along with the <span class="hlt">shock</span> passage frequency distribution. The low frequency portion of the <span class="hlt">shock</span> spectra, where most of the energy is concentrated, is satisfactorily predicted by this method.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22303418','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22303418"><span id="translatedtitle">Observation of hole injection boost via two <span class="hlt">parallel</span> paths in Pentacene thin-film transistors by employing Pentacene: 4, 4″-tris(3-methylphenylphenylamino) triphenylamine: MoO{sub 3} buffer <span class="hlt">layer</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Yan, Pingrui; Liu, Ziyang; Liu, Dongyang; Wang, Xuehui; Yue, Shouzhen; Zhao, Yi; Zhang, Shiming</p> <p>2014-11-01</p> <p>Pentacene organic thin-film transistors (OTFTs) were prepared by introducing 4, 4″-tris(3-methylphenylphenylamino) triphenylamine (m-MTDATA): MoO{sub 3}, Pentacene: MoO{sub 3}, and Pentacene: m-MTDATA: MoO{sub 3} as buffer <span class="hlt">layers</span>. These OTFTs all showed significant performance improvement comparing to the reference device. Significantly, we observe that the device employing Pentacene: m-MTDATA: MoO{sub 3} buffer <span class="hlt">layer</span> can both take advantage of charge transfer complexes formed in the m-MTDATA: MoO{sub 3} device and suitable energy level alignment existed in the Pentacene: MoO{sub 3} device. These two <span class="hlt">parallel</span> paths led to a high mobility, low threshold voltage, and contact resistance of 0.72 cm{sup 2}/V s, −13.4 V, and 0.83 kΩ at V{sub ds} = − 100 V. This work enriches the understanding of MoO{sub 3} doped organic materials for applications in OTFTs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070018926','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070018926"><span id="translatedtitle"><span class="hlt">Shock</span> Prevention</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1978-01-01</p> <p>The electrician pictured is installing a General Electric Ground Fault Interrupter (GFI), a device which provides protection against electrical <span class="hlt">shock</span> in the home or in industrial facilities. <span class="hlt">Shocks</span> due to defective wiring in home appliances or other electrical equipment can cause severe burns, even death. As a result, the National Electrical Code now requires GFIs in all new homes constructed. This particular type of GFI employs a sensing element which derives from technology acquired in space projects by SCI Systems, Inc., Huntsville, Alabama, producer of sensors for GE and other manufacturers of GFI equipment. The sensor is based on the company's experience in developing miniaturized circuitry for space telemetry and other spacecraft electrical systems; this experience enabled SCI to package interruptor circuitry in the extremely limited space available and to produce sensory devices at practicable cost. The tiny sensor measures the strength of the electrical current and detects current differentials that indicate a fault in the functioning of an electrical system. The sensing element then triggers a signal to a disconnect mechanism in the GFI, which cuts off the current in the faulty circuit.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=computer+AND+parallel&pg=5&id=EJ481919','ERIC'); return false;" href="http://eric.ed.gov/?q=computer+AND+parallel&pg=5&id=EJ481919"><span id="translatedtitle"><span class="hlt">Parallel</span> Information Processing.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Rasmussen, Edie M.</p> <p>1992-01-01</p> <p>Examines <span class="hlt">parallel</span> computer architecture and the use of <span class="hlt">parallel</span> processors for text. Topics discussed include <span class="hlt">parallel</span> algorithms; performance evaluation; <span class="hlt">parallel</span> information processing; <span class="hlt">parallel</span> access methods for text; <span class="hlt">parallel</span> and distributed information retrieval systems; <span class="hlt">parallel</span> hardware for text; and network models for information…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.nhlbi.nih.gov/health/health-topics/topics/shock','NIH-MEDLINEPLUS'); return false;" href="http://www.nhlbi.nih.gov/health/health-topics/topics/shock"><span id="translatedtitle">What Is Cardiogenic <span class="hlt">Shock</span>?</span></a></p> <p><a target="_blank" href="http://medlineplus.gov/">MedlinePlus</a></p> <p></p> <p></p> <p>... page from the NHLBI on Twitter. What Is Cardiogenic <span class="hlt">Shock</span>? Cardiogenic (kar-dee-oh-JE-nik) <span class="hlt">shock</span> is ... treated right away. The most common cause of cardiogenic <span class="hlt">shock</span> is damage to the heart muscle from a ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JAP...119i5903K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JAP...119i5903K"><span id="translatedtitle"><span class="hlt">Shock</span> compression response of highly reactive Ni + Al multilayered thin foils</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kelly, Sean C.; Thadhani, Naresh N.</p> <p>2016-03-01</p> <p>The <span class="hlt">shock</span>-compression response of Ni + Al multilayered thin foils is investigated using laser-accelerated thin-foil plate-impact experiments over the pressure range of 2 to 11 GPa. The foils contain alternating Ni and Al <span class="hlt">layers</span> (<span class="hlt">parallel</span> but not flat) of nominally 50 nm bilayer spacing. The goal is to determine the equation of state and <span class="hlt">shock</span>-induced reactivity of these highly reactive fully dense thin-foil materials. The laser-accelerated thin-foil impact set-up involved combined use of photon-doppler-velocimetry to monitor the acceleration and impact velocity of an aluminum flyer, and VISAR interferometry was used to monitor the back free-surface velocity of the impacted Ni + Al multilayered target. The <span class="hlt">shock</span>-compression response of the Ni + Al target foils was determined using experimentally measured parameters and impedance matching approach, with error bars identified considering systematic and experimental errors. Meso-scale CTH <span class="hlt">shock</span> simulations were performed using real imported microstructures of the cross-sections of the multilayered Ni + Al foils to compute the Hugoniot response (assuming no reaction) for correlation with their experimentally determined equation of state. It was observed that at particle velocities below ˜150 m/s, the experimentally determined equation of state trend matches the CTH-predicted inert response and is consistent with the observed unreacted state of the recovered Ni + Al target foils from this velocity regime. At higher particle velocities, the experimentally determined equation of state deviates from the CTH-predicted inert response. A complete and self-sustained reaction is also seen in targets recovered from experiments performed at these higher particle velocities. The deviation in the measured equation of state, to higher <span class="hlt">shock</span> speeds and expanded volumes, combined with the observation of complete reaction in the recovered multilayered foils, confirmed via microstructure characterization, is indicative of the occurrence</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AIPC.1436..110D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AIPC.1436..110D"><span id="translatedtitle">Ion acceleration near CME-driven interplanetary <span class="hlt">shocks</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Desai, Mihir; Dayeh, Maher; Smith, Charles; Mason, Glenn; Lee, Martin</p> <p>2012-05-01</p> <p>We have surveyed properties of the magnetic field power spectral densities and energetic ions and compared them with the <span class="hlt">shock</span> normal angles of 74 CME-driven IP <span class="hlt">shocks</span> observed at ACE and Wind during solar cycle 23. We searched for events that exhibited clear signatures of first-order Fermi acceleration at quasi-<span class="hlt">parallel</span> <span class="hlt">shocks</span> and <span class="hlt">shock</span>-drift acceleration at quasi-perpendicular <span class="hlt">shocks</span> as predicted by the diffusive <span class="hlt">shock</span> acceleration theory. Our results show that events with clear signatures of either <span class="hlt">shock</span>-drift or first-order Fermi acceleration at 1 AU are rare, with 64 of the 74 IP <span class="hlt">shocks</span> (~87%) exhibiting mixed signatures. We classify the remaining ten events as follows. (1) Four quasi-perpendicular <span class="hlt">shocks</span> with θBn>70° exhibit no enhancements in the magnetic field power spectrum around the proton gyro-frequency and a slight hardening or no change in the ~80-300 keV/nucleon CNO spectral index across the <span class="hlt">shocks</span>, indicating the absence of upstream wave activity and the re-acceleration of a pre-existing suprathermal seed spectrum. (2) Six quasi-<span class="hlt">parallel</span> or oblique IP <span class="hlt">shocks</span> with θBn<70° exhibit significant enhancements in the power spectral densities around the proton gyro-frequency and are accompanied by unfolding (softening) of the ~80-300 keV/nucleon CNO spectral index across the <span class="hlt">shocks</span>, indicating the acceleration and efficient trapping of <300 keV/nucleon CNO ions by the Alfvén waves that were most likely excited by the accelerated protons as they streamed away from the <span class="hlt">shocks</span>. In this paper, we present contrasting energetic particle and magnetic field observations near 2 IP <span class="hlt">shocks</span> at 1 AU to highlight the complex signatures associated with the two distinct types of <span class="hlt">shock</span> acceleration mechanisms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940009447','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940009447"><span id="translatedtitle">Thermal <span class="hlt">shock</span> resistance of ceramic matrix composites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Carper, D. M.; Nied, H. F.</p> <p>1993-01-01</p> <p>The experimental and analytical investigation of the thermal <span class="hlt">shock</span> phenomena in ceramic matrix composites is detailed. The composite systems examined were oxide-based, consisting of an aluminosilicate matrix with either polycrystalline aluminosilicate or single crystal alumina fiber reinforcement. The program was divided into three technical tasks; baseline mechanical properties, thermal <span class="hlt">shock</span> modeling, and thermal <span class="hlt">shock</span> testing. The analytical investigation focused on the development of simple expressions for transient thermal stresses induced during thermal <span class="hlt">shock</span>. The effect of various material parameters, including thermal conductivity, elastic modulus, and thermal expansion, were examined analytically for their effect on thermal <span class="hlt">shock</span> performance. Using a simple maximum stress criteria for each constituent, it was observed that fiber fracture would occur only at the most extreme thermal <span class="hlt">shock</span> conditions and that matrix fracture, splitting <span class="hlt">parallel</span> to the reinforcing fiber, was to be expected for most practical cases. Thermal <span class="hlt">shock</span> resistance for the two material systems was determined experimentally by subjecting plates to sudden changes in temperature on one surface while maintaining the opposite surface at a constant temperature. This temperature change was varied in severity (magnitude) and in number of <span class="hlt">shocks</span> applied to a given sample. The results showed that for the most severe conditions examined that only surface matrix fracture was present with no observable fiber fracture. The impact of this damage on material performance was limited to the matrix dominated properties only. Specifically, compression strength was observed to decrease by as much as 50 percent from the measured baseline.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004SPIE.5641..276S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004SPIE.5641..276S"><span id="translatedtitle"><span class="hlt">Parallel</span> valveless micropump with two flexible diaphragms</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Su, Yufeng; Chen, Wenyuan; Cui, Feng; Zhang, Weiping</p> <p>2004-12-01</p> <p>This paper presents a <span class="hlt">parallel</span> dynamic passive valveless micropump, which consists of three <span class="hlt">layers</span>-valve, diaphragm and electromagnetic coil. The valve is wetly etched in a silicon wafer, the diaphragm is a PDMS (polydimethyl siloxane) film spun on a silicon wafer with embedded permanent magnet posts, and the coil is electroplated on a silicon substrate. Under the actuation of the magnetic field of the coil, the flexible diaphragm can be displaced upwards and downwards. After analyzing magnetic and mechanical characteristic of the flexible membrane and direction-dependence of the diffuser, this paper designed a micropump. And the relative length (L/d) of the micropump"s diffuser is 4.An 7×7 array of permanent magnetic posts is embedded in the PDMS film. Two diaphragms work in an anti-step mode, which can relieve the liquid <span class="hlt">shock</span> and increase the discharge of the micropump. ANSYS« and Matlab« are adopted to analyze the actuation effect of the coil and the flow characteristic of the micropump. Results show that when actuated under a 0.3A, 100Hz current ,the displacement of the diaphragm is more than 30μm, and the discharge of the micropump is about 6μL/s.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998joso.proc..120D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998joso.proc..120D"><span id="translatedtitle">Numerical MHD modeling of fast CME <span class="hlt">shocks</span> with a dimple.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>de Sterck, H.</p> <p></p> <p>SMM/Coronagraph and SOHO/LASCO observations show that some fast CMEs in the corona with propagation speed estimated to be slightly above the Alfvén speed, have bright fronts that are flattened or contain a concave-outward dimple. Often these CMEs show traces of post <span class="hlt">shock</span> structure and some show an apparent double-loop structure. It has been pointed out that ideal MHD <span class="hlt">shock</span> theory does not allow a simple concave-inward fast <span class="hlt">shock</span> solution to exist in this parameter regime. Numerical ideal MHD simulations are presented to show that the <span class="hlt">shock</span> forming in this parameter regime has complicated multiple structures. The <span class="hlt">shock</span> front is composed of fast and intermediate <span class="hlt">shock</span> parts, resulting in a <span class="hlt">shock</span> surface with a concave outward dimple. This <span class="hlt">shock</span> front interacts with shear <span class="hlt">layers</span> and additional <span class="hlt">shocks</span> in the downstram part of the flow. A slow switch-off <span class="hlt">shock</span> trailing the leading <span class="hlt">shock</span> front in a distinct V-shape with depleted density, causes a definite double-loop appearance. This flow contains most of the possible MHD discontinuities and some very particular features, like slow switch-off <span class="hlt">shocks</span>, intermediate <span class="hlt">shocks</span>, and hydrodynamic and intermediate compound <span class="hlt">shocks</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110006930','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110006930"><span id="translatedtitle">Data <span class="hlt">Parallel</span> Line Relaxation (DPLR) Code User Manual: Acadia - Version 4.01.1</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wright, Michael J.; White, Todd; Mangini, Nancy</p> <p>2009-01-01</p> <p>Data-<span class="hlt">Parallel</span> Line Relaxation (DPLR) code is a computational fluid dynamic (CFD) solver that was developed at NASA Ames Research Center to help mission support teams generate high-value predictive solutions for hypersonic flow field problems. The DPLR Code Package is an MPI-based, <span class="hlt">parallel</span>, full three-dimensional Navier-Stokes CFD solver with generalized models for finite-rate reaction kinetics, thermal and chemical non-equilibrium, accurate high-temperature transport coefficients, and ionized flow physics incorporated into the code. DPLR also includes a large selection of generalized realistic surface boundary conditions and links to enable loose coupling with external thermal protection system (TPS) material response and <span class="hlt">shock</span> <span class="hlt">layer</span> radiation codes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920004649','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920004649"><span id="translatedtitle">The effect of a type 3 and type 4 <span class="hlt">shock/shock</span> interaction on heat transfer in the stagnation region</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wilson, Dennis</p> <p>1991-01-01</p> <p>One of the major engineering challenges in designing the National Aerospace Plane, NASP, is to overcome augmented heating on the intake cowl lip from <span class="hlt">shock/shock</span> interactions. The <span class="hlt">shock/shock</span> interaction arises when the bow <span class="hlt">shock</span> from the craft's nose interferes with the bow <span class="hlt">shock</span> from the cowl lip. Considering only the region immediately around the cowl lip, the problem geometry may be simplified as that of an oblique <span class="hlt">shock</span> impinging on a bow <span class="hlt">shock</span> from a circular cylinder. Edney classified six different interference patterns resulting from an oblique-<span class="hlt">shock</span>/curved bow-<span class="hlt">shock</span> interaction. Of these six types, type 3 and 4 are most significant in that augmented surface heat transfer may be ten to thirty times greater than the case without the <span class="hlt">shock/shock</span> interaction. The objective was to begin to develop a mathematical model which is capable of predicting the effect of a type 3 and 4 <span class="hlt">shock/shock</span> interaction in the stagnation region of an arbitrary 2-D body. This model must be capable of predicting the maximum surface heat flux and the surface stagnation point pressure once the outer (effectively inviscid) flowfield is given. Therefore, it must capture the unsteady physics of the impinging shear <span class="hlt">layer</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/405753','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/405753"><span id="translatedtitle">Experimental and theoretical investigations of <span class="hlt">shock</span>-induced flow of reactive porous media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Baer, M.R.; Graham, R.A.; Anderson, M.U.; Sheffield, S.A.; Gustavsen, R.L.</p> <p>1996-11-01</p> <p>In this work, the microscale processes of consolidation, deformation and reaction features of <span class="hlt">shocked</span> porous materials are studied. Time- resolve particle velocities and stress fields associated with dispersive compaction waves are measured in gas-gun experiments. In these tests, a thin porous <span class="hlt">layer</span> of HMX is <span class="hlt">shock</span>-loaded at varied levels. At high impact, significant reaction is triggered by the rapid material distortion during compaction. In <span class="hlt">parallel</span> modeling studies, continuum mixture theory is applied to describe the behavior of averaged wave-fields in heterogeneous media. One-dimensional simulations of gas-gun experiments demonstrate that the wave features and interactions with viscoelastic materials in the gauge package are well described by mixture theory, including reflected wave behavior and conditions where significant reaction is initiated. Numerical simulations of impact on a collection of discrete HMX `crystals` are also presented using <span class="hlt">shock</span> physics analysis. Three-dimensional simulations indicate that rapid distortion occurs at material contact points; the nature of the dispersive fields includes large amplitude fluctuations of stress with wavelengths of several particle diameters. Localization of energy causes `hot-spots` due to <span class="hlt">shock</span> focusing and plastic work as material flows into interstitial regions. These numerical experiments demonstrate that `hot-spots` are strongly influenced by multiple crystal interactions. This mesoscale study provides new insights into micromechanical behavior of heterogeneous energetic materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006ApJ...641..978M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006ApJ...641..978M"><span id="translatedtitle">Weibel Filament Decay and Thermalization in Collisionless <span class="hlt">Shocks</span> and Gamma-Ray Burst Afterglows</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Milosavljević, Miloš; Nakar, Ehud</p> <p>2006-04-01</p> <p>Models for the synchrotron emission of gamma-ray burst afterglows suggest that the magnetic field is generated in the <span class="hlt">shock</span> wave that forms as relativistic ejecta plow through the circumburst medium. Transverse Weibel instability efficiently generates magnetic fields near equipartition with the postshock energy density. The detailed saturated state of the instability, as seen in particle-in-cell simulations, consists of magnetically self-pinched current filaments. The filaments are <span class="hlt">parallel</span> to the direction of propagation of the <span class="hlt">shock</span> and are about a plasma skin depth in radius, forming a quasi-two-dimensional structure. We argue that the Weibel filaments are susceptible to pressure-driven instabilities and use a rudimentary analytical model to illustrate the development of a particular, kinklike unstable mode. The instabilities destroy the quasi-two-dimensional structure of the Weibel filaments. For wavelengths longer than the skin depth, the kinklike mode grows at the rate equal to the speed of light divided by the wavelength. We calculate the transport of collisionless test particles in the filaments experiencing the instability and show that the particles diffuse in energy. This diffusion marks the beginning of thermalization in the <span class="hlt">shock</span> transition <span class="hlt">layer</span> and causes initial magnetic field decay as particles escape from the filaments. We discuss the implications of these results for the structure of the <span class="hlt">shock</span> and the polarization of the afterglow.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/86949','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/86949"><span id="translatedtitle">Large-eddy simulation of the Rayleigh-Taylor instability on a massively <span class="hlt">parallel</span> computer</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Amala, P.A.K.</p> <p>1995-03-01</p> <p>A computational model for the solution of the three-dimensional Navier-Stokes equations is developed. This model includes a turbulence model: a modified Smagorinsky eddy-viscosity with a stochastic backscatter extension. The resultant equations are solved using finite difference techniques: the second-order explicit Lax-Wendroff schemes. This computational model is implemented on a massively <span class="hlt">parallel</span> computer. Programming models on massively <span class="hlt">parallel</span> computers are next studied. It is desired to determine the best programming model for the developed computational model. To this end, three different codes are tested on a current massively <span class="hlt">parallel</span> computer: the CM-5 at Los Alamos. Each code uses a different programming model: one is a data <span class="hlt">parallel</span> code; the other two are message passing codes. Timing studies are done to determine which method is the fastest. The data <span class="hlt">parallel</span> approach turns out to be the fastest method on the CM-5 by at least an order of magnitude. The resultant code is then used to study a current problem of interest to the computational fluid dynamics community. This is the Rayleigh-Taylor instability. The Lax-Wendroff methods handle <span class="hlt">shocks</span> and sharp interfaces poorly. To this end, the Rayleigh-Taylor linear analysis is modified to include a smoothed interface. The linear growth rate problem is then investigated. Finally, the problem of the randomly perturbed interface is examined. Stochastic backscatter breaks the symmetry of the stationary unstable interface and generates a mixing <span class="hlt">layer</span> growing at the experimentally observed rate. 115 refs., 51 figs., 19 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015EGUGA..17.1210N&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015EGUGA..17.1210N&link_type=ABSTRACT"><span id="translatedtitle">Particle Acceleration in <span class="hlt">Shock-Shock</span> Interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nakanotani, Masaru; Matsukiyo, Shuichi; Hada, Tohru</p> <p>2015-04-01</p> <p>Collisionless <span class="hlt">shock</span> waves play a crucial role in producing high energy particles. One of the most plausible acceleration mechanisms is the first order Fermi acceleration in which non-thermal particles statistically gain energy while scattered by MHD turbulence both upstream and downstream of a <span class="hlt">shock</span>. Indeed, X-ray emission from energetic particles accelerated at supernova remnant <span class="hlt">shocks</span> is often observed [e.g., Uchiyama et al., 2007]. Most of the previous studies on <span class="hlt">shock</span> acceleration assume the presence of a single <span class="hlt">shock</span>. In space, however, two <span class="hlt">shocks</span> frequently come close to or even collide with each other. For instance, it is observed that a CME (coronal mass ejection) driven <span class="hlt">shock</span> collides with the earth's bow <span class="hlt">shock</span> [Hietala et al., 2011], or interplanetary <span class="hlt">shocks</span> pass through the heliospheric termination <span class="hlt">shock</span> [Lu et al., 1999]. Colliding <span class="hlt">shocks</span> are observed also in high power laser experiments [Morita et al., 2013]. It is expected that <span class="hlt">shock-shock</span> interactions efficiently produce high energy particles. A previous work using hybrid simulation [Cargill et al., 1986] reports efficient ion acceleration when supercritical two <span class="hlt">shocks</span> collide. In the hybrid simulation, however, the electron dynamics cannot be resolved so that electron acceleration cannot be discussed in principle. Here, we perform one-dimensional full Particle-in-Cell (PIC) simulations to examine colliding two symmetric oblique <span class="hlt">shocks</span> and the associated electron acceleration. In particular, the following three points are discussed in detail. 1. Energetic electrons are observed upstream of the two <span class="hlt">shocks</span> before their collision. These energetic electrons are efficiently accelerated through multiple reflections at the two <span class="hlt">shocks</span> (Fermi acceleration). 2. The reflected electrons excite large amplitude upstream waves. Electron beam cyclotron instability [Hasegawa, 1975] and electron fire hose instability [Li et al., 2000] appear to occur. 3. The large amplitude waves can scatters energetic electrons in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010PhDT........43W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010PhDT........43W"><span id="translatedtitle">The microphysics of collisionless <span class="hlt">shocks</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wilson, Lynn Bruce, III</p> <p>2010-11-01</p> <p> event in that study had low frequency waves consistent with shocklets. The shocklets are seen simultaneously with diffuse ion distributions. Both the shocklets and precursor whistlers are seen simultaneously with anisotropic electron distributions unstable to whistler anisotropy and heat flux instabilities. The IP <span class="hlt">shock</span> with upstream shocklets showed much stronger electron heating across the <span class="hlt">shock</span> ramp than the four events without upstream shocklets. Further investigation of the atypical IP <span class="hlt">shock</span> found the strong heating to be associated with large amplitude (> 100 mV/m) solitary waves and electron Bernstein waves. The observed heating and waveforms are likely due to instabilities driven by the free energy provided by reflected ions at this supercritical IP <span class="hlt">shock</span>, not the DC macroscopic fields. The particle heating observed for the event with shocklets was observed to be different from other events with similar <span class="hlt">shock</span> parameters, suggesting a different dissipation mechanism. The work presented in this thesis has helped increase the understanding of the microphysics of IP <span class="hlt">shocks</span> in addition to raising new questions regarding the energy dissipation mechanisms dominating in the ramp regions. The initial work focused on a statistical study of high frequency waveforms in IP <span class="hlt">shock</span> ramps. The study results suggested a re-evaluation of the relative importance of anomalous resistivity due to wave-particle interactions. This assertion was further strengthened by the atypical particle heating observed in the 04/06/2000 event which we claimed clearly showed a dependence on the observed waveforms. Thus, the nearly ubiquitous observations of large amplitude IAWs in the ramp regions of IP <span class="hlt">shocks</span> raises doubts about ignoring these high frequency fluctuations. In addition to these findings, we also observed a low frequency wave mode which is only supposed to exist upstream of quasi-<span class="hlt">parallel</span> <span class="hlt">shocks</span> with small radii of curvatures. All of these findings have increased our knowledge of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007PhDT.......154K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007PhDT.......154K"><span id="translatedtitle">Adaptive finite element simulation of flow and transport applications on <span class="hlt">parallel</span> computers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kirk, Benjamin Shelton</p> <p></p> <p> design and to demonstrate the capability for resolving complex multiscale processes efficiently and reliably. The first application considered is the simulation of chemotactic biological systems such as colonies of Escherichia coli. This work appears to be the first application of AMR to chemotactic processes. These systems exhibit transient, highly localized features and are important in many biological processes, which make them ideal for simulation with adaptive techniques. A nonlinear reaction-diffusion model for such systems is described and a finite element formulation is developed. The solution methodology is described in detail. Several phenomenological studies are conducted to study chemotactic processes and resulting biological patterns which use the <span class="hlt">parallel</span> adaptive refinement capability developed in this work. The other application study is much more extensive and deals with fine scale interactions for important hypersonic flows arising in aerospace applications. These flows are characterized by highly nonlinear, convection-dominated flowfields with very localized features such as <span class="hlt">shock</span> waves and boundary <span class="hlt">layers</span>. These localized features are well-suited to simulation with adaptive techniques. A novel treatment of the inviscid flux terms arising in a streamline-upwind Petrov-Galerkin finite element formulation of the compressible Navier-Stokes equations is also presented and is found to be superior to the traditional approach. The <span class="hlt">parallel</span> adaptive finite element formulation is then applied to several complex flow studies, culminating in fully three-dimensional viscous flows about complex geometries such as the Space Shuttle Orbiter. Physical phenomena such as viscous/inviscid interaction, <span class="hlt">shock</span> wave/boundary <span class="hlt">layer</span> interaction, <span class="hlt">shock/shock</span> interaction, and unsteady acoustic-driven flowfield response are considered in detail. A computational investigation of a 25°/55° double cone configuration details the complex multiscale flow features and investigates a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19940002815&hterms=Arts+crafts&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D%2528Arts%2Bcrafts%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19940002815&hterms=Arts+crafts&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D%2528Arts%2Bcrafts%2529"><span id="translatedtitle">EASI - EQUILIBRIUM AIR <span class="hlt">SHOCK</span> INTERFERENCE</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Glass, C. E.</p> <p>1994-01-01</p> <p>New research on hypersonic vehicles, such as the National Aero-Space Plane (NASP), has raised concerns about the effects of <span class="hlt">shock</span>-wave interference on various structural components of the craft. State-of-the-art aerothermal analysis software is inadequate to predict local flow and heat flux in areas of extremely high heat transfer, such as the surface impingement of an Edney-type supersonic jet. EASI revives and updates older computational methods for calculating inviscid flow field and maximum heating from <span class="hlt">shock</span> wave interference. The program expands these methods to solve problems involving the six <span class="hlt">shock</span>-wave interference patterns on a two-dimensional cylindrical leading edge with an equilibrium chemically reacting gas mixture (representing, for example, the scramjet cowl of the NASP). The inclusion of gas chemistry allows for a more accurate prediction of the maximum pressure and heating loads by accounting for the effects of high temperature on the air mixture. Caloric imperfections and specie dissociation of high-temperature air cause <span class="hlt">shock</span>-wave angles, flow deflection angles, and thermodynamic properties to differ from those calculated by a calorically perfect gas model. EASI contains pressure- and temperature-dependent thermodynamic and transport properties to determine heating rates, and uses either a calorically perfect air model or an 11-specie, 7-reaction reacting air model at equilibrium with temperatures up to 15,000 K for the inviscid flowfield calculations. EASI solves the flow field and the associated maximum surface pressure and heat flux for the six common types of <span class="hlt">shock</span> wave interference. Depending on the type of interference, the program solves for <span class="hlt">shock-wave/boundary-layer</span> interaction, expansion-fan/boundary-<span class="hlt">layer</span> interaction, attaching shear <span class="hlt">layer</span> or supersonic jet impingement. Heat flux predictions require a knowledge (from experimental data or relevant calculations) of a pertinent length scale of the interaction. Output files contain flow</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970001819','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970001819"><span id="translatedtitle">Laser Light Scattering by <span class="hlt">Shock</span> Waves</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Panda, J.; Adamovsky, G.</p> <p>1995-01-01</p> <p>Scattering of coherent light as it propagates <span class="hlt">parallel</span> to a <span class="hlt">shock</span> wave, formed in front of a bluff cylindrical body placed in a supersonic stream, is studied experimentally and numerically. Two incident optical fields are considered. First, a large diameter collimated beam is allowed to pass through the <span class="hlt">shock</span> containing flow. The light intensity distribution in the resultant shadowgraph image, measured by a low light CCD camera, shows well-defined fringes upstream and downstream of the shadow cast by the <span class="hlt">shock</span>. In the second situation, a narrow laser beam is brought to a grazing incidence on the <span class="hlt">shock</span> and the scattered light, which appears as a diverging sheet from the point of interaction, is visualized and measured on a screen placed normal to the laser path. Experiments are conducted on <span class="hlt">shocks</span> formed at various free-stream Mach numbers, M, and total pressures, P(sub 0). It is found that the widths of the <span class="hlt">shock</span> shadows in a shadowgraph image become independent of M and P(sub 0) when plotted against the jump in the refractive index, (Delta)n, created across the <span class="hlt">shock</span>. The total scattered light measured from the narrow laser beam and <span class="hlt">shock</span> interaction also follows the same trend. In the numerical part of the study, the <span class="hlt">shock</span> is assumed to be a 'phase object', which introduces phase difference between the upstream and downstream propagating parts of the light disturbances. For a given shape and (Delta)n of the bow <span class="hlt">shock</span> the phase and amplitude modulations are first calculated by ray tracing. The wave front is then propagated to the screen using the Fresnet diffraction equation. The calculated intensity distribution, for both of the incident optical fields, shows good agreement with the experimental data.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007PhR...443....1M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007PhR...443....1M"><span id="translatedtitle"><span class="hlt">Shocks</span> and cold fronts in galaxy clusters</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Markevitch, Maxim; Vikhlinin, Alexey</p> <p>2007-05-01</p> <p>The currently operating X-ray imaging observatories provide us with an exquisitely detailed view of the Megaparsec-scale plasma atmospheres in nearby galaxy clusters. At z<0.05, the Chandra's 1 angular resolution corresponds to linear resolution of less than a kiloparsec, which is smaller than some interesting linear scales in the intracluster plasma. This enables us to study the previously unseen hydrodynamic phenomena in clusters: classic bow <span class="hlt">shocks</span> driven by the infalling subclusters, and the unanticipated “cold fronts,” or sharp contact discontinuities between regions of gas with different entropies. The ubiquitous cold fronts are found in mergers as well as around the central density peaks in “relaxed” clusters. They are caused by motion of cool, dense gas clouds in the ambient higher-entropy gas. These clouds are either remnants of the infalling subclusters, or the displaced gas from the cluster's own cool cores. Both <span class="hlt">shock</span> fronts and cold fronts provide novel tools to study the intracluster plasma on microscopic and cluster-wide scales, where the dark matter gravity, thermal pressure, magnetic fields, and ultrarelativistic particles are at play. In particular, these discontinuities provide the only way to measure the gas bulk velocities in the plane of the sky. The observed temperature jumps at cold fronts require that thermal conduction across the fronts is strongly suppressed. Furthermore, the width of the density jump in the best-studied cold front is smaller than the Coulomb mean free path for the plasma particles. These findings show that transport processes in the intracluster plasma can easily be suppressed. Cold fronts also appear less prone to hydrodynamic instabilities than expected, hinting at the formation of a <span class="hlt">parallel</span> magnetic field <span class="hlt">layer</span> via magnetic draping. This may make it difficult to mix different gas phases during a merger. A sharp electron temperature jump across the best-studied <span class="hlt">shock</span> front has shown that the electron proton</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SSRv..191..519S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SSRv..191..519S"><span id="translatedtitle">Relativistic <span class="hlt">Shocks</span>: Particle Acceleration and Magnetization</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sironi, L.; Keshet, U.; Lemoine, M.</p> <p>2015-10-01</p> <p>We review the physics of relativistic <span class="hlt">shocks</span>, which are often invoked as the sources of non-thermal particles in pulsar wind nebulae (PWNe), gamma-ray bursts (GRBs), and active galactic nuclei (AGN) jets, and as possible sources of ultra-high energy cosmic-rays. We focus on particle acceleration and magnetic field generation, and describe the recent progress in the field driven by theory advances and by the rapid development of particle-in-cell (PIC) simulations. In weakly magnetized or quasi <span class="hlt">parallel-shocks</span> (i.e. where the magnetic field is nearly aligned with the flow), particle acceleration is efficient. The accelerated particles stream ahead of the <span class="hlt">shock</span>, where they generate strong magnetic waves which in turn scatter the particles back and forth across the <span class="hlt">shock</span>, mediating their acceleration. In contrast, in strongly magnetized quasi-perpendicular <span class="hlt">shocks</span>, the efficiencies of both particle acceleration and magnetic field generation are suppressed. Particle acceleration, when efficient, modifies the turbulence around the <span class="hlt">shock</span> on a long time scale, and the accelerated particles have a characteristic energy spectral index of s_{γ}˜eq2.2 in the ultra-relativistic limit. We discuss how this novel understanding of particle acceleration and magnetic field generation in relativistic <span class="hlt">shocks</span> can be applied to high-energy astrophysical phenomena, with an emphasis on PWNe and GRB afterglows.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015IAUGA..2288056F&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015IAUGA..2288056F&link_type=ABSTRACT"><span id="translatedtitle">Generation of collisionless <span class="hlt">shock</span> in laser-produced plasmas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fiuza, Frederico</p> <p>2015-08-01</p> <p>Collisionless <span class="hlt">shocks</span> are ubiquitous in astrophysical environments and are tightly connected with magnetic-field amplification and particle acceleration. The fast progress in high-power laser technology is bringing the study of high Mach number <span class="hlt">shocks</span> into the realm of laboratory plasmas, where in situ measurements can be made helping us understand the fundamental kinetic processes behind <span class="hlt">shocks</span>. I will discuss the recent progress in laser-driven <span class="hlt">shock</span> experiments at state-of-the-art facilities like NIF and Omega and how these results, together with ab initio massively <span class="hlt">parallel</span> simulations, can impact our understanding of magnetic field amplification and particle acceleration in astrophysical plasmas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013APS..SHK.W3004R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013APS..SHK.W3004R"><span id="translatedtitle">Fiber Bragg Grating sensor for <span class="hlt">shock</span> wave diagnostics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ravid, Avi; Shafir, Ehud; Zilberman, Shlomi; Berkovic, Garry; Glam, Benny; Appelbaum, Gabriel</p> <p>2013-06-01</p> <p>Fiber Bragg Grating (FBG) sensor response was studied in gas-gun <span class="hlt">shock</span> wave experiments. The sensors were embedded in PMMA target subjected to planar <span class="hlt">shock</span> waves under 1 GPa. Two orientations of the FBG sensor with respect to the <span class="hlt">shock</span> plane were examined: <span class="hlt">parallel</span> and perpendicular. The shift of the reflected wavelength was measured with a system based on commonly available communication grade add-drop filters that covered the maximal expected wavelength swing. The FBG sensors survived the <span class="hlt">shock</span> and their strain-to-wavelength response was determined by comparison to the calculated strain based on the known PMMA EOS and VISAR measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1613648K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1613648K"><span id="translatedtitle">Electron physics in <span class="hlt">shock</span> waves</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kilian, Patrick</p> <p>2014-05-01</p> <p>The non-relativistic <span class="hlt">shocks</span> that we find in the solar wind (no matter if driven by CMEs or encounters with planets) are dominated by ion dynamics. Therefore a detailed treatment of electrons is often neglegted to gain significant reductions in computational effort. With recent super computers and massively <span class="hlt">parallel</span> codes it is possible to perform self-consistent kinetic simulations using particle in cell code. This allows to study the heating of the electrons as well as the acceleration to superthermal energies. These energetic electrons are interesting for couple of reasons. e.g. as an influence on plasma instabilities or for the generation of plasma waves.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140006630','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140006630"><span id="translatedtitle">Whistler Waves Associated with Weak Interplanetary <span class="hlt">Shocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Velez, J. C. Ramirez; Blanco-Cano, X.; Aguilar-Rodriguez, E.; Russell, C. T.; Kajdic, P.; Jian,, L. K.; Luhmann, J. G.</p> <p>2012-01-01</p> <p>We analyze the properties of 98 weak interplanetary <span class="hlt">shocks</span> measured by the dual STEREO spacecraft over approximately 3 years during the past solar minimum. We study the occurrence of whistler waves associated with these <span class="hlt">shocks</span>, which on average are high beta <span class="hlt">shocks</span> (0.2 < Beta < 10). We have compared the waves properties upstream and downstream of the <span class="hlt">shocks</span>. In the upstream region the waves are mainly circularly polarized, and in most of the cases (approx. 75%) they propagate almost <span class="hlt">parallel</span> to the ambient magnetic field (<30 deg.). In contrast, the propagation angle with respect to the <span class="hlt">shock</span> normal varies in a broad range of values (20 deg. to 90 deg.), suggesting that they are not phase standing. We find that the whistler waves can extend up to 100,000 km in the upstream region but in most cases (88%) are contained in a distance within 30,000 km from the <span class="hlt">shock</span>. This corresponds to a larger region with upstream whistlers associated with IP <span class="hlt">shocks</span> than previously reported in the literature. The maximum amplitudes of the waves are observed next to the <span class="hlt">shock</span> interface, and they decrease as the distance to the <span class="hlt">shock</span> increases. In most cases the wave propagation direction becomes more aligned with the magnetic field as the distance to the <span class="hlt">shock</span> increases. These two facts suggest that most of the waves in the upstream region are Landau damping as they move away from the <span class="hlt">shock</span>. From the analysis we also conclude that it is likely that the generation mechanism of the upstream whistler waves is taking place at the <span class="hlt">shock</span> interface. In the downstream region, the waves are irregularly polarized, and the fluctuations are very compressive; that is, the compressive component of the wave clearly dominates over the transverse one. The majority of waves in the downstream region (95%) propagate at oblique angles with respect to the ambient magnetic field (>60 deg.). The wave propagation with respect to the <span class="hlt">shock</span>-normal direction has no preferred direction and varies similarly to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910057958&hterms=birth+order&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dbirth%2Border','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910057958&hterms=birth+order&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dbirth%2Border"><span id="translatedtitle">Hypersonic <span class="hlt">Shock/Boundary-Layer</span> Interaction Database</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Settles, G. S.; Dodson, L. J.</p> <p>1991-01-01</p> <p>Turbulence modeling is generally recognized as the major problem obstructing further advances in computational fluid dynamics (CFD). A closed solution of the governing Navier-Stokes equations for turbulent flows of practical consequence is still far beyond grasp. At the same time, the simplified models of turbulence which are used to achieve closure of the Navier-Stokes equations are known to be rigorously incorrect. While these models serve a definite purpose, they are inadequate for the general prediction of hypersonic viscous/inviscid interactions, mixing problems, chemical nonequilibria, and a range of other phenomena which must be predicted in order to design a hypersonic vehicle computationally. Due to the complexity of turbulence, useful new turbulence models are synthesized only when great expertise is brought to bear and considerable intellectual energy is expended. Although this process is fundamentally theoretical, crucial guidance may be gained from carefully-executed basic experiments. Following the birth of a new model, its testing and validation once again demand comparisons with data of unimpeachable quality. This report concerns these issues which arise from the experimental aspects of hypersonic modeling and represents the results of the first phase of an effort to develop compressible turbulence models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980201093','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980201093"><span id="translatedtitle">Performance of Low Dissipative High Order <span class="hlt">Shock</span>-Capturing Schemes for <span class="hlt">Shock</span>-Turbulence Interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sandham, N. D.; Yee, H. C.</p> <p>1998-01-01</p> <p>Accurate and efficient direct numerical simulation of turbulence in the presence of <span class="hlt">shock</span> waves represents a significant challenge for numerical methods. The objective of this paper is to evaluate the performance of high order compact and non-compact central spatial differencing employing total variation diminishing (TVD) <span class="hlt">shock</span>-capturing dissipations as characteristic based filters for two model problems combining <span class="hlt">shock</span> wave and shear <span class="hlt">layer</span> phenomena. A vortex pairing model evaluates the ability of the schemes to cope with shear <span class="hlt">layer</span> instability and eddy <span class="hlt">shock</span> waves, while a <span class="hlt">shock</span> wave impingement on a spatially-evolving mixing <span class="hlt">layer</span> model studies the accuracy of computation of vortices passing through a sequence of <span class="hlt">shock</span> and expansion waves. A drastic increase in accuracy is observed if a suitable artificial compression formulation is applied to the TVD dissipations. With this modification to the filter step the fourth-order non-compact scheme shows improved results in comparison to second-order methods, while retaining the good <span class="hlt">shock</span> resolution of the basic TVD scheme. For this characteristic based filter approach, however, the benefits of compact schemes or schemes with higher than fourth order are not sufficient to justify the higher complexity near the boundary and/or the additional computational cost.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22365245','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22365245"><span id="translatedtitle">SEP acceleration in CME driven <span class="hlt">shocks</span> using a hybrid code</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gargaté, L.; Fonseca, R. A.; Silva, L. O.</p> <p>2014-09-01</p> <p>We perform hybrid simulations of a super-Alfvénic quasi-<span class="hlt">parallel</span> <span class="hlt">shock</span>, driven by a coronal mass ejection (CME), propagating in the outer coronal/solar wind at distances of between 3 to 6 solar radii. The hybrid treatment of the problem enables the study of the <span class="hlt">shock</span> propagation on the ion timescale, preserving ion kinetics and allowing for a self-consistent treatment of the <span class="hlt">shock</span> propagation and particle acceleration. The CME plasma drags the embedded magnetic field lines stretching from the sun, and propagates out into interplanetary space at a greater velocity than the in situ solar wind, driving the <span class="hlt">shock</span>, and producing very energetic particles. Our results show that electromagnetic Alfvén waves are generated at the <span class="hlt">shock</span> front. The waves propagate upstream of the <span class="hlt">shock</span> and are produced by the counter-streaming ions of the solar wind plasma being reflected at the <span class="hlt">shock</span>. A significant fraction of the particles are accelerated in two distinct phases: first, particles drift from the <span class="hlt">shock</span> and are accelerated in the upstream region, and second, particles arriving at the <span class="hlt">shock</span> get trapped and are accelerated at the <span class="hlt">shock</span> front. A fraction of the particles diffused back to the <span class="hlt">shock</span>, which is consistent with the Fermi acceleration mechanism.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080004653','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080004653"><span id="translatedtitle">Multi-<span class="hlt">shock</span> assembly for protecting a spacecraft surface from hypervelocity impactors</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dvorak, Bruce D. (Inventor)</p> <p>2001-01-01</p> <p>A hypervelocity impact shield assembly for protecting a spacecraft surface from hypervelocity impactors. The shield assembly includes at least one sacrificial impactor disrupting/<span class="hlt">shocking</span> <span class="hlt">layer</span> of hypervelocity impactor disrupting/<span class="hlt">shocking</span> material. A primary spacing element, including space-rated open cell foam material, is positioned between the at least one sacrificial impactor disrupting/<span class="hlt">shocking</span> <span class="hlt">layer</span> and a spacecraft surface. A cover member is arranged and disposed relative to the sacrificial impactor disrupting/<span class="hlt">shocking</span> <span class="hlt">layer</span> and the primary spacing element to maintain the integrity of the hypervelocity impact shield assembly. In the event of exposure to a hypervelocity impactor, the sacrificial impactor disrupting/<span class="hlt">shocking</span> <span class="hlt">layer</span> is perforated while <span class="hlt">shocking</span> the impactor breaking it into fragments, and/or melting it, and/or vaporizing it, thus providing a dispersion in the form of an expanding debris cloud/plume which spreads the impact energy of the impactor over a volume formed by the primary spacing element between the sacrificial impactor disrupting/<span class="hlt">shocking</span> <span class="hlt">layer</span> and the spacecraft surface. This significantly reduces impact lethality at the spacecraft surface. The space-rated open cell foam material provides an extremely lightweight, low-cost, efficient means of spacing and supporting the at least one sacrificial impactor disrupting/<span class="hlt">shocking</span> <span class="hlt">layer</span> before, during, and after launch. In a preferred embodiment, the invention is in the form of a multi-<span class="hlt">shock</span> assembly including a plurality of sacrificial impactor disrupting/<span class="hlt">shocking</span> <span class="hlt">layers</span>. In such instance, the hypervelocity impact shield assembly includes a plurality of secondary spacing elements. Each secondary spacing element is positioned adjacent an associated sacrificial impactor disrupting/<span class="hlt">shocking</span> <span class="hlt">layer</span> to form a multi-<span class="hlt">shock</span> subassembly. Thus, a plurality of multi-<span class="hlt">shock</span> subassemblies are provided which include alternating <span class="hlt">layers</span> of sacrificial impactor disrupting/<span class="hlt">shocking</span> <span class="hlt">layers</span> and secondary spacing</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950046668&hterms=downstream&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Ddownstream','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950046668&hterms=downstream&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Ddownstream"><span id="translatedtitle">Plasma waves downstream of weak collisionless <span class="hlt">shocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Coroniti, F. V.; Greenstadt, E. W.; Moses, S. L.; Smith, E. J.; Tsurutani, B. T.</p> <p>1993-01-01</p> <p>In September 1983 the International Sun Earth Explorer 3 (ISEE 3) International Cometary Explorer (ICE) spacecraft made a long traversal of the distant dawnside flank region of the Earth's magnetosphere and had many encounters with the low Mach number bow <span class="hlt">shock</span>. These weak <span class="hlt">shocks</span> excite plasma wave electric field turbulence with amplitudes comparable to those detected in the much stronger bow <span class="hlt">shock</span> near the nose region. Downstream of quasi-perpendicular (quasi-<span class="hlt">parallel</span>) <span class="hlt">shocks</span>, the E field spectra exhibit a strong peak (plateau) at midfrequencies (1 - 3 kHz); the plateau shape is produced by a low-frequency (100 - 300 Hz) emission which is more intense behind downstream of two quasi-perpendicular <span class="hlt">shocks</span> show that the low frequency signals are polarized <span class="hlt">parallel</span> to the magnetic field, whereas the midfrequency emissions are unpolarized or only weakly polarized. A new high frequency (10 - 30 kHz) emission which is above the maximum Doppler shift exhibit a distinct peak at high frequencies; this peak is often blurred by the large amplitude fluctuations of the midfrequency waves. The high-frequency component is strongly polarized along the magnetic field and varies independently of the lower-frequency waves.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JAP...118f3904A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JAP...118f3904A"><span id="translatedtitle">Superconducting magnetoresistance effect observed in Co/Nb/Co trilayers under a <span class="hlt">parallel</span> magnetic field: The importance of matching the width of magnetic domain walls of the Co <span class="hlt">layers</span> with the thickness of the Nb interlayer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Aristomenopoulou, E.; Stamopoulos, D.</p> <p>2015-08-01</p> <p>Magnetoresistance effects observed in ferromagnet/superconductor (FM/SC) hybrids, FM/SC bilayers (BLs) and FM/SC/FM trilayers (TLs), have attracted much interest. Here, we focus on the stray-fields-based superconducting magnetoresistance effect (sMRE) observed in Co(dCo)/Nb(dNb)/Co(dCo) TLs with sufficiently thick Co outer <span class="hlt">layers</span> so that out-of-plane magnetic domains (MDs) and MDs walls (MDWs) emerge all over their surface when subjected to a <span class="hlt">parallel</span> external magnetic field, Hex, equal to the coercive field, Hc. To explore the conditions necessary for maximization of the sMRE, we focus on the different kinds of the stray dipolar fields, Hdip, that emerge at the interior of the out-of-plane MDs and at the boundaries of MDWs; these have a different inherent tendency to create straight and semi-loop vortices, respectively. In the recent literature, the creation of straight and semi-loop vortices has been addressed at some extent both theoretically [Laiho et al., Phys. Rev. B 67, 144522 (2003)] and experimentally [Bobba et al., Phys. Rev. B 89, 214502 (2014)] for the case of FM/SC BLs. Here, we address these issues in FM/SC/FM TLs in connection to the sMRE. Specifically, we focus on an experimental finding reported recently [D. Stamopoulos and E. Aristomenopoulou, J. Appl. Phys. 116, 233908 (2014)]; strong magnetostatic coupling of the FM outer <span class="hlt">layers</span> is accompanied by an intense sMRE in TLs in which the thickness of the SC interlayer, dSC, matches the width of MDWs, DMDWs. To investigate this finding, we employ simulations-modeling and energy-considerations and propose two quantitative criteria that facilitate the creation of straight vortices over semi-loop ones. The first focuses on the maximization of the stray Hdip that occur at the interior of the out-of-plane MDs. The second enables the estimation of a crossover between the preferable creation of one kind of vortices over the other. Both criteria respond well, when tested against experimental results. These</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...826...48M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...826...48M"><span id="translatedtitle">Suprathermal Electrons at Saturn's Bow <span class="hlt">Shock</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Masters, A.; Sulaiman, A. H.; Sergis, N.; Stawarz, L.; Fujimoto, M.; Coates, A. J.; Dougherty, M. K.</p> <p>2016-07-01</p> <p>The leading explanation for the origin of galactic cosmic rays is particle acceleration at the <span class="hlt">shocks</span> surrounding young supernova remnants (SNRs), although crucial aspects of the acceleration process are unclear. The similar collisionless plasma <span class="hlt">shocks</span> frequently encountered by spacecraft in the solar wind are generally far weaker (lower Mach number) than these SNR <span class="hlt">shocks</span>. However, the Cassini spacecraft has shown that the <span class="hlt">shock</span> standing in the solar wind sunward of Saturn (Saturn's bow <span class="hlt">shock</span>) can occasionally reach this high-Mach number astrophysical regime. In this regime Cassini has provided the first in situ evidence for electron acceleration under quasi-<span class="hlt">parallel</span> upstream magnetic conditions. Here we present the full picture of suprathermal electrons at Saturn's bow <span class="hlt">shock</span> revealed by Cassini. The downstream thermal electron distribution is resolved in all data taken by the low-energy electron detector (CAPS-ELS, <28 keV) during <span class="hlt">shock</span> crossings, but the higher energy channels were at (or close to) background. The high-energy electron detector (MIMI-LEMMS, >18 keV) measured a suprathermal electron signature at 31 of 508 crossings, where typically only the lowest energy channels (<100 keV) were above background. We show that these results are consistent with the theory in which the “injection” of thermal electrons into an acceleration process involves interaction with whistler waves at the <span class="hlt">shock</span> front, and becomes possible for all upstream magnetic field orientations at high Mach numbers like those of the strong <span class="hlt">shocks</span> around young SNRs. A future dedicated study will analyze the rare crossings with evidence for relativistic electrons (up to ˜1 MeV).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/108114','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/108114"><span id="translatedtitle">Special <span class="hlt">parallel</span> processing workshop</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p></p> <p>1994-12-01</p> <p>This report contains viewgraphs from the Special <span class="hlt">Parallel</span> Processing Workshop. These viewgraphs deal with topics such as <span class="hlt">parallel</span> processing performance, message passing, queue structure, and other basic concept detailing with <span class="hlt">parallel</span> processing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012APS..DPPGP8042W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012APS..DPPGP8042W"><span id="translatedtitle">Magnetized collisionless <span class="hlt">shock</span> studies using high velocity plasmoids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weber, Thomas; Intrator, Thomas; Gao, Kevin</p> <p>2012-10-01</p> <p>Magnetized collisionless <span class="hlt">shocks</span> are ubiquitous throughout the cosmos and are observed to accelerate particles to relativistic velocities, amplify magnetic fields, transport energy, and create non-thermal distributions. They exhibit transitional scale lengths much shorter than the collisional mean free path and are mediated by collective interactions rather than Coulomb collisions. The Magnetized <span class="hlt">Shock</span> Experiment (MSX) leverages advances in Field Reversed Configuration (FRC) plasmoid formation and acceleration to produce highly supersonic and super-Alfvènic supercritical <span class="hlt">shocks</span> with pre-existing magnetic field at perpendicular, <span class="hlt">parallel</span> or oblique angles to the direction of propagation. Adjustable <span class="hlt">shock</span> speed, density, and magnetic field provide unique access to a range of parameter space relevant to a variety of naturally occurring <span class="hlt">shocks</span>. This effort examines experimentally, analytically, and numerically the physics of collisionless <span class="hlt">shock</span> formation, structure, and kinetic effects in a laboratory setting and draw comparisons between experimental data and astronomical observations. Approved for Public Release: LA-UR-12-22886</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013APS..DPPGP8123W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013APS..DPPGP8123W"><span id="translatedtitle">Overview and recent progress of the Magnetized <span class="hlt">Shock</span> Experiment (MSX)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weber, T. E.; Intrator, T. P.; Smith, R. J.; Hutchinson, T. M.; Boguski, J. C.; Sears, J. A.; Swan, H. O.; Gao, K. W.; Chapdelaine, L. J.; Winske, D.; Dunn, J. P.</p> <p>2013-10-01</p> <p>The Magnetized <span class="hlt">Shock</span> Experiment (MSX) has been constructed to study the physics of super-Alfvènic, supercritical, magnetized <span class="hlt">shocks</span>. Exhibiting transitional length and time scales much smaller than can be produced through collisional processes, these <span class="hlt">shocks</span> are observed to create non-thermal distributions, amplify magnetic fields, and accelerate particles to relativistic velocities. <span class="hlt">Shocks</span> are produced through the acceleration and subsequent stagnation of Field Reversed Configuration (FRC) plasmoids against a high-flux magnetic mirror with a conducting boundary or a plasma target with embedded field. Adjustable <span class="hlt">shock</span> velocity, density, and magnetic geometry (B <span class="hlt">parallel</span>, perpendicular, or oblique to k) provide unique access to a wide range of dimensionless parameters relevant to astrophysical <span class="hlt">shocks</span>. Information regarding the experimental configuration, diagnostics suite, recent simulations, experimental results, and physics goals will be presented. This work is supported by DOE OFES and NNSA under LANS contract DE-AC52-06NA25369 Approved for Public Release: LA-UR-13-24859.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..SHK.F1003W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..SHK.F1003W"><span id="translatedtitle">Fluorescence anisotropy measurements under <span class="hlt">shock</span> compression</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Jue; Bassett, Will; Banishev, Alexandr; Dlott, Dana</p> <p>2015-06-01</p> <p>Fluorescence anisotropy measurements, where the <span class="hlt">parallel</span> and perpendicular polarized emissions from probe molecules are acquired simultaneously, provide direct measurement of molecular rotational dynamics. In our experiments, the fluorescence from rhodamine 6G dye in various materials under GPa <span class="hlt">shocks</span> produced by laser-driven flyer plates is collected, separated into two orthogonally-polarized beams using a Wollaston prism and detected with a streak camera. In liquids, the molecular rotations result from rotational diffusion and in solids from shear flow. The rotation rates can be used to determine the viscosity of the <span class="hlt">shocked</span> medium.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020041930','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020041930"><span id="translatedtitle">Tolerant (<span class="hlt">parallel</span>) Programming</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>DiNucci, David C.; Bailey, David H. (Technical Monitor)</p> <p>1997-01-01</p> <p>In order to be truly portable, a program must be tolerant of a wide range of development and execution environments, and a <span class="hlt">parallel</span> program is just one which must be tolerant of a very wide range. This paper first defines the term "tolerant programming", then describes many <span class="hlt">layers</span> of tools to accomplish it. The primary focus is on F-Nets, a formal model for expressing computation as a folded partial-ordering of operations, thereby providing an architecture-independent expression of tolerant <span class="hlt">parallel</span> algorithms. For implementing F-Nets, Cooperative Data Sharing (CDS) is a subroutine package for implementing communication efficiently in a large number of environments (e.g. shared memory and message passing). Software Cabling (SC), a very-high-level graphical programming language for building large F-Nets, possesses many of the features normally expected from today's computer languages (e.g. data abstraction, array operations). Finally, L2(sup 3) is a CASE tool which facilitates the construction, compilation, execution, and debugging of SC programs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1048692','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1048692"><span id="translatedtitle">Applied <span class="hlt">Parallel</span> Metadata Indexing</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jacobi, Michael R</p> <p>2012-08-01</p> <p>The GPFS Archive is <span class="hlt">parallel</span> archive is a <span class="hlt">parallel</span> archive used by hundreds of users in the Turquoise collaboration network. It houses 4+ petabytes of data in more than 170 million files. Currently, users must navigate the file system to retrieve their data, requiring them to remember file paths and names. A better solution might allow users to tag data with meaningful labels and searach the archive using standard and user-defined metadata, while maintaining security. last summer, I developed the backend to a tool that adheres to these design goals. The backend works by importing GPFS metadata into a MongoDB cluster, which is then indexed on each attribute. This summer, the author implemented security and developed the user interfae for the search tool. To meet security requirements, each database table is associated with a single user, which only stores records that the user may read, and requires a set of credentials to access. The interface to the search tool is implemented using FUSE (Filesystem in USErspace). FUSE is an intermediate <span class="hlt">layer</span> that intercepts file system calls and allows the developer to redefine how those calls behave. In the case of this tool, FUSE interfaces with MongoDB to issue queries and populate output. A FUSE implementation is desirable because it allows users to interact with the search tool using commands they are already familiar with. These security and interface additions are essential for a usable product.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006CompM..38....1R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006CompM..38....1R"><span id="translatedtitle">The modeling of the <span class="hlt">shock</span> response of powdered ceramic materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rajendran, A. M.; Ashmawi, W. M.; Zikry, M. A.</p> <p>2006-06-01</p> <p>A two-cap constitutive model that incorporates inelastic yielding, frictional sliding, and densification was modified for <span class="hlt">shock</span>-loading applications, and used to model <span class="hlt">shock</span>-wave propagation of a powdered ceramic that is constrained by aluminum <span class="hlt">layers</span> in a system, which is impacted by a flyer plate. The numerical results included analyses of the effects of <span class="hlt">shock</span> stress amplitudes on densification, unloading behaviors, stress attenuation and dispersion, and stress and pressure distributions. An understanding of how interfacial impedances affect <span class="hlt">shock</span>-front attenuation, dispersion, and propagation were obtained through modeling different <span class="hlt">shock</span>-load conditions. The constitutive and computational models were validated with detailed simulations of <span class="hlt">shock</span>-front experiments pertaining to powdered ceramics. It is shown how <span class="hlt">shock</span> amplitude duration and rise time are related to stress evolution, and how physically limiting values result in inelastic damage. This analysis underscores how modeling with the appropriate constitutive description can provide insights on how powdered ceramics behave under impact-loading conditions.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920024638','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920024638"><span id="translatedtitle">Steady state risetimes of <span class="hlt">shock</span> waves in the atmosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Raspet, Richard; Bass, Henry; Yao, Lixin; Wu, Wenliang</p> <p>1992-01-01</p> <p>A square wave shape is used in the Pestorius algorithm to calculate the risetime of a step <span class="hlt">shock</span> in the atmosphere. These results agree closely with steady <span class="hlt">shock</span> calculations. The healing distance of perturbed <span class="hlt">shocks</span> due to finite wave effects is then investigated for quasi-steady <span class="hlt">shocks</span>. Perturbed 100 Pa <span class="hlt">shocks</span> require on the order of 1.0 km travel distance to return to within 10 percent of their steady <span class="hlt">shock</span> risetime. For 30 Pa <span class="hlt">shocks</span>, the minimum recovery distance increases to 3.0 km. It is unlikely that finite wave effects can remove the longer risetimes and irregular features introduced into the sonic boom by turbulent scattering in the planetary boundary <span class="hlt">layer</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750020965','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750020965"><span id="translatedtitle">Numerical computation of three-dimensional blunt body flow fields with an impinging <span class="hlt">shock</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Holst, T. L.; Tannehill, J. C.</p> <p>1975-01-01</p> <p>A time-marching finite-difference method was used to solve the compressible Navier-Stokes equations for the three-dimensional wing-leading-edge <span class="hlt">shock</span> impingement problem. The bow <span class="hlt">shock</span> was treated as a discontinuity across which the exact <span class="hlt">shock</span> jump conditions were applied. All interior <span class="hlt">shock</span> <span class="hlt">layer</span> detail such as shear <span class="hlt">layers</span>, <span class="hlt">shock</span> waves, jets, and the wall boundary <span class="hlt">layer</span> were automatically captured in the solution. The impinging <span class="hlt">shock</span> was introduced by discontinuously changing the freestream conditions across the intersection line at the bow <span class="hlt">shock</span>. A special storage-saving procedure for sweeping through the finite-difference mesh was developed which reduces the required amount of computer storage by at least a factor of two without sacrificing the execution time. Numerical results are presented for infinite cylinder blunt body cases as well as the three-dimensional <span class="hlt">shock</span> impingement case. The numerical results are compared with existing experimental and theoretical results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950046210&hterms=Neptune&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DNeptune','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950046210&hterms=Neptune&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DNeptune"><span id="translatedtitle">Neptune inbound bow <span class="hlt">shock</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Szabo, Adam; Lepping, Ronald P.</p> <p>1995-01-01</p> <p>Voyager 2 crossed the inbound or upstream Neptunian bow <span class="hlt">shock</span> at 1430 spacecraft event time on August 24 in 1989 (Belcher et al., 1989). The plasma and magnetic field measurements allow us to study the solar wind interaction with the outermost gas giant. To fully utilize all of the spacecraft observations, an improved nonlinear least squares, 'Rankine-Hugoniot' magnetohydrodynamic <span class="hlt">shock</span>-fitting technique has been developed (Szabo, 1994). This technique is applied to the Neptunian data set. We find that the upstream bow <span class="hlt">shock</span> normal points nearly exactly toward the Sun consistent with any reasonable large-scale model of the bow <span class="hlt">shock</span> for a near subsolar crossing. The <span class="hlt">shock</span> was moving outward with a speed of 14 +/- 12 km/s. The <span class="hlt">shock</span> can be characterized as a low beta, high Mach number, strong quasi-perpendicular <span class="hlt">shock</span>. Finally, the <span class="hlt">shock</span> microstructure features are resolved and found to scale well with theoretical expectations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhDT.......224P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT.......224P"><span id="translatedtitle">Particle acceleration at <span class="hlt">shocks</span> in the inner heliosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Parker, Linda Neergaard</p> <p></p> <p>This dissertation describes a study of particle acceleration at <span class="hlt">shocks</span> via the diffusive <span class="hlt">shock</span> acceleration mechanism. Results for particle acceleration at both quasi-<span class="hlt">parallel</span> and quasi-perpendicular <span class="hlt">shocks</span> are presented to address the question of whether there are sufficient particles in the solar wind thermal core, modeled as either a Maxwellian or kappa- distribution, to account for the observed accelerated spectrum. Results of accelerating the theoretical upstream distribution are compared to energetic observations at 1 AU. It is shown that the particle distribution in the solar wind thermal core is sufficient to explain the accelerated particle spectrum downstream of the <span class="hlt">shock</span>, although the shape of the downstream distribution in some cases does not follow completely the theory of diffusive <span class="hlt">shock</span> acceleration, indicating possible additional processes at work in the <span class="hlt">shock</span> for these cases. Results show good to excellent agreement between the theoretical and observed spectral index for one third to one half of both quasi-<span class="hlt">parallel</span> and quasi-perpendicular <span class="hlt">shocks</span> studied herein. Coronal mass ejections occurring during periods of high solar activity surrounding solar maximum can produce <span class="hlt">shocks</span> in excess of 3-8 <span class="hlt">shocks</span> per day. During solar minimum, diffusive <span class="hlt">shock</span> acceleration at <span class="hlt">shocks</span> can generally be understood on the basis of single independent <span class="hlt">shocks</span> and no other <span class="hlt">shock</span> necessarily influences the diffusive <span class="hlt">shock</span> acceleration mechanism. In this sense, diffusive <span class="hlt">shock</span> acceleration during solar minimum may be regarded as Markovian. By contrast, diffusive <span class="hlt">shock</span> acceleration of particles at periods of high solar activity (e.g. solar maximum) see frequent, closely spaced <span class="hlt">shocks</span> that include the effects of particle acceleration at preceding and following <span class="hlt">shocks</span>. Therefore, diffusive <span class="hlt">shock</span> acceleration of particles at solar maximum cannot be modeled on the basis of diffusive <span class="hlt">shock</span> acceleration as a single, independent <span class="hlt">shock</span> and the process is essentially non-Markovian. A</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910015431','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910015431"><span id="translatedtitle"><span class="hlt">Parallel</span> computing using a Lagrangian formulation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Liou, May-Fun; Loh, Ching Yuen</p> <p>1991-01-01</p> <p>A new Lagrangian formulation of the Euler equation is adopted for the calculation of 2-D supersonic steady flow. The Lagrangian formulation represents the inherent <span class="hlt">parallelism</span> of the flow field better than the common Eulerian formulation and offers a competitive alternative on <span class="hlt">parallel</span> computers. The implementation of the Lagrangian formulation on the Thinking Machines Corporation CM-2 Computer is described. The program uses a finite volume, first-order Godunov scheme and exhibits high accuracy in dealing with multidimensional discontinuities (slip-line and <span class="hlt">shock</span>). By using this formulation, a better than six times speed-up was achieved on a 8192-processor CM-2 over a single processor of a CRAY-2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1136636','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1136636"><span id="translatedtitle">Biomass <span class="hlt">shock</span> pretreatment</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Holtzapple, Mark T.; Madison, Maxine Jones; Ramirez, Rocio Sierra; Deimund, Mark A.; Falls, Matthew; Dunkelman, John J.</p> <p>2014-07-01</p> <p>Methods and apparatus for treating biomass that may include introducing a biomass to a chamber; exposing the biomass in the chamber to a <span class="hlt">shock</span> event to produce a <span class="hlt">shocked</span> biomass; and transferring the <span class="hlt">shocked</span> biomass from the chamber. In some aspects, the method may include pretreating the biomass with a chemical before introducing the biomass to the chamber and/or after transferring <span class="hlt">shocked</span> biomass from the chamber.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5803931','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5803931"><span id="translatedtitle">Inferences drawn from <span class="hlt">shock</span>-enhanced turbulent mixing analyses</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Buckingham, A.C.</p> <p>1987-10-16</p> <p>This discussion concerns analyses of physical <span class="hlt">shock</span>-tube and <span class="hlt">shock</span>-boundary <span class="hlt">layer</span> interaction experiments, supplemented by computations. The basic issue is that of evaluating the influence of reflected <span class="hlt">shock</span> waves on enhancing the balance of turbulent kinetic energy and resultant turbulent materials mixing during implosion and <span class="hlt">shock</span> reflection intervals. Increases in random velocity amplitudes of a factor of 5 or greater implying turbulent kinetic energy increases of a factor of 12 or more have been observed in some low Mach Number <span class="hlt">shock</span>-tube and boundary-<span class="hlt">layer</span> <span class="hlt">shock</span> wave interaction experiments. These results are analyzed to estimate their influence on increased turbulent material mixing subsequent to <span class="hlt">shock</span> interaction. The analyses are developed with the assistance of two-dimensional, pseudospectral free turbulent field <span class="hlt">shock</span> interaction numerical simulations as well as compressible turbulent boundary-<span class="hlt">layer</span> <span class="hlt">shock</span> interaction calculations. Of particular interest is the influence of Mach Number and pre-existing turbulent intensity on the enhancement ratios. 24 refs., 8 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.nhlbi.nih.gov/health/health-topics/topics/shock/causes','NIH-MEDLINEPLUS'); return false;" href="http://www.nhlbi.nih.gov/health/health-topics/topics/shock/causes"><span id="translatedtitle">What Causes Cardiogenic <span class="hlt">Shock</span>?</span></a></p> <p><a target="_blank" href="http://medlineplus.gov/">MedlinePlus</a></p> <p></p> <p></p> <p>... page from the NHLBI on Twitter. What Causes Cardiogenic <span class="hlt">Shock</span>? Immediate Causes Cardiogenic <span class="hlt">shock</span> occurs if the heart suddenly can't pump ... to the body. The most common cause of cardiogenic <span class="hlt">shock</span> is damage to the heart muscle from a ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22365443','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22365443"><span id="translatedtitle">Particle energization during solar maximum: Diffusive <span class="hlt">shock</span> acceleration at multiple <span class="hlt">shocks</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Neergaard Parker, L.; Zank, G. P.</p> <p>2014-08-01</p> <p>We present a model for the acceleration of particles at multiple <span class="hlt">shocks</span> using an approach related to box models. A distribution of particles is diffusively accelerated inside the box while simultaneously experiencing decompression through adiabatic expansion and losses from the convection and diffusion of particles out of the box by either the method used in Melrose and Pope and Pope and Melrose or by the approach introduced in Zank et al. where we solve the transport equation by a method analogous to operator splitting. The second method incorporates the additional loss terms of convection and diffusion and allows for the use of a variable time between <span class="hlt">shocks</span>. We use a maximum injection energy (E{sub max}) appropriate for quasi-<span class="hlt">parallel</span> and quasi-perpendicular <span class="hlt">shocks</span>. We provide a preliminary application of the diffusive acceleration of particles by multiple <span class="hlt">shocks</span> with frequencies appropriate for solar maximum.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016cosp...41E1388N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016cosp...41E1388N"><span id="translatedtitle">Colliding Two <span class="hlt">Shocks</span>: 1-D full Particle-in-Cell Simulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nakanotani, Masaru; Hada, T.; Matsukiyo, Shuichi; Mazelle, Christian</p> <p>2016-07-01</p> <p><span class="hlt">Shock-shock</span> interactions occur on various places in space and the interaction can produce high energy particles. A coronal mass ejection driven <span class="hlt">shock</span> can collide with the Earth's bow <span class="hlt">shock</span> [Hietala et al., 2011]. This study reported that ions are accelerated by the first Fermi acceleration between the two <span class="hlt">shocks</span> before the collision. An electron acceleration through an interplanetary <span class="hlt">shock</span>-Earth's bow <span class="hlt">shock</span> interaction was also reported [Terasawa et al., 1997]. <span class="hlt">Shock-shock</span> interactions can occur in astrophysical phenomena as well as in the heliosphere. For example, a young supernova <span class="hlt">shock</span> can collide with the wind termination <span class="hlt">shock</span> of a massive star if they are close to each other [Bykov et al., 2013]. Although hybrid simulations (ions and electrons treated as super-particles and mass-less fluid, respectively) were carried out to understand the kinetic nature of a <span class="hlt">shock-shock</span> interaction [Cargill et al., 1986], hybrid simulations cannot resolve electron dynamics and non-thermal electrons. We, therefore, use one-dimensional full particle-in-cell (PIC) simulations to investigate a <span class="hlt">shock-shock</span> interaction in which two <span class="hlt">shocks</span> collide head-on. In a case of quasi-perpendicular <span class="hlt">shocks</span>, electrons are accelerated by the mirror reflection between the two <span class="hlt">shocks</span> before the collision (Fermi acceleration). On the other hand, because ions cannot go back upstream, the electron acceleration mechanism does not occur for ions. In a case of quasi-<span class="hlt">parallel</span> <span class="hlt">shocks</span>, ions can go back upstream and are accelerated at the <span class="hlt">shocks</span>. The accelerated ions have great effect on the <span class="hlt">shock</span> structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19810014880','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19810014880"><span id="translatedtitle">Kinetic theory and turbulent discontinuities. [<span class="hlt">shock</span> tube flow</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Johnson, J. A., III; I, L.; Li, Y.; Ramaian, R.; Santigo, J. P.</p> <p>1981-01-01</p> <p><span class="hlt">Shock</span> tube discontinuities were used to test and extend a kinetic theory of turbulence. In <span class="hlt">shock</span> wave and contact surface fluctuations, coherent phenomena were found which provide new support for the microscopic nonempirical approach to turbulent systems, especially those with boundary <span class="hlt">layer</span>-like instabilities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.7709B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.7709B"><span id="translatedtitle">Foreshocks ahead of interplanetary <span class="hlt">shocks</span> observed by STEREO.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Blanco-Cano, Xochitl; Kajdic, Primoz; Russell, Christopher T.; Jian, Lan K.; Luhmann, Janet G.; Aguilar-Rodriguez, Ernesto</p> <p>2015-04-01</p> <p>Interplanetary (IP) <span class="hlt">shocks</span> can be driven in the solar wind by coronal mass ejections and stream interactions. <span class="hlt">Shocks</span> can perturb large extensions of the heliosphere. In this work we study <span class="hlt">shocks</span> observed by STEREO during the years 2007-2014. During this period IP <span class="hlt">shocks</span> had Mach numbers MMs ~1.1-4, and the majority were quasi-perpendicular (θBn > 45° ) at the time of spacecraft crossing. We analyze wave properties in the foreshock regions that preced the <span class="hlt">shocks</span>. We find that when the <span class="hlt">shock</span> is very oblique with angle θBn > 60° a short region of the upstream side is permeated by whistler waves with frequency f~ 1 Hz. For some less oblique <span class="hlt">shocks</span> (60° > θBn > 45° ), whistlers appear close to the <span class="hlt">shocks</span>, and wave spectra show two extra peaks, with frequencies f~10-1, 10-2 Hz. The origin of these two wave components may be explained in terms of whistlers propagating from adjacent regions of the <span class="hlt">shock</span>, or by local instabilities. When the <span class="hlt">shock</span> is quasi-<span class="hlt">parallel</span> (θBn</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DPPNO7010N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DPPNO7010N"><span id="translatedtitle">Investigating <span class="hlt">shock</span>-driven Richtmyer-Meshkov ripple evolution before and after re-<span class="hlt">shock</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nagel, S. R.; Huntington, C. M.; MacLaren, S. A.; Raman, K. S.; Baumann, T.; Benedetti, L. R.; Doane, D. M.; Islam, T. S.; Felker, S.; Holder, J. P.; Seugling, R. M.; Wang, P.; Zhou, Y. K.; Doss, F. W.; Flippo, K. A.; Perry, T. S.</p> <p>2015-11-01</p> <p>Late-time Rayleigh-Taylor/Richtmyer-Meshkov(RM) ripple growth in an opposing-<span class="hlt">shock</span> geometry is investigated using x-ray area backlit imaging of a <span class="hlt">shock</span>-tube with indirectly driven <span class="hlt">shocks</span>. The <span class="hlt">shocks</span> are driven from opposing sides of the tube. The ablator <span class="hlt">layer</span> on one side has pre-imposed ripples in the form of a sine wave with two amplitudes and a single wavelength. This ablator includes an opaque tracer <span class="hlt">layer</span> that is used to track the perturbed interface as it is driven into a lower density foam. The ablator on the opposing side of the tube is flat, and is used to launch the <span class="hlt">shock</span> that re-<span class="hlt">shocks</span> the rippled interface. A large-area backlighter and gated x-ray radiography is used to capture images at different times during the RM instability growth. Here, first measurements obtained with this experimental platform at the NIF, including the optimization of the platform are presented. The RM ripple evolution before and after re-<span class="hlt">shock</span>, including a possible loss of initial conditions are, also discussed. The data that informs the codes is compared to simulation results Work supported by U.S. Department of Energy under Contract DE- AC52-06NA27279. LLNL-ABS-674941.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/106430','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/106430"><span id="translatedtitle"><span class="hlt">Parallel</span> rendering techniques for massively <span class="hlt">parallel</span> visualization</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hansen, C.; Krogh, M.; Painter, J.</p> <p>1995-07-01</p> <p>As the resolution of simulation models increases, scientific visualization algorithms which take advantage of the large memory. and <span class="hlt">parallelism</span> of Massively <span class="hlt">Parallel</span> Processors (MPPs) are becoming increasingly important. For large applications rendering on the MPP tends to be preferable to rendering on a graphics workstation due to the MPP`s abundant resources: memory, disk, and numerous processors. The challenge becomes developing algorithms that can exploit these resources while minimizing overhead, typically communication costs. This paper will describe recent efforts in <span class="hlt">parallel</span> rendering for polygonal primitives as well as <span class="hlt">parallel</span> volumetric techniques. This paper presents rendering algorithms, developed for massively <span class="hlt">parallel</span> processors (MPPs), for polygonal, spheres, and volumetric data. The polygon algorithm uses a data <span class="hlt">parallel</span> approach whereas the sphere and volume render use a MIMD approach. Implementations for these algorithms are presented for the Thinking Ma.chines Corporation CM-5 MPP.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012HEDP....8..161V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012HEDP....8..161V"><span id="translatedtitle">Simulating radiative <span class="hlt">shocks</span> in nozzle <span class="hlt">shock</span> tubes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>van der Holst, B.; Tóth, G.; Sokolov, I. V.; Daldorff, L. K. S.; Powell, K. G.; Drake, R. P.</p> <p>2012-06-01</p> <p>We use the recently developed Center for Radiative <span class="hlt">Shock</span> Hydrodynamics (CRASH) code to numerically simulate laser-driven radiative <span class="hlt">shock</span> experiments. These <span class="hlt">shocks</span> are launched by an ablated beryllium disk and are driven down xenon-filled plastic tubes. The simulations are initialized by the two-dimensional version of the Lagrangian Hyades code which is used to evaluate the laser energy deposition during the first 1.1 ns. Later times are calculated with the CRASH code. CRASH solves for the multi-material hydrodynamics with separate electron and ion temperatures on an Eulerian block-adaptive-mesh and includes a multi-group flux-limited radiation diffusion and electron thermal heat conduction. The goal of the present paper is to demonstrate the capability to simulate radiative <span class="hlt">shocks</span> of essentially three-dimensional experimental configurations, such as circular and elliptical nozzles. We show that the compound <span class="hlt">shock</span> structure of the primary and wall <span class="hlt">shock</span> is captured and verify that the <span class="hlt">shock</span> properties are consistent with order-of-magnitude estimates. The synthetic radiographs produced can be used for comparison with future nozzle experiments at high-energy-density laser facilities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5090912','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5090912"><span id="translatedtitle"><span class="hlt">Parallel</span> algorithms and architectures</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Albrecht, A.; Jung, H.; Mehlhorn, K.</p> <p>1987-01-01</p> <p>Contents of this book are the following: Preparata: Deterministic simulation of idealized <span class="hlt">parallel</span> computers on more realistic ones; Convex hull of randomly chosen points from a polytope; Dataflow computing; <span class="hlt">Parallel</span> in sequence; Towards the architecture of an elementary cortical processor; <span class="hlt">Parallel</span> algorithms and static analysis of <span class="hlt">parallel</span> programs; <span class="hlt">Parallel</span> processing of combinatorial search; Communications; An O(nlogn) cost <span class="hlt">parallel</span> algorithms for the single function coarsest partition problem; Systolic algorithms for computing the visibility polygon and triangulation of a polygonal region; and RELACS - A recursive layout computing system. <span class="hlt">Parallel</span> linear conflict-free subtree access.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1712474B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1712474B"><span id="translatedtitle"><span class="hlt">Shock</span> Acceleration of Electrons: The Role of Mach Number and <span class="hlt">Shock</span> Surface Fluctuations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Burgess, David; Haynes, Christopher; Gingell, Peter; Hellinger, Petr</p> <p>2015-04-01</p> <p>Energetic electrons are a common feature of interplanetary <span class="hlt">shocks</span> and planetary bow <span class="hlt">shocks</span>, and they are invoked as a key component of models of nonthermal radio emission, such as solar radio bursts and radio emission in the outer heliosphere. A simulation study is carried out of electron acceleration for quasi-perpendicular <span class="hlt">shocks</span>, typical of the <span class="hlt">shocks</span> in the solar wind. Two and three-dimensional self-consistent hybrid simulations of quasi-perpendicular <span class="hlt">shocks</span> provide the electric and magnetic fields in which test particle electrons are followed. A range of different Mach numbers and <span class="hlt">shock</span> normal angles are investigated. When the Mach number is low, the results agree with theory assuming magnetic moment conserving reflection, with electron energy gains of a factor only 2 to 3. For high Mach numbers, i.e., super-critical, the <span class="hlt">shock</span> front has a dynamic rippled character. In this case the electrons can suffer scattering in the ion-scale turbulence within the <span class="hlt">shock</span> <span class="hlt">layer</span>, producing higher energy gains and some modification of the loss-cone distribution functions predicted by magnetic moment conservation. In addition, acceleration to high energies is present over a wider range of <span class="hlt">shock</span> normal angles. Distribution functions for reflected and transmitted electrons are computed based on initial upstream kappa distributions similar to the solar wind electron distribution, allowing quantitative comparisons with observations. In addition, the impact of upstream turbulence on the structure of low Mach number <span class="hlt">shocks</span> is examined, in order to investigate whether such <span class="hlt">shocks</span> can also produce efficient acceleration due to additional electron scattering.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003PhDT........31J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003PhDT........31J"><span id="translatedtitle">Mixing and <span class="hlt">shocks</span> in geophysical shallow water models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jacobson, Tivon</p> <p></p> <p>In the first section, a reduced two-<span class="hlt">layer</span> shallow water model for fluid mixing is described. The model is a nonlinear hyperbolic quasilinear system of partial differential equations, derived by taking the limit as the upper <span class="hlt">layer</span> becomes infinitely deep. It resembles the shallow water equations, but with an active buoyancy. Fluid entrainment is supposed to occur from the upper <span class="hlt">layer</span> to the lower. Several physically motivated closures are proposed, including a robust closure based on maximizing a mixing entropy (also defined and derived) at <span class="hlt">shocks</span>. The structure of <span class="hlt">shock</span> solutions is examined. The Riemann problem is solved by setting the <span class="hlt">shock</span> speed to maximize the production of mixing entropy. <span class="hlt">Shock</span>-resolving finite-volume numerical models are presented with and without topographic forcing. Explicit <span class="hlt">shock</span> tracking is required for strong <span class="hlt">shocks</span>. The constraint that turbulent energy production be positive is considered. The model has geophysical applications in studying the dynamics of dense sill overflows in the ocean. The second section discusses stationary <span class="hlt">shocks</span> of the shallow water equations in a reentrant rotating channel with wind stress and topography. Asymptotic predictions for the <span class="hlt">shock</span> location, strength, and associated energy dissipation are developed by taking the topographic perturbation to be small. The scaling arguments for the asymptotics are developed by demanding integrated energy and momentum balance, with the result that the free surface perturbation is of the order of the square root of the topographic perturbation. <span class="hlt">Shock</span> formation requires that linear waves be nondispersive, which sets a solvability condition on the mean flow and which leads to a class of generalized Kelvin waves. Two-dimensional <span class="hlt">shock</span>-resolving numerical simulations validate the asymptotic expressions and demonstrate the presence of stationary separated flow <span class="hlt">shocks</span> in some cases. Geophysical applications are considered. Overview sections on <span class="hlt">shock</span>-resolving numerical methods</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120009629','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120009629"><span id="translatedtitle">Electromagnetic Whistler Precursors at Supercritical Interplanetary <span class="hlt">Shocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wilson, L. B., III</p> <p>2012-01-01</p> <p>We present observations of electromagnetic precursor waves, identified as whistler mode waves, at supercritical interplanetary <span class="hlt">shocks</span> using the Wind search coil magnetometer. The precursors propagate obliquely with respect to the local magnetic field, <span class="hlt">shock</span> normal vector, solar wind velocity, and they are not phase standing structures. All are right-hand polarized with respect to the magnetic field (spacecraft frame), and all but one are right-hand polarized with respect to the <span class="hlt">shock</span> normal vector in the normal incidence frame. Particle distributions show signatures of specularly reflected gyrating ions, which may be a source of free energy for the observed modes. In one event, we simultaneously observe perpendicular ion heating and <span class="hlt">parallel</span> electron acceleration, consistent with wave heating/acceleration due to these waves.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19750047899&hterms=metamorphism&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dmetamorphism','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19750047899&hterms=metamorphism&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dmetamorphism"><span id="translatedtitle">Experimental <span class="hlt">shock</span> metamorphism of maximum microcline</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Robertson, P. B.</p> <p>1975-01-01</p> <p>A series of recovery experiments are conducted to study the behavior of single-crystal perthitic maximum microcline <span class="hlt">shock</span>-loaded to a peak pressure of 417 kbar. Microcline is found to deform in a manner similar to quartz and other alkali feldspars. It is observed that <span class="hlt">shock</span>-induced cleavages occur initially at or slightly below the Hugoniot elastic limit (60-85 kbar), that <span class="hlt">shock</span>-induced rather than thermal disordering begins above the Hugoniot elastic limit, and that all types of planar elements form <span class="hlt">parallel</span> to crystallographic planes of low Miller indices. When increasing pressure, it is found that bulk density, refractive indices, and birefringence of the recovered material decrease and approach diaplectic glass values, whereas disappearance and weakening of reflections in Debye-Sherrer patterns are due to disordering of the feldspar lattice.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <center> <div class="footer-extlink text-muted"><small>Some links on this page may take you to non-federal websites. 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