Science.gov

Sample records for compressive shock wave

  1. Failure waves in shock-compressed glasses

    NASA Astrophysics Data System (ADS)

    Kanel, Gennady I.

    2005-07-01

    The failure wave is a network of cracks that are nucleated on the surface and propagate into the elastically stressed body. It is a mode of catastrophic fracture in an elastically stressed media whose relevance is not limited to impact events. In the presentation, main properties of the failure waves are summarized and discussed. It has been shown that the failure wave is really a wave process which is characterized by small increase of the longitudinal stress and corresponding increments of the particle velocity and the density. The propagation velocity of the failure wave is less than the sound speed; it is not directly related to the compressibility but is determined by the crack growth speed. Transformation of elastic compression wave followed by the failure wave in a thick glass plate into typical two-wave configuration in a pile of thin glass plates confirms crucial role of the surfaces. The latter, as well as specific kinematics of the process distinguishes the failure wave from a time-dependent inelastic compressive behavior of brittle materials. The failure wave is steady if the stress state ahead of it is supported unchanging. Mechanism of this self-supporting propagation of compressive fracture is not quite clear as yet. On the other hand, collected data about its kinematics allow formulating phenomenological models of the phenomenon. In some sense the process is similar to the diffusion of cracks from a source on the glass surface. However, the diffusion-like models contradict to observed steady propagation of the failure wave. Analogy with a subsonic combustion wave looks more fruitful. Computer simulations based on the phenomenological combustion-like model reproduces well all kinematical aspects of the phenomenon.

  2. Intense shock waves and shock-compressed gas flows in the channels of rail accelerators

    NASA Astrophysics Data System (ADS)

    Bobashev, S. V.; Zhukov, B. G.; Kurakin, R. O.; Ponyaev, S. A.; Reznikov, B. I.; Tverdokhlebov, K. V.

    2015-01-01

    Shock wave generation and shock-compressed gas flows attendant on the acceleration of an striker-free plasma piston in the channels of electromagnetic rail accelerators (railguns) are studied. Experiments are carried out in channels filled with helium or argon to an initial pressure of 25-500 Torr. At a pressure of 25 Torr, Mach numbers equal 32 in argon and 16 in helium. It is found that with the initial currents and gas initial densities in the channels being the same, the shock wave velocities in both gases almost coincide. Unlike standard shock tubes, a high electric field (up to 300 V/cm) present in the channel governs the motion of a shock-compressed layer. Once the charged particle concentration behind the shock wave becomes sufficiently high, the field causes part of the discharge current to pass through the shock-compressed layer. As a result, the glow of the layer becomes much more intense.

  3. Energetic Particle Transport in Strong Compressive Wave Turbulence Near Shocks

    SciTech Connect

    Le Roux, J.A.; Zank, G.P.; Li, G.; Webb, G.M.

    2005-08-01

    Strong interplanetary coronal mass ejection driven shocks are often accompanied by high levels of low frequency compressive wave turbulence. This might require a non-linear kinetic theory approach to properly describe energetic particle transport in their vicinity. We present a non-linear diffusive kinetic theory for suprathermal particle transport and stochastic acceleration along the background magnetic field in strong compressive dynamic wave turbulence to which small-scale Alfven waves are coupled. Our theory shows that the standard cosmic-ray transport equation must be revised for low suprathermal particle energies to accommodate fundamental changes in spatial diffusion (standard diffusion becomes turbulent diffusion) as well as modifications to particle convection, and adiabatic energy changes. In addition, a momentum diffusion term, which generates accelerated suprathermal particle spectra with a hard power law, must be added. Such effective first stage acceleration possibly leads to efficient injection of particles into second stage diffusive shock acceleration as described by standard theory.

  4. A study on compressive shock wave propagation in metallic foams

    NASA Astrophysics Data System (ADS)

    Wang, Zhihua; Zhang, Yifen; Ren, Huilan; Zhao, Longmao

    2010-02-01

    Metallic foam can dissipate a large amount of energy due to its relatively long stress plateau, which makes it widely applicable in the design of structural crashworthiness. However, in some experimental studies, stress enhancement has been observed when the specimens are subjected to intense impact loads, leading to severe damage to the objects being protected. This paper studies this phenomenon on a 2D mass-spring-bar model. With the model, a constitutive relationship of metal foam and corresponding loading and unloading criteria are presented; a nonlinear kinematics equilibrium equation is derived, where an explicit integration algorithm is used to calculate the characteristic of the compressive shock wave propagation within the metallic foam; the effect of heterogeneous distribution of foam microstructures on the shock wave features is also included. The results reveal that under low impact pulses, considerable energy is dissipated during the progressive collapse of foam cells, which then reduces the crush of objects. When the pulse is sufficiently high, on the other hand, stress enhancement may take place, especially in the heterogeneous foams, where high peak stresses usually occur. The characteristics of compressive shock wave propagation in the foam and the magnitude and location of the peak stress produced are strongly dependent on the mechanical properties of the foam material, amplitude and period of the pulse, as well as the homogeneity of the microstructures. This research provides valuable insight into the reliability of the metallic foams used as a protective structure.

  5. Experimental Results on Shock-Wave Interaction on Compression Ramps

    NASA Astrophysics Data System (ADS)

    Passaro, A.; Fantoni, G.; Biagioni, L.; Cardone, G.

    2005-02-01

    A set of new experimental tests was carried out with intrusive and non-intrusive measurements related to Shock-Wave Boundary-Layer Interaction (SWBLI) on a 15 deg compression ramp model in a Mach 6 flow with total enthalpy of 1.8-2.5 MJ/kg. The facility was the modified High Enthalpy Arc-heated Tunnel at Alta, Pisa, Italy, with improved performance and diagnostics, in order to provide good control on the actual properties of the tunnel flow. The model shape and test conditions were the same of the previous test campaign carried out during the FESTIP programme. The new results confirmed a good agreement between intrusive and non-intrusive measurements and were also compared with success with numerical predictions, eventually explaining the discrepancy on wall heat flux that was found on the previous test campaign.

  6. Shock wave compression and metallization of simple molecules

    SciTech Connect

    Ross, M.; Radousky, H.B.

    1988-03-01

    In this paper we combine shock wave studies and metallization of simple molecules in a single overview. The unifying features are provided by the high shock temperatures which lead to a metallic-like state in the rare gases and to dissociation of diatomic molecules. In the case of the rare gases, electronic excitation into the conduction band leads to a metallic-like inert gas state at lower than metallic densities and provides information regarding the closing of the band gap. Diatomic dissociation caused by thermal excitation also leads to a final metallic-like or monatomic state. Ina ddition, shock wave data can provide information concerning the short range intermolecular force of the insulator that can be useful for calculating the metallic phase transition as for example in the case of hydrogen. 69 refs., 36 figs., 2 tabs.

  7. Shock-Wave Compression and Joule-Thomson Expansion

    NASA Astrophysics Data System (ADS)

    Hoover, Wm. G.; Hoover, Carol G.; Travis, Karl P.

    2014-04-01

    Structurally stable atomistic one-dimensional shock waves have long been simulated by injecting fresh cool particles and extracting old hot particles at opposite ends of a simulation box. The resulting shock profiles demonstrate tensor temperature, Txx≠Tyy and Maxwell's delayed response, with stress lagging strain rate and heat flux lagging temperature gradient. Here this same geometry, supplemented by a short-ranged external "plug" field, is used to simulate steady Joule-Kelvin throttling flow of hot dense fluid through a porous plug, producing a dilute and cooler product fluid.

  8. Shock-wave compression and Joule-Thomson expansion.

    PubMed

    Hoover, Wm G; Hoover, Carol G; Travis, Karl P

    2014-04-11

    Structurally stable atomistic one-dimensional shock waves have long been simulated by injecting fresh cool particles and extracting old hot particles at opposite ends of a simulation box. The resulting shock profiles demonstrate tensor temperature, Txx≠Tyy and Maxwell's delayed response, with stress lagging strain rate and heat flux lagging temperature gradient. Here this same geometry, supplemented by a short-ranged external "plug" field, is used to simulate steady Joule-Kelvin throttling flow of hot dense fluid through a porous plug, producing a dilute and cooler product fluid.

  9. Shock formation and the ideal shape of ramp compression waves

    SciTech Connect

    Swift, D C; Kraus, R G; Loomis, E; Hicks, D G; McNaney, J M; Johnson, R P

    2008-05-29

    We derive expressions for shock formation based on the local curvature of the flow characteristics during dynamic compression. Given a specific ramp adiabat, calculated for instance from the equation of state for a substance, the ideal nonlinear shape for an applied ramp loading history can be determined. We discuss the region affected by lateral release, which can be presented in compact form for the ideal loading history. Example calculations are given for representative metals and plastic ablators. Continuum dynamics (hydrocode) simulations were in good agreement with the algebraic forms. Example applications are presented for several classes of laser-loading experiment, identifying conditions where shocks are desired but not formed, and where long duration ramps are desired.

  10. Evolutions of elastic-plastic shock compression waves in different materials

    NASA Astrophysics Data System (ADS)

    Kanel, G. I.; Zaretsky, E. B.; Razorenov, S. V.; Savinykh, A. S.; Garkushin, G. V.

    2017-01-01

    In the paper, we discuss such unexpected features in the wave evolution in solids as a departure from self-similar development of the wave process which is accompanied with apparent sub-sonic wave propagation, changes of shape of elastic precursor wave as a result of variations in the material structure and the temperature, unexpected peculiarities of reflection of elastic-plastic waves from free surface, effects of internal friction at shock compression of glasses and some other effects.

  11. Shockless and shock wave compression of ballistic gel to 1.3 GPa

    NASA Astrophysics Data System (ADS)

    Toyoda, Y.; Gupta, Y. M.

    2014-10-01

    Plate impact experiments were conducted to determine the dynamic compression response of two ballistic gel concentrations (10 wt. % and 20 wt. %) subjected to uniaxial strain loading to 1.3 GPa. Shockless and shock wave compression of gel samples was achieved through flyer plate impacts on fused silica and z-cut quartz plates, respectively, placed ahead of the samples. Laser interferometry was used to measure the input compression wave profile and the propagated wave profile in each experiment. Using established wave analysis methods, the longitudinal stress-density compression results were obtained for each type of loading. The 20 wt. % gel showed a stiffer compression response than the 10 wt. % gel; the difference corresponded to the gel properties at ambient conditions. The shockless experiments provided both the loading paths and the peak states for this type of loading. Although the differences were small, the peak states achieved in shockless compression were below the shock wave (Hugoniot) data for both gel concentrations. The shockless compression results presented here are the first such results on gels, and provide the gel response at loading rates that are intermediate between the shock wave response and lower loading rate response. As such, they are expected to be useful for incorporating the dynamic compression response of gels in numerical simulations of impact phenomena.

  12. Assessment of high-resolution methods for numerical simulations of compressible turbulence with shock waves

    SciTech Connect

    Johnsen, Eric Larsson, Johan Bhagatwala, Ankit V.; Cabot, William H.; Moin, Parviz; Olson, Britton J.; Rawat, Pradeep S.; Shankar, Santhosh K.; Sjoegreen, Bjoern; Yee, H.C.; Zhong Xiaolin; Lele, Sanjiva K.

    2010-02-20

    Flows in which shock waves and turbulence are present and interact dynamically occur in a wide range of applications, including inertial confinement fusion, supernovae explosion, and scramjet propulsion. Accurate simulations of such problems are challenging because of the contradictory requirements of numerical methods used to simulate turbulence, which must minimize any numerical dissipation that would otherwise overwhelm the small scales, and shock-capturing schemes, which introduce numerical dissipation to stabilize the solution. The objective of the present work is to evaluate the performance of several numerical methods capable of simultaneously handling turbulence and shock waves. A comprehensive range of high-resolution methods (WENO, hybrid WENO/central difference, artificial diffusivity, adaptive characteristic-based filter, and shock fitting) and suite of test cases (Taylor-Green vortex, Shu-Osher problem, shock-vorticity/entropy wave interaction, Noh problem, compressible isotropic turbulence) relevant to problems with shocks and turbulence are considered. The results indicate that the WENO methods provide sharp shock profiles, but overwhelm the physical dissipation. The hybrid method is minimally dissipative and leads to sharp shocks and well-resolved broadband turbulence, but relies on an appropriate shock sensor. Artificial diffusivity methods in which the artificial bulk viscosity is based on the magnitude of the strain-rate tensor resolve vortical structures well but damp dilatational modes in compressible turbulence; dilatation-based artificial bulk viscosity methods significantly improve this behavior. For well-defined shocks, the shock fitting approach yields good results.

  13. On the formation of Friedlander waves in a compressed-gas-driven shock tube

    PubMed Central

    Tasissa, Abiy F.; Hautefeuille, Martin; Fitek, John H.; Radovitzky, Raúl A.

    2016-01-01

    Compressed-gas-driven shock tubes have become popular as a laboratory-scale replacement for field blast tests. The well-known initial structure of the Riemann problem eventually evolves into a shock structure thought to resemble a Friedlander wave, although this remains to be demonstrated theoretically. In this paper, we develop a semi-analytical model to predict the key characteristics of pseudo blast waves forming in a shock tube: location where the wave first forms, peak over-pressure, decay time and impulse. The approach is based on combining the solutions of the two different types of wave interactions that arise in the shock tube after the family of rarefaction waves in the Riemann solution interacts with the closed end of the tube. The results of the analytical model are verified against numerical simulations obtained with a finite volume method. The model furnishes a rational approach to relate shock tube parameters to desired blast wave characteristics, and thus constitutes a useful tool for the design of shock tubes for blast testing. PMID:27118888

  14. On the formation of Friedlander waves in a compressed-gas-driven shock tube.

    PubMed

    Tasissa, Abiy F; Hautefeuille, Martin; Fitek, John H; Radovitzky, Raúl A

    2016-02-01

    Compressed-gas-driven shock tubes have become popular as a laboratory-scale replacement for field blast tests. The well-known initial structure of the Riemann problem eventually evolves into a shock structure thought to resemble a Friedlander wave, although this remains to be demonstrated theoretically. In this paper, we develop a semi-analytical model to predict the key characteristics of pseudo blast waves forming in a shock tube: location where the wave first forms, peak over-pressure, decay time and impulse. The approach is based on combining the solutions of the two different types of wave interactions that arise in the shock tube after the family of rarefaction waves in the Riemann solution interacts with the closed end of the tube. The results of the analytical model are verified against numerical simulations obtained with a finite volume method. The model furnishes a rational approach to relate shock tube parameters to desired blast wave characteristics, and thus constitutes a useful tool for the design of shock tubes for blast testing.

  15. Control of shock-wave boundary-layer interactions by bleed in supersonic mixed compression inlets

    NASA Technical Reports Server (NTRS)

    Fukuda, M. K.; Reshotko, E.; Hingst, W. R.

    1975-01-01

    An experimental investigation has been conducted to determine the effect of bleed region geometry and bleed rate on shock wave-boundary layer interactions in an axisymmetric, mixed-compression inlet at a Mach number of 2.5. The full realizable reduction in transformed form factor is obtained by bleeding off about half the incident boundary layer mass flow. Bleeding upstream or downstream of the shock-induced pressure rise is preferable to bleeding across the shock-induced pressure rise. Slanted holes are more effective than normal holes. Two different bleed hole sizes were tested without detectable difference in performance.

  16. Control of shock wave-boundary layer interactions by bleed in supersonic mixed compression inlets

    NASA Technical Reports Server (NTRS)

    Fukuda, M. K.; Hingst, W. G.; Reshotko, E.

    1975-01-01

    An experimental investigation was conducted to determine the effect of bleed on a shock wave-boundary layer 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 layer after a shock wave-boundary layer 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 layer mass flow. More bleeding does not yield further reduction. Bleeding upstream or downstream of the shock-induced pressure rise is preferable to bleeding across the shock-induced pressure rise.

  17. Shock-wave compression of silica gel as a model material for comets

    NASA Astrophysics Data System (ADS)

    Arasuna, Akane; Okuno, Masayuki; Chen, Liliang; Mashimo, Tsutomu; Okudera, Hiroki; Mizukami, Tomoyuki; Arai, Shoji

    2016-07-01

    A shock-wave compression experiment using synthesized silica gel was investigated as a model for a comet impact event on the Earth's surface. The sample shocked at 20.7 GPa showed considerable structural changes, a release of water molecules, and the dehydration of silanol (Si-OH) that led to the formation of a new Si-O-Si network structure containing larger rings (e.g., six-membered ring of SiO4 tetrahedra). The high aftershock temperature at 20.7 GPa, which could be close to 800 °C, influenced the sample structure. However, some silanols, which were presumed to be the mutually hydrogen-bonded silanol group, remained at pressures >20.7 GPa. This type of silanol along with a small number of water molecules may remain even after shock compression at 30.9 GPa, although the intermediate structure of the sample recovered was similar to that of silica glass.

  18. Nonstandard Analysis and Shock Wave Jump Conditions in a One-Dimensional Compressible Gas

    SciTech Connect

    Roy S. Baty, F. Farassat, John A. Hargreaves

    2007-05-25

    Nonstandard analysis is a relatively new area of mathematics in which infinitesimal numbers can be defined and manipulated rigorously like real numbers. This report presents a fairly comprehensive tutorial on nonstandard analysis for physicists and engineers with many examples applicable to generalized functions. To demonstrate the power of the subject, the problem of shock wave jump conditions is studied for a one-dimensional compressible gas. It is assumed that the shock thickness occurs on an infinitesimal interval and the jump functions in the thermodynamic and fluid dynamic parameters occur smoothly across this interval. To use conservations laws, smooth pre-distributions of the Dirac delta measure are applied whose supports are contained within the shock thickness. Furthermore, smooth pre-distributions of the Heaviside function are applied which vary from zero to one across the shock wave. It is shown that if the equations of motion are expressed in nonconservative form then the relationships between the jump functions for the flow parameters may be found unambiguously. The analysis yields the classical Rankine-Hugoniot jump conditions for an inviscid shock wave. Moreover, non-monotonic entropy jump conditions are obtained for both inviscid and viscous flows. The report shows that products of generalized functions may be defined consistently using nonstandard analysis; however, physically meaningful products of generalized functions must be determined from the physics of the problem and not the mathematical form of the governing equations.

  19. Nonstandard Analysis and Shock Wave Jump Conditions in a One-Dimensional Compressible Gas

    NASA Technical Reports Server (NTRS)

    Baty, Roy S.; Farassat, Fereidoun; Hargreaves, John

    2007-01-01

    Nonstandard analysis is a relatively new area of mathematics in which infinitesimal numbers can be defined and manipulated rigorously like real numbers. This report presents a fairly comprehensive tutorial on nonstandard analysis for physicists and engineers with many examples applicable to generalized functions. To demonstrate the power of the subject, the problem of shock wave jump conditions is studied for a one-dimensional compressible gas. It is assumed that the shock thickness occurs on an infinitesimal interval and the jump functions in the thermodynamic and fluid dynamic parameters occur smoothly across this interval. To use conservations laws, smooth pre-distributions of the Dirac delta measure are applied whose supports are contained within the shock thickness. Furthermore, smooth pre-distributions of the Heaviside function are applied which vary from zero to one across the shock wave. It is shown that if the equations of motion are expressed in nonconservative form then the relationships between the jump functions for the flow parameters may be found unambiguously. The analysis yields the classical Rankine-Hugoniot jump conditions for an inviscid shock wave. Moreover, non-monotonic entropy jump conditions are obtained for both inviscid and viscous flows. The report shows that products of generalized functions may be defined consistently using nonstandard analysis; however, physically meaningful products of generalized functions must be determined from the physics of the problem and not the mathematical form of the governing equations.

  20. Shock compression of precompressed deuterium

    SciTech Connect

    Armstrong, M R; Crowhurst, J C; Zaug, J M; Bastea, S; Goncharov, A F; Militzer, B

    2011-07-31

    Here we report quasi-isentropic dynamic compression and thermodynamic characterization of solid, precompressed deuterium over an ultrafast time scale (< 100 ps) and a microscopic length scale (< 1 {micro}m). We further report a fast transition in shock wave compressed solid deuterium that is consistent with the ramp to shock transition, with a time scale of less than 10 ps. These results suggest that high-density dynamic compression of hydrogen may be possible on microscopic length scales.

  1. Boundaries of the ambiguity area upon reflection of compression shock waves

    NASA Astrophysics Data System (ADS)

    Bulat, P. V.; Upyrev, V. V.

    2016-01-01

    Oblique shock waves can be reflected from hard walls, the axis, or the plane of symmetry, as well as from other counterpropagating shock waves with the formation of regular and Mach shock wave configurations. The specific form of shock wave structures is determined by the parameters of the problem: Mach number and intensity of incident shock waves. On the plane of parameters, there exists an ambiguity area in which laws of conservation admit both the regular and Mach reflection of shock waves. The boundaries of this region have been determined.

  2. Shock compression of nitrobenzene

    NASA Astrophysics Data System (ADS)

    Kozu, Naoshi; Arai, Mitsuru; Tamura, Masamitsu; Fujihisa, Hiroshi; Aoki, Katsutoshi; Yoshida, Masatake; Kondo, Ken-Ichi

    1999-06-01

    The Hugoniot (4 - 30 GPa) and the isotherm (1 - 7 GPa) of nitrobenzene have been investigated by shock and static compression experiments. Nitrobenzene has the most basic structure of nitro aromatic compounds, which are widely used as energetic materials, but nitrobenzene has been considered not to explode in spite of the fact its calculated heat of detonation is similar to TNT, about 1 kcal/g. Explosive plane-wave generators and diamond anvil cell were used for shock and static compression, respectively. The obtained Hugoniot consists of two linear lines, and the kink exists around 10 GPa. The upper line agrees well with the Hugoniot of detonation products calculated by KHT code, so it is expected that nitrobenzene detonates in that area. Nitrobenzene solidifies under 1 GPa of static compression, and the isotherm of solid nitrobenzene was obtained by X-ray diffraction technique. Comparing the Hugoniot and the isotherm, nitrobenzene is in liquid phase under experimented shock condition. From the expected phase diagram, shocked nitrobenzene seems to remain metastable liquid in solid phase region on that diagram.

  3. Evolutions of elastic-plastic shock compression waves in different materials

    NASA Astrophysics Data System (ADS)

    Kanel, G. I.; Zaretsky, E. B.; Razorenov, S. V.; Savinykh, A. S.; Garkushin, G. V.

    2015-06-01

    Measurements of decay of the elastic precursor wave are used to determine the initial plastic strain rate as a function of the stress. Last years we performed large series of such kind experiments with metals and alloys at various temperatures, ceramics and glasses. In course of these measurements we observed several unexpected effects which have not got exhaustive explanations yet. In the presentation, we'll discuss a departure from self-similar development of the wave process which is accompanied with apparent sub-sonic wave propagation, changes of shape of elastic precursor wave as a result of variations in the material structure and the temperature, unexpected peculiarities of reflection of elastic-plastic waves from free surface, effects of internal friction at shock compression of glasses and some other effects. It seems the experimental data contain more information about kinetics of the time-dependent phenomena than we are able to get from their analysis now. Financial support from the Russian Science Foundation via Grant No 14-12-01127 is gratefully acknowledged.

  4. Simulation of systems for shock wave/compression waves damping in technological plants

    NASA Astrophysics Data System (ADS)

    Sumskoi, S. I.; Sverchkov, A. M.; Lisanov, M. V.; Egorov, A. F.

    2016-09-01

    At work of pipeline systems, flow velocity decrease can take place in the pipeline as a result of the pumps stop, the valves shutdown. As a result, compression waves appear in the pipeline systems. These waves can propagate in the pipeline system, leading to its destruction. This phenomenon is called water hammer (water hammer flow). The most dangerous situations occur when the flow is stopped quickly. Such urgent flow cutoff often takes place in an emergency situation when liquid hydrocarbons are being loaded into sea tankers. To prevent environment pollution it is necessary to stop the hydrocarbon loading urgently. The flow in this case is cut off within few seconds. To prevent an increase in pressure in a pipeline system during water hammer flow, special protective systems (pressure relief systems) are installed. The approaches to systems of protection against water hammer (pressure relief systems) modeling are described in this paper. A model of certain pressure relief system is considered. It is shown that in case of an increase in the intensity of hydrocarbons loading at a sea tanker, presence of the pressure relief system allows to organize safe mode of loading.

  5. Diffraction of a shock wave by a compression corner; regular and single Mach reflection

    NASA Technical Reports Server (NTRS)

    Vijayashankar, V. S.; Kutler, P.; Anderson, D.

    1976-01-01

    The two dimensional, time dependent Euler equations which govern the flow field resulting from the injection of a planar shock with a compression corner are solved with initial conditions that result in either regular reflection or single Mach reflection of the incident planar shock. The Euler equations which are hyperbolic are transformed to include the self similarity of the problem. A normalization procedure is employed to align the reflected shock and the Mach stem as computational boundaries to implement the shock fitting procedure. A special floating fitting scheme is developed in conjunction with the method of characteristics to fit the slip surface. The reflected shock, the Mach stem, and the slip surface are all treated as harp discontinuities, thus, resulting in a more accurate description of the inviscid flow field. The resulting numerical solutions are compared with available experimental data and existing first-order, shock-capturing numerical solutions.

  6. Excitation of dayside chorus waves due to magnetic field line compression in response to interplanetary shocks

    NASA Astrophysics Data System (ADS)

    Zhou, Chen; Li, Wen; Thorne, Richard M.; Bortnik, Jacob; Ma, Qianli; An, Xin; Zhang, Xiao-jia; Angelopoulos, Vassilis; Ni, Binbin; Gu, Xudong; Fu, Song; Zhao, Zhengyu

    2015-10-01

    The excitation of magnetospheric whistler-mode chorus in response to interplanetary (IP) shocks is investigated using wave data from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft. As an example, we show a typical chorus wave excitation following an IP shock event that was observed by THEMIS in the postnoon sector near the magnetopause on 3 August 2010. We then analyze characteristic changes during this event and perform a survey of similar events during the period 2008-2014 using the THEMIS and OMNI data set. Our statistical analysis demonstrates that the chorus wave excitation/intensification in response to IP shocks occurs only at high L shells (L > 8) on the dayside. We analyzed the variations of magnetic curvature following the arrival of the IP shock and found that IP shocks lead to more homogeneous background magnetic field configurations in the near-equatorial dayside magnetosphere; and therefore, the threshold of nonlinear chorus wave growth is likely to be reduced, favoring chorus wave generation. Our results provide the observational evidence to support the concept that the geomagnetic field line configuration plays a key role in the excitation of dayside chorus.

  7. A Parametric Approach to Shape Field-Relevant Blast Wave Profiles in Compressed-Gas-Driven Shock Tube

    PubMed Central

    Sundaramurthy, Aravind; Chandra, Namas

    2014-01-01

    Detonation of a high-explosive produces shock-blast wave, shrapnel, and gaseous products. While direct exposure to blast is a concern near the epicenter, shock-blast can affect subjects, even at farther distances. When a pure shock-blast wave encounters the subject, in the absence of shrapnels, fall, or gaseous products the loading is termed as primary blast loading and is the subject of this paper. The wave profile is characterized by blast overpressure, positive time duration, and impulse and called herein as shock-blast wave parameters (SWPs). These parameters in turn are uniquely determined by the strength of high explosive and the distance of the human subjects from the epicenter. The shape and magnitude of the profile determine the severity of injury to the subjects. As shown in some of our recent works (1–3), the profile not only determines the survival of the subjects (e.g., animals) but also the acute and chronic biomechanical injuries along with the following bio-chemical sequelae. It is extremely important to carefully design and operate the shock tube to produce field-relevant SWPs. Furthermore, it is vital to identify and eliminate the artifacts that are inadvertently introduced in the shock-blast profile that may affect the results. In this work, we examine the relationship between shock tube adjustable parameters (SAPs) and SWPs that can be used to control the blast profile; the results can be easily applied to many of the laboratory shock tubes. Further, replication of shock profile (magnitude and shape) can be related to field explosions and can be a standard in comparing results across different laboratories. Forty experiments are carried out by judiciously varying SAPs such as membrane thickness, breech length (66.68–1209.68 mm), measurement location, and type of driver gas (nitrogen, helium). The effects SAPs have on the resulting shock-blast profiles are shown. Also, the shock-blast profiles of a TNT explosion from ConWep software is

  8. Shock compression modeling of metallic single crystals: comparison of finite difference, steady wave, and analytical solutions

    SciTech Connect

    Lloyd, Jeffrey T.; Clayton, John D.; Austin, Ryan A.; McDowell, David L.

    2015-07-10

    Background: The shock response of metallic single crystals can be captured using a micro-mechanical description of the thermoelastic-viscoplastic material response; however, using a such a description within the context of traditional numerical methods may introduce a physical artifacts. Advantages and disadvantages of complex material descriptions, in particular the viscoplastic response, must be framed within approximations introduced by numerical methods. Methods: Three methods of modeling the shock response of metallic single crystals are summarized: finite difference simulations, steady wave simulations, and algebraic solutions of the Rankine-Hugoniot jump conditions. For the former two numerical techniques, a dislocation density based framework describes the rate- and temperature-dependent shear strength on each slip system. For the latter analytical technique, a simple (two-parameter) rate- and temperature-independent linear hardening description is necessarily invoked to enable simultaneous solution of the governing equations. For all models, the same nonlinear thermoelastic energy potential incorporating elastic constants of up to order 3 is applied. Results: Solutions are compared for plate impact of highly symmetric orientations (all three methods) and low symmetry orientations (numerical methods only) of aluminum single crystals shocked to 5 GPa (weak shock regime) and 25 GPa (overdriven regime). Conclusions: For weak shocks, results of the two numerical methods are very similar, regardless of crystallographic orientation. For strong shocks, artificial viscosity affects the finite difference solution, and effects of transverse waves for the lower symmetry orientations not captured by the steady wave method become important. The analytical solution, which can only be applied to highly symmetric orientations, provides reasonable accuracy with regards to prediction of most variables in the final shocked state but, by construction, does not provide insight

  9. Shock compression modeling of metallic single crystals: comparison of finite difference, steady wave, and analytical solutions

    DOE PAGES

    Lloyd, Jeffrey T.; Clayton, John D.; Austin, Ryan A.; ...

    2015-07-10

    Background: The shock response of metallic single crystals can be captured using a micro-mechanical description of the thermoelastic-viscoplastic material response; however, using a such a description within the context of traditional numerical methods may introduce a physical artifacts. Advantages and disadvantages of complex material descriptions, in particular the viscoplastic response, must be framed within approximations introduced by numerical methods. Methods: Three methods of modeling the shock response of metallic single crystals are summarized: finite difference simulations, steady wave simulations, and algebraic solutions of the Rankine-Hugoniot jump conditions. For the former two numerical techniques, a dislocation density based framework describes themore » rate- and temperature-dependent shear strength on each slip system. For the latter analytical technique, a simple (two-parameter) rate- and temperature-independent linear hardening description is necessarily invoked to enable simultaneous solution of the governing equations. For all models, the same nonlinear thermoelastic energy potential incorporating elastic constants of up to order 3 is applied. Results: Solutions are compared for plate impact of highly symmetric orientations (all three methods) and low symmetry orientations (numerical methods only) of aluminum single crystals shocked to 5 GPa (weak shock regime) and 25 GPa (overdriven regime). Conclusions: For weak shocks, results of the two numerical methods are very similar, regardless of crystallographic orientation. For strong shocks, artificial viscosity affects the finite difference solution, and effects of transverse waves for the lower symmetry orientations not captured by the steady wave method become important. The analytical solution, which can only be applied to highly symmetric orientations, provides reasonable accuracy with regards to prediction of most variables in the final shocked state but, by construction, does not provide

  10. Shock compression of liquid hydrazine

    SciTech Connect

    Garcia, B.O.; Chavez, D.J.

    1996-05-01

    Liquid hydrazine (N{sub 2}H{sub 4}) is a propellant used for aerospace propulsion and power systems. Because the propellant modules can be subject to debris impacts during their use, the shock states that can occur in the hydrazine need to be characterized to safely predict its response. Several shock compression experiments have been conducted to investigate the shock detonability of liquid hydrazine; however, the experiments{close_quote} results disagree. Therefore, in this study, we reproduced each experiment numerically to evaluate in detail the shock wave profiles generated in the liquid hydrazine. This paper presents the results of each numerical simulation and compares the results to those obtained in experiment. {copyright} {ital 1996 American Institute of Physics.}

  11. Shock compression of liquid hydrazine

    SciTech Connect

    Garcia, B.O.; Chavez, D.J.

    1995-01-01

    Liquid hydrazine (N{sub 2}H{sub 4}) is a propellant used by the Air Force and NASA for aerospace propulsion and power systems. Because the propellant modules that contain the hydrazine can be subject to debris impacts during their use, the shock states that can occur in the hydrazine need to be characterized to safely predict its response. Several shock compression experiments have been conducted in an attempt to investigate the detonability of liquid hydrazine; however, the experiments results disagree. Therefore, in this study, we reproduced each experiment numerically to evaluate in detail the shock wave profiles generated in the liquid hydrazine. This paper presents the results of each numerical simulation and compares the results to those obtained in experiment. We also present the methodology of our approach, which includes chemical kinetic experiments, chemical equilibrium calculations, and characterization of the equation of state of liquid hydrazine.

  12. Shock waves data for minerals

    NASA Technical Reports Server (NTRS)

    Ahrens, Thomas J.; Johnson, Mary L.

    1994-01-01

    Shock compression of the materials of planetary interiors yields data which upon comparison with density-pressure and density-sound velocity profiles constrain internal composition and temperature. Other important applications of shock wave data and related properties are found in the impact mechanics of terrestrial planets and solid satellites. Shock wave equation of state, shock-induced dynamic yielding and phase transitions, and shock temperature are discussed. In regions where a substantial phase change in the material does not occur, the relationship between the particle velocity, U(sub p), and the shock velocity, U(sub s), is given by U(sub s) = C(sub 0) + S U(sub p), where C(sub 0) is the shock velocity at infinitesimally small particle velocity, or the ambient pressure bulk sound velocity. Numerical values for the shock wave equation of state for minerals and related materials of the solar system are provided.

  13. On the numerical solution of two-dimensional, laminar compressible flows with imbedded shock waves.

    NASA Technical Reports Server (NTRS)

    Goodrich, W. D.; Lamb, J. P.; Bertin, J. J.

    1972-01-01

    The complete, time-dependent Navier-Stokes equations are expressed in conservation form and solved by employing an explicit finite difference numerical technique which incorporates artificial viscosity terms of the form first suggested by Rusanov for numerical stability in the vicinity of shock waves. Surface boundary conditions are developed in a consistent and unique manner through the use of a physically oriented extrapolation procedure. From numerical experimentation an extended range for the explicit stability parameter is established. Also employed is an additional convergence parameter which relates incremental spatial steps. Convergence of the transient solution to a steady state flow was obtained after 400 to 500 time steps.

  14. Shock compression of polyvinyl chloride

    NASA Astrophysics Data System (ADS)

    Neogi, Anupam; Mitra, Nilanjan

    2016-04-01

    This study presents shock compression simulation of atactic polyvinyl chloride (PVC) using ab-initio and classical molecular dynamics. The manuscript also identifies the limits of applicability of classical molecular dynamics based shock compression simulation for PVC. The mechanism of bond dissociation under shock loading and its progression is demonstrated in this manuscript using the density functional theory based molecular dynamics simulations. The rate of dissociation of different bonds at different shock velocities is also presented in this manuscript.

  15. Spall strength and ejecta production of gold under explosively driven shock wave compression

    SciTech Connect

    La Lone, B. M.; Stevens, G. D.; Turley, W. D.; Veeser, L. R.; Holtkamp, D. B.

    2013-12-16

    Explosively driven shock wave experiments were conducted to characterize the spall strength and ejecta production of high-purity cast gold samples. The samples were from 0.75 to 1.84 mm thick and 30 mm in diameter. Peak stresses up to 44 GPa in gold were generated using PBX-9501 high explosive. Sample free surface and ejecta velocities were recorded using photonic Doppler velocimetry techniques. Lithium niobate pins were used to quantify the time dependence of the ejecta density and the total ejected mass. An optical framing camera for time-resolved imaging and a single-image x-ray radiograph were used for additional characterization. Free surface velocities exhibited a range of spall strengths from 1.7 to 2.4 GPa (mean: 2.0 ±0.3 GPa). The pullback signals were faint, minimal ringing was observed in the velocity records, and the spall layer continued to decelerate after first pull back. These results suggest finite tensile strength was present for some time after the initial void formation. Ejecta were observed for every sample with a roughened free surface, and the ejecta density increased with increased surface roughness, which was different in every experiment. The total ejected mass is consistent with the missing mass model.

  16. Shock wave compression of hexagonal-close-packed metal single crystals: Time-dependent, anisotropic elastic-plastic response of beryllium

    SciTech Connect

    Winey, J. M.; Gupta, Y. M.

    2014-07-21

    Understanding and modeling the response of hcp metals to high stress impulsive loading is challenging because the lower crystal symmetry, compared to cubic metals, results in a significantly more complex material response. To gain insight into the inelastic deformation of hcp metals subjected to high dynamic stresses, shock wave compression of single crystals provides a useful approach because different inelastic deformation mechanisms can be examined selectively by shock compression along different crystal orientations. As a representative example, we report, here, on wave propagation simulations for beryllium (Be) single crystals shocked along the c-axis, a-axis, and several low-symmetry directions to peak stresses reaching 7 GPa. The simulations utilized a time-dependent, anisotropic material model that incorporated dislocation dynamics, deformation twinning, and shear cracking based descriptions of inelastic deformation. The simulation results showed good overall agreement with measured wave profiles for all the different crystal orientations examined [Pope and Johnson, J. Appl. Phys. 46, 720 (1975)], including features arising from wave mode coupling due to the highly anisotropic inelastic response of Be. This good agreement demonstrates that the measured profiles can be understood in terms of dislocation slip along basal, prismatic, and pyramidal planes, together with deformation twinning along (101{sup ¯}2) planes. Our results show that the response of shocked Be single crystals involves the simultaneous operation of multiple, distinct inelastic deformation mechanisms for all orientations except the c-axis. For shocked c-axis Be, the measured wave profiles do not provide good discrimination between pyramidal slip and other inelastic deformation mechanisms, such as shear cracking. The findings presented here provide insight into the complex inelastic deformation response of shocked Be single crystals and are expected to be useful for other hcp crystals

  17. Shock compression profiles in ceramics

    SciTech Connect

    Grady, D.E.; Moody, R.L.

    1996-03-01

    An investigation of the shock compression properties of high-strength ceramics has been performed using controlled planar impact techniques. In a typical experimental configuration, a ceramic target disc is held stationary, and it is struck by plates of either a similar ceramic or by plates of a well-characterized metal. All tests were performed using either a single-stage propellant gun or a two-stage light-gas gun. Particle velocity histories were measured with laser velocity interferometry (VISAR) at the interface between the back of the target ceramic and a calibrated VISAR window material. Peak impact stresses achieved in these experiments range from about 3 to 70 GPa. Ceramics tested under shock impact loading include: Al{sub 2}O{sub 3}, AlN, B{sub 4}C, SiC, Si{sub 3}N{sub 4}, TiB{sub 2}, WC and ZrO{sub 2}. This report compiles the VISAR wave profiles and experimental impact parameters within a database-useful for response model development, computational model validation studies, and independent assessment of the physics of dynamic deformation on high-strength, brittle solids.

  18. Analysis of Temperature Measurement at LEAD/LiF Interface Under Shock Wave Compression

    NASA Astrophysics Data System (ADS)

    Chauvin, C.; Hereil, P. L.; Sinatti, F.

    2007-12-01

    Temperature is a fundamental parameter to validate the equation of state. A high-speed three-wavelength pyrometer has been improved at CEG to perform measurements at low temperature (<500 K) at the interface of a lead target and a LiF window at about 8 GPa. Besides, to reduce uncertainties of true temperature of this interface, the use of an emissive layer allows us to increase the emissivity of the shocked surface. The emissivity of the shocked interface is thereby restricted in the 0.9 and 1 range and improves the accuracy of the temperature measurement.

  19. Design and Testing of CO2 Compression Using Supersonic Shock Wave Technology

    SciTech Connect

    Koopman, Aaron

    2015-06-01

    This report summarizes work performed by Ramgen and subcontractors in pursuit of the design and construction of a 10 MW supersonic CO2 compressor and supporting facility. The compressor will demonstrate application of Ramgen’s supersonic compression technology at an industrial scale using CO2 in a closed-loop. The report includes details of early feasibility studies, CFD validation and comparison to experimental data, static test experimental results, compressor and facility design and analyses, and development of aerodynamic tools. A summary of Ramgen's ISC Engine program activity is also included. This program will demonstrate the adaptation of Ramgen's supersonic compression and advanced vortex combustion technology to result in a highly efficient and cost effective alternative to traditional gas turbine engines. The build out of a 1.5 MW test facility to support the engine and associated subcomponent test program is summarized.

  20. The interaction of laser radiation with explosively driven shock wave compressed Xe plasmas

    NASA Astrophysics Data System (ADS)

    Zaporozhets, Yu B.; Mintsev, V. B.; Gryaznov, V. K.; Reinholz, H.; Röpke, G.; Fortov, V. E.

    2016-11-01

    The analysis of the response of dense plasma to electromagnetic waves of moderate intensity can be used as a tool to investigate the validity of the physical models describing the behavior of matter under extreme conditions. Within this work the new experimental data on oblique incidence of polarized electromagnetic wave are presented. The study of polarized reflectivity properties of nonideal xenon plasma was accomplished using laser light at ν las = 2.83 × 1014 s-1 (λ las = 1064 nm) and ν las = 5.66 × 1014 s-1 (λ las = 532 nm). The measurements of polarized reflectivity coefficients of explosively driven dense plasmas have been carried out at incident angles up to θ = 78°. The plasma composition was calculated within a chemical picture. The integration of Maxwell equations to construct the spatial profile of the density of charge carriers of plasmas was based on an interpolation formula for DC conductivity.

  1. FLOW FIELD IN SUPERSONIC MIXED-COMPRESSION INLETS AT ANGLE OF ATTACK USING THE THREE DIMENSIONAL METHOD OF CHARACTERISTICS WITH DISCRETE SHOCK WAVE FITTING

    NASA Technical Reports Server (NTRS)

    Bishop, A. R.

    1994-01-01

    This computer program calculates the flow field in the supersonic portion of a mixed-compression aircraft inlet at non-zero angle of attack. This approach is based on the method of characteristics for steady three-dimensional flow. The results of this program agree with those produced by the two-dimensional method of characteristics when axisymmetric flow fields are calculated. Except in regions of high viscous interaction and boundary layer removal, the results agree well with experimental data obtained for threedimensional flow fields. The flow field in a variety of axisymmetric mixed compression inlets can be calculated using this program. The bow shock wave and the internal shock wave system are calculated using a discrete shock wave fitting procedure. The internal flow field can be calculated either with or without the discrete fitting of the internal shock wave system. The influence of molecular transport can be included in the calculation of the external flow about the forebody and in the calculation of the internal flow when internal shock waves are not discretely fitted. The viscous and thermal diffussion effects are included by treating them as correction terms in the method of characteristics procedure. Dynamic viscosity is represented by Sutherland's law and thermal conductivity is represented as a quadratic function of temperature. The thermodynamic model used is that of a thermally and calorically perfect gas. The program assumes that the cowl lip is contained in a constant plane and that the centerbody contour and cowl contour are smooth and have continuous first partial derivatives. This program cannot calculate subsonic flow, the external flow field if the bow shock wave does not exist entirely around the forebody, or the internal flow field if the bow flow field is injected into the annulus. Input to the program consists of parameters to control execution, to define the geometry, and the vehicle orientation. Output consists of a list of parameters

  2. Uncertainty Assessments of 2D and Axisymmetric Hypersonic Shock Wave - Turbulent Boundary Layer Interaction Simulations at Compression Corners

    NASA Technical Reports Server (NTRS)

    Gnoffo, Peter A.; Berry, Scott A.; VanNorman, John W.

    2011-01-01

    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 shock emanating from a compression corner and interacting with a fully developed turbulent boundary layer 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 shock-turbulent-boundary-layer 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 shock-turbulent-boundary-layer interactions by Roy and Blottner and with more recent computations of MacLean.

  3. Laser-Driven Shock Compression Results on Deuterium

    NASA Astrophysics Data System (ADS)

    Hicks, D. G.; Celliers, P. M.; Collins, G. W.; Eggert, J. H.; Moon, S. J.; Foord, M. E.; Boehly, T. R.; Collins, T. J. B.; Vianello, E.; Jacobs-Perkins, D.; Meyerhofer, D. D.

    2003-10-01

    Laser-driven shock wave experiments have been performed at OMEGA to explore the equation of state of deuterium under double and single shock compression. We have developed a new technique of using a calibrated, high-pressure transparent material, quartz, which has enabled precision optical interferometer measurements of shock velocities. This approach significantly reduces the possibility of systematic error arising from shock unsteadiness. In the double-shock experiments, where quartz is used as a re-shock anvil, the results indicate deuterium has a compressibility that is close to the new SESAME and ab initio models below 1 Mbar but exhibits higher compressibility at larger pressures. In the single-shock, aluminum impedance-match experiments, quartz is used to accurately infer the shock velocity in aluminum; results from these recent experiments will be presented.

  4. Rayleigh-Taylor Shock Waves

    SciTech Connect

    Olson, B J; Cook, A W

    2007-08-30

    Beginning from a state of hydrostatic equilibrium, in which a heavy gas rests atop a light gas in a constant gravitational field, Rayleigh-Taylor instability at the interface will launch a shock wave into the upper fluid. The rising bubbles of lighter fluid act like pistons, compressing the heavier fluid ahead of the fronts and generating shocklets. These shocklets coalesce in multidimensional fashion into a strong normal shock, which increases in strength as it propagates upwards. Large-eddy simulations demonstrate that the shock Mach number increases faster in three dimensions than it does in two dimensions. The generation of shocks via Rayleigh-Taylor instability could have profound implications for astrophysical flows.

  5. Fabrication of graded density impactor via underwater shock wave and quasi-isentropic compression testing at two-stage gas gun facility

    NASA Astrophysics Data System (ADS)

    Sun, Wei; Li, Xiaojie; Hokamoto, Kazuyuki

    2014-12-01

    We show direct evidence that underwater shock wave enables us to bond multithin plates with flat, parallel, and high-strength interfaces, which are key requirements for functionally graded material (also called graded density impactor). This phenomenon is ascribed to the super short duration of the high-speed underwater shock wave, reducing the surface tension, diffusion, evaporation, deposition, and viscous flow of matter. Thin magnesium, aluminum, titanium, copper, and molybdenum foils were welded together and designed with the increase in density. Experimental evidence and numerical simulation show that well bonding between the multilayer structures. Microstructure examinations reveal that the dominant interfacial form shifts from waviness to linearity. Graded density impactor with multilayer structure is proved that can produce quasi-isentropic compression in two-stage gas gun experiment with a designed pressure loading profile, which suggests a feasible method to simulate the conditions we want to study that were previously inaccessible in a precisely controlled laboratory environment.

  6. New Developments in the Physical Chemistry of Shock Compression

    NASA Astrophysics Data System (ADS)

    Dlott, Dana D.

    2011-05-01

    This review discusses new developments in shock compression science with a focus on molecular media. Some basic features of shock and detonation waves, nonlinear excitations that can produce extreme states of high temperature and high pressure, are described. Methods of generating and detecting shock waves are reviewed, especially those using tabletop lasers that can be interfaced with advanced molecular diagnostics. Newer compression methods such as shockless compression and precompression shock that generate states of cold dense molecular matter are discussed. Shock compression creates a metallic form of hydrogen, melts diamond, and makes water a superionic liquid with unique catalytic properties. Our understanding of detonations at the molecular level has improved a great deal as a result of advanced nonequilibrium molecular simulations. Experimental measurements of detailed molecular behavior behind a detonation front might be available soon using femtosecond lasers to produce nanoscale simulated detonation fronts.

  7. When shock waves collide

    SciTech Connect

    Martinez, D.; Hartigan, P.; Frank, A.; Hansen, E.; Yirak, K.; Liao, A. S.; Graham, P.; Foster, J.; Wilde, B.; Blue, B.; Rosen, P.; Farley, D.; Paguio, R.

    2016-06-01

    Supersonic outflows from objects as varied as stellar jets, massive stars, and novae often exhibit multiple shock waves that overlap one another. When the intersection angle between two shock waves exceeds a critical value, the system reconfigures its geometry to create a normal shock known as a Mach stem where the shocks meet. Mach stems are important for interpreting emission-line images of shocked gas because a normal shock produces higher postshock temperatures, and therefore a higher-excitation spectrum than does an oblique shock. In this paper, we summarize the results of a series of numerical simulations and laboratory experiments designed to quantify how Mach stems behave in supersonic plasmas that are the norm in astrophysical flows. The experiments test analytical predictions for critical angles where Mach stems should form, and quantify how Mach stems grow and decay as intersection angles between the incident shock and a surface change. While small Mach stems are destroyed by surface irregularities and subcritical angles, larger ones persist in these situations and can regrow if the intersection angle changes to become more favorable. Furthermore, the experimental and numerical results show that although Mach stems occur only over a limited range of intersection angles and size scales, within these ranges they are relatively robust, and hence are a viable explanation for variable bright knots observed in Hubble Space Telescope images at the intersections of some bow shocks in stellar jets.

  8. When shock waves collide

    DOE PAGES

    Martinez, D.; Hartigan, P.; Frank, A.; ...

    2016-06-01

    Supersonic outflows from objects as varied as stellar jets, massive stars, and novae often exhibit multiple shock waves that overlap one another. When the intersection angle between two shock waves exceeds a critical value, the system reconfigures its geometry to create a normal shock known as a Mach stem where the shocks meet. Mach stems are important for interpreting emission-line images of shocked gas because a normal shock produces higher postshock temperatures, and therefore a higher-excitation spectrum than does an oblique shock. In this paper, we summarize the results of a series of numerical simulations and laboratory experiments designed tomore » quantify how Mach stems behave in supersonic plasmas that are the norm in astrophysical flows. The experiments test analytical predictions for critical angles where Mach stems should form, and quantify how Mach stems grow and decay as intersection angles between the incident shock and a surface change. While small Mach stems are destroyed by surface irregularities and subcritical angles, larger ones persist in these situations and can regrow if the intersection angle changes to become more favorable. Furthermore, the experimental and numerical results show that although Mach stems occur only over a limited range of intersection angles and size scales, within these ranges they are relatively robust, and hence are a viable explanation for variable bright knots observed in Hubble Space Telescope images at the intersections of some bow shocks in stellar jets.« less

  9. Shock and Static Compression of Nitrobenzene

    NASA Astrophysics Data System (ADS)

    Kozu, Naoshi; Arai, Mitsuru; Tamura, Masamitsu; Fujihisa, Hiroshi; Aoki, Katsutoshi; Yoshida, Masatake

    2000-08-01

    The Hugoniot and static compression curve (isotherm) were investigated using explosive plane wave generators and diamond anvil cells, respectively. The obtained Hugoniot from the shock experiments is represented by two linear lines: Us=2.52+1.23 up (0.8shock velocity and the particle velocity in km/s, respectively. A kink exists at around 15 GPa. The line for the higher particle velocities agrees well with the Hugoniot of detonation products calculated by the CHEETAH code. This suggests that nitrobenzene detonates in this range. Under static high pressure over 7 GPa, nitrobenzene undergoes a reaction that is expected to be polymerization. Considering the Hugoniot and the isotherm, it is plausible that shocked nitrobenzene (<15 GPa) is in the liquid state.

  10. The behavior of a compressible turbulent boundary layer in a shock-wave-induced adverse pressure gradient. Ph.D. Thesis - Washington Univ., Seattle, Aug. 1972

    NASA Technical Reports Server (NTRS)

    Rose, W. C.

    1973-01-01

    The results of an experimental investigation of the mean- and fluctuating-flow properties of a compressible turbulent boundary layer in a shock-wave-induced adverse pressure gradient are presented. The turbulent boundary layer developed on the wall of an axially symmetric nozzle and test section whose nominal free-stream Mach number and boundary-layer thickness Reynolds number were 4 and 100,000, respectively. The adverse pressure gradient was induced by an externally generated conical shock 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 layer 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 shock-wave - boundary-layer interaction significantly alters the turbulent mixing characteristics of the boundary layer.

  11. TIMING OF SHOCK WAVES

    DOEpatents

    Tuck, J.L.

    1955-03-01

    This patent relates to means for ascertaining the instant of arrival of a shock wave in an exploslve charge and apparatus utilizing this means to coordinate the timing of two operations involving a short lnterval of time. A pair of spaced electrodes are inserted along the line of an explosive train with a voltage applied there-across which is insufficient to cause discharge. When it is desired to initiate operation of a device at the time the explosive shock wave reaches a particular point on the explosive line, the device having an inherent time delay, the electrodes are located ahead of the point such that the ionization of the area between the electrodes caused by the traveling explosive shock wave sends a signal to initiate operation of the device to cause it to operate at the proper time. The operated device may be photographic equipment consisting of an x-ray illuminating tube.

  12. Shock compression and quasielastic release in tantalum

    SciTech Connect

    Johnson, J.N.; Hixson, R.S.; Tonks, D.L.; Gray, G.T. III

    1993-06-01

    Previous studies of quasielastic release in shock-loaded FCC metals have shown a strong influence of the defect state on the leading edge, or first observable arrival, of release wave, due to large density of pinned dislocation segments behind the shock front, their relatively large pinning separation, and a very short response time as determined by drag coefficient in shock-compressed state. This effect is entirely equivalent to problems associated with elastic moduli determination using ultrasonic methods. This is particularly true for FCC metals, which have an especially low Peierls stress, or inherent lattice resistance, that has little influence in pinning dislocation segments and inhibiting anelastic deformation. BCC metals, on the other hand, have a large Peierls stress that essentially holds dislocation segments in place at low net applied shear stresses and thus allows fully elastic deformation to occur in the complete absence of anelastic behavior. Shock-compression and release experiments have been performed on tantalum (BCC), with the observation that the leading release disturbance is indeed elastic. This conclusion is established by examination of experimental VISAR records taken at the tantalum/sapphire (window) interface in a symmetric-impact experiment which subjects the sample to a peak longitudinal stress of approximately 7.3 GPa, in comparison with characteristic code calculations.

  13. Shock wave interactions with liquid sheets

    NASA Astrophysics Data System (ADS)

    Jeon, H.; Eliasson, V.

    2017-04-01

    Shock wave interactions with a liquid sheet are investigated by impacting planar liquid sheets of varying thicknesses with a planar shock wave. A square frame was designed to hold a rectangular liquid sheet, with a thickness of 5 or 10 mm, using plastic membranes and cotton wires to maintain the planar shape and minimize bulge. The flat liquid sheet, consisting of either water or a cornstarch and water mixture, was suspended in the test section of a shock tube. Incident shock waves with Mach numbers of M_s = 1.34 and 1.46 were considered. A schlieren technique with a high-speed camera was used to visualize the shock wave interaction with the liquid sheets. High-frequency pressure sensors were used to measure wave speed, overpressure, and impulse both upstream and downstream of the liquid sheet. Results showed that no transmitted shock wave could be observed through the liquid sheets, but compression waves induced by the shock-accelerated liquid coalesced into a shock wave farther downstream. A thicker liquid sheet resulted in a lower peak overpressure and impulse, and a cornstarch suspension sheet showed a higher attenuation factor compared to a water sheet.

  14. Micromechanical strength effects in shock compression of solids

    SciTech Connect

    Johnson, J.N.

    1993-06-01

    Time-resolved shock-wave measurements and post-shock recovery have long been used for inferring the underlaying micromechanics controlling high-rate deformation of solids; this requires considerable subjective interpretation. In spite of this, progress has been made in experimentation and theoretical interpretation of the shock-compression/release cycle and some of the results are reviewed here for weak shocks. This cycle involves the elements of the elastic precursor, plastic loading wave, pulse duration, release wave, and post-mortem examination. Those topics are examined, with emphasis on the second and fourth elements. Cu and Ta results show how shock data can be used to determine the transition from deformation mechanism of thermal activation to that of dislocation drag. Release-wave studies indicate that the leading observable release disturbance in fcc metals may not be propagating with the ideal longitudinal elastic-wave speed. 5 figs, 18 refs.

  15. Micromechanical strength effects in shock compression of solids

    SciTech Connect

    Johnson, J.N.

    1993-01-01

    Time-resolved shock-wave measurements and post-shock recovery have long been used for inferring the underlaying micromechanics controlling high-rate deformation of solids; this requires considerable subjective interpretation. In spite of this, progress has been made in experimentation and theoretical interpretation of the shock-compression/release cycle and some of the results are reviewed here for weak shocks. This cycle involves the elements of the elastic precursor, plastic loading wave, pulse duration, release wave, and post-mortem examination. Those topics are examined, with emphasis on the second and fourth elements. Cu and Ta results show how shock data can be used to determine the transition from deformation mechanism of thermal activation to that of dislocation drag. Release-wave studies indicate that the leading observable release disturbance in fcc metals may not be propagating with the ideal longitudinal elastic-wave speed. 5 figs, 18 refs.

  16. Exhaust Nozzle Plume and Shock Wave Interaction

    NASA Technical Reports Server (NTRS)

    Castner, Raymond S.; Elmiligui, Alaa; Cliff, Susan

    2013-01-01

    Fundamental research for sonic boom reduction is needed to quantify the interaction of shock waves generated from the aircraft wing or tail surfaces with the exhaust plume. Both the nozzle exhaust plume shape and the tail shock shape may be affected by an interaction that may alter the vehicle sonic boom signature. The plume and shock interaction was studied using Computational Fluid Dynamics simulation on two types of convergent-divergent nozzles and a simple wedge shock generator. The nozzle plume effects on the lower wedge compression region are evaluated for two- and three-dimensional nozzle plumes. Results show that the compression from the wedge deflects the nozzle plume and shocks form on the deflected lower plume boundary. The sonic boom pressure signature of the wedge is modified by the presence of the plume, and the computational predictions show significant (8 to 15 percent) changes in shock amplitude.

  17. Whistler Waves Associated with Weak Interplanetary Shocks

    NASA Technical Reports Server (NTRS)

    Velez, J. C. Ramirez; Blanco-Cano, X.; Aguilar-Rodriguez, E.; Russell, C. T.; Kajdic, P.; Jian,, L. K.; Luhmann, J. G.

    2012-01-01

    We analyze the properties of 98 weak interplanetary shocks 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 shocks, which on average are high beta shocks (0.2 < Beta < 10). We have compared the waves properties upstream and downstream of the shocks. In the upstream region the waves are mainly circularly polarized, and in most of the cases (approx. 75%) they propagate almost parallel to the ambient magnetic field (<30 deg.). In contrast, the propagation angle with respect to the shock 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 shock. This corresponds to a larger region with upstream whistlers associated with IP shocks than previously reported in the literature. The maximum amplitudes of the waves are observed next to the shock interface, and they decrease as the distance to the shock increases. In most cases the wave propagation direction becomes more aligned with the magnetic field as the distance to the shock increases. These two facts suggest that most of the waves in the upstream region are Landau damping as they move away from the shock. From the analysis we also conclude that it is likely that the generation mechanism of the upstream whistler waves is taking place at the shock 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 shock-normal direction has no preferred direction and varies similarly to

  18. Shock waves: The Maxwell-Cattaneo case.

    PubMed

    Uribe, F J

    2016-03-01

    Several continuum theories for shock waves give rise to a set of differential equations in which the analysis of the underlying vector field can be done using the tools of the theory of dynamical systems. We illustrate the importance of the divergences associated with the vector field by considering the ideas by Maxwell and Cattaneo and apply them to study shock waves in dilute gases. By comparing the predictions of the Maxwell-Cattaneo equations with shock wave experiments we are lead to the following conclusions: (a) For low compressions (low Mach numbers: M) the results from the Maxwell-Cattaneo equations provide profiles that are in fair agreement with the experiments, (b) as the Mach number is increased we find a range of Mach numbers (1.27 ≈ M(1) < M < M(2) ≈ 1.90) such that numerical shock wave solutions to the Maxwell-Cattaneo equations cannot be found, and

  19. Shock Propagation and Instability Structures in Compressed Silica Aerogels

    SciTech Connect

    Howard, W M; Molitoris, J D; DeHaven, M R; Gash, A E; Satcher, J H

    2002-05-30

    We have performed a series of experiments examining shock propagation in low density aerogels. High-pressure ({approx}100 kbar) shock waves are produced by detonating high explosives. Radiography is used to obtain a time sequence imaging of the shocks as they enter and traverse the aerogel. We compress the aerogel by impinging shocks waves on either one or both sides of an aerogel slab. The shock wave initially transmitted to the aerogel is very narrow and flat, but disperses and curves as it propagates. Optical images of the shock front reveal the initial formation of a hot dense region that cools and evolves into a well-defined microstructure. Structures observed in the shock front are examined in the framework of hydrodynamic instabilities generated as the shock traverses the low-density aerogel. The primary features of shock propagation are compared to simulations, which also include modeling the detonation of the high explosive, with a 2-D Arbitrary Lagrange Eulerian hydrodynamics code The code includes a detailed thermochemical equation of state and rate law kinetics. We will present an analysis of the data from the time resolved imaging diagnostics and form a consistent picture of the shock transmission, propagation and instability structure.

  20. Radiative Shock Waves In Emerging Shocks

    NASA Astrophysics Data System (ADS)

    Drake, R. Paul; Doss, F.; Visco, A.

    2011-05-01

    In laboratory experiments we produce radiative shock waves having dense, thin shells. These shocks are similar to shocks emerging from optically thick environments in astrophysics in that they are strongly radiative with optically thick shocked layers and optically thin or intermediate downstream layers through which radiation readily escapes. Examples include shocks breaking out of a Type II supernova (SN) and the radiative reverse shock during the early phases of the SN remnant produced by a red supergiant star. We produce these shocks by driving a low-Z plasma piston (Be) at > 100 km/s into Xe gas at 1.1 atm. pressure. The shocked Xe collapses to > 20 times its initial density. Measurements of structure by radiography and temperature by several methods confirm that the shock wave is strongly radiative. We observe small-scale perturbations in the post-shock layer, modulating the shock and material interfaces. We describe a variation of the Vishniac instability theory of decelerating shocks 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.

  1. An Evaluation of the Compressive Properties of Helmet Pads Pre- and Post-Shock Wave Overpressure Exposure

    DTIC Science & Technology

    2015-08-14

    HELMET PADS HEAD (ANATOMY) TRAUMATIC BRAIN INJURY HELMETS SHOCK TUBES ACH(ADVANCED COMBAT HELMET) U.S...4 Figure 5. RED Head , manufactured by Humanetics and modified by UNL. ................................ 5 Figure 6...Surface pressure sensor locations on the RED Head . ..................................................... 5 Figure 7. External shock tube exit with RED

  2. SPHERICAL SHOCK WAVES IN SOLIDS

    DTIC Science & Technology

    Contents: Introduction-Reasons for Studying Spherical Shock Waves, Physics of Cavity Expansion due to Explosive Impact, General Nature of Shock Waves...Governing Differential Equation of Self-Similar Motion; Application of the Theory of Self-Similar Motion to the Problem of Expansion of a Spherical

  3. Atomistic molecular dynamics simulations of shock compressed quartz

    NASA Astrophysics Data System (ADS)

    Farrow, M. R.; Probert, M. I. J.

    2011-07-01

    Atomistic non-equilibrium molecular dynamics simulations of shock wave compression of quartz have been performed using the so-called BKS semi-empirical potential of van Beest, Kramer, and van Santen [Phys. Rev. B 43, 5068 (1991)], 10.1103/PhysRevB.43.5068 to construct the Hugoniot of quartz. Our scheme mimics the real world experimental set up by using a flyer-plate impactor to initiate the shock wave and is the first shock wave simulation that uses a geometry optimised system of a polar slab in a three-dimensional system employing periodic boundary conditions. Our scheme also includes the relaxation of the surface dipole in the polar quartz slab which is an essential pre-requisite to a stable simulation. The original BKS potential is unsuited to shock wave calculations and so we propose a simple modification. With this modification, we find that our calculated Hugoniot is in good agreement with experimental shock wave data up to 25 GPa, but significantly diverges beyond this point. We conclude that our modified BKS potential is suitable for quartz under representative pressure conditions of the Earth core, but unsuitable for high-pressure shock wave simulations. We also find that the BKS potential incorrectly prefers the β-quartz phase over the α-quartz phase at zero-temperature, and that there is a β → α phase-transition at 6 GPa.

  4. Shock-wave properties of soda-lime glass

    SciTech Connect

    Grady, D.E.; Chhabildas, L.C.

    1996-11-01

    Planar impact experiments and wave profile measurements provided single and double shock equation of state data to 30 GPa. Both compression wave wave profile structure and release wave data were used to infer time-dependent strength and equation of state properties for soda-lime glass.

  5. Isentropic compressive wave generator and method of making same

    DOEpatents

    Barker, L.M.

    An isentropic compressive wave generator and method of making same are disclosed. The wave generator comprises a disk or flat pillow member having component materials of different shock impedances formed in a configuration resulting in a smooth shock impedance gradient over the thickness thereof for interpositioning between an impactor member and a target specimen for producing a shock wave of a smooth predictable rise time. The method of making the pillow member comprises the reduction of the component materials to a powder form and forming the pillow member by sedimentation and compressive techniques.

  6. Shock Wave Structure in Particulate Composites

    NASA Astrophysics Data System (ADS)

    Rauls, Michael; Ravichandran, Guruswami

    2015-06-01

    Shock wave experiments are conducted on a particulate composite consisting of a polymethyl methacrylate (PMMA) matrix reinforced by glass beads. Such a composite with an impedance mismatch of 4.3 closely mimics heterogeneous solids of interest such as concrete and energetic materials. The composite samples are prepared using a compression molding process. The structure and particle velocity rise times of the shocks are examined using forward ballistic experiments. Reverse ballistic experiments are used to track how the interface density influences velocity overshoot above the steady state particle velocity. The effects of particle size (0.1 to 1 mm) and volume fraction of glass beads (30-40%) on the structure of the leading shock wave are investigated. It is observed that the rise time increases with increasing particle size and scales linearly for the range of particle sizes considered here. Results from numerical simulations using CTH are compared with experimental results to gain insights into wave propagation in heterogeneous particulate composites.

  7. Shock compression response of Ti+B reactive powder mixtures

    NASA Astrophysics Data System (ADS)

    Gonzales, M.; Gurumurthy, A.; Kennedy, G. B.; Gokhale, A. M.; Thadhani, N. N.

    2014-05-01

    The shock compression response of Ti+2B (1:2 Ti:B stoichiometric ratio) reactive powder mixtures at ~50% theoretical material density (TMD) is investigated for shock pressures up to 5 GPa to investigate the possible shock-induced chemical reactivity of this highly exothermic mixture. The shock adiabat is produced from instrumented parallel-plate gas-gun impact experiments on encapsulated powders using poly-vinylidene fluoride (PVDF) stress gauges to measure the input and propagated stresses and wave speed in the powder. The shock compression regime is probed from crush-up to full density and onward to assess the potential onset of a shock-induced chemical reaction event in the powder mixture. A series of two-dimensional continuum meso-scale simulations on validated simulated microstructures are performed to predict the shock compression response and identify the meso-scale mechanics that are essential for reaction. The suitability of the synthetic microstructural representations is evaluated by comparing the experimental and predicted pressure traces.

  8. Shock compression response of Ti+B reactive powder mixtures

    NASA Astrophysics Data System (ADS)

    Gonzales, Manny; Gurumurthy, Ashok; Kennedy, Gregory; Gokhale, Arun; Thadhani, Naresh

    2013-06-01

    The shock compression response of Ti+2B (1:2 Ti:B stoichiometric ratio) reactive powder mixtures at ~50% theoretical material density (TMD) is investigated for shock pressures up to 5 GPa to investigate the possible shock-induced chemical reactivity of this highly exothermic mixture. The shock adiabat is produced from instrumented parallel-plate gas-gun impact experiments on encapsulated powders using poly-vinylidene fluoride (PVDF) stress gauges to measure the input and propagated stress and wave speed in the powder. The shock compression regime is probed from crush-up to full density and onward to assess the potential onset of a shock-induced chemical reaction event in the powder mixture. A series of two-dimensional continuum meso-scale simulations on real and simulated microstructures are performed to predict the shock compression response and identify the meso-scale mechanics that is essential for the so-called ``ballotechnic'' reaction. These meso-scale mechanics are investigated through stereological evolution metrics that track particle interface evolution and their respective field variables. The suitability of the synthetic microstructural representations is evaluated by comparing the experimental and predicted pressure traces. We gratefully acknowledge support and funding from DTRA through Grant No. HDTRA1-10-1-0038 and the National Defense Science and Engineering Graduate (NDSEG) Fellowship through the High Performance Computing and Modernization Office (HPCMO).

  9. Magnetically accelerated foils for shock wave experiments

    NASA Astrophysics Data System (ADS)

    Neff, Stephan; Ford, Jessica; Martinez, David; Plechaty, Christopher; Wright, Sandra; Presura, Radu

    2008-04-01

    The interaction of shock waves with inhomogeneous media is important in many astrophysical problems, e.g. the role of shock compression in star formation. Using scaled experiments with inhomogeneous foam targets makes it possible to study relevant physics in the laboratory, to better understand the mechanisms of shock compression and to benchmark astrophysical simulation codes. Experiments with flyer-generated shock waves have been performed on the Z machine in Sandia. The Zebra accelerator at the Nevada Terawatt Facility (NTF) allows for complementary experiments with high repetition rate. First experiments on Zebra demonstrated flyer acceleration to sufficiently high velocities (around 2 km/s) and that laser shadowgraphy can image sound fronts in transparent targets. Based on this, we designed an optimized setup to improve the flyer parameters (higher speed and mass) to create shock waves in transparent media. Once x-ray backlighting with the Leopard laser at NTF is operational, we will switch to foam targets with parameters relevant for laboratory astrophysics.

  10. Shock waves: The Maxwell-Cattaneo case

    NASA Astrophysics Data System (ADS)

    Uribe, F. J.

    2016-03-01

    Several continuum theories for shock waves give rise to a set of differential equations in which the analysis of the underlying vector field can be done using the tools of the theory of dynamical systems. We illustrate the importance of the divergences associated with the vector field by considering the ideas by Maxwell and Cattaneo and apply them to study shock waves in dilute gases. By comparing the predictions of the Maxwell-Cattaneo equations with shock wave experiments we are lead to the following conclusions: (a) For low compressions (low Mach numbers: M ) the results from the Maxwell-Cattaneo equations provide profiles that are in fair agreement with the experiments, (b) as the Mach number is increased we find a range of Mach numbers (1.27 ≈M1shock wave solutions to the Maxwell-Cattaneo equations cannot be found, and (c) for greater Mach numbers (M >M2) shock wave solutions can be found though they differ significantly from experiments.

  11. Density Shock Waves in Confined Microswimmers

    NASA Astrophysics Data System (ADS)

    Tsang, Alan Cheng Hou; Kanso, Eva

    2016-01-01

    Motile and driven particles confined in microfluidic channels exhibit interesting emergent behavior, from propagating density bands to density shock waves. A deeper understanding of the physical mechanisms responsible for these emergent structures is relevant to a number of physical and biomedical applications. Here, we study the formation of density shock waves in the context of an idealized model of microswimmers confined in a narrow channel and subject to a uniform external flow. Interestingly, these density shock waves exhibit a transition from "subsonic" with compression at the back to "supersonic" with compression at the front of the population as the intensity of the external flow increases. This behavior is the result of a nontrivial interplay between hydrodynamic interactions and geometric confinement, and it is confirmed by a novel quasilinear wave model that properly captures the dependence of the shock formation on the external flow. These findings can be used to guide the development of novel mechanisms for controlling the emergent density distribution and the average population speed, with potentially profound implications on various processes in industry and biotechnology, such as the transport and sorting of cells in flow channels.

  12. Flow behind concave shock waves

    NASA Astrophysics Data System (ADS)

    Mölder, S.

    2017-03-01

    Curved shock theory is introduced and applied to calculate the flow behind concave shock waves. For sonic conditions, three characterizing types of flow are identified, based on the orientation of the sonic line, and it is shown that, depending on the ratio of shock curvatures, a continuously curving shock can exist with Type III flow, where the sonic line intercepts the reflected characteristics from the shock, thus preventing the formation of a reflected shock. The necessary shock curvature ratio for a Type III sonic point does not exist for a hyperbolic shock so that it will revert to Mach reflection for all Mach numbers. A demonstration is provided, by CFD calculations, at Mach 1.2 and 3.

  13. Shock compression of simulated adobe

    NASA Astrophysics Data System (ADS)

    Braithwaite, C. H.; Church, P. D.; Gould, P. J.; Stewart, B.; Jardine, A. P.

    2017-01-01

    A series of plate impact experiments were conducted to investigate the shock response of a simulant for adobe, a traditional form of building material widely used around the world. Air dried bricks were sourced from the London brick company, dry machined and impacted at a range of velocities in a single stage gas gun. The shock Hugoniot was determined (Us =2.26up+0.37) as well as release information. The material was found to behave in a manner which was similar to that of loose sand and considerably less stiff than a weak porous sandstone. The effect of any cementing of the grains was examined by shocking powdered samples contained within a cell arrangement.

  14. Stress relaxation in vanadium under shock and shockless dynamic compression

    SciTech Connect

    Kanel, G. I.; Razorenov, S. V.; Garkushin, G. V.; Savinykh, A. S.; Zaretsky, E. B.

    2015-07-28

    Evolutions of elastic-plastic waves have been recorded in three series of plate impact experiments with annealed vanadium samples under conditions of shockless and combined ramp and shock dynamic compression. The shaping of incident wave profiles was realized using intermediate base plates made of different silicate glasses through which the compression waves were entered into the samples. Measurements of the free surface velocity histories revealed an apparent growth of the Hugoniot elastic limit with decreasing average rate of compression. The growth was explained by “freezing” of the elastic precursor decay in the area of interaction of the incident and reflected waves. A set of obtained data show that the current value of the Hugoniot elastic limit and plastic strain rate is rather associated with the rate of the elastic precursor decay than with the local rate of compression. The study has revealed the contributions of dislocation multiplications in elastic waves. It has been shown that independently of the compression history the material arrives at the minimum point between the elastic and plastic waves with the same density of mobile dislocations.

  15. Magnetically accelerated foils for shock wave experiments

    NASA Astrophysics Data System (ADS)

    Neff, S.; Ford, J.; Wright, S.; Martinez, D.; Plechaty, C.; Presura, R.

    2009-08-01

    Many astrophysical phenomena involve the interaction of a shock wave with an inhomogeneous background medium. Using scaled experiments with inhomogeneous foam targets makes it possible to study relevant physics in the laboratory to better understand the mechanisms of shock compression and to benchmark astrophysical simulation codes. First experiments on Zebra at the Nevada Terawatt Facility (NTF) have demonstrated flyer acceleration to sufficiently high velocities (up to 5 km/s) and that laser shadowgraphy can image sound fronts in transparent targets. Based on this, we designed an optimized setup to improve the flyer parameters (higher speed and mass) to create shock waves in transparent media. Once x-ray backlighting with the Leopard laser at NTF is operational, we will switch to foam targets with parameters relevant for laboratory astrophysics.

  16. Historical Background of Ultrahigh Pressure Shock Compression Experiments at LLNL: 1973 to 2000

    SciTech Connect

    Nellis, W.J.

    2000-10-09

    My purpose is to recount the historical development of ultrahigh pressure shock compression experiments at LLNL, which I experienced in the period 1973 to 2000. I used several experimental techniques: shock-impedance-match experiments using planar shock waves driven by nuclear explosives (NIMs), the Janus Laser, a railgun, and a two-stage light-gas gun.

  17. Shock waves show icebreaking promise

    SciTech Connect

    Wesley, R.H.; Stowell, W.R.

    1985-11-01

    State-of-the-art technology that is readily applicable in other offshore areas does not function adequately in Arctic regions. The common offshore problem in the Arctic, whether it be related to transportation, construction, drilling or production, is ice. Technology utilizing the phenomenal characteristics of the shock wave now exists that will allow relief from the ice problem in all of these categories. The feasibility of using shock waves for icebreaking is discussed.

  18. Compressive passive millimeter wave imager

    DOEpatents

    Gopalsami, Nachappa; Liao, Shaolin; Elmer, Thomas W; Koehl, Eugene R; Heifetz, Alexander; Raptis, Apostolos C

    2015-01-27

    A compressive scanning approach for millimeter wave imaging and sensing. A Hadamard mask is positioned to receive millimeter waves from an object to be imaged. A subset of the full set of Hadamard acquisitions is sampled. The subset is used to reconstruct an image representing the object.

  19. Shock waves in polycrystalline iron.

    PubMed

    Kadau, Kai; Germann, Timothy C; Lomdahl, Peter S; Albers, Robert C; Wark, Justin S; Higginbotham, Andrew; Holian, Brad Lee

    2007-03-30

    The propagation of shock waves through polycrystalline iron is explored by large-scale atomistic simulations. For large enough shock strengths the passage of the wave causes the body-centered-cubic phase to transform into a close-packed phase with most structure being isotropic hexagonal-close-packed (hcp) and, depending on shock strength and grain orientation, some fraction of face-centered-cubic (fcc) structure. The simulated shock Hugoniot is compared to experiments. By calculating the extended x-ray absorption fine structure (EXAFS) directly from the atomic configurations, a comparison to experimental EXAFS measurements of nanosecond-laser shocks shows that the experimental data is consistent with such a phase transformation. However, the atomistically simulated EXAFS spectra also show that an experimental distinction between the hcp or fcc phase is not possible based on the spectra alone.

  20. Hugoniot Measurements of Silicon Shock Compressed to 25 Mbar

    NASA Astrophysics Data System (ADS)

    Henderson, B.; Polsin, D. N.; Boehly, T. R.; Gregor, M. C.; Hu, S. X.; Collins, G. W.; Rygg, J. R.; Fratanduono, D. E.; Celliers, P. M.

    2016-10-01

    We present results of laser-driven shock experiments that compressed silicon samples to 25 Mbar. Impedance matching to a quartz reference provided Hugoniot data. Since silicon is opaque, a quartz witness was placed adjacent to the silicon samples; this afforded the use of the unsteady wave correction to increase the precision of the transit-time measurements of shock velocity. Results are compared both SESAME tables and to quantum molecular dynamics calculations. This material is based upon work supported by the Department Of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  1. Modeling shock waves in orthotropic elastic materials

    NASA Astrophysics Data System (ADS)

    Vignjevic, Rade; Campbell, James C.; Bourne, Neil K.; Djordjevic, Nenad

    2008-08-01

    A constitutive relationship for modeling of shock wave propagation in orthotropic materials is proposed for nonlinear explicit transient large deformation computer codes (hydrocodes). A procedure for separation of material volumetric compression (compressibility effects equation of state) from deviatoric strain effects is formulated, which allows for the consistent calculation of stresses in the elastic regime as well as in the presence of shock waves. According to this procedure the pressure is defined as the state of stress that results in only volumetric deformation, and consequently is a diagonal second order tensor. As reported by Anderson et al. [Comput. Mech. 15, 201 (1994)], the shock response of an orthotropic material cannot be accurately predicted using the conventional decomposition of the stress tensor into isotropic and deviatoric parts. This paper presents two different stress decompositions based on the assumption that the stress tensor is split into two components: one component is due to volumetric strain and the other is due to deviatoric strain. Both decompositions are rigorously derived. In order to test their ability to describe shock propagation in orthotropic materials, both algorithms were implemented in a hydrocode and their predictions were compared to experimental plate impact data. The material considered was a carbon fiber reinforced epoxy material, which was tested in both the through-thickness and longitudinal directions. The ψ decomposition showed good agreement with the physical behavior of the considered material, while the ζ decomposition significantly overestimated the longitudinal stresses.

  2. Rupture-disk-less shock-tube with compression tube driven by free piston

    NASA Astrophysics Data System (ADS)

    Abe, T.; Ogura, E.; Sato, S.; Funabiki, K.

    A new technique is proposed for a shock tube driven by a freely moving piston. In a conventional free-piston-driven shock tube, a rupture disk is employed between the compression tube and the shock generation tube. In the present method, however, the conventional rupture disk is replaced by a newly developed fast action valve which is activated by the compressed gas generated in the compression tube. The present method enables us to generate high Mach number shock waves of arbitrary strength with good reproducibility. The performance of the new method is demonstrated experimentally. This also enables us to be carefree to scattering of fragments of the rupture disk.

  3. Shock wave-droplet interaction

    NASA Astrophysics Data System (ADS)

    Habibi Khoshmehr, Hamed; Krechetnikov, Rouslan

    2016-11-01

    Disintegration of a liquid droplet under the action of a shock wave is experimentally investigated. The shock wave-pulse is electromagnetically generated by discharging a high voltage capacitor into a flat spiral coil, above which an isolated circular metal membrane is placed in a close proximity. The Lorentz force arising due to the eddy current induced in the membrane abruptly accelerates it away from the spiral coil thus generating a shock wave. The liquid droplet placed at the center of the membrane, where the maximum deflection occurs, is disintegrated in the process of interaction with the shock wave. The effects of droplet viscosity and surface tension on the droplet destruction are studied with high-speed photography. Water-glycerol solution at different concentrations is used for investigating the effect of viscosity and various concentrations of water-sugar and water-ethanol solution are used for studying the effect of surface tension. Here we report on how the metamorphoses, which a liquid drop undergoes in the process of interaction with a shock wave, are affected by varied viscosity and surface tension.

  4. Interaction of a swept shock wave and a supersonic wake

    NASA Astrophysics Data System (ADS)

    He, G.; Zhao, Y. X.; Zhou, J.

    2017-03-01

    The interaction of a swept shock wave and a supersonic wake has been studied. The swept shock wave is generated by a swept compression sidewall, and the supersonic wake is generated by a wake generator. The flow field is visualized with the nanoparticle-based planar laser scattering method, and a supplementary numerical simulation is conducted by solving the Reynolds-averaged Navier-Stokes equations. The results show that the pressure rise induced by the swept shock wave can propagate upstream in the wake, which makes the location where vortices are generated move upstream, thickens the laminar section of the wake, and enlarges the generated vortices. The wake is swept away from the swept compression sidewall by the pressure gradient of the swept shock wave. This pressure gradient is not aligned with the density gradient of the supersonic wake, so the baroclinic torque generates streamwise vorticity and changes the distribution of the spanwise vorticity. The wake shock is curved, so the flow downstream of it is non-uniform, leaving the swept shock wave being distorted. A three-dimensional Mach disk structure is generated when the wake shock interacts with the swept shock wave.

  5. 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.

  6. Shock compression experiments on Lithium Deuteride single crystals.

    SciTech Connect

    Knudson, Marcus D.; Desjarlais, Michael Paul; Lemke, Raymond W.

    2014-10-01

    S hock compression exper iments in the few hundred GPa (multi - Mabr) regime were performed on Lithium Deuteride (LiD) single crystals . This study utilized the high velocity flyer plate capability of the Sandia Z Machine to perform impact experiments at flyer plate velocities in the range of 17 - 32 km/s. Measurements included pressure, density, and temperature between %7E200 - 600 GPa along the Principal Hugoniot - the locus of end states achievable through compression by large amplitude shock waves - as well as pressure and density of re - shock states up to %7E900 GPa . The experimental measurements are compared with recent density functional theory calculations as well as a new tabular equation of state developed at Los Alamos National Labs.

  7. History of shock wave lithotripsy

    NASA Astrophysics Data System (ADS)

    Delius, Michael

    2000-07-01

    The first reports on the fragmentation of human calculi with ultrasound appeared in the fifties. Initial positive results with an extracorporeal approach with continuous wave ultrasound could, however, not be reproduced. A more promising result was found by generating the acoustic energy either in pulsed or continuous form directly at the stone surface. The method was applied clinically with success. Extracorporeal shock-wave generators unite the principle of using single ultrasonic pulses with the principle of generating the acoustic energy outside the body and focusing it through the skin and body wall onto the stone. Häusler and Kiefer reported the first successful contact-free kidney stone destruction by shock waves. They had put the stone in a water filled cylinder and generated a shock wave with a high speed water drop which was fired onto the water surface. To apply the new principle in medicine, both Häusler and Hoff's group at Dornier company constructed different shock wave generators for the stone destruction; the former used a torus-shaped reflector around an explosion wire, the latter the electrode-ellipsoid system. The former required open surgery to access the kidney stone, the latter did not. It was introduced into clinical practice after a series of experiments in Munich.

  8. Shock compression of [001] single crystal silicon

    DOE PAGES

    Zhao, S.; Remington, B.; Hahn, E. N.; ...

    2016-03-14

    Silicon is ubiquitous in our advanced technological society, yet our current understanding of change to its mechanical response at extreme pressures and strain-rates is far from complete. This is due to its brittleness, making recovery experiments difficult. High-power, short-duration, laser-driven, shock compression and recovery experiments on [001] silicon (using impedance-matched momentum traps) unveiled remarkable structural changes observed by transmission electron microscopy. As laser energy increases, corresponding to an increase in peak shock pressure, the following plastic responses are are observed: surface cleavage along {111} planes, dislocations and stacking faults; bands of amorphized material initially forming on crystallographic orientations consistent withmore » dislocation slip; and coarse regions of amorphized material. Molecular dynamics simulations approach equivalent length and time scales to laser experiments and reveal the evolution of shock-induced partial dislocations and their crucial role in the preliminary stages of amorphization. Furthermore, application of coupled hydrostatic and shear stresses produce amorphization below the hydrostatically determined critical melting pressure under dynamic shock compression.« less

  9. Shock compression of [001] single crystal silicon

    SciTech Connect

    Zhao, S.; Remington, B.; Hahn, E. N.; Kad, B.; Bringa, E. M.; Meyers, M. A.

    2016-03-14

    Silicon is ubiquitous in our advanced technological society, yet our current understanding of change to its mechanical response at extreme pressures and strain-rates is far from complete. This is due to its brittleness, making recovery experiments difficult. High-power, short-duration, laser-driven, shock compression and recovery experiments on [001] silicon (using impedance-matched momentum traps) unveiled remarkable structural changes observed by transmission electron microscopy. As laser energy increases, corresponding to an increase in peak shock pressure, the following plastic responses are are observed: surface cleavage along {111} planes, dislocations and stacking faults; bands of amorphized material initially forming on crystallographic orientations consistent with dislocation slip; and coarse regions of amorphized material. Molecular dynamics simulations approach equivalent length and time scales to laser experiments and reveal the evolution of shock-induced partial dislocations and their crucial role in the preliminary stages of amorphization. Furthermore, application of coupled hydrostatic and shear stresses produce amorphization below the hydrostatically determined critical melting pressure under dynamic shock compression.

  10. Shock compression of [001] single crystal silicon

    NASA Astrophysics Data System (ADS)

    Zhao, S.; Hahn, E. N.; Kad, B.; Remington, B. A.; Bringa, E. M.; Meyers, M. A.

    2016-05-01

    Silicon is ubiquitous in our advanced technological society, yet our current understanding of change to its mechanical response at extreme pressures and strain-rates is far from complete. This is due to its brittleness, making recovery experiments difficult. High-power, short-duration, laser-driven, shock compression and recovery experiments on [001] silicon (using impedance-matched momentum traps) unveiled remarkable structural changes observed by transmission electron microscopy. As laser energy increases, corresponding to an increase in peak shock pressure, the following plastic responses are are observed: surface cleavage along {111} planes, dislocations and stacking faults; bands of amorphized material initially forming on crystallographic orientations consistent with dislocation slip; and coarse regions of amorphized material. Molecular dynamics simulations approach equivalent length and time scales to laser experiments and reveal the evolution of shock-induced partial dislocations and their crucial role in the preliminary stages of amorphization. Application of coupled hydrostatic and shear stresses produce amorphization below the hydrostatically determined critical melting pressure under dynamic shock compression.

  11. Shock compression properties of silicon carbide

    SciTech Connect

    Grady, D.E.; Kipp, M.E.

    1993-07-01

    An investigation of the shock compression and release properties of silicon carbide ceramic has been performed. A series of planar impact experiments has been completed in which stationary target discs of ceramic were struck by plates of either similar ceramic or other appropriate material at velocities up to 2.2 km/s with a propellant gun facility. The particle velocity history at the interface between the back of the target ceramic and a lithium-fluoride window material was measured with laser velocity interferometry (VISAR). Impact stresses achieved in these experiments range between about 10 and 50 GPa. Numerical solutions and analytic methods were used to determine the dynamic compression and release stress-strain behavior of the ceramic. Further analysis of the data was performed to determine dynamic strength and compressibility properties of silicon carbide.

  12. Optical distortion in the field of a lithotripter shock wave

    NASA Astrophysics Data System (ADS)

    Carnell, M. T.; Emmony, D. C.

    1995-10-01

    The schlieren observation of cavitation phenomena produced in the tail of a lithotripter shock wave has indicated the presence of some interesting features. The images produced appear to indicate that cavitation transients in the field of a shock wave propagate nonsymmetrically; this is not the case. The apparent lack of symmetry exhibited by the primary cavitation transients is due to a complex optical lensing effect, which is brought about by the change in refractive index associated with the pressure profile of the shock wave. Objects seen through or immersed in the shock-wave field of an electromagnetic acoustic transducer, such as cavitation, appear highly distorted because of the strong positive and negative lensing effects of the compression and rarefaction cycles of the shock wave. A modification of the schlieren technique called the scale method has been used to model the distortion introduced by the shock wave and consequently explain the cavitation distortion. The technique has also been used to quantitatively analyze and partially reconstruct the lithotripter shock wave. The combination of schlieren and scale imaging gives more information about the refractive index field and therefore the shock-wave structure itself.

  13. Vibrational spectroscopic investigations of shock-compressed liquid nitrogen and shock-compressed liquid nitromethane

    SciTech Connect

    Moore, D.S.; Schmidt, S.C.

    1989-01-01

    Vibrational spectra of liquid nitrogen and liquid nitromethane shock compressed to several high pressure/high temperature states were recorded using single-pulse multiplex coherent anti-Stokes Raman scattering. Vibrational frequencies were extracted from the data by computer spectral simulation techniques. Vibrational frequencies of liquid nitrogen were found to increase monotonically up to /approx/17.5 GPa single shock and /approx/30 GPa double shock and then to decrease with further increases in pressure. The consequence of the decrease in vibrational frequency on the Grueneisen mode gamma and its effect on the N/sub 2/ equation-of-state is discussed. A model is developed that includes the thermally-excited vibrational state transitions in the synthesized spectral fits of the nitromethane CARS data. The adequacy of the model for interpretation of CARS spectra in both ambient and shock-compressed nitromethane is discussed. 42 refs., 5 figs., 1 tab.

  14. Diagnostic of shock wave processes

    NASA Astrophysics Data System (ADS)

    Urtiew, P. A.

    1992-05-01

    Experimental measurements of high rate processes taking place in a shock wave dynamic environment require that the diagnostic systems have fast response and high resolution. This is not a trivial requirement considering the fact that under shock loading one can expect not only sudden changes of state across the shock discontinuity but also subsequent changes in pressure, temperature and volume due to chemical reaction, phase change and other transformations which may also take place behind the shock wave. Among the various parameters which provide direct ties to theoretical studies of the equation of state and at the same time yield to relatively accurate experimental measurements are shock velocity, particle velocity and pressure. Described here are the optical techniques VISAR and Fabry Perot interferometer for observing particle and free surface velocities in transparent media as well as in situ foil gauges for measuring pressure and particle velocity within the sample. Although these techniques are not new they have been continuously improved and upgraded at our facility to yield greater accuracy, reliability and state of the art performance. The emphasis in this paper is on the operational features of the measuring techniques, but examples of experimental results are also included.

  15. Millimeter-wave compressive holography.

    PubMed

    Cull, Christy Fernandez; Wikner, David A; Mait, Joseph N; Mattheiss, Michael; Brady, David J

    2010-07-01

    We describe an active millimeter-wave holographic imaging system that uses compressive measurements for three-dimensional (3D) tomographic object estimation. Our system records a two-dimensional (2D) digitized Gabor hologram by translating a single pixel incoherent receiver. Two approaches for compressive measurement are undertaken: nonlinear inversion of a 2D Gabor hologram for 3D object estimation and nonlinear inversion of a randomly subsampled Gabor hologram for 3D object estimation. The object estimation algorithm minimizes a convex quadratic problem using total variation (TV) regularization for 3D object estimation. We compare object reconstructions using linear backpropagation and TV minimization, and we present simulated and experimental reconstructions from both compressive measurement strategies. In contrast with backpropagation, which estimates the 3D electromagnetic field, TV minimization estimates the 3D object that produces the field. Despite undersampling, range resolution is consistent with the extent of the 3D object band volume.

  16. IN-SITU PROBING OF LATTICE RESPONSE IN SHOCK COMPRESSED MATERIALS USING X-RAY DIFFRACTION

    SciTech Connect

    Hawreliak, James; Butterfield, Martin; El-Dasher, Bassem; Kalantar, Daniel; McNaney, James; Remington, Bruce; Lorenzana, Hector; Davies, Huw; Park, Nigel; Thorton, Lee; Higginbotham, Andrew; Kimminau, Giles; Murphy, William; Nagler, Bob; Whitcher, Thomas; Wark, Justin; Milathianaki, Despina

    2007-12-12

    Lattice level measurements of material response under extreme conditions are required to build a phenomenological understanding of the shock response of solids. We have successfully used laser produced plasma x-ray sources coincident with laser driven shock waves to make in-situ measurements of the lattice response during shock compression for both single crystal and polycrystalline materials. Using a detailed analysis of shocked single crystal iron which has undergone the {alpha}-{epsilon} phase transition we can constrain the transition mechanism to be consistent with a compression and shuffle of alternate lattice planes.

  17. In-situ probing of lattice response in shock compressed materials using x-ray diffraction

    SciTech Connect

    Hawreliak, J; Butterfield, M; Davies, H; El-Dasher, B; Higginbotham, A; Kalantar, D; Kimminau, G; McNaney, J; Milathianaki, D; Murphy, W; Nagler, B; Lorenzana, H; Park, N; Remington, B; Thorton, L; Whitcher, T; Wark, J; Lorenzana, H

    2007-07-17

    Lattice level measurements of material response under extreme conditions are required to build a phenomenological understanding of the shock response of solids. We have successfully used laser produced plasma x-ray sources coincident with laser driven shock waves to make in-situ measurements of the lattice response during shock compression for both single crystal and polycrystalline materials. Using a detailed analysis of shocked single crystal iron which has undergone the {alpha} - {var_epsilon} phase transition we can constrain the transition mechanism to be consistent with a compression and shuffle of alternate lattice planes.

  18. The role of granular shocks in dust-layer dispersal by shock waves

    NASA Astrophysics Data System (ADS)

    Houim, Ryan; Ugarte, Orlando; Oran, Elaine

    2016-11-01

    Exactly how dust-layers are lifted and dispersed by shocks has been a longstanding question in compressible multiphase flow. Understanding the mechanism for this, however, is extremely important for early control of dust explosions. We address this problem by numerically solving a set of equations that couples a fully compressible representation of a gas with a kinetic-theory model for a granular medium (see) to simulate a shock propagating along the surface of a dust layer. The results show that the majority of the dispersed dust is lifted by hydrodynamic shear directly behind the shock wave. Simultaneously, large forces are produced behind the shock that compact the dust layer and create a granular shock. The effects from this granular shock on the surface of the dust layer destabilize the gas-dust boundary layer, which, in turn, enhances turbulence and the rate of dust dispersal.

  19. Shock wave absorber having apertured plate

    DOEpatents

    Shin, Y.W.; Wiedermann, A.H.; Ockert, C.E.

    1983-08-26

    The shock or energy absorber disclosed herein utilizes an apertured plate maintained under the normal level of liquid flowing in a piping system and disposed between the normal liquid flow path and a cavity pressurized with a compressible gas. The degree of openness (or porosity) of the plate is between 0.01 and 0.60. The energy level of a shock wave travelling down the piping system thus is dissipated by some of the liquid being jetted through the apertured plate toward the cavity. The cavity is large compared to the quantity of liquid jetted through the apertured plate, so there is little change in its volume. The porosity of the apertured plate influences the percentage of energy absorbed.

  20. Shock wave absorber having apertured plate

    DOEpatents

    Shin, Yong W.; Wiedermann, Arne H.; Ockert, Carl E.

    1985-01-01

    The shock or energy absorber disclosed herein utilizes an apertured plate maintained under the normal level of liquid flowing in a piping system and disposed between the normal liquid flow path and a cavity pressurized with a compressible gas. The degree of openness (or porosity) of the plate is between 0.01 and 0.60. The energy level of a shock wave travelling down the piping system thus is dissipated by some of the liquid being jetted through the apertured plate toward the cavity. The cavity is large compared to the quantity of liquid jetted through the apertured plate, so there is little change in its volume. The porosity of the apertured plate influences the percentage of energy absorbed.

  1. Effects of shock structure on temperature field in compressible turbulence

    NASA Astrophysics Data System (ADS)

    Ni, Qionglin; Chen, Shiyi

    2014-11-01

    Effects of shock structure on temperature in compressible turbulence were investigated. The small-scale shocklets and large-scale shock waves were appeared in the flows driven by solenoidal and compressive forcings, i.e. SFT & CFT, respectively. In SFT the temperature had Kolmogorov spectrum and ramp-cliff structures, while in CFT it obeyed Burgers spectrum and was dominated by large-scale rarefaction and compression. The power-law exponents for the p.d.f. of large negative dilatation were -2.5 in SFT and -3.5 in CFT, approximately corresponded to model results. The isentropic approximation of thermodynamic variables showed that in SFT, the isentropic derivation was reinforced when turbulent Mach number increased. At similar turbulent Mach number, the variables in CFT exhibited more anisentropic. It showed that the transport of temperature was increased by the small-scale viscous dissipation and the large-scale pressure-dilatation. The distribution of positive and negative components of pressure-dilatation confirmed the mechanism of negligible pressure-dilatation at small scales. Further, the positive skewness of p.d.f.s of pressure-dilatation implied that the conversion from kinetic to internal energy by compression was more intense than the opposite process by rarefaction.

  2. Material response mechanisms are needed to obtain highly accurate experimental shock wave data

    NASA Astrophysics Data System (ADS)

    Forbes, Jerry W.

    2017-01-01

    The field of shock wave compression of matter has provided a simple set of equations relating thermodynamic and kinematic parameters that describe the conservation of mass, momentum and energy across a steady plane shock wave with one-dimensional flow. Well-known condensed matter shock wave experimental results will be reviewed to see whether the assumptions required for deriving these simple R-H equations are satisfied. Note that the material compression model is not required for deriving the 1-D conservation flow equations across a steady plane shock front. However, this statement is misleading from a practical experimental viewpoint since obtaining small systematic errors in shock wave measured parameters requires the material compression and release mechanisms to be known. A review will be presented on errors in shock wave data from common experimental techniques for elastic-plastic solids. Issues related to time scales of experiments, steady waves with long rise times and detonations will also be discussed

  3. Nonstandard Analysis and Jump Conditions for Converging Shock Waves

    NASA Technical Reports Server (NTRS)

    Baty, Roy S.; Farassat, Fereidoun; Tucker, Don H.

    2008-01-01

    Nonstandard analysis is an area of modern mathematics which studies abstract number systems containing both infinitesimal and infinite numbers. This article applies nonstandard analysis to derive jump conditions for one-dimensional, converging shock waves in a compressible, inviscid, perfect gas. It is assumed that the shock thickness occurs on an infinitesimal interval and the jump functions in the thermodynamic and fluid dynamic parameters occur smoothly across this interval. Predistributions of the Heaviside function and the Dirac delta measure are introduced to model the flow parameters across a shock wave. The equations of motion expressed in nonconservative form are then applied to derive unambiguous relationships between the jump functions for the flow parameters.

  4. Nonstandard analysis and jump conditions for converging shock waves

    NASA Astrophysics Data System (ADS)

    Baty, Roy S.; Farassat, F.; Tucker, Don H.

    2008-06-01

    Nonstandard analysis is an area of modern mathematics that studies abstract number systems containing both infinitesimal and infinite numbers. This article applies nonstandard analysis to derive jump conditions for one-dimensional, converging shock waves in a compressible, inviscid, perfect gas. It is assumed that the shock thickness occurs on an infinitesimal interval and the jump functions in the thermodynamic and fluid dynamic parameters occur smoothly across this interval. Predistributions of the Heaviside function and the Dirac delta measure are introduced to model the flow parameters across a shock wave. The equations of motion expressed in nonconservative form are then applied to derive unambiguous relationships between the jump functions for the flow parameters.

  5. Computation of Thermally Perfect Oblique Shock Wave Properties

    NASA Technical Reports Server (NTRS)

    Tatum, Kenneth E.

    1997-01-01

    A set of compressible flow relations describing flow properties across oblique shock waves, derived for a thermally perfect, calorically imperfect gas, is applied within the existing thermally perfect gas (TPG) computer code. The relations are based upon the specific heat expressed as a polynomial function of temperature. The updated code produces tables of compressible flow properties of oblique shock waves, as well as the original properties of normal shock waves and basic isentropic flow, in a format similar to the tables for normal shock waves found in NACA Rep. 1135. The code results are validated in both the calorically perfect and the calorically imperfect, thermally perfect temperature regimes through comparisons with the theoretical methods of NACA Rep. 1135. The advantages of the TPG code for oblique shock wave calculations, as well as for the properties of isentropic flow and normal shock waves, are its ease of use and its applicability to any type of gas (monatomic, diatomic, triatomic, polyatomic, or any specified mixture thereof).

  6. Computation of Thermally Perfect Properties of Oblique Shock Waves

    NASA Technical Reports Server (NTRS)

    Tatum, Kenneth E.

    1996-01-01

    A set of compressible flow relations describing flow properties across oblique shock waves, derived for a thermally perfect, calorically imperfect gas, is applied within the existing thermally perfect gas (TPG) computer code. The relations are based upon a value of cp expressed as a polynomial function of temperature. The updated code produces tables of compressible flow properties of oblique shock waves, as well as the original properties of normal shock waves and basic isentropic flow, in a format similar to the tables for normal shock waves found in NACA Rep. 1135. The code results are validated in both the calorically perfect and the calorically imperfect, thermally perfect temperature regimes through comparisons with the theoretical methods of NACA Rep. 1135, and with a state-of-the-art computational fluid dynamics code. The advantages of the TPG code for oblique shock wave calculations, as well as for the properties of isentropic flow and normal shock waves, are its ease of use, and its applicability to any type of gas (monatomic, diatomic, triatomic, polyatomic, or any specified mixture thereof).

  7. Bow shock and magnetosheath waves at Mercury

    NASA Technical Reports Server (NTRS)

    Fairfield, D. H.; Behannon, K. W.

    1975-01-01

    Mariner 10 measurements at the Mercury bow shock provide examples where the magnetic field is approximately parallel or perpendicular to the bow shock normal. Upstream of a broad irregular parallel shock, left hand circularly polarized waves are observed which cut off very sharply at approximately 4 Hz. Upstream of a perpendicular shock, 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 shock. The magnetosheath downstream of the parallel shock is disturbed more than that downstream of the perpendicular shock 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.

  8. Inelastic response of silicon to shock compression

    SciTech Connect

    Higginbotham, Andrew; Stubley, P. G.; Comley, A. J.; Eggert, J. H.; Foster, J. M.; Kalantar, D. H.; McGonegle, D.; Patel, S.; Peacock, L. J.; Rothman, S. D.; Smith, R. F.; Suggit, M. J.; Wark, J. S.

    2016-04-13

    The elastic and inelastic response of [001] oriented silicon to laser compression has been a topic of considerable discussion for well over a decade, yet there has been little progress in understanding the basic behaviour of this apparently simple material. We present experimental x-ray diffraction data showing complex elastic strain profiles in laser compressed samples on nanosecond timescales. We also present molecular dynamics and elasticity code modelling which suggests that a pressure induced phase transition is the cause of the previously reported ‘anomalous’ elastic waves. Moreover, this interpretation allows for measurement of the kinetic timescales for transition. Lastly, this model is also discussed in the wider context of reported deformation of silicon to rapid compression in the literature.

  9. Inelastic response of silicon to shock compression

    DOE PAGES

    Higginbotham, Andrew; Stubley, P. G.; Comley, A. J.; ...

    2016-04-13

    The elastic and inelastic response of [001] oriented silicon to laser compression has been a topic of considerable discussion for well over a decade, yet there has been little progress in understanding the basic behaviour of this apparently simple material. We present experimental x-ray diffraction data showing complex elastic strain profiles in laser compressed samples on nanosecond timescales. We also present molecular dynamics and elasticity code modelling which suggests that a pressure induced phase transition is the cause of the previously reported ‘anomalous’ elastic waves. Moreover, this interpretation allows for measurement of the kinetic timescales for transition. Lastly, this modelmore » is also discussed in the wider context of reported deformation of silicon to rapid compression in the literature.« less

  10. Inelastic response of silicon to shock compression

    PubMed Central

    Higginbotham, A.; Stubley, P. G.; Comley, A. J.; Eggert, J. H.; Foster, J. M.; Kalantar, D. H.; McGonegle, D.; Patel, S.; Peacock, L. J.; Rothman, S. D.; Smith, R. F.; Suggit, M. J.; Wark, J. S.

    2016-01-01

    The elastic and inelastic response of [001] oriented silicon to laser compression has been a topic of considerable discussion for well over a decade, yet there has been little progress in understanding the basic behaviour of this apparently simple material. We present experimental x-ray diffraction data showing complex elastic strain profiles in laser compressed samples on nanosecond timescales. We also present molecular dynamics and elasticity code modelling which suggests that a pressure induced phase transition is the cause of the previously reported ‘anomalous’ elastic waves. Moreover, this interpretation allows for measurement of the kinetic timescales for transition. This model is also discussed in the wider context of reported deformation of silicon to rapid compression in the literature. PMID:27071341

  11. Burnett-Cattaneo continuum theory for shock waves

    NASA Astrophysics Data System (ADS)

    Holian, Brad Lee; Mareschal, Michel; Ravelo, Ramon

    2011-02-01

    We model strong shock-wave propagation, both in the ideal gas and in the dense Lennard-Jones fluid, using a refinement of earlier work, which accounts for the cold compression in the early stages of the shock rise by a nonlinear, Burnett-like, strain-rate dependence of the thermal conductivity, and relaxation of kinetic-temperature components on the hot, compressed side of the shock front. The relaxation of the disequilibrium among the three components of the kinetic temperature, namely, the difference between the component in the direction of a planar shock wave and those in the transverse directions, particularly in the region near the shock front, is accomplished at a much more quantitative level by a rigorous application of the Cattaneo-Maxwell relaxation equation to a reference solution, namely, the steady shock-wave solution of linear Navier-Stokes-Fourier theory, along with the nonlinear Burnett heat-flux term. Our new continuum theory is in nearly quantitative agreement with nonequilibrium molecular-dynamics simulations under strong shock-wave conditions, using relaxation parameters obtained from the reference solution.

  12. The History of the APS Shock Compression of Condensed Matter Topical Group

    SciTech Connect

    Forbes, J W

    2001-05-02

    In order to provide broader scientific recognition and to advance the science of shock compressed condensed matter, a group of American Physical Society (APS) members worked within the Society to make this field an active part of the APS. Individual papers were presented at APS meetings starting in the 1940's and shock wave sessions were organized starting with the 1967 Pasadena meeting. Shock wave topical conferences began in 1979 in Pullman, WA. Signatures were obtained on a petition in 1984 from a balanced cross-section of the shock wave community to form an APS Topical Group (TG). The APS Council officially accepted the formation of the Shock Compression of Condensed Matter (SCCM) TG at its October 1984 meeting. This action firmly aligned the shock wave field with a major physical science organization. Most early topical conferences were sanctioned by the APS while those held after 1992 were official APS meetings. The topical group organizes a shock wave topical conference in odd numbered years while participating in shock wave/high pressure sessions at APS general meetings in even numbered years.

  13. Vorticity and Wave Motion in a Compressible Protoplanetary Disk

    NASA Technical Reports Server (NTRS)

    Davis, Sanford S.; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    The impact of an isolated vortex in a compressible Keplerian disk is examined using higher order numerical solutions of the Euler and entropy-conserving Energy equations. The vortex is stretched by the background shear flow with longer lasting anticyclonic vortices persisting for about 10 vortex revolutions. Simultaneously, the vortex emits transient radial waves consisting mainly of axisymmetrical weak shock waves and a slower, nonaxisymmetric Rossby wave. These waves may contribute to certain transient events in protoplanetary disks. The vortex stretching and waves were found to have little long-term feedback on the baseline 'standard solar nebula' disk structure and confirm the extremely stable structure of non self-gravitating disks.

  14. Multi-Scale Shock Compression Simulations of Metals and Metallic Phase Transitions

    NASA Astrophysics Data System (ADS)

    Goldman, Nir; Fried, Larry

    2011-03-01

    We present a straightforward method for efficient molecular dynamics (MD) simulation of shock compression of materials that experience thermal electronic excitations at high pressure and temperature. Previous studies have shown that exclusion of the electronic temperature at extreme conditions can result in incorrect computation of dynamic and equation of state properties. The Multi-Scale Shock Technique (MSST) is a simulation methodology based on the Navier--Stokes equations for compressible flow that enables MD simulation of a shock wave with relatively small computational cost. We extend MSST to allow for changes in the electronic entropy during shock compression while conserving Hugoniot conditions. This allows for simulation of significantly higher shock velocities than previously possibly with MSST. We have used our simulation methodology in density functional tight binding simulations of shock compressed silicon. We observe that at high shock velocities inclusion of a non-zero electron temperature results in lower computed shock Hugoniot temperatures and pressures. Our methodology is well suited for shock compression simulations of any material that experiences changes in its electronic entropy under extreme thermodynamic conditions. Prepared by LLNL under Contract DE-AC52-07NA27344.

  15. Compressed Sensing Meets Wave Chaology

    NASA Astrophysics Data System (ADS)

    Pinto, Innocenzo M.; Addesso, Paolo; Principe, Maria

    2015-03-01

    The Wigner distribution is an important tool in the study of high-frequency wave-packet dynamics in ray-chaotic enclosures. Smoothing the Wigner distribution helps improving its readability, by suppressing nonlinear artifacts, but spoils its resolution. Adding a sparsity constraint to smoothing, in the spirit of the compressed coding paradigm, restores resolution while still avoiding artifacts. The result is particularly valuable in the perspective of complexity gauging via Renyi-Wehrl entropy measures. Representative numerical experiments are presented to substantiate such clues.

  16. Experimental study of highly compressed iron user laser driven shocks

    NASA Astrophysics Data System (ADS)

    Benuzzi-Mounaix, Alessandra; Huser, Gael; Koenig, Michel; Grandjouan, Nicolas; Faral, Bernard; Batani, Dimitri; Henry, Emeric; Tomasini, Michaela; Hall, Thomas; Romain, Jp; Resseguier, Thibault; Hallouin, Martine; Guyot, François

    2001-06-01

    Experiments with lasers have recently provided important improvements in our knowledge of highly compressed matter (in particular, Equation Of State). We present recent results on iron which are relevant to planetary physics1. We measured the free surface velocity of the compressed iron by using a VISAR diagnostic2, and the shock velocity through step targets on the same shot3. An absolute EOS is then deduced for the lower pressures (1-3 Mbar). For higher pressures (3-7 Mbar), we compared release wave in vacuum with calculassions based on SESAME EOS . With a iron+LiF window, we also determined a release wave in iron for the transmitted shock in the window. The experiments have been performed at the LULI laboratory of the Ecole Polytechnique. References 1 W. Anderson, et al., J. Geophys. Research 99, 4273 (1994). 2 P. M. Celliers, et al., Applied Phys. Lett. 73, 1320 (1998). 3 M. Koenig, et al., Phys. Rev. Lett. 74, 2260 (1995).

  17. History of the APS Topical Group on Shock Compression of Condensed Matter

    SciTech Connect

    Forbes, J W

    2001-10-19

    In order to provide broader scientific recognition and to advance the science of shock compressed condensed matter, a group of American Physical Society (APS) members worked within the Society to make this field an active part of the APS. Individual papers were presented at APS meetings starting in the 1940's and shock wave sessions were organized starting with the 1967 Pasadena meeting. Shock wave topical conferences began in 1979 in Pullman, WA. Signatures were obtained on a petition in 1984 from a balanced cross-section of the shock wave community to form an APS Topical Group (TG). The APS Council officially accepted the formation of the Shock Compression of Condensed Matter (SCCM) TG at its October 1984 meeting. This action firmly aligned the shock wave field with a major physical science organization. Most early topical conferences were sanctioned by the APS while those held after 1992 were official APS meetings. The topical group organizes a shock wave topical conference in odd numbered years while participating in shock wavehigh pressure sessions at APS general meetings in even numbered years.

  18. Shock compression response of forsterite above 250 GPa

    PubMed Central

    Sekine, Toshimori; Ozaki, Norimasa; Miyanishi, Kohei; Asaumi, Yuto; Kimura, Tomoaki; Albertazzi, Bruno; Sato, Yuya; Sakawa, Youichi; Sano, Takayoshi; Sugita, Seiji; Matsui, Takafumi; Kodama, Ryosuke

    2016-01-01

    Forsterite (Mg2SiO4) is one of the major planetary materials, and its behavior under extreme conditions is important to understand the interior structure of large planets, such as super-Earths, and large-scale planetary impact events. Previous shock compression measurements of forsterite indicate that it may melt below 200 GPa, but these measurements did not go beyond 200 GPa. We report the shock response of forsterite above ~250 GPa, obtained using the laser shock wave technique. We simultaneously measured the Hugoniot and temperature of shocked forsterite and interpreted the results to suggest the following: (i) incongruent crystallization of MgO at 271 to 285 GPa, (ii) phase transition of MgO at 285 to 344 GPa, and (iii) remelting above ~470 to 500 GPa. These exothermic and endothermic reactions are seen to occur under extreme conditions of pressure and temperature. They indicate complex structural and chemical changes in the system MgO-SiO2 at extreme pressures and temperatures and will affect the way we understand the interior processes of large rocky planets as well as material transformation by impacts in the formation of planetary systems. PMID:27493993

  19. Shock compression response of forsterite above 250 GPa.

    PubMed

    Sekine, Toshimori; Ozaki, Norimasa; Miyanishi, Kohei; Asaumi, Yuto; Kimura, Tomoaki; Albertazzi, Bruno; Sato, Yuya; Sakawa, Youichi; Sano, Takayoshi; Sugita, Seiji; Matsui, Takafumi; Kodama, Ryosuke

    2016-08-01

    Forsterite (Mg2SiO4) is one of the major planetary materials, and its behavior under extreme conditions is important to understand the interior structure of large planets, such as super-Earths, and large-scale planetary impact events. Previous shock compression measurements of forsterite indicate that it may melt below 200 GPa, but these measurements did not go beyond 200 GPa. We report the shock response of forsterite above ~250 GPa, obtained using the laser shock wave technique. We simultaneously measured the Hugoniot and temperature of shocked forsterite and interpreted the results to suggest the following: (i) incongruent crystallization of MgO at 271 to 285 GPa, (ii) phase transition of MgO at 285 to 344 GPa, and (iii) remelting above ~470 to 500 GPa. These exothermic and endothermic reactions are seen to occur under extreme conditions of pressure and temperature. They indicate complex structural and chemical changes in the system MgO-SiO2 at extreme pressures and temperatures and will affect the way we understand the interior processes of large rocky planets as well as material transformation by impacts in the formation of planetary systems.

  20. IN SITU ELLIPSOMETRY FOR SHOCK COMPRESSION MEASUREMENTS

    SciTech Connect

    Bakshi, L.; Eliezer, S.; Appelbaum, G.; Nissim, N.; Perelmutter, L.; Mond, M.

    2009-12-28

    Knowledge about the optical properties of materials at high pressure and high temperature is needed for EOS research. Ellipsometry measures the change in the polarization of a probe beam reflected from a surface. From the change in polarization, the real and imaginary parts of the time dependent complex index of refraction can be extracted. From the measured optical properties, fundamental physical properties of the material, such as emissivity, phase transitions, and electrical conductivity can be extracted. A dynamic ellipsometry measurement system with nanosecond resolution was built in order to measure all four stocks parameters. Gas gun was used to accelerate the impact flyer. Our experiments concentrated on the optical properties of 1020 steel targets with impact pressure range of 40-250 kbar. Although there are intrinsic difficulties with dynamic ellipsometric measurements, distinct changes were observed for 1020 steel under shock compression larger than 130 kbar, the alpha->epsilon phase transition.

  1. Vibrational spectroscopy in shock-compressed liquids

    SciTech Connect

    Schmidt, S.C.; Moore, D.S.

    1992-01-01

    Coherent anti-Stokes Raman spectroscopy is being used to study the structure and energy transfer in simple molecular liquids at the high pressures and temperatures characteristic of explosive detonation. Dense fluids to several thousand degrees temperature and several hundred kilobars pressure are obtained using the shock-compression technique. Vibrational frequencies, third-order susceptibility ratios, and linewidths have been measured for N{sub 2}, O{sub 2}, CO, mixtures of N{sub 2}, O{sub 2}, and CO, and N{sub 2}O. Frequencies are found to increase with pressure. The transition intensity and line-width data suggest that thermal equilibrium of the vibrational levels is attained in less than a few nanoseconds at these high pressures and temperatures. Vibrational temperatures obtained are compared to those derived from equation-of-state calculations.

  2. Vibrational spectroscopy in shock-compressed liquids

    SciTech Connect

    Schmidt, S.C.; Moore, D.S.

    1992-03-01

    Coherent anti-Stokes Raman spectroscopy is being used to study the structure and energy transfer in simple molecular liquids at the high pressures and temperatures characteristic of explosive detonation. Dense fluids to several thousand degrees temperature and several hundred kilobars pressure are obtained using the shock-compression technique. Vibrational frequencies, third-order susceptibility ratios, and linewidths have been measured for N{sub 2}, O{sub 2}, CO, mixtures of N{sub 2}, O{sub 2}, and CO, and N{sub 2}O. Frequencies are found to increase with pressure. The transition intensity and line-width data suggest that thermal equilibrium of the vibrational levels is attained in less than a few nanoseconds at these high pressures and temperatures. Vibrational temperatures obtained are compared to those derived from equation-of-state calculations.

  3. Studies of Shock Wave Interactions with Homogeneous and Isotropic Turbulence

    NASA Technical Reports Server (NTRS)

    Briassulis, G.; Agui, J.; Watkins, C. B.; Andreopoulos, Y.

    1998-01-01

    A nearly homogeneous nearly isotropic compressible turbulent flow interacting with a normal shock wave has been studied experimentally in a large shock tube facility. Spatial resolution of the order of 8 Kolmogorov viscous length scales was achieved in the measurements of turbulence. A variety of turbulence generating grids provide a wide range of turbulence scales. Integral length scales were found to substantially decrease through the interaction with the shock wave in all investigated cases with flow Mach numbers ranging from 0.3 to 0.7 and shock Mach numbers from 1.2 to 1.6. The outcome of the interaction depends strongly on the state of compressibility of the incoming turbulence. The length scales in the lateral direction are amplified at small Mach numbers and attenuated at large Mach numbers. Even at large Mach numbers amplification of lateral length scales has been observed in the case of fine grids. In addition to the interaction with the shock the present work has documented substantial compressibility effects in the incoming homogeneous and isotropic turbulent flow. The decay of Mach number fluctuations was found to follow a power law similar to that describing the decay of incompressible isotropic turbulence. It was found that the decay coefficient and the decay exponent decrease with increasing Mach number while the virtual origin increases with increasing Mach number. A mechanism possibly responsible for these effects appears to be the inherently low growth rate of compressible shear layers emanating from the cylindrical rods of the grid.

  4. Cavitation in shock wave lithotripsy

    NASA Astrophysics Data System (ADS)

    Bailey, Michael R.; Crum, Lawrence A.; Sapozhnikov, Oleg A.; Evan, Andrew P.; McAteer, James A.; Colonius, Tim; Cleveland, Robin O.

    2003-10-01

    A case is presented for the important role of cavitation in stone comminution and tissue injury in shock wave lithotripsy (SWL). Confocal hydrophones and a coincidence algorithm were used to detect cavitation in kidney parenchyma. Elevated hydrostatic pressure dissolved cavitation nuclei and suppressed cell injury and stone comminution in vitro. A low-insertion-loss, thin, mylar film nearly eliminated stone erosion and crack formation only when in direct contact with the stone. This result indicates not only that cavitation is important in both cracking and erosion but also that bubbles act at the surface. Time inversion of the shock wave by use of a pressure-release reflector reduced the calculated pressure at bubble collapse and the measured depth of bubble-induced pits in aluminum. Correspondingly tissue injury in vivo was nearly eliminated. Cavitation was localized and intensified by the use of synchronously triggered, facing lithotripters. This dual pulse lithotripter enhanced comminution at its focus and reduced lysis in surrounding blood samples. The enhancement of comminution was lost when stones were placed in glycerol, which retarded bubble implosion. Thus, cavitation is important in comminution and injury and can be controlled to optimize efficacy and safety. [Work supported by NIH DK43381, DK55674, and FIRCA.

  5. Shock Wave Technology and Application: An Update☆

    PubMed Central

    Rassweiler, Jens J.; Knoll, Thomas; Köhrmann, Kai-Uwe; McAteer, James A.; Lingeman, James E.; Cleveland, Robin O.; Bailey, Michael R.; Chaussy, Christian

    2012-01-01

    Context The introduction of new lithotripters has increased problems associated with shock wave application. Recent studies concerning mechanisms of stone disintegration, shock wave focusing, coupling, and application have appeared that may address some of these problems. Objective To present a consensus with respect to the physics and techniques used by urologists, physicists, and representatives of European lithotripter companies. Evidence acquisition We reviewed recent literature (PubMed, Embase, Medline) that focused on the physics of shock waves, theories of stone disintegration, and studies on optimising shock wave application. In addition, we used relevant information from a consensus meeting of the German Society of Shock Wave Lithotripsy. Evidence synthesis Besides established mechanisms describing initial fragmentation (tear and shear forces, spallation, cavitation, quasi-static squeezing), the model of dynamic squeezing offers new insight in stone comminution. Manufacturers have modified sources to either enlarge the focal zone or offer different focal sizes. The efficacy of extracorporeal shock wave lithotripsy (ESWL) can be increased by lowering the pulse rate to 60–80 shock waves/min and by ramping the shock wave energy. With the water cushion, the quality of coupling has become a critical factor that depends on the amount, viscosity, and temperature of the gel. Fluoroscopy time can be reduced by automated localisation or the use of optical and acoustic tracking systems. There is a trend towards larger focal zones and lower shock wave pressures. Conclusions New theories for stone disintegration favour the use of shock wave sources with larger focal zones. Use of slower pulse rates, ramping strategies, and adequate coupling of the shock wave head can significantly increase the efficacy and safety of ESWL. PMID:21354696

  6. Molecular dynamics simulation of the plastic behavior anisotropy of shock-compressed monocrystal nickel

    NASA Astrophysics Data System (ADS)

    Chen, Ya-Zhou; Zhou, Liu-Cheng; He, Wei-Feng; Sun, Yu; Li, Ying-Hong; Jiao, Yang; Luo, Si-Hai

    2017-01-01

    Molecular dynamics simulations were used to study the plastic behavior of monocrystalline nickel under shock compression along the [100] and [110] orientations. The shock Hugoniot relation, local stress curve, and process of microstructure development were determined. Results showed the apparent anisotropic behavior of monocrystalline nickel under shock compression. The separation of elastic and plastic waves was also obvious. Plastic deformation was more severely altered along the [110] direction than the [100] direction. The main microstructure phase transformed from face-centered cubic to body-centered cubic and generated a large-scale and low-density stacking fault along the family of { 111 } crystal planes under shock compression along the [100] direction. By contrast, the main mechanism of plastic deformation in the [110] direction was the nucleation of the hexagonal, close-packed phase, which generated a high density of stacking faults along the [110] and [1̅10] directions.

  7. Thermophysical properties of multi-shock compressed dense argon

    SciTech Connect

    Chen, Q. F. Zheng, J.; Gu, Y. J.; Chen, Y. L.; Cai, L. C.; Shen, Z. J.

    2014-02-21

    In contrast to the single shock compression state that can be obtained directly via experimental measurements, the multi-shock compression states, however, have to be calculated with the aid of theoretical models. In order to determine experimentally the multiple shock states, a diagnostic approach with the Doppler pins system (DPS) and the pyrometer was used to probe multiple shocks in dense argon plasmas. Plasma was generated by a shock reverberation technique. The shock was produced using the flyer plate impact accelerated up to ∼6.1 km/s by a two-stage light gas gun and introduced into the plenum argon gas sample, which was pre-compressed from the environmental pressure to about 20 MPa. The time-resolved optical radiation histories were determined using a multi-wavelength channel optical transience radiance pyrometer. Simultaneously, the particle velocity profiles of the LiF window was measured with multi-DPS. The states of multi-shock compression argon plasma were determined from the measured shock velocities combining the particle velocity profiles. We performed the experiments on dense argon plasmas to determine the principal Hugonoit up to 21 GPa, the re-shock pressure up to 73 GPa, and the maximum measure pressure of the fourth shock up to 158 GPa. The results are used to validate the existing self-consistent variational theory model in the partial ionization region and create new theoretical models.

  8. Biological Effects of Shock Waves on Infection

    NASA Astrophysics Data System (ADS)

    Gnanadhas, Divya Prakash; Janardhanraj, S.; Chakravortty, Dipshikha; Gopalan, Jagadeesh

    Shock waves have been successfully used for disintegrating kidney stones[1], noninvasive angiogenic approach[2] and for the treatment of osteoporosis[3]. Recently shock waves have been used to treat different medical conditions including intestinal anastomosis[4], wound healing[5], Kienböck's disease[6] and articular cartilage defects[7].

  9. Evolution Of Nonlinear Waves in Compressing Plasma

    SciTech Connect

    P.F. Schmit, I.Y. Dodin, and N.J. Fisch

    2011-05-27

    Through particle-in-cell simulations, the evolution of nonlinear plasma waves is examined in one-dimensional collisionless plasma undergoing mechanical compression. Unlike linear waves, whose wavelength decreases proportionally to the system length L(t), nonlinear waves, such as solitary electron holes, conserve their characteristic size {Delta} during slow compression. This leads to a substantially stronger adiabatic amplification as well as rapid collisionless damping when L approaches {Delta}. On the other hand, cessation of compression halts the wave evolution, yielding a stable mode.

  10. Reflection of curved shock waves

    NASA Astrophysics Data System (ADS)

    Mölder, S.

    2017-03-01

    Shock curvatures are related to pressure gradients, streamline curvatures and vorticity in flows with planar and axial symmetry. Explicit expressions, in an influence coefficient format, are used to relate post-shock pressure gradient, streamline curvature and vorticity to pre-shock gradients and shock curvature in steady flow. Using higher order, von Neumann-type, compatibility conditions, curved shock theory is applied to calculate the flow near singly and doubly curved shocks on curved surfaces, in regular shock reflection and in Mach reflection. Theoretical curved shock shapes are in good agreement with computational fluid dynamics calculations and experiment.

  11. Shock Wave Dynamics in Weakly Ionized Plasmas

    NASA Technical Reports Server (NTRS)

    Johnson, Joseph A., III

    1999-01-01

    An investigation of the dynamics of shock waves in weakly ionized argon plasmas has been performed using a pressure ruptured shock tube. The velocity of the shock is observed to increase when the shock traverses the plasma. The observed increases cannot be accounted for by thermal effects alone. Possible mechanisms that could explain the anomalous behavior include a vibrational/translational relaxation in the nonequilibrium plasma, electron diffusion across the shock front resulting from high electron mobility, and the propagation of ion-acoustic waves generated at the shock front. Using a turbulence model based on reduced kinetic theory, analysis of the observed results suggest a role for turbulence in anomalous shock dynamics in weakly ionized media and plasma-induced hypersonic drag reduction.

  12. Optical carrier wave shocking: detection and dispersion.

    PubMed

    Kinsler, P; Radnor, S B P; Tyrrell, J C A; New, G H C

    2007-06-01

    Carrier wave shocking is studied using the pseudospectral spatial-domain (PSSD) technique. We describe the shock detection diagnostics necessary for this numerical study and verify them against theoretical shocking predictions for the dispersionless case. These predictions show a carrier envelope phase and pulse bandwidth sensitivity in the single-cycle regime. The flexible dispersion management offered by the PSSD enables us to independently control the linear and nonlinear dispersion. Customized dispersion profiles allow us to analyze the development of both carrier self-steepening and shocks. The results exhibit a marked asymmetry between normal and anomalous dispersion, both in the limits of the shocking regime and in the (near) shocked pulse wave forms. Combining these insights, we offer some suggestions on how carrier shocking (or at least extreme self-steepening) might be realized experimentally.

  13. Development of microcapsules for shock wave DDS and angiogenesis using shock waves

    NASA Astrophysics Data System (ADS)

    Tamagawa, M.; Yamanoi, I.; Iwakura, S.

    2006-05-01

    This paper describes the trial of making microcapsules including a bubble for shock wave drug delivery systems, evaluation of their mechanical properties and angiogenesis using plane shock waves. We have proposed drug delivery systems (DDS) using shock waves. In this system, a microcapsule including a gas bubble is flown in the blood vessel, and finally broken by shock induced microjet, then drug is reached to the affected part. In this paper, the mechanism for deformation and disintegration of capsules in our previous works is reviewed, and the trials of making special microcapsules are discussed. To determine Young's modulus of capsule membrane, the membrane is deformed by the aspiration device and compared with computational result by FEM. As for angiogenesis using shock wave, the effects of shock waves under 0.4 MPa on cell growth rate is investigated. It is found that increasing rate of cell population by working shock waves is faster than the control cells.

  14. Shock wave equation of state of muscovite

    NASA Technical Reports Server (NTRS)

    Sekine, Toshimori; Rubin, Allan M.; Ahrens, Thomas J.

    1991-01-01

    Shock wave data were obtained between 20 and 140 GPa for natural muscovite obtained from Methuen Township (Ontario), in order to provide a shock-wave equation of state for this crustal hydrous mineral. The shock equation of state data could be fit by a linear shock velocity (Us) versus particle velocity (Up) relation Us = 4.62 + 1.27 Up (km/s). Third-order Birch-Murnaghan equation of state parameters were found to be K(OS) = 52 +/-4 GPa and K-prime(OS) = 3.2 +/-0.3 GPa. These parameters are comparable to those of other hydrous minerals such as brucite, serpentine, and tremolite.

  15. Overview of shock waves in medicine

    NASA Astrophysics Data System (ADS)

    Cleveland, Robin O.

    2003-10-01

    A brief overview of three applications of shock waves is presented. Shock wave lithotripsy (SWL) has been in clinical use for more than 20 years. In the United States it is used to treat more than 80% of kidney stone cases and has wide acceptance with patients because it is a noninvasive procedure. Despite SWLs enormous success there is no agreement on how shock waves comminute stones. There is also a general acceptance that shock waves lead to trauma to the soft tissue of the kidney. Yet there has been little forward progress in developing lithotripters which provide comminution with less side-effects, indeed the original machine is still considered the gold standard. The last decade has seen the advent of new shock wave devices for treating principally musculoskeletal indications, such as plantar fasciitis, tennis elbow, and bone fractures that do not heal. This is referred to as shock wave therapy (SWT). The mechanisms by which SWT works are even less well understood than SWL and the consequences of bioeffects have also not been studied in detail. Shock waves have also been shown to be effective at enhancing drug delivery into cells and assisting with gene transfection. [Work partially supported by NIH.

  16. Database for properties of materials studied in experiments using shock waves

    NASA Astrophysics Data System (ADS)

    Zhernokletov, M. V.; Trunin, R. F.; Gudarenko, L. F.; Trushchin, V. D.; Gushchina, O. N.

    1997-07-01

    During nearly 50-year period of development of the dynamic methods for studying material properties Russia accumulated a large amount of experimental data for more than 200 individual materials, compounds, condensed media and gases. Practically all the information is obtained at RFNC-VNIIEF. For the accumulated experimental data systematization and visualization the database being presented was developed. At its development DBMS Paradox for Windows was used. The database is a set of interconnected tables storing: the data for shock compression of continuous materials; the data for shock compression of heated materials; the data for shock compression of porous materials; the data for shock compression of materials by the second shock wave; expansion adiabats of shock-compressed continuous materials; expansion adiabats of shock-compressed porous materials; the data for the rate of scattering of shock-compressed materials to air; the data for sound speed in shock-compressed materials. Currently the database stores the data for the following material types: metals; metal hydrides and nitrides; carbides and oxides; mixtures; solid organic materials; alkali metal halogenides; minerals and rocks; water and saturated water solutions of salts; organic liquids. As the data is (and will be) transferred to the Experimental data base from a great number of various sources (papers and reports), it also stores the complete list of these sources.

  17. Shock wave structure in a lattice gas

    NASA Astrophysics Data System (ADS)

    Broadwell, James E.; Han, Donghee

    2007-05-01

    The motion and structure of shock and expansion waves in a simple particle system, a lattice gas and cellular automaton, are determined in an exact computation. Shock wave solutions, also exact, of a continuum description, a model Boltzmann equation, are compared with the lattice results. The comparison demonstrates that, as proved by Caprino et al. ["A derivation of the Broadwell equation," Commun. Math. Phys. 135, 443 (1991)] only when the lattice processes are stochastic is the model Boltzmann description accurate. In the strongest shock wave, the velocity distribution function is the bimodal function proposed by Mott-Smith.

  18. Elimination of cavitation-related attenuation in shock wave lithotripsy

    NASA Astrophysics Data System (ADS)

    Sankin, G. N.; Lautz, J. M.; Simmons, W. N.; Zhong, P.; Frank, S. T.; Szeri, A. J.

    2017-03-01

    In shock wave lithotripsy (SWL), acoustic pulses with a leading compression wave followed by a tensile wave are delivered into the patient's body using a water-filled coupling cushion. Cavitation-related acoustic energy loss in the coupling unit depends critically on water conditions, e.g. dissolved gas concentration and exchange flow rate. We have systematically investigated the attenuation mechanism in the coupling water via pressure measurements and cavitation characterization. In non-degassed water the bubble cluster became progressively dense (i.e., proliferated because of gas diffusion into bubbles and splitting of bubbles into many daughter bubbles) in shock waves delivered at 1 Hz leading to reduction in the tensile wave duration from a nominal value of 4.6 to 1.8 µs. To reduce cavitation in the coupling water along the beam path, we have used a continuous jet flow to remove residual daughter bubbles between consecutive shocks. As a result, stone fragmentation efficiency was increased from 16±4% to 30±5% (p = 0.002) after 250 shocks. Such a hydrodynamic approach for tensile wave attenuation in the coupling water may be used to provide a flexible means for a novel treatment strategy with tissue protection.

  19. Thermal transport in shock wave–compressed solids using pulsed laser heating

    SciTech Connect

    La Lone, B. M.; Capelle, G.; Stevens, G. D.; Turley, W. D.; Veeser, L. R.

    2014-07-01

    A pulsed laser heating method was developed for determining thermal transport properties of solids under shock-wave compression. While the solid is compressed, a laser deposits a known amount of heat onto the sample surface, which is held in the shocked state by a transparent window. The heat from the laser briefly elevates the surface temperature and then diffuses into the interior via one-dimensional heat conduction. The thermal effusivity is determined from the time history of the resulting surface temperature pulse, which is recorded with optical pyrometry. Thermal effusivity is the square root of the product of thermal conductivity and volumetric heat capacity and is the key thermal transport parameter for relating the surface temperature to the interior temperature of the sample in a dynamic compression experiment. Therefore, this method provides information that is needed to determine the thermodynamic state of the interior of a compressed metal sample from a temperature measurement at the surface. The laser heat method was successfully demonstrated on tin that was shock compressed with explosives to a stress and temperature of ~25 GPa and ~1300 K. In this state, tin was observed to have a thermal effusivity of close to twice its ambient value. The implications on determining the interior shock wave temperature of tin are discussed.

  20. Thermal transport in shock wave–compressed solids using pulsed laser heating

    SciTech Connect

    La Lone, B. M. Capelle, G.; Stevens, G. D.; Turley, W. D.; Veeser, L. R.

    2014-07-15

    A pulsed laser heating method was developed for determining thermal transport properties of solids under shock-wave compression. While the solid is compressed, a laser deposits a known amount of heat onto the sample surface, which is held in the shocked state by a transparent window. The heat from the laser briefly elevates the surface temperature and then diffuses into the interior via one-dimensional heat conduction. The thermal effusivity is determined from the time history of the resulting surface temperature pulse, which is recorded with optical pyrometry. Thermal effusivity is the square root of the product of thermal conductivity and volumetric heat capacity and is the key thermal transport parameter for relating the surface temperature to the interior temperature of the sample in a dynamic compression experiment. Therefore, this method provides information that is needed to determine the thermodynamic state of the interior of a compressed metal sample from a temperature measurement at the surface. The laser heat method was successfully demonstrated on tin that was shock compressed with explosives to a stress and temperature of ∼25 GPa and ∼1300 K. In this state, tin was observed to have a thermal effusivity of close to twice its ambient value. The implications on determining the interior shock wave temperature of tin are discussed.

  1. Stability of shock waves in high temperature plasmas

    SciTech Connect

    Das, Madhusmita; Bhattacharya, Chandrani; Menon, S. V. G.

    2011-10-15

    The Dyakov-Kontorovich criteria for spontaneous emission of acoustic waves behind shock fronts are investigated for high temperature aluminum and beryllium plasmas. To this end, the Dyakov and critical stability parameters are calculated from Rankine-Hugoniot curves using a more realistic equation of state (EOS). The cold and ionic contributions to the EOS are obtained via scaled binding energy and mean field theory, respectively. A screened hydrogenic model, including l-splitting, is used to calculate the bound electron contribution to the electronic EOS. The free electron EOS is obtained from Fermi-Dirac statistics. Predictions of the model for ionization curves and shock Hugoniot are found to be in excellent agreement with available experimental and theoretical data. It is observed that the electronic EOS has significant effect on the stability of the planar shock front. While the shock is stable for low temperatures and pressures, instability sets in as temperature rises. The basic reason is ionization of electronic shells and consequent increase in electronic specific heat. The temperatures and densities of the unstable region correspond to those where electronic shells get ionized. With the correct modeling of bound electrons, we find that shock instability for Al occurs at a compression ratio {approx}5.4, contrary to the value {approx}3 reported in the literature. Free electrons generated in the ionization process carry energy from the shock front, thereby giving rise to spontaneously emitted waves, which decay the shock front.

  2. Shock compression dynamics under a microscope

    NASA Astrophysics Data System (ADS)

    Dlott, Dana D.

    2017-01-01

    Our laboratory has developed a tabletop laser miniflyer launcher used for a wide variety of studies in the physical and chemical sciences. The flyers, typically 0.7 mm in diameter, can be used to shock microgram quantities of interesting materials. Frequently 100 shock experiments per day are performed. A microscope objective transmits the photon Doppler velocimeter (PDV) flyer plate diagnostic and various laser beams, and collects signals from the shocked materials that can be transmitted to video cameras, spectrographs, streak cameras, etc. In this paper I describe the flyer plate apparatus and then discuss three recent efforts: (1) Shock dissipation in nanoporous media; (2) Probing micropressures in shocked microstructured media; and (3) Shock initiation of nanotechnology reactive materials.

  3. Turbulence modeling in shock wave/turbulent boundary layer interactions

    NASA Technical Reports Server (NTRS)

    Smits, A. J.

    1992-01-01

    The research performed was an experimental program to help develop turbulence models for shock wave boundary layer interactions. The measurements were taken in a Mach 3, 16 deg compression corner interaction, at a unit Reynolds number of 63 x 10(exp 6)/m. The data consisted of heat transfer data taken upstream and downstream of the interaction, hot wire measurements of the instantaneous temperature and velocity fluctuations to verify the Strong Reynolds Analogy, and single- and double-pulsed Rayleigh scattering images to study the development of the instantaneous shock/turbulence interaction.

  4. Dynamic Shock Compression of Copper to Multi-Megabar Pressure

    NASA Astrophysics Data System (ADS)

    Haill, T. A.; Furnish, M. D.; Twyeffort, L. L.; Arrington, C. L.; Lemke, R. W.; Knudson, M. D.; Davis, J.-P.

    2015-11-01

    Copper is an important material for a variety of shock and high energy density applications and experiments. Copper is used as a standard reference material to determine the EOS properties of other materials. The high conductivity of copper makes it useful as an MHD driver layer in high current dynamic materials experiments on Sandia National Laboratories Z machine. Composite aluminum/copper flyer plates increase the dwell time in plate impact experiments by taking advantage of the slower wave speeds in copper. This presentation reports on recent efforts to reinstate a composite Al/Cu flyer capability on Z and to extend the range of equation-of-state shock compression data through the use of hyper-velocity composite flyers and symmetric planar impact with copper targets. We will present results from multi-dimensional ALEGRA MHD simulations, as well as experimental designs and methods of composite flyer fabrication. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. DOE's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  5. The microphysics of collisionless shock waves.

    PubMed

    Marcowith, A; Bret, A; Bykov, A; Dieckman, M E; Drury, L O'C; Lembège, B; Lemoine, M; Morlino, G; Murphy, G; Pelletier, G; Plotnikov, I; Reville, B; Riquelme, M; Sironi, L; Novo, A Stockem

    2016-04-01

    Collisionless shocks, that is shocks mediated by electromagnetic processes, are customary in space physics and in astrophysics. They are to be found in a great variety of objects and environments: magnetospheric and heliospheric shocks, supernova remnants, pulsar winds and their nebulæ, active galactic nuclei, gamma-ray bursts and clusters of galaxies shock waves. Collisionless shock microphysics enters at different stages of shock formation, shock dynamics and particle energization and/or acceleration. It turns out that the shock phenomenon is a multi-scale non-linear problem in time and space. It is complexified by the impact due to high-energy cosmic rays in astrophysical environments. This review adresses the physics of shock formation, shock dynamics and particle acceleration based on a close examination of available multi-wavelength or in situ observations, analytical and numerical developments. A particular emphasis is made on the different instabilities triggered during the shock formation and in association with particle acceleration processes with regards to the properties of the background upstream medium. It appears that among the most important parameters the background magnetic field through the magnetization and its obliquity is the dominant one. The shock velocity that can reach relativistic speeds has also a strong impact over the development of the micro-instabilities and the fate of particle acceleration. Recent developments of laboratory shock experiments has started to bring some new insights in the physics of space plasma and astrophysical shock waves. A special section is dedicated to new laser plasma experiments probing shock physics.

  6. Origin of compression-induced failure in brittle solids under shock loading

    NASA Astrophysics Data System (ADS)

    Huang, J. Y.; Li, Y.; Liu, Q. C.; Zhou, X. M.; Liu, L. W.; Liu, C. L.; Zhu, M. H.; Luo, S. N.

    2015-10-01

    The origin of compression-induced failure in brittle solids has been a subject of debate. Using in situ, high-speed, strain field mapping of a representative material, polymethylmethacrylate, we reveal that shock loading leads to heterogeneity in a compressive strain field, which in turn gives rise to localized lateral tension and shear through Poisson's effects, and, subsequently, localized microdamage. A failure wave nucleates from the impact surface and its propagation into the microdamage zone is self-sustained, triggering interior failure. Its velocity increases with increasing shock strength and eventually approaches the shock velocity. The seemingly puzzling phenomena observed in previous experiments, including incubation time, failure wave velocity variations, and surface roughness effects, can all be explained consistently with the nucleation and growth of the microdamage, and the effects of loading strength and preexisting defects.

  7. Shock waves on complex networks

    PubMed Central

    Mones, Enys; Araújo, Nuno A. M.; Vicsek, Tamás; Herrmann, Hans J.

    2014-01-01

    Power grids, road maps, and river streams are examples of infrastructural networks which are highly vulnerable to external perturbations. An abrupt local change of load (voltage, traffic density, or water level) might propagate in a cascading way and affect a significant fraction of the network. Almost discontinuous perturbations can be modeled by shock waves which can eventually interfere constructively and endanger the normal functionality of the infrastructure. We study their dynamics by solving the Burgers equation under random perturbations on several real and artificial directed graphs. Even for graphs with a narrow distribution of node properties (e.g., degree or betweenness), a steady state is reached exhibiting a heterogeneous load distribution, having a difference of one order of magnitude between the highest and average loads. Unexpectedly we find for the European power grid and for finite Watts-Strogatz networks a broad pronounced bimodal distribution for the loads. To identify the most vulnerable nodes, we introduce the concept of node-basin size, a purely topological property which we show to be strongly correlated to the average load of a node. PMID:24821422

  8. Lagrangian averaging, nonlinear waves, and shock regularization

    NASA Astrophysics Data System (ADS)

    Bhat, Harish S.

    In this thesis, we explore various models for the flow of a compressible fluid as well as model equations for shock formation, one of the main features of compressible fluid flows. We begin by reviewing the variational structure of compressible fluid mechanics. We derive the barotropic compressible Euler equations from a variational principle in both material and spatial frames. Writing the resulting equations of motion requires certain Lie-algebraic calculations that we carry out in detail for expository purposes. Next, we extend the derivation of the Lagrangian averaged Euler (LAE-alpha) equations to the case of barotropic compressible flows. The derivation in this thesis involves averaging over a tube of trajectories etaepsilon centered around a given Lagrangian flow eta. With this tube framework, the LAE-alpha equations are derived by following a simple procedure: start with a given action, expand via Taylor series in terms of small-scale fluid fluctuations xi, truncate, average, and then model those terms that are nonlinear functions of xi. We then analyze a one-dimensional subcase of the general models derived above. We prove the existence of a large family of traveling wave solutions. Computing the dispersion relation for this model, we find it is nonlinear, implying that the equation is dispersive. We carry out numerical experiments that show that the model possesses smooth, bounded solutions that display interesting pattern formation. Finally, we examine a Hamiltonian partial differential equation (PDE) that regularizes the inviscid Burgers equation without the addition of standard viscosity. Here alpha is a small parameter that controls a nonlinear smoothing term that we have added to the inviscid Burgers equation. We show the existence of a large family of traveling front solutions. We analyze the initial-value problem and prove well-posedness for a certain class of initial data. We prove that in the zero-alpha limit, without any standard viscosity

  9. Photoacoustic shock wave emission and cavitation from structured optical fiber tips

    SciTech Connect

    Mohammadzadeh, M.; Gonzalez-Avila, S. R.; Ohl, C. D.; Wan, Y. C.; Wang, X.; Zheng, H.

    2016-01-11

    Photoacoustic waves generated at the tip of an optical fiber consist of a compressive shock wave followed by tensile diffraction waves. These tensile waves overlap along the fiber axis and form a cloud of cavitation bubbles. We demonstrate that shaping the fiber tip through micromachining alters the number and direction of the emitted waves and cavitation clouds. Shock wave emission and cavitation patterns from five distinctively shaped fiber tips have been studied experimentally and compared to a linear wave propagation model. In particular, multiple shock wave emission and generation of strong tension away from the fiber axis have been realized using modified fiber tips. These altered waveforms may be applied for novel microsurgery protocols, such as fiber-based histotripsy, by utilizing bubble-shock wave interaction.

  10. Existence Regions of Shock Wave Triple Configurations

    ERIC Educational Resources Information Center

    Bulat, Pavel V.; Chernyshev, Mikhail V.

    2016-01-01

    The aim of the research is to create the classification for shock wave triple configurations and their existence regions of various types: type 1, type 2, type 3. Analytical solutions for limit Mach numbers and passing shock intensity that define existence region of every type of triple configuration have been acquired. The ratios that conjugate…

  11. Shock induced damage and damage threshold of optical K9 glass investigated by laser-driven shock wave

    NASA Astrophysics Data System (ADS)

    Song, Yunfei; Yu, Guoyang; Jiang, Lilin; Zheng, Xianxu; Liu, Yuqiang; Yang, Yanqiang

    2011-04-01

    The shock wave driven by short laser pulse is used to study the damage of brittle material K9 glass. The damage morphology of K9 glass surface indicates that the material has experienced different loading modes, respectively, at the central area and the surrounding area of the shock wave. At the central area of shock wave, the wavefront is plane and has a uniform pressure distribution, the material mainly suffers a longitudinal shock pressure; but on the edge the shock wave, the wavefront is approximately spherical, besides longitudinal pressure, transverse tensile stress will emerge inside the material. In the latter case, the damage threshold of the material is much smaller than that in the case of compressing by longitudinal pressure only. According to the relationship between damage area and shock pressure, an experimental method is proposed to measure the damage threshold of materials under shock loading. The damage threshold of K9 glass under spherical shock wave is measured to be about 1.12 GPa; and the damage threshold under plane shock wave is estimated to be between 1.82 and 1.98 GPa. They are much bigger than the damage threshold under static pressure. This method could also be used to measure the damage threshold of other materials when loaded by dynamic pressure.

  12. Nonlinear Fresnel diffraction of weak shock waves.

    PubMed

    Coulouvrat, François; Marchiano, Régis

    2003-10-01

    Fresnel diffraction at a straight edge is revisited for nonlinear acoustics. Considering the penumbra region as a diffraction boundary layer governed by the KZ equation and its associated jump relations for shocks, similarity laws are established for the diffraction of a step shock, an "N" wave, or a periodic sawtooth wave. Compared to the linear case described by the well-known Fresnel functions, it is shown that weak shock waves penetrate more deeply into the shadow zone than linear waves. The thickness of the penumbra increases as a power of the propagation distance, power 1 for a step shock, or 3/4 for an N wave, as opposed to power 1/2 for a periodic sawtooth wave or a linear wave. This is explained considering the frequency spectrum of the waveform and its nonlinear evolution along the propagation, and is confirmed by direct numerical simulations of the KZ equation. New formulas for the Rayleigh/Fresnel distance in the case of nonlinear diffraction of weak shock waves by a large, finite aperture are deduced from the present study.

  13. Shock compression of condensed matter using Eulerian multimaterial method: Applications to multidimensional shocks, deflagration, detonation, and laser ablation

    SciTech Connect

    Yoh, Jack J.; Kim, Ki-hong

    2008-06-01

    The reactive flow analysis of high energy material is performed using hydro shock compression of condensed matter (SCCM) tool that is being developed for handling complex multimaterial dynamics involving energetic and inert matters. Typically, the reacting flows of high energy materials such as fires and explosions give rise to strong nonlinear shock waves and high strain rate deformation of metallic confinements at unusually high pressure and temperature. In order to address difficulties associated with analyzing such complex systems, we have developed a suite of modeling capabilities for elegantly handling large gradients and high strain rates in solids as well as reactive shock waves present in gaseous phase. Mathematical formulation of explosive dynamics involving condensed matter is explained with an emphasis on validating and application of hydro-SCCM to a series of problems of high-speed multimaterial dynamics in nature. A detailed numerical description of a level-set based reactive ghost fluid approach is reported in a separate paper.

  14. Isentropic compressive wave generator impact pillow and method of making same

    DOEpatents

    Barker, Lynn M.

    1985-01-01

    An isentropic compressive wave generator and method of making same. The w generator comprises a disk or flat "pillow" member having component materials of different shock impedances formed in a configuration resulting in a smooth shock impedance gradient over the thickness thereof for interpositioning between an impactor member and a target specimen for producing a shock wave of a smooth predictable rise time. The method of making the pillow member comprises the reduction of the component materials to a powder form and forming the pillow member by sedimentation and compressive techniques.

  15. Shock-wave dynamics during oil-filled transformer explosions

    NASA Astrophysics Data System (ADS)

    Efremov, V. P.; Ivanov, M. F.; Kiverin, A. D.; Utkin, A. V.

    2016-08-01

    This paper presents a numerical and experimental study of the shock-wave processes evolving inside a closed vessel filled with mineral oil. Obtained experimental Hugoniot data for oil are compared with the corresponding data for water. It is found that compression of mineral oil and water can be described by approximately the same Hugoniot over a wide pressure range. Such similarity allows the use of water instead of mineral oil in the transformer explosion experiments and to describe the compression processes in both liquids using similar equations of state. The Kuznetsov equation of state for water is adopted for a numerical study of mineral oil compression. The features of the evolution of shock waves within mineral oil are analyzed using two-dimensional numerical simulations. Numerical results show that different energy sources may cause different scenarios of loading on the shell. The principal point is the phase transition taking place at relatively high temperatures for the case of high-power energy sources. In this case, a vapor-gaseous bubble emerges that qualitatively changes the dynamics of compression waves and the pattern of loads induced on the shell. Taking into account the features of the process together with the concept of water-oil similarity, the present work presents a new approach for experimental modeling of transformer shell destruction using an explosion with given characteristics in a water-filled shell.

  16. Role of shock compression technique for scientific and engineering studies

    NASA Astrophysics Data System (ADS)

    Asay, J. R.; Chhabildas, L. C.

    Shock compression techniques have been used for several decades to study the dynamic states of matter in temperature and pressure regimes inaccessible by other methods. Several experimental loading methods were developed for these studies, including the use of high explosives, high-velocity launchers, and energy deposition. Most recently the development of laboratory techniques for launching flat-plate impactors to velocities of 12 km/s has greatly expanded our ability to study equation-of-state (EOS) and dynamic mechanical properties in regimes previously inaccessible. This paper presents a brief review of the status of high-velocity launchers developed for the purpose of studying dynamic material response. Also included in this paper, a discussion of the launcher capabilities for probing the high-pressure EOS and mechanical response of materials. The range of material property information available from these studies is briefly reviewed and several applications are illustrated. The following methods are discussed: (1) measurements of the shock Hugoniot equation of state and unloading adiabats from the shocked state; (2) techniques for measuring mechanical strength to Mbar pressures under shock and isentropic loading; (3) measurement of tensile failure and the fragmentation of materials; (4) measurement of shock-induced vaporization; and (5) direct measurements of shear properties under shock loading. Shock compression techniques were useful in a variety of current applications, such as debris shield design for spacecraft, analysis of ground shock propagation in geological materials, and shock synthesis of materials.

  17. Peculiarities of evolution of shock waves generated by boiling coolant

    NASA Astrophysics Data System (ADS)

    Alekseev, M. V.; Vozhakov, I. S.; Lezhnin, S. I.; Pribaturin, N. A.

    2016-11-01

    Simulation of compression wave generation and evolution at the disk target was performed for the case of explosive-type boiling of coolant; the boiling is initiated by endwall rupture of a high-pressure pipeline. The calculations were performed for shock wave amplitude at different times and modes of pipe rupture. The simulated pressure of a target-reflected shock wave is different from the theoretical value for ideal gas; this discrepancy between simulation and theory becomes lower at higher distances of flow from the nozzle exit. Comparative simulation study was performed for flow of two-phase coolant with account for slip flow effect and for different sizes of droplets. Simulation gave the limiting droplet size when the single-velocity homogeneous flow model is valid, i.e., the slip flow effect is insignificant.

  18. Fluorescence depolarization measurements under shock compression

    NASA Astrophysics Data System (ADS)

    Wang, Jue; Banishev, Alexandr; Bassett, Will P.; Dlott, Dana D.

    2017-01-01

    Measurements of the time-dependent fluorescence depolarization of emissive probe molecules enable real-time observations of molecular rotations in shocked materials. In shocked solids, molecular rotations occur as a result of shear deformations. An apparatus is described to measure time-dependent fluorescence depolarization of shocked materials using laser-driven flyer plates and either a picosecond or a nanosecond probe laser. The emission was separated into parallel and perpendicular channels and imaged onto a streak camera. Time-dependent fluorescence depolarization of rhodamine 6G (R6G) dye dissolved in poly-methyl methacrylate (PMMA) was measured with a 16 ns duration impact at 1 km s-1. A partial depolarization of the dye emission was observed to occur during a 150 ns period after the shock.

  19. A study of the weak shock wave propagating over a porous wall/cavity system

    NASA Astrophysics Data System (ADS)

    Kim, H. D.; Jung, S. J.; Aoki, T.; Setoguchi, T.

    2005-12-01

    The present computational study addresses the attenuation of the shock wave propagating in a duct, using a porous wall/cavity system. In the present study, a weak shock wave propagating over the porous wall/cavity system is investigated with computational fluid dynamics. A total variation diminishing scheme is employed to solve the unsteady, two-dimensional, compressible, Navier-Stokes equations. The Mach number of an initial shock wave is changed in the range from 1.02 to 1.12. Several different types of porous wall/cavity systems are tested to investigate the passive control effects. The results show that wall pressure strongly fluctuates due to diffraction and reflection processes of the shock waves behind the incident shock wave. From the results, it is understood that for effective alleviation of tunnel impulse waves, the length of the perforated region should be sufficiently long.

  20. a Study of the Shock Sensitivity of PBX 9501 Damaged by Compressive Loading

    NASA Astrophysics Data System (ADS)

    Thompson, D. G.; Gustavsen, R. L.; Hooks, D. E.; Peterson, P. D.; DeLuca, R.; Stahl, D. B.; Hagelberg, S. I.; Alcon, R. R.

    2007-12-01

    We have studied the effects of damage caused by compressive loading on the shock sensitivity of the plastic bonded explosive PBX 9501. PBX 9501 consists of 95 wt. % HMX and 5 wt. % nitroplasticized Estane binder. The binder is a mixture of 49 wt. % Estane® 5703 (BF Goodrich), 49 wt. % Nitroplasticizer (a eutectic mixture of bis(2,2-dinitropropyl)formal and bis(2,2 dinitropropyl)acetal), and 2 wt. % Irganox® 1010 stabilizer. PBX 9501 cubes, 25.4 mm on a side, were compressed to various uniaxial loads in an Instron machine. After loading, 10×10 mm cross-sections, 3.5 mm thick, were taken from the center of each cube. These slices were then subjected to nearly identical 35 kbar shocks. Transmitted shock wave profiles were measured using interface velocimetry (VISAR). Comparison of shock wave growth is a measure of shock sensitivity. Results on four samples indicate little change in sensitivity caused by compressive loading.

  1. Plasma shock waves excited by THz radiation

    NASA Astrophysics Data System (ADS)

    Rudin, S.; Rupper, G.; Shur, M.

    2016-10-01

    The shock plasma waves in Si MOS, InGaAs and GaN HEMTs are launched at a relatively small THz power that is nearly independent of the THz input frequency for short channel (22 nm) devices and increases with frequency for longer (100 nm to 1 mm devices). Increasing the gate-to-channel separation leads to a gradual transition of the nonlinear waves from the shock waves to solitons. The mathematics of this transition is described by the Korteweg-de Vries equation that has the single propagating soliton solution.

  2. Holographic interferometric observation of shock wave focusing to extracorporeal shock wave lithotripsy

    NASA Astrophysics Data System (ADS)

    Takayama, Kazuyoshi; Obara, Tetsuro; Onodera, Osamu

    1991-04-01

    Underwater shock wave focusing is successfully applied to disintegrate and remove kidney stones or gallbladder stones without using surgical operations. This treatment is one of the most peaceful applications ofshock waves and is named as the Extracorporeal Shock Wave Lithotripsy. Ajoint research project is going on between the Institute ofFluid Science, Tohoku University and the School ofMedicine, Tohoku University. The paper describes a result of the fundamental research on the underwater shock wave focusing applied to the ESWL. Quantitatively to visualize the underwater shock waves, various optical flow visualization techniques were successfully used such as holographic interferometry, and shadowgraphs combined with Ima-Con high speed camera. Double exposure holographic interferometric observation revealed the mechanism of generation, propagation and focusing of underwater shock waves. The result of the present research was already used to manufacture a prototype machine and it has already been applied successfully to ESWL crinical treatments. However, despite of success in the clinical treatments, important fundamental questions still remain unsolved, i.e., effects of underwater shock wave focusing on tissue damage during the treatment. Model experiments were conducted to clarify mechanism of the tissue damage associated with the ESWL. Shock-bubble interactions were found responsible to the tissue damage during the ESWL treatment. In order to interprete experimental findings and to predict shock wave behavior and high pressures, a numerical simulation was carried. The numerical results agreed with the experiments.

  3. Proton radiography of a shock-compressed target

    SciTech Connect

    Ravasio, A.; Benuzzi-Mounaix, A.; Loupias, B.; Ozaki, N.; Vinci, T.; Koenig, M.; Romagnani, L.; Cecchetti, C.; Borghesi, M.; Le Pape, S.; Hicks, D.; MacKinnon, A.; Park, H. S.; Patel, P.; Batani, D.; Dezulian, R.; Boehly, T.; Gremillet, L.; Henry, E.; Schiavi, A.

    2010-07-15

    In this paper we report on the radiography of a shock-compressed target using laser produced proton beams. A low-density carbon foam target was shock compressed by long pulse high-energy laser beams. The shock front was transversally probed with a proton beam produced in the interaction of a high intensity laser beam with a gold foil. We show that from radiography data, the density profile in the shocked target can be deduced using Monte Carlo simulations. By changing the delay between long and short pulse beams, we could probe different plasma conditions and structures, demonstrating that the details of the steep density gradient can be resolved. This technique is validated as a diagnostic for the investigation of warm dense plasmas, allowing an in situ characterization of high-density contrasted plasmas.

  4. Weak-shock theory for spherical shock waves

    SciTech Connect

    Curtis, W.D.; Rosenkilde, C.E.; Yee, K.S.

    1982-03-01

    We develop weak shock theory in a form which would allow us to utilize output from a hydrodynamic code (e.g. KOVEC) as either an initial or boundary condition and then follow the wave evolution to much greater distances than the codes themselves can attain.

  5. Laser driven single shock compression of fluid deuterium from 45 to 220 GPa

    SciTech Connect

    Hicks, D; Boehly, T; Celliers, P; Eggert, J; Moon, S; Meyerhofer, D; Collins, G

    2008-03-23

    The compression {eta} of liquid deuterium between 45 and 220 GPa under laser-driven shock loading has been measured using impedance matching to an aluminum (Al) standard. An Al impedance match model derived from a best fit to absolute Hugoniot data has been used to quantify and minimize the systematic errors caused by uncertainties in the high-pressure Al equation of state. In deuterium below 100 GPa results show that {eta} {approx_equal} 4.2, in agreement with previous impedance match data from magnetically-driven flyer and convergent-explosive shock wave experiments; between 100 and 220 GPa {eta} reaches a maximum of {approx}5.0, less than the 6-fold compression observed on the earliest laser-shock experiments but greater than expected from simple extrapolations of lower pressure data. Previous laser-driven double-shock results are found to be in good agreement with these single-shock measurements over the entire range under study. Both sets of laser-shock data indicate that deuterium undergoes an abrupt increase in compression at around 110 GPa.

  6. Turbulent water coupling in shock wave lithotripsy.

    PubMed

    Lautz, Jaclyn; Sankin, Georgy; Zhong, Pei

    2013-02-07

    Previous studies have demonstrated that stone comminution decreases with increased pulse repetition frequency as a result of bubble proliferation in the cavitation field of a shock wave lithotripter (Pishchalnikov et al 2011 J. Acoust. Soc. Am. 130 EL87-93). If cavitation nuclei remain in the propagation path of successive lithotripter pulses, especially in the acoustic coupling cushion of the shock wave source, they will consume part of the incident wave energy, leading to reduced tensile pressure in the focal region and thus lower stone comminution efficiency. We introduce a method to remove cavitation nuclei from the coupling cushion between successive shock exposures using a jet of degassed water. As a result, pre-focal bubble nuclei lifetime quantified by B-mode ultrasound imaging was reduced from 7 to 0.3 s by a jet with an exit velocity of 62 cm s(-1). Stone fragmentation (percent mass <2 mm) after 250 shocks delivered at 1 Hz was enhanced from 22 ± 6% to 33 ± 5% (p = 0.007) in water without interposing tissue mimicking materials. Stone fragmentation after 500 shocks delivered at 2 Hz was increased from 18 ± 6% to 28 ± 8% (p = 0.04) with an interposing tissue phantom of 8 cm thick. These results demonstrate the critical influence of cavitation bubbles in the coupling cushion on stone comminution and suggest a potential strategy to improve the efficacy of contemporary shock wave lithotripters.

  7. Damage mechanisms in shock wave lithotripsy (SWL)

    NASA Astrophysics Data System (ADS)

    Lokhandwalla, Murtuza

    Shock wave lithotripsy is a 'non-invasive' therapy for treating kidney stones. Focused shock waves fragment stones to a size that can be passed naturally. There is, however, considerable tissue injury, and the mechanisms of stone fragmentation and tissue injury are not well understood. This work investigates potential tissue damage mechanisms, with an aim towards enhancing stone fragmentation and minimizing tissue damage. Lysis of red blood cells (RBC's) due to in vitro exposure to shock waves was investigated. Fluid flow-fields induced by a non-uniform shock wave, as well as radial expansion/implosion of a bubble was hypothesized to cause cell lysis. Both the above flow-fields constitute an unsteady extensional flow, exerting inertial as well as viscous forces on the RBC membrane. The resultant membrane tension and the membrane areal strain due to the above flow-fields were estimated. Both were found to exert a significantly higher inertial force (50--100 mN/m) than the critical membrane tension (10 mN/m). Bubble-induced flow-field was estimated to last for a longer duration (˜1 microsec) compared to the shock-induced flow (˜1 ns) and hence, was predicted to be lytically more effective, in typical in vitro experimental conditions. However, in vivo conditions severely constrain bubble growth, and cell lysis due to shock-induced shear could be dominant. Hemolysis due to shock-induced shear, in absence of cavitation, was experimentally investigated. The lithotripter-generated shock wave was refocused by a parabolic reflector. This refocused wave-field had a tighter focus (smaller beam-width and a higher amplitude) than the lithotripter wave-field. Cavitation was eliminated by applying overpressure to the fluid. Acoustic emissions due to bubble activity were monitored by a novel passive cavitation detector (HP-PCD). Aluminum foils were also used to differentiate cavitational from non-cavitational mode of damage. RBC's were exposed to the reflected wave-field from

  8. Calculation of the flow field in supersonic mixed-compression inlets at angle of attack using the three-dimensional method of characteristics with discrete shock wave fitting

    NASA Technical Reports Server (NTRS)

    Vadyak, J.; Hoffman, J. D.

    1978-01-01

    The influence of molecular transport is included in the computation by treating viscous and thermal diffusion terms in the governing partial differential equations as correction terms in the method of characteristics scheme. The development of a production type computer program is reported which is capable of calculating the flow field in a variety of axisymmetric mixed-compression aircraft inlets. The results agreed well with those produced by the two-dimensional method characteristics when axisymmetric flow fields are computed. For three-dimensional flow fields, the results agree well with experimental data except in regions of high viscous interaction and boundary layer removal.

  9. 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.

  10. Shock compression experiments on Lithium Deuteride (LiD) single crystals

    SciTech Connect

    Knudson, Marcus D.; Desjarlais, Michael P.; Lemke, Raymond W.

    2014-10-01

    Shock compression experiments in the few hundred GPa (multi-Mabr) regime were performed on Lithium Deuteride (LiD) single crystals. This study utilized the high velocity flyer plate capability of the Sandia Z Machine to perform impact experiments at flyer plate velocities in the range of 17-32 km/s. Measurements included pressure, density, and temperature between ~200-600 GPa along the Principal Hugoniot – the locus of end states achievable through compression by large amplitude shock waves – as well as pressure and density of re - shock states up to ~900 GPa. Lastly, the experimental measurements are compared with recent density functional theory calculations as well as a new tabular equation of state developed at Los Alamos National Labs.

  11. Shock compression experiments on Lithium Deuteride (LiD) single crystals

    NASA Astrophysics Data System (ADS)

    Knudson, M. D.; Desjarlais, M. P.; Lemke, R. W.

    2016-12-01

    Shock compression experiments in the few hundred GPa (multi-Mbar) regime were performed on Lithium Deuteride single crystals. This study utilized the high velocity flyer plate capability of the Sandia Z Machine to perform impact experiments at flyer plate velocities in the range of 17-32 km/s. Measurements included pressure, density, and temperature between ˜190 and 570 GPa along the Principal Hugoniot—the locus of end states achievable through compression by large amplitude shock waves—as well as pressure and density of reshock states up to ˜920 GPa. The experimental measurements are compared with density functional theory calculations, tabular equation of state models, and legacy nuclear driven results that have been reanalyzed using modern equations of state for the shock wave standards used in the experiments.

  12. Shock compression experiments on Lithium Deuteride (LiD) single crystals

    SciTech Connect

    Knudson, M. D.; Desjarlais, M. P.; Lemke, R. W.

    2016-12-21

    Shock compression experiments in the few hundred GPa (multi-Mabr) regime were performed on Lithium Deuteride (LiD) single crystals. This study utilized the high velocity flyer plate capability of the Sandia Z Machine to perform impact experiments at flyer plate velocities in the range of 17-32 km/s. Measurements included pressure, density, and temperature between ~200-600 GPa along the Principal Hugoniot – the locus of end states achievable through compression by large amplitude shock waves – as well as pressure and density of re - shock states up to ~900 GPa. Lastly, the experimental measurements are compared with recent density functional theory calculations as well as a new tabular equation of state developed at Los Alamos National Labs.

  13. Shock compression experiments on Lithium Deuteride (LiD) single crystals

    DOE PAGES

    Knudson, M. D.; Desjarlais, M. P.; Lemke, R. W.

    2016-12-21

    Shock compression experiments in the few hundred GPa (multi-Mabr) regime were performed on Lithium Deuteride (LiD) single crystals. This study utilized the high velocity flyer plate capability of the Sandia Z Machine to perform impact experiments at flyer plate velocities in the range of 17-32 km/s. Measurements included pressure, density, and temperature between ~200-600 GPa along the Principal Hugoniot – the locus of end states achievable through compression by large amplitude shock waves – as well as pressure and density of re - shock states up to ~900 GPa. Lastly, the experimental measurements are compared with recent density functional theorymore » calculations as well as a new tabular equation of state developed at Los Alamos National Labs.« less

  14. Shock compression experiments on Lithium Deuteride (LiD) single crystals

    DOE PAGES

    Knudson, M. D.; Desjarlais, M. P.; Lemke, R. W.

    2016-12-21

    Shock compression experiments in the few hundred GPa (multi-Mbar) regime were performed on Lithium Deuteride single crystals. This study utilized the high velocity flyer plate capability of the Sandia Z Machine to perform impact experiments at flyer plate velocities in the range of 17–32 km/s. Measurements included pressure, density, and temperature between ~190 and 570 GPa along the Principal Hugoniot—the locus of end states achievable through compression by large amplitude shock waves—as well as pressure and density of reshock states up to ~920 GPa. As a result, the experimental measurements are compared with density functional theory calculations, tabular equation ofmore » state models, and legacy nuclear driven results that have been reanalyzed using modern equations of state for the shock wave standards used in the experiments.« less

  15. Shock compression experiments on Lithium Deuteride (LiD) single crystals

    SciTech Connect

    Knudson, M. D.; Desjarlais, M. P.; Lemke, R. W.

    2016-12-21

    Shock compression experiments in the few hundred GPa (multi-Mbar) regime were performed on Lithium Deuteride single crystals. This study utilized the high velocity flyer plate capability of the Sandia Z Machine to perform impact experiments at flyer plate velocities in the range of 17–32 km/s. Measurements included pressure, density, and temperature between ~190 and 570 GPa along the Principal Hugoniot—the locus of end states achievable through compression by large amplitude shock waves—as well as pressure and density of reshock states up to ~920 GPa. As a result, the experimental measurements are compared with density functional theory calculations, tabular equation of state models, and legacy nuclear driven results that have been reanalyzed using modern equations of state for the shock wave standards used in the experiments.

  16. High-energy synchrotron X-ray radiography of shock-compressed materials

    NASA Astrophysics Data System (ADS)

    Rutherford, Michael E.; Chapman, David J.; Collinson, Mark A.; Jones, David R.; Music, Jasmina; Stafford, Samuel J. P.; Tear, Gareth R.; White, Thomas G.; Winters, John B. R.; Drakopoulos, Michael; Eakins, Daniel E.

    2015-06-01

    This presentation will discuss the development and application of a high-energy (50 to 250 keV) synchrotron X-ray imaging method to study shock-compressed, high-Z samples at Beamline I12 at the Diamond Light Source synchrotron (Rutherford-Appleton Laboratory, UK). Shock waves are driven into materials using a portable, single-stage gas gun designed by the Institute of Shock Physics. Following plate impact, material deformation is probed in-situ by white-beam X-ray radiography and complimentary velocimetry diagnostics. The high energies, large beam size (13 x 13 mm), and appreciable sample volumes (~ 1 cm3) viable for study at Beamline I12 compliment existing in-house pulsed X-ray capabilities and studies at the Dynamic Compression Sector. The authors gratefully acknowledge the ongoing support of Imperial College London, EPSRC, STFC and the Diamond Light Source, and AWE Plc.

  17. Nonplanar Shock Waves in Dusty Plasmas

    SciTech Connect

    Mamun, A. A.; Shukla, P. K.

    2011-11-29

    Nonplanar (viz. cylindrical and spherical) electro-acoustic [dust-ion-acoustic (DIA) and dust-acoustic (DA)] shock waves have been investigated by employing the reductive perturbation method. The dust charge fluctuation (strong correlation among highly charged dust) is the source of dissipation, and is responsible for the formation of the DIA (DA) shock structures. The effects of cylindrical and spherical geometries on the time evolution of DIA and DA shock structures are examined and identified. The combined effects of vortex-like electron distribution and dust charge fluctuation (dust-correlation and effective dust-temperature) on the basic features of nonplanar DIA (DA) shock waves are pinpointed. The implications of our results in laboratory dusty plasma experiments are briefly discussed.

  18. Nonplanar Shock Waves in Dusty Plasmas

    NASA Astrophysics Data System (ADS)

    Mamun, A. A.; Shukla, P. K.

    2011-11-01

    Nonplanar (viz. cylindrical and spherical) electro-acoustic [dust-ion-acoustic (DIA) and dust-acoustic (DA)] shock waves have been investigated by employing the reductive perturbation method. The dust charge fluctuation (strong correlation among highly charged dust) is the source of dissipation, and is responsible for the formation of the DIA (DA) shock structures. The effects of cylindrical and spherical geometries on the time evolution of DIA and DA shock structures are examined and identified. The combined effects of vortex-like electron distribution and dust charge fluctuation (dust-correlation and effective dust-temperature) on the basic features of nonplanar DIA (DA) shock waves are pinpointed. The implications of our results in laboratory dusty plasma experiments are briefly discussed.

  19. Emission lifetimes of a fluorescent dye under shock compression

    SciTech Connect

    Liu, Wei-long; Bassett, Will P.; Christensen, James M.; Dlott, Dana D.

    2015-10-15

    The emission lifetimes of rhodamine 6G (R6G), were measured under shock compression to 9.1 GPa, with the dual intent of better understanding molecular photophysics in extreme environments and assessing the usefulness of fluorescence lifetime microscopy to measure spatially-dependent pressure distributions in shocked microstructured media. R6G was studied as free dye dissolved in poly-methyl methacrylate (PMMA), or dye encapsulated in silica microparticles suspended in PMMA. Thin layers of these materials in impedance-matched geometries were subjected to planar single-stage shocks created by laser-driven flyer plates. A synchronized femtosecond laser excited the dye at selected times relative to flyer plate arrival and the emission lifetimes were measured with a streak camera. Lifetimes decreased when shocks arrived. The lifetime decrease was attributed to a shock-induced enhancement of R6G nonradiative relaxation. At least part of the relaxation involved shock-enhanced intersystem crossing. For free dye in PMMA, the lifetime decrease during the shock was shown to be a linear function of shock pressure from 0-9 GPa, with a slope of -0.22 ns·GPa-1. Furthermore, the linear relationship makes it simple to convert lifetimes into pressures. Lifetime measurements in shocked microenvironments may be better than emission intensity measurements, since lifetimes are sensitive to the surrounding environment, but insensitive to intensity variations associated with the motion and optical properties of a dynamically changing structure.

  20. Emission lifetimes of a fluorescent dye under shock compression

    DOE PAGES

    Liu, Wei-long; Bassett, Will P.; Christensen, James M.; ...

    2015-10-15

    The emission lifetimes of rhodamine 6G (R6G), were measured under shock compression to 9.1 GPa, with the dual intent of better understanding molecular photophysics in extreme environments and assessing the usefulness of fluorescence lifetime microscopy to measure spatially-dependent pressure distributions in shocked microstructured media. R6G was studied as free dye dissolved in poly-methyl methacrylate (PMMA), or dye encapsulated in silica microparticles suspended in PMMA. Thin layers of these materials in impedance-matched geometries were subjected to planar single-stage shocks created by laser-driven flyer plates. A synchronized femtosecond laser excited the dye at selected times relative to flyer plate arrival and themore » emission lifetimes were measured with a streak camera. Lifetimes decreased when shocks arrived. The lifetime decrease was attributed to a shock-induced enhancement of R6G nonradiative relaxation. At least part of the relaxation involved shock-enhanced intersystem crossing. For free dye in PMMA, the lifetime decrease during the shock was shown to be a linear function of shock pressure from 0-9 GPa, with a slope of -0.22 ns·GPa-1. Furthermore, the linear relationship makes it simple to convert lifetimes into pressures. Lifetime measurements in shocked microenvironments may be better than emission intensity measurements, since lifetimes are sensitive to the surrounding environment, but insensitive to intensity variations associated with the motion and optical properties of a dynamically changing structure.« less

  1. Shear wave measurements in shock-induced, high-pressure phases

    SciTech Connect

    Aidun, J.B.

    1993-01-01

    Structural phase transformations under shock loading are of considerable interest for understanding the response of solids under nonhydrostatic stresses and at high strain-rates. Examining shock-induced transformations from continuum level measurements is fundamentally constrained by the inability to directly identify microscopic processes, and also by the limited number of material properties that can be directly measured. ne latter limitation can be reduced by measuring both shear and compression waves using Lagrangian gauges in combined, compression and shear loading. The shear wave serves as an important, real-time probe of the shocked state and unloading response. Using results from a recent study of CaCO[sub 3], the unique information obtained from the shear wave speed and the detailed structure of the shear wave are shown to be useful for distinguishing the effects of phase transformations from yielding, as well as in characterizing the high-pressure phases and the yielding process under shock loading.

  2. Shear wave measurements in shock-induced, high-pressure phases

    SciTech Connect

    Aidun, J.B.

    1993-07-01

    Structural phase transformations under shock loading are of considerable interest for understanding the response of solids under nonhydrostatic stresses and at high strain-rates. Examining shock-induced transformations from continuum level measurements is fundamentally constrained by the inability to directly identify microscopic processes, and also by the limited number of material properties that can be directly measured. ne latter limitation can be reduced by measuring both shear and compression waves using Lagrangian gauges in combined, compression and shear loading. The shear wave serves as an important, real-time probe of the shocked state and unloading response. Using results from a recent study of CaCO{sub 3}, the unique information obtained from the shear wave speed and the detailed structure of the shear wave are shown to be useful for distinguishing the effects of phase transformations from yielding, as well as in characterizing the high-pressure phases and the yielding process under shock loading.

  3. Magnetoacoustic shock waves in dissipative degenerate plasmas

    SciTech Connect

    Hussain, S.; Mahmood, S.

    2011-11-15

    Quantum magnetoacoustic shock waves are studied in homogenous, magnetized, dissipative dense electron-ion plasma by using two fluid quantum magneto-hydrodynamic (QMHD) model. The weak dissipation effects in the system are taken into account through kinematic viscosity of the ions. The reductive perturbation method is employed to derive Korteweg-de Vries Burgers (KdVB) equation for magnetoacoustic wave propagating in the perpendicular direction to the external magnetic field in dense plasmas. The strength of magnetoacoustic shock is investigated with the variations in plasma density, magnetic field intensity, and ion kinematic viscosity of dense plasma system. The necessary condition for the existence of monotonic and oscillatory shock waves is also discussed. The numerical results are presented for illustration by using the data of astrophysical dense plasma situations such as neutron stars exist in the literature.

  4. Laser Light Scattering by Shock Waves

    NASA Technical Reports Server (NTRS)

    Panda, J.; Adamovsky, G.

    1995-01-01

    Scattering of coherent light as it propagates parallel to a shock 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 shock 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 shock. In the second situation, a narrow laser beam is brought to a grazing incidence on the shock 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 shocks formed at various free-stream Mach numbers, M, and total pressures, P(sub 0). It is found that the widths of the shock 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 shock. The total scattered light measured from the narrow laser beam and shock interaction also follows the same trend. In the numerical part of the study, the shock 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 shock 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.

  5. Reflection and Refraction of Acoustic Waves by a Shock Wave

    NASA Technical Reports Server (NTRS)

    Brillouin, J.

    1957-01-01

    The presence of sound waves in one or the other of the fluid regions on either side of a shock wave is made apparent, in the region under superpressure, by acoustic waves (reflected or refracted according to whether the incident waves lie in the region of superpressure or of subpressure) and by thermal waves. The characteristics of these waves are calculated for a plane, progressive, and uniform incident wave. In the case of refraction, the refracted acoustic wave can, according to the incidence, be plane, progressive, and uniform or take the form of an 'accompanying wave' which remains attached to the front of the shock while sliding parallel to it. In all cases, geometrical constructions permit determination of the kinematic characteristics of the reflected or refractive acoustic waves. The dynamic relationships show that the amplitude of the reflected wave is always less than that of the incident wave. The amplitude of the refracted wave, whatever its type, may in certain cases be greater than that of the incident wave.

  6. Frequency shift measurement in shock-compressed materials

    DOEpatents

    Moore, David S.; Schmidt, Stephen C.

    1985-01-01

    A method for determining molecular vibrational frequencies in shock-compressed transparent materials. A single laser beam pulse is directed into a sample material while the material is shock-compressed from a direction opposite that of the incident laser beam. A Stokes beam produced by stimulated Raman scattering is emitted back along the path of the incident laser beam, that is, in the opposite direction to that of the incident laser beam. The Stokes beam is separated from the incident beam and its frequency measured. The difference in frequency between the Stokes beam and the incident beam is representative of the characteristic frequency of the Raman active mode of the sample. Both the incident beam and the Stokes beam pass perpendicularly through the shock front advancing through the sample, thereby minimizing adverse effects of refraction.

  7. Amorphization and nanocrystallization of silcon under shock compression

    SciTech Connect

    Remington, B. A.; Wehrenberg, C. E.; Zhao, S.; Hahn, E. N.; Kad, B.; Bringa, E. M.; Meyers, M. A.

    2015-11-06

    High-power, short-duration, laser-driven, shock compression and recovery experiments on [001] silicon unveiled remarkable structural changes above a pressure threshold. Two distinct amorphous regions were identified: (a) a bulk amorphous layer close to the surface and (b) amorphous bands initially aligned with {111} slip planes. Further increase of the laser energy leads to the re-crystallization of amorphous silicon into nanocrystals with high concentration of nano-twins. This amorphization is produced by the combined effect of high magnitude hydrostatic and shear stresses under dynamic shock compression. Shock-induced defects play a very important role in the onset of amorphization. Calculations of the free energy changes with pressure and shear, using the Patel-Cohen methodology, are in agreement with the experimental results. Molecular dynamics simulation corroborates the amorphization, showing that it is initiated by the nucleation and propagation of partial dislocations. As a result, the nucleation of amorphization is analyzed qualitatively by classical nucleation theory.

  8. Mechanochemistry for shock wave energy dissipation

    NASA Astrophysics Data System (ADS)

    Shaw, William L.; Ren, Yi; Moore, Jeffrey S.; Dlott, Dana D.

    2017-01-01

    Using a laser-driven flyer-plate apparatus to launch 75 μm thick Al flyers up to 2.8 km/s, we developed a technique for detecting the attenuation of shock waves by mechanically-driven chemical reactions. The attenuating sample was spread on an ultrathin Au mirror deposited onto a glass window having a known Hugoniot. As shock energy exited the sample and passed through the mirror, into the glass, photonic Doppler velocimetry monitored the velocity profile of the ultrathin mirror. Knowing the window Hugoniot, the velocity profile could be quantitatively converted into a shock energy flux or fluence. The flux gave the temporal profile of the shock front, and showed how the shock front was reshaped by passing through the dissipative medium. The fluence, the time-integrated flux, showed how much shock energy was transmitted through the sample. Samples consisted of microgram quantities of carefully engineered organic compounds selected for their potential to undergo negative-volume chemistry. Post mortem analytical methods were used to confirm that shock dissipation was associated with shock-induced chemical reactions.

  9. Stimulated Raman scattering from ice-VIII by shock-induced compression in liquid water

    NASA Astrophysics Data System (ADS)

    Men, Zhiwei; Li, Zuowei; Zhou, Mi; Lu, Guohui; Zou, Bo; Li, Zhanlong; Sun, Chenglin

    2012-03-01

    Stimulated Raman scattering (SRS) from ice-VIII was investigated using shock-induced compression (SIC) generated by laser-induced breakdown in liquid water. Three backward SRS peaks of OH stretching vibrations and one backward SRS characteristic peak of lattice translation were observed. The SRS spectra indicated that the ice-VIII structure is formed by SIC, as the trajectory of the SIC passes through the stable pressure-temperature range of ice-VIII. The static electric field generated by electron jets protects proton-ordered structure. The laser-induced shock wave mechanism is also discussed.

  10. Propagation of shock waves through clouds

    NASA Astrophysics Data System (ADS)

    Zhou, Xin Xin

    1990-10-01

    The behavior of a shock wave propagating into a cloud consisting of an inert gas, water vapor and water droplets was investigated. This has particular application to sonic bangs propagating in the atmosphere. The finite different method of MacCormack is extended to solve the one and two dimensional, two phase flow problems in which mass, momentum and energy transfers are included. The FCT (Fluid Corrected Transport) technique developed by Boris and Book was used in the basic numerical scheme as a powerful corrective procedure. The results for the transmitted shock waves propagating in a one dimensional, semi infinite cloud obtained by the finite difference approach are in good agreement with previous results by Kao using the method characteristics. The advantage of the finite difference method is its adaptability to two and three dimensional problems. Shock wave propagation through a finite cloud and into an expansion with a 90 degree corner was investigated. It was found that the transfer processes between the two phases in two dimensional flow are much more complicated than in the one dimensional flow cases. This is mainly due to the vortex and expansion wave generated at the corner. In the case considered, further complications were generated by the reflected shock wave from the floor. Good agreement with experiment was found for one phase flow but experimental data for the two phase case is not yet available to validate the two phase calculations.

  11. Hydrodynamic simulations of gaseous Argon shock compression experiments

    NASA Astrophysics Data System (ADS)

    Garcia, Daniel B.; Dattelbaum, Dana M.; Goodwin, Peter M.; Sheffield, Stephen A.; Morris, John S.; Gustavsen, Richard L.; Burkett, Michael W.

    2017-01-01

    The lack of published Ar gas shock data motivated an evaluation of the Ar Equation of State (EOS) in gas phase initial density regimes. In particular, these regimes include initial pressures in the range of 13.8 - 34.5 bar (0.025 - 0.056 g/ cm3) and initial shock velocities around 0.2 cm/μs. The objective of the numerical evaluation was to develop a physical understanding of the EOS behavior of shocked and subsequently multiply re-shocked Ar gas through Pagosa numerical simulations utilizing the SESAME equation of state. Pagosa is a Los Alamos National Laboratory 2-D and 3-D Eulerian continuum dynamics code capable of modeling high velocity compressible flow with multiple materials. The approach involved the use of gas gun experiments to evaluate the shock and multiple re-shock behavior of pressurized Ar gas to validate Pagosa simulations and the SESAME EOS. Additionally, the diagnostic capability within the experiments allowed for the EOS to be fully constrained with measured shock velocity, particle velocity and temperature. The simulations demonstrate excellent agreement with the experiments in the shock velocity/particle velocity space, and reasonable comparisons for the ionization temperatures.

  12. Shock compressing diamond to a conducting fluid.

    PubMed

    Bradley, D K; Eggert, J H; Hicks, D G; Celliers, P M; Moon, S J; Cauble, R C; Collins, G W

    2004-11-05

    Laser generated shock reflectance data show that diamond undergoes a continuous transition from optically absorbing to reflecting between Hugoniot pressures 600

  13. Shock Compressing Diamond to a Conducting Fluid

    SciTech Connect

    Bradley, D K; Eggert, J H; Hicks, D G; Celliers, P M; Moon, S J; Cauble, R C; Collins, G W

    2004-07-29

    Laser generated shock reflectance data show that diamond undergoes a continuous transition from optically absorbing to reflecting between Hugoniot pressures 600

  14. Acoustic field of a ballistic shock wave therapy device.

    PubMed

    Cleveland, Robin O; Chitnis, Parag V; McClure, Scott R

    2007-08-01

    Shock wave therapy (SWT) refers to the use of focused shock waves for treatment of musculoskeletal indications including plantar fascitis and dystrophic mineralization of tendons and joint capsules. Measurements were made of a SWT device that uses a ballistic source. The ballistic source consists of a handpiece within which compressed air (1-4 bar) is used to fire a projectile that strikes a metal applicator placed on the skin. The projectile generates stress waves in the applicator that transmit as pressure waves into tissue. The acoustic fields from two applicators were measured: one applicator was 15 mm in diameter and the surface slightly convex and the second was 12 mm in diameter the surface was concave. Measurements were made in a water tank and both applicators generated a similar pressure pulse consisting of a rectangular positive phase (4 micros duration and up to 8 MPa peak pressure) followed by a predominantly negative tail (duration of 20 micros and peak negative pressure of -6 MPa), with many oscillations. The rise times of the waveforms were around 1 micros and were shown to be too long for the pulses to be considered shock waves. Measurements of the field indicated that region of high pressure was restricted to the near-field (20-40 mm) of the source and was consistent with the Rayleigh distance. The measured acoustic field did not display focusing supported by calculations, which demonstrated that the radius of curvature of the concave surface was too large to effect a focusing gain. Other SWT devices use electrohydraulic, electromagnetic and piezoelectric sources that do result in focused shock waves. This difference in the acoustic fields means there is potentially a significant mechanistic difference between a ballistic source and other SWT devices.

  15. Burnett-Cattaneo continuum theory for shock waves

    NASA Astrophysics Data System (ADS)

    Holian, Brad Lee; Mareschal, Michel; Ravelo, R.

    2012-03-01

    We model strong shockwave propagation, both in the ideal gas and in the dense Lennard- Jones fluid, using a refinement of earlier work, which accounts for the cold compression in the early stages of the shock rise by a nonlinear, Burnett-like, strain-rate dependence of the thermal conductivity, and relaxation of kinetic temperature components on the hot, compressed side of the shock front. The relaxation of the disequilibrium among the three components of the kinetic temperature, namely, the difference between the component in the direction of a planar shock wave and those in the transverse directions, particularly in the region near the shock front, is accomplished at a much more quantitative level by the first-ever rigorous application of the Cattaneo-Maxwell relaxation equation to a reference solution, namely, the steady shockwave solution of linear Navier- Stokes-Fourier theory, along with the nonlinear Burnett heat-flux term. Our new continuum theory is in nearly quantitative agreement with non-equilibrium molecular-dynamics simulations under strong shockwave conditions, using relaxation parameters obtained from the reference solution.

  16. Burnett-Cattaneo continuum theory for shock waves

    NASA Astrophysics Data System (ADS)

    Holian, Brad Lee; Mareschal, Michel; Ravelo, Ramon

    2011-06-01

    We model strong shockwave propagation, both in the ideal gas and in the dense Lennard-Jones fluid, using a refinement of earlier work, which accounts for the cold compression in the early stages of the shock rise by a nonlinear, Burnett-like, strain-rate dependence of the thermal conductivity, and relaxation of kinetic temperature components on the hot, compressed side of the shock front. The relaxation of the disequilibrium among the three components of the kinetic temperature, namely, the difference between the component in the direction of a planar shock wave and those in the transverse directions, particularly in the region near the shock front, is accomplished at a much more quantitative level by the first-ever rigorous application of the Cattaneo-Maxwell relaxation equation to a reference solution, namely, the steady shockwave solution of linear Navier-Stokes-Fourier theory, along with the nonlinear Burnett heat-flux term. Our new continuum theory is in nearly quantitative agreement with non-equilibrium molecular-dynamics simulations under strong shockwave conditions, using relaxation parameters obtained from the reference solution.

  17. Experimental Plans for Subsystems of a Shock Wave Driven Gas Core Reactor

    NASA Technical Reports Server (NTRS)

    Kazeminezhad, F.; Anghai, S.

    2008-01-01

    This Contractor Report proposes a number of plans for experiments on subsystems of a shock wave driven pulsed magnetic induction gas core reactor (PMI-GCR, or PMD-GCR pulsed magnet driven gas core reactor). Computer models of shock generation and collision in a large-scale PMI-GCR shock tube have been performed. Based upon the simulation results a number of issues arose that can only be addressed adequately by capturing experimental data on high pressure (approx.1 atmosphere or greater) partial plasma shock wave effects in large bore shock tubes ( 10 cm radius). There are three main subsystems that are of immediate interest (for appraisal of the concept viability). These are (1) the shock generation in a high pressure gas using either a plasma thruster or pulsed high magnetic field, (2) collision of MHD or gas dynamic shocks, their interaction time, and collision pile-up region thickness, and (3) magnetic flux compression power generation (not included here).

  18. Shock Waves and the Origin of Life

    DTIC Science & Technology

    1977-01-01

    The thunder shock-wave can be approximated by the so-called cyl- indrical ’blast wave theory ’ (22, 24) for a single lightning stroke. The ’ theory ’ is... theory can be finally tested. Historically, the question of how life originated received the answer which was contemporarily available within the...Origin of Species," that the theory of spontaneous gpneration was finally aisproved by Louis Pasteur. In a series of exceptiorally lucid experiments

  19. Plasma waves downstream of weak collisionless shocks

    NASA Technical Reports Server (NTRS)

    Coroniti, F. V.; Greenstadt, E. W.; Moses, S. L.; Smith, E. J.; Tsurutani, B. T.

    1993-01-01

    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 shock. These weak shocks excite plasma wave electric field turbulence with amplitudes comparable to those detected in the much stronger bow shock near the nose region. Downstream of quasi-perpendicular (quasi-parallel) shocks, 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 shocks show that the low frequency signals are polarized parallel 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.

  20. Thin Foil Acceleration Method for Measuring the Unloading Isentropes of Shock-Compressed Matter

    SciTech Connect

    Asay, J.R.; Chhabildas, L.C.; Fortov, V.E.; Kanel, G.I.; Khishchenko, K.V.; Lomonosov, I.V.; Mehlhorn, T.; Razorenov, S.V.; Utkin, A.V.

    1999-07-21

    This work has been performed as part of the search for possible ways to utilize the capabilities of laser and particle beams techniques in shock wave and equation of state physics. The peculiarity of these techniques is that we have to deal with micron-thick targets and not well reproducible incident shock wave parameters, so all measurements should be of a high resolution and be done in one shot. Besides the Hugoniots, the experimental basis for creating the equations of state includes isentropes corresponding to unloading of shock-compressed matter. Experimental isentrope data are most important in the region of vaporization. With guns or explosive facilities, the unloading isentrope is recovered from a series of experiments where the shock wave parameters in plates of standard low-impedance materials placed behind the sample are measured [1,2]. The specific internal energy and specific volume are calculated from the measured p(u) release curve which corresponds to the Riemann integral. This way is not quite suitable for experiments with beam techniques where the incident shock waves are not well reproducible. The thick foil method [3] provides a few experimental points on the isentrope in one shot. When a higher shock impedance foil is placed on the surface of the material studied, the release phase occurs by steps, whose durations correspond to that for the shock wave to go back and forth in the foil. The velocity during the different steps, connected with the knowledge of the Hugoniot of the foil, allows us to determine a few points on the isentropic unloading curve. However, the method becomes insensitive when the low pressure range of vaporization is reached in the course of the unloading. The isentrope in this region can be measured by recording the smooth acceleration of a thin witness plate foil. With the mass of the foil known, measurements of the foil acceleration will give us the vapor pressure.

  1. Shock compression and release of a-axis magnesium single crystals: Anisotropy and time dependent inelastic response

    NASA Astrophysics Data System (ADS)

    Renganathan, P.; Winey, J. M.; Gupta, Y. M.

    2017-01-01

    To gain insight into inelastic deformation mechanisms for shocked hexagonal close-packed (hcp) metals, particularly the role of crystal anisotropy, magnesium (Mg) single crystals were subjected to shock compression and release along the a-axis to 3.0 and 4.8 GPa elastic impact stresses. Wave profiles measured at several thicknesses, using laser interferometry, show a sharply peaked elastic wave followed by the plastic wave. Additionally, a smooth and featureless release wave is observed following peak compression. When compared with wave profiles measured previously for c-axis Mg [Winey et al., J. Appl. Phys. 117, 105903 (2015)], the elastic wave amplitudes for a-axis Mg are lower for the same propagation distance, and less attenuation of elastic wave amplitude is observed for a given peak stress. The featureless release wave for a-axis Mg is in marked contrast to the structured features observed for c-axis unloading. Numerical simulations, using a time-dependent anisotropic modeling framework, showed that the wave profiles calculated using prismatic slip or (10 1 ¯ 2 ) twinning, individually, do not match the measured compression profiles for a-axis Mg. However, a combination of slip and twinning provides a good overall match to the measured compression profiles. In contrast to compression, prismatic slip alone provides a reasonable match to the measured release wave profiles; (10 1 ¯ 2 ) twinning due to its uni-directionality is not activated during release. The experimental results and wave profile simulations for a-axis Mg presented here are quite different from the previously published c-axis results, demonstrating the important role of crystal anisotropy in the time-dependent inelastic deformation of Mg single crystals under shock compression and release.

  2. Shock compression and release of a-axis magnesium single crystals: Anisotropy and time dependent inelastic response

    DOE PAGES

    Renganathan, P.; Winey, J. M.; Gupta, Y. M.

    2017-01-19

    Here, to gain insight into inelastic deformation mechanisms for shocked hexagonal close-packed (hcp) metals, particularly the role of crystal anisotropy, magnesium (Mg) single crystals were subjected to shock compression and release along the a-axis to 3.0 and 4.8 GPa elastic impact stresses. Wave profiles measured at several thicknesses, using laser interferometry, show a sharply peaked elastic wave followed by the plastic wave. Additionally, a smooth and featureless release wave is observed following peak compression. When compared to wave profiles measured previously for c-axis Mg, the elastic wave amplitudes for a-axis Mg are lower for the same propagation distance, and less attenuation of elastic wave amplitude is observed for a given peak stress. The featureless release wave for a-axis Mg is in marked contrast to the structured features observed for c-axis unloading. Numerical simulations, using a time-dependent anisotropic modeling framework, showed that the wave profiles calculated using prismatic slip or (10more » $$\\bar{1}$$2) twinning, individually, do not match the measured compression profiles for a-axis Mg. However, a combination of slip and twinning provides a good overall match to the measured compression profiles. In contrast to compression,prismatic slip alone provides a reasonable match to the measured release wave profiles; (10$$\\bar{1}$$2) twinning due to its uni-directionality is not activated during release. The experimental results and wave profile simulations for a-axis Mg presented here are quite different from the previously published c-axis results, demonstrating the important role of crystal anisotropy on the time-dependent inelastic deformation of Mg single crystals under shock compression and release.« less

  3. Using phase contrast imaging to measure the properties of shock compressed aerogel

    NASA Astrophysics Data System (ADS)

    Hawreliak, James; Erskine, Dave; Schropp, Andres; Galtier, Eric C.; Heimann, Phil

    2017-01-01

    The Hugoniot states of low density materials, such as silica aerogel, are used in high energy density physics research because they can achieve a range of high temperature and pressure states through shock compression. The shock properties of 100mg/cc silica aerogel were studied at the Materials in Extreme Conditions end station using x-ray phase contrast imaging of spherically expanding shock waves. The shockwaves were generated by focusing a high power 532nm laser to a 50μm focal spot on a thin aluminum ablator. The shock speed was measured in separate experiments using line-VISAR measurements from the reflecting shock front. The relative timing between the x-ray probe and the optical laser pump was varied so x-ray PCI images were taken at pressures between 10GPa and 30GPa. Modeling the compression of the foam in the strong shock limit uses a Gruneisen parameter of 0.49 to fit the data rather than a value of 0.66 that would correspond to a plasma state.

  4. 21 CFR 876.5990 - Extracorporeal shock wave lithotripter.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... focuses ultrasonic shock waves into the body to noninvasively fragment urinary calculi within the kidney... Notifications (510(k)'s) for Extracorporeal Shock Wave Lithotripters Indicated for the Fragmentation of...

  5. 21 CFR 876.5990 - Extracorporeal shock wave lithotripter.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... focuses ultrasonic shock waves into the body to noninvasively fragment urinary calculi within the kidney... Notifications (510(k)'s) for Extracorporeal Shock Wave Lithotripters Indicated for the Fragmentation of...

  6. 21 CFR 876.5990 - Extracorporeal shock wave lithotripter.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... focuses ultrasonic shock waves into the body to noninvasively fragment urinary calculi within the kidney... Notifications (510(k)'s) for Extracorporeal Shock Wave Lithotripters Indicated for the Fragmentation of...

  7. Passive control of unsteady condensation shock wave

    NASA Astrophysics Data System (ADS)

    Setoguchi, Toshiaki; Matsuo, Shigeru; Shimamoto, Katsumi; Yasugi, Shinichi; Yu, Shen

    2000-12-01

    A rapid expansion of moist air or steam in a supersonic nozzle gives rise to nonequilibrium condensation phenomena. Thereby, if the heat released by condensation of water vapour exceeds a certain quantity, the flow will become unstable and periodic flow oscillations of the unsteady condensation shock wave will occur. For the passive control of shock-boundary layer interaction using the porous wall with a plenum underneath, many papers have been presented on the application of the technique to transonic airfoil flows. In this paper, the passive technique is applied to three types of oscillations of the unsteady condensation shock wave generated in a supersonic nozzle in order to suppress the unsteady behavior. As a result, the effects of number of slits and length of cavity on the aspect of flow field have been clarified numerically using a 3rd-order MUSCL type TVD finite-difference scheme with a second-order fractional-step for time integration.

  8. Shock wave absorber having a deformable liner

    DOEpatents

    Youngdahl, C.K.; Wiedermann, A.H.; Shin, Y.W.; Kot, C.A.; Ockert, C.E.

    1983-08-26

    This invention discloses a shock wave absorber for a piping system carrying liquid. The absorber has a plastically deformable liner defining the normal flow boundary for an axial segment of the piping system, and a nondeformable housing is spaced outwardly from the liner so as to define a gas-tight space therebetween. The flow capacity of the liner generally corresponds to the flow capacity of the piping system line, but the liner has a noncircular cross section and extends axially of the piping system line a distance between one and twenty times the diameter thereof. Gas pressurizes the gas-tight space equal to the normal liquid pressure in the piping system. The liner has sufficient structural capacity to withstand between one and one-half and two times this normal liquid pressures; but at greater pressures it begins to plastically deform initially with respect to shape to a more circular cross section, and then with respect to material extension by circumferentially stretching the wall of the liner. A high energy shock wave passing through the liner thus plastically deforms the liner radially into the gas space and progressively also as needed in the axial direction of the shock wave to minimize transmission of the shock wave beyond the absorber.

  9. The Collisions of Chondrules Behind Shock Waves

    NASA Technical Reports Server (NTRS)

    Ciesla, F. J.; Hood, L. L.

    2004-01-01

    One of the reasons that the mechanism(s) responsible for the formation of chondrules has remained so elusive is that each proposed mechanism must be able to explain a large number of features observed in chondrules. Most models of chondrule formation focus on matching the expected thermal histories of chondrules: rapid heating followed by cooling during crystallization at rates between approx. 10-1000 K/hr [1], and references therein]. Thus far, only models for large shock waves in the solar nebula have quantitatively shown that the thermal evolution of millimeter-sized particles in the nebula can match these inferred thermal histories [2-4]. While this is a positive step for the shock wave model, further testing is needed to see if other properties of chondrules can be explained in the context of this model. One area of interest is understanding the collisional evolution of chondrules after they encounter a shock wave. These collisions could lead to sticking, destruction, or bouncing. Here we focus on understanding what conditions are needed for these different outcomes to occur and try to reconcile the seemingly contradictory conclusions reached by studies of compound chondrule formation and chondrule destruction by collisions behind a shock wave.

  10. Uncovering the Secret of Shock Wave Lithotripsy

    NASA Astrophysics Data System (ADS)

    Zhong, P.

    Shock wave lithotripsy (SWL) is an engineering innovation that has revolutionized the treatment of kidney stone disease since the early 1980s [1] - [3]. Today, SWL is the first-line therapy for millions of patients worldwide with renal and upper urinary stones [3, 4].

  11. 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.

  12. Finite element modelling of radial shock wave therapy for chronic plantar fasciitis.

    PubMed

    Alkhamaali, Zaied K; Crocombe, Andrew D; Solan, Matthew C; Cirovic, Srdjan

    2016-01-01

    Therapeutic use of high-amplitude pressure waves, or shock wave therapy (SWT), is emerging as a popular method for treating musculoskeletal disorders. However, the mechanism(s) through which this technique promotes healing are unclear. Finite element models of a shock wave source and the foot were constructed to gain a better understanding of the mechanical stimuli that SWT produces in the context of plantar fasciitis treatment. The model of the shock wave source was based on the geometry of an actual radial shock wave device, in which pressure waves are generated through the collision of two metallic objects: a projectile and an applicator. The foot model was based on the geometry reconstructed from magnetic resonance images of a volunteer and it comprised bones, cartilage, soft tissue, plantar fascia, and Achilles tendon. Dynamic simulations were conducted of a single and of two successive shock wave pulses administered to the foot. The collision between the projectile and the applicator resulted in a stress wave in the applicator. This wave was transmitted into the soft tissue in the form of compression-rarefaction pressure waves with an amplitude of the order of several MPa. The negative pressure at the plantar fascia reached values of over 1.5 MPa, which could be sufficient to generate cavitation in the tissue. The results also show that multiple shock wave pulses may have a cumulative effect in terms of strain energy accumulation in the foot.

  13. Imaging Shock Waves in Diamond with Both High Temporal and Spatial Resolution at an XFEL

    PubMed Central

    Schropp, Andreas; Hoppe, Robert; Meier, Vivienne; Patommel, Jens; Seiboth, Frank; Ping, Yuan; Hicks, Damien G.; Beckwith, Martha A.; Collins, Gilbert W.; Higginbotham, Andrew; Wark, Justin S.; Lee, Hae Ja; Nagler, Bob; Galtier, Eric C.; Arnold, Brice; Zastrau, Ulf; Hastings, Jerome B.; Schroer, Christian G.

    2015-01-01

    The advent of hard x-ray free-electron lasers (XFELs) has opened up a variety of scientific opportunities in areas as diverse as atomic physics, plasma physics, nonlinear optics in the x-ray range, and protein crystallography. In this article, we access a new field of science by measuring quantitatively the local bulk properties and dynamics of matter under extreme conditions, in this case by using the short XFEL pulse to image an elastic compression wave in diamond. The elastic wave was initiated by an intense optical laser pulse and was imaged at different delay times after the optical pump pulse using magnified x-ray phase-contrast imaging. The temporal evolution of the shock wave can be monitored, yielding detailed information on shock dynamics, such as the shock velocity, the shock front width, and the local compression of the material. The method provides a quantitative perspective on the state of matter in extreme conditions. PMID:26086176

  14. Imaging Shock Waves in Diamond with Both High Temporal and Spatial Resolution at an XFEL.

    PubMed

    Schropp, Andreas; Hoppe, Robert; Meier, Vivienne; Patommel, Jens; Seiboth, Frank; Ping, Yuan; Hicks, Damien G; Beckwith, Martha A; Collins, Gilbert W; Higginbotham, Andrew; Wark, Justin S; Lee, Hae Ja; Nagler, Bob; Galtier, Eric C; Arnold, Brice; Zastrau, Ulf; Hastings, Jerome B; Schroer, Christian G

    2015-06-18

    The advent of hard x-ray free-electron lasers (XFELs) has opened up a variety of scientific opportunities in areas as diverse as atomic physics, plasma physics, nonlinear optics in the x-ray range, and protein crystallography. In this article, we access a new field of science by measuring quantitatively the local bulk properties and dynamics of matter under extreme conditions, in this case by using the short XFEL pulse to image an elastic compression wave in diamond. The elastic wave was initiated by an intense optical laser pulse and was imaged at different delay times after the optical pump pulse using magnified x-ray phase-contrast imaging. The temporal evolution of the shock wave can be monitored, yielding detailed information on shock dynamics, such as the shock velocity, the shock front width, and the local compression of the material. The method provides a quantitative perspective on the state of matter in extreme conditions.

  15. Imaging shock waves in diamond with both high temporal and spatial resolution at an XFEL

    SciTech Connect

    Schropp, Andreas; Hoppe, Robert; Meier, Vivienne; Patommel, Jens; Seiboth, Frank; Ping, Yuan; Hicks, Damien G.; Beckwith, Martha A.; Collins, Gilbert W.; Higginbotham, Andrew; Wark, Justin S.; Lee, Hae Ja; Nagler, Bob; Galtier, Eric C.; Arnold, Brice; Zastrau, Ulf; Hastings, Jerome B.; Schroer, Christian G.

    2015-06-18

    The advent of hard x-ray free-electron lasers (XFELs) has opened up a variety of scientific opportunities in areas as diverse as atomic physics, plasma physics, nonlinear optics in the x-ray range, and protein crystallography. In this article, we access a new field of science by measuring quantitatively the local bulk properties and dynamics of matter under extreme conditions, in this case by using the short XFEL pulse to image an elastic compression wave in diamond. The elastic wave was initiated by an intense optical laser pulse and was imaged at different delay times after the optical pump pulse using magnified x-ray phase-contrast imaging. The temporal evolution of the shock wave can be monitored, yielding detailed information on shock dynamics, such as the shock velocity, the shock front width, and the local compression of the material. The method provides a quantitative perspective on the state of matter in extreme conditions.

  16. Wave energy devices with compressible volumes.

    PubMed

    Kurniawan, Adi; Greaves, Deborah; Chaplin, John

    2014-12-08

    We present an analysis of wave energy devices with air-filled compressible submerged volumes, where variability of volume is achieved by means of a horizontal surface free to move up and down relative to the body. An analysis of bodies without power take-off (PTO) systems is first presented to demonstrate the positive effects a compressible volume could have on the body response. Subsequently, two compressible device variations are analysed. In the first variation, the compressible volume is connected to a fixed volume via an air turbine for PTO. In the second variation, a water column separates the compressible volume from another volume, which is fitted with an air turbine open to the atmosphere. Both floating and bottom-fixed, axisymmetric, configurations are considered, and linear analysis is employed throughout. Advantages and disadvantages of each device are examined in detail. Some configurations with displaced volumes less than 2000 m(3) and with constant turbine coefficients are shown to be capable of achieving 80% of the theoretical maximum absorbed power over a wave period range of about 4 s.

  17. Wave energy devices with compressible volumes

    PubMed Central

    Kurniawan, Adi; Greaves, Deborah; Chaplin, John

    2014-01-01

    We present an analysis of wave energy devices with air-filled compressible submerged volumes, where variability of volume is achieved by means of a horizontal surface free to move up and down relative to the body. An analysis of bodies without power take-off (PTO) systems is first presented to demonstrate the positive effects a compressible volume could have on the body response. Subsequently, two compressible device variations are analysed. In the first variation, the compressible volume is connected to a fixed volume via an air turbine for PTO. In the second variation, a water column separates the compressible volume from another volume, which is fitted with an air turbine open to the atmosphere. Both floating and bottom-fixed, axisymmetric, configurations are considered, and linear analysis is employed throughout. Advantages and disadvantages of each device are examined in detail. Some configurations with displaced volumes less than 2000 m3 and with constant turbine coefficients are shown to be capable of achieving 80% of the theoretical maximum absorbed power over a wave period range of about 4 s. PMID:25484609

  18. Generation and propagation of shock waves in the exhaust pipe of a 4 cycle automobile engine

    NASA Astrophysics Data System (ADS)

    Sekine, N.; Matsumura, S.; Aoki, K.; Takayama, K.

    1990-07-01

    An experimental investigation was made of reduction of noise generated in the exhaust pipe of a half liter 4-cycle water-cooled automobile gasoline engine. The pressure measurement along the exhaust pipe showed the nonlinear transition of compression waves discharged from the exhaust port of the engine into shock waves. In order to obtain a direct evidence of shock waves in the exhaust pipe, a flow visualization study was also conducted using a double exposure holographic interferometry. Weak shock waves of Mach number 1.09 exist in the exhaust pipe. For the purpose of collecting the data for designing optimum muffler configurations, additional shock tube experiments were carried out. The results indicates that the study of the non-linear wave interaction and propagation is important for the design of muffler.

  19. Shock wave structure in heterogeneous reactive media

    SciTech Connect

    Baer, M.R.

    1997-06-01

    Continuum mixture theory and mesoscale modeling are applied to describe the behavior of shock-loaded heterogeneous media. One-dimensional simulations of gas-gun experiments demonstrate that the wave features are well described by mixture theory, including reflected wave behavior and conditions where significant reaction is initiated. Detailed wave fields are resolved in numerical simulations of impact on a lattice of discrete explosive {open_quotes}crystals{close_quotes}. It is shown that rapid distortion first occurs at material contact points; the nature of the dispersive fields includes large amplitude fluctuations of stress over several particle pathlengths. Localization of energy causes {open_quotes}hot-spots{close_quotes} due to shock focusing and plastic work as material flows into interstitial regions.

  20. Plasmons in strongly coupled shock-compressed matter

    SciTech Connect

    Neumayer, P; Fortmann, C; Doppner, T; Davis, P; Falcone, R W; Kritcher, A L; Landen, O L; Lee, H J; Lee, R W; Niemann, C; Pape, S L; Glenzer, S H

    2010-04-15

    We present the first measurements of the plasmon dispersion and damping in laser shock-compressed solid matter. Petawatt laser produced K-{alpha} radiation scatters on boron targets compressed by a 10 ns-long 400 J laser pulse. In the vicinity of the Fermi momentum, the scattering spectra show dispersionless, collisionally damped plasmons, indicating a strongly coupled electron liquid. These observations agree with x-ray scattering calculations that include both the Born-Mermin approximation to account for electron-ion collisional damping and local field corrections reflecting electron-electron correlations.

  1. Predicting the optical behaviour of shock compressed dielectrics

    NASA Astrophysics Data System (ADS)

    Tear, Gareth R.; Proud, William G.

    2017-01-01

    An anisotropic photoelastic model for predicting the optical properties of shock compressed anisotropic dielectrics has been developed for the purpose of investigating the effect of experimental tilt. This model has been used to predict the expected effect of impact and crystallographic tilt on birefringence measurements for a plate impact experiment. It was found that the expected systematic error to the birefringence measurement caused by experimental tilt was likely to be negligible. Predictions for various common anisotropic minerals compressed along the a-axis are also presented and the model is compared to experimental plate impact data from PMMA and sapphire.

  2. Method and apparatus for determining pressure-induced frequency-shifts in shock-compressed materials

    DOEpatents

    Moore, David S.; Schmidt, Stephen C.

    1985-01-01

    A method and an apparatus for conducting coherent anti-Stokes Raman scattering spectroscopy in shock-compressed materials are disclosed. The apparatus includes a sample vessel having an optically transparent wall and an opposing optically reflective wall. Two coherent laser beams, a pump beam and a broadband Stokes beam, are directed through the window and focused on a portion of the sample. In the preferred embodiment, a projectile is fired from a high-pressure gas gun to impact the outside of the reflective wall, generating a planar shock wave which travels through the sample toward the window. The pump and Stokes beams result in the emission from the shock-compressed sample of a coherent anti-Stokes beam, which is emitted toward the approaching reflective wall of the vessel and reflected back through the window. The anti-Stokes beam is folded into a spectrometer for frequency analysis. The results of such analysis are useful for determining chemical and physical phenomena which occur during the shock-compression of the sample.

  3. Method and apparatus for determining pressure-induced frequency-shifts in shock-compressed materials

    DOEpatents

    Moore, D.S.; Schmidt, S.C.

    1983-12-16

    A method and an apparatus for conducting coherent anti-Stokes Raman scattering spectroscopy in shock-compressed materials are disclosed. The apparatus includes a sample vessel having an optically transparent wall and an opposing optically reflective wall. Two coherent laser beams, a pump beam and a broadband Stokes beam, are directed through the window and focused on a portion of the sample. In the preferred embodiment, a projectile is fired from a high-pressure gas gun to impact the outside of the reflective wall, generating a planar shock wave which travels through the sample toward the window. The pump and Stokes beams result in the emission from the shock-compressed sample of a coherent anti-Stokes beam, which is emitted toward the approaching reflective wall of the vessel and reflected back through the window. The anti-Stokes beam is folded into a spectrometer for frequency analysis. The results of such analysis are useful for determining chemical and physical phenomena which occur during the shock-compression of the sample.

  4. Development of a broadband reflectivity diagnostic for laser driven shock compression experiments

    SciTech Connect

    Ali, S. J.; Bolme, C. A.; Collins, G. W.; Jeanloz, R.

    2015-04-01

    A normal - incidence visible and near - infrared Shock Wave Optical Reflectivity Diagnostic (SWORD) was constructed to investigate changes in the optical properties of materials under dynamic laser compression . Documenting wavelength - and time - dependent changes in the optical properties of laser - shock compressed samples has been difficult, primarily due to the small sample sizes and short time scales involved , but we succeeded in doing so by broadening a series of time delayed 800 - nm pulses from an ultra fast Ti: sapphire laser to generate high - intensity broadband light at nanosecond time scales . This diagnostic was demonstrated over the wavelength range 450 to 1150 nm with up to 16 time displaced spectra during a single shock experiment. Simultaneous off - normal incidence velocity interferometry (VISAR) characterize d the sample under laser - compression , and also provide d a n independent reflectivity measurement at 532 nm wavelength . Lastly, the shock - driven semiconductor - to - metallic transition in germanium was documented by way of reflectivity measurements with 0.5 ns time resolution and a wavelength resolution of 10 nm .

  5. A new apparatus to induce lysis of planktonic microbial cells by shock compression, cavitation and spray

    PubMed Central

    Schiffer, A.; Gardner, M. N.; Lynn, R. H.

    2017-01-01

    Experiments were conducted on an aqueous growth medium containing cultures of Escherichia coli (E. coli) XL1-Blue, to investigate, in a single experiment, the effect of two types of dynamic mechanical loading on cellular integrity. A bespoke shock tube was used to subject separate portions of a planktonic bacterial culture to two different loading sequences: (i) shock compression followed by cavitation, and (ii) shock compression followed by spray. The apparatus allows the generation of an adjustable loading shock wave of magnitude up to 300 MPa in a sterile laboratory environment. Cultures of E. coli were tested with this apparatus and the spread-plate technique was used to measure the survivability after mechanical loading. The loading sequence (ii) gave higher mortality than (i), suggesting that the bacteria are more vulnerable to shear deformation and cavitation than to hydrostatic compression. We present the results of preliminary experiments and suggestions for further experimental work; we discuss the potential applications of this technique to sterilize large volumes of fluid samples.

  6. Shock wave interactions between slender bodies. Some aspects of three-dimensional shock wave diffraction

    NASA Astrophysics Data System (ADS)

    Hooseria, S. J.; Skews, B. W.

    2017-01-01

    A complex interference flowfield consisting of multiple shocks and expansion waves is produced when high-speed slender bodies are placed in close proximity. The disturbances originating from a generator body impinge onto the adjacent receiver body, modifying the local flow conditions over the receiver. This paper aims to uncover the basic gas dynamics produced by two closely spaced slender bodies in a supersonic freestream. Experiments and numerical simulations were used to interpret the flowfield, where good agreement between the predictions and measurements was observed. The numerical data were then used to characterise the attenuation associated with shock wave diffraction, which was found to be interdependent with the bow shock contact perimeter over the receiver bodies. Shock-induced boundary layer separation was observed over the conical and hemispherical receiver bodies. These strong viscous-shock interactions result in double-reflected, as well as double-diffracted shock wave geometries in the interference region, and the diffracting waves progress over the conical and hemispherical receivers' surfaces in "lambda" type configurations. This gives evidence that viscous effects can have a substantial influence on the local bow shock structure surrounding high-speed slender bodies in close proximity.

  7. Enhanced densification under shock compression in porous silicon

    DOE PAGES

    Lane, J. Matthew; Thompson, Aidan Patrick; Vogler, Tracy

    2014-10-27

    Under shock compression, most porous materials exhibit lower densities for a given pressure than that of a full-dense sample of the same material. However, some porous materials exhibit an anomalous, or enhanced, densification under shock compression. The mechanism driving this behavior was not completely determined. We present evidence from atomistic simulation that pure silicon belongs to this anomalous class of materials and demonstrate the associated mechanisms responsible for the effect in porous silicon. Atomistic response indicates that local shear strain in the neighborhood of collapsing pores catalyzes a local solid-solid phase transformation even when bulk pressures are below the thermodynamicmore » phase transformation pressure. This metastable, local, and partial, solid-solid phase transformation, which accounts for the enhanced densification in silicon, is driven by the local stress state near the void, not equilibrium thermodynamics. This mechanism may also explain the phenomenon in other covalently bonded materials.« less

  8. Enhanced densification under shock compression in porous silicon

    SciTech Connect

    Lane, J. Matthew; Thompson, Aidan Patrick; Vogler, Tracy

    2014-10-27

    Under shock compression, most porous materials exhibit lower densities for a given pressure than that of a full-dense sample of the same material. However, some porous materials exhibit an anomalous, or enhanced, densification under shock compression. The mechanism driving this behavior was not completely determined. We present evidence from atomistic simulation that pure silicon belongs to this anomalous class of materials and demonstrate the associated mechanisms responsible for the effect in porous silicon. Atomistic response indicates that local shear strain in the neighborhood of collapsing pores catalyzes a local solid-solid phase transformation even when bulk pressures are below the thermodynamic phase transformation pressure. This metastable, local, and partial, solid-solid phase transformation, which accounts for the enhanced densification in silicon, is driven by the local stress state near the void, not equilibrium thermodynamics. This mechanism may also explain the phenomenon in other covalently bonded materials.

  9. Frequency shift measurement in shock-compressed materials

    DOEpatents

    Moore, D.S.; Schmidt, S.C.

    1984-02-21

    A method is disclosed for determining molecular vibrational frequencies in shock-compressed transparent materials. A single laser beam pulse is directed into a sample material while the material is shock-compressed from a direction opposite that of the incident laser beam. A Stokes beam produced by stimulated Raman scattering is emitted back along the path of the incident laser beam, that is, in the opposite direction to that of the incident laser beam. The Stokes beam is separated from the incident beam and its frequency measured. The difference in frequency between the Stokes beam and the incident beam is representative of the characteristic frequency of the Raman active mode of the sample. Both the incident beam and the Stokes beam pass perpendicularly through the stock front advancing through the sample, thereby minimizing adverse effects of refraction.

  10. Numerical simulation of shock wave generation and focusing in shock wave lithotripsy

    NASA Astrophysics Data System (ADS)

    Krimmel, Jeff; Colonius, Tim

    2007-11-01

    Shock wave lithotripsy is a procedure where focused shock waves are fired at kidney stones in order to pulverize them. Many lithotripters with different source mechanisms and reflector shapes (or lenses) are in clinical use, but accurate prediction of focal region pressure is made difficult by nonlinearity and cavitation. We report on development of a numerical simulation framework aimed at accurate prediction of focal region flow physics. Shock wave generation and beam focusing are simulated via the Euler equations with MUSCL-type shock capturing scheme and adaptive mesh-refinement (Berger and Oliger, 1984). In future work, a bubbly cavitating flow model will be added. Electrohydraulic, electromagnetic, and piezoelectric lithotripters are modeled with axisymmetric and three-dimensional geometries. In the electrohydraulic case, a simple expanding bubble model simulates spark firing. In the piezoelectric case, a boundary condition prescribing the motion of individual elements is used. Amplitudes and durations of calculated focal region waveforms are in reasonable agreement with experimental data.

  11. A multi-scale approach to molecular dynamics simulations of shock waves

    SciTech Connect

    Reed, E J; Fried, L E; Manaa, M R; Joannopoulos, J D

    2004-09-03

    Study of the propagation of shock waves in condensed matter has led to new discoveries ranging from new metastable states of carbon [1] to the metallic conductivity of hydrogen in Jupiter, [2] but progress in understanding the microscopic details of shocked materials has been extremely difficult. Complications can include the unexpected formation of metastable states of matter that determine the structure, instabilities, and time-evolution of the shock wave. [1,3] The formation of these metastable states can depend on the time-dependent thermodynamic pathway that the material follows behind the shock front. Furthermore, the states of matter observed in the shock wave can depend on the timescale on which observation is made. [4,1] Significant progress in understanding these microscopic details has been made through molecular dynamics simulations using the popular non-equilibrium molecular dynamics (NEMD) approach to atomistic simulation of shock compression. [5] The NEMD method involves creating a shock at one edge of a large system by assigning some atoms at the edge a fixed velocity. The shock propagates across the computational cell to the opposite side. The computational work required by NEMD scales at least quadratically in the evolution time because larger systems are needed for longer simulations to prevent the shock wave from reflecting from the edge of the computational cell and propagating back into the cell. When quantum mechanical methods with poor scaling of computational effort with system size are employed, this approach to shock simulations rapidly becomes impossible.

  12. Colloidal solitary waves with temperature dependent compressibility

    NASA Astrophysics Data System (ADS)

    Azmi, A.; Marchant, T. R.

    2014-05-01

    Spatial solitary waves which form in colloidal suspensions of dielectric nanoparticles are considered. The interactions, or compressibility, of the colloidal particles, is modelled using a series in the particle density, or packing fraction, where the virial, or series, coefficients depend on the type of particle interaction model. Both the theoretical hard disk and sphere repulsive models, and a model with temperature dependent compressibility, are considered. Experimental results show that particle interactions can be temperature dependent and either repulsive or attractive in nature, so we model the second virial coefficient using a physically realistic temperature power law. One- and two-dimensional semi-analytical colloidal solitary wave solutions are found. Trial functions, based on the form of the nonlinear Schrödinger equation soliton, are used, together with averaging, to develop the semi-analytical solutions. When the background packing fraction is low, the one-dimensional solitary waves have three solutions branches (with a bistable regime) while the two-dimensional solitary waves have two solution branches, with a single stable branch. The temperature dependent second virial coefficient results in changes to the solitary wave properties and the parameter space, in which multiple solutions branches occur. An excellent comparison is found between the semi-analytical and numerical solutions.

  13. Experimental Investigation of Passive Shock Wave Mitigation using Obstacle Arrangements

    NASA Astrophysics Data System (ADS)

    Nguyen, Monica; Wan, Qian; Eliasson, Veronica

    2014-11-01

    With its vast range in applications, especially in the defense industry, shock wave mitigation is an ongoing research area of interest to the shock dynamics community. Passive shock wave mitigation methods range from forcing the shock wave to abruptly change its direction to introducing barriers or obstacles of various shapes and materials in the path of the shock wave. Obstacles provide attenuation through complicated shock wave interactions and reflections. In this work, we have performed shock tube experiments to investigate shock wave mitigation due to solid obstacles placed along the curve of a logarithmic spiral. Different shapes (cylindrical and square) of obstacles with different materials (solid and foam) have been used. High-speed schlieren optics and background-oriented schlieren techniques have been used together with pressure measurements to quantify the effects of mitigation. Results have also been compared to numerical simulations and show good agreement.

  14. Shock compression behavior of a S2-glass fiber reinforced polymer composite

    NASA Astrophysics Data System (ADS)

    Tsai, Liren; Yuan, Fuping; Prakash, Vikas; Dandekar, Dattatraya P.

    2009-05-01

    Synthetic heterogeneous material systems, e.g., layered composite materials with organic matrices reinforced by glass fibers (GRP), are attractive materials for a variety of lightweight armor applications. However, while the dynamic response of homogeneous materials, such as, metals and ceramics, has been well documented, the ballistic response of heterogeneous material systems is poorly understood. In the present study, in an attempt to better understand the shock-induced compression response of GRPs, a series of plate impact experiments were conducted on a S2-glas fiber reinforced polymer composite comprising S2-glass woven roving in a Cycom 4102 polyester resin matrix. The plate-impact experiments were conducted using an 82.5 mm bore single-stage gas-gun at the Case Western Reserve University. The history of the shock-induced free-surface particle velocity at the rear surface of the target plate was monitored using the multibeam VALYN™ VISAR system. The results of the experiments indicate the absence of an elastic front in the shock-induced free-surface particle velocity profile in the GRP. Moreover, in the low impact velocity range, relatively weak late-time oscillations are observed in the particle velocity profiles. Increasing the amplitude of the shock-induced compression resulted in a decrease in the rise-time of the shock wave front. The critical shock stress amplitude at which a clear shock-front is seen to develop during the shock loading was determined to be between 1.5 and 2.0 GPa. The results of the experiments are used to obtain the equation of state of the GRP in the stress range 0.04-20 GPa. Moreover, the Hugoniot curve (Hugoniot stress versus Hugoniot strain) was calculated using the Rankine-Hugoniot relationships; the departure of the Hugoniot stress versus the particle velocity curve from linearity allowed the estimation of the Hugoniot elastic limit of the GRP to be about 1.6 GPa.

  15. Characterization of mechanical shock waves in aluminum 6061-T6 using a high power laser pulse

    NASA Astrophysics Data System (ADS)

    Gonzalez Romero, J. R.; García-Torales, G.; Gómez Rosas, G.; Ocaña, J. L.; Flores, Jorge L.

    2016-09-01

    Strengthening techniques allows enhance metal physical properties. Laser shock peening (LSP) technique consist in a surface treatment which a high power laser pulse induces a compressive residual stress field through mechanical shock waves, increasing hardness, corrosion resistance, fatigue resistance. In comparison with the shot peening technique, LSP is a method that allows precision controlling the laser incidence on the surface under treatment increasing the surface quality in the surface under treatment. In this work, mechanical shock waves are induced in aluminum and measure using two different experimental approaches. First, using a PVDZ sensors and secondly, strain gauges are used. Experimental results are presented.

  16. Pseudo-shock waves and their interactions in high-speed intakes

    NASA Astrophysics Data System (ADS)

    Gnani, F.; Zare-Behtash, H.; Kontis, K.

    2016-04-01

    In an air-breathing engine the flow deceleration from supersonic to subsonic conditions takes places inside the isolator through a gradual compression consisting of a series of shock waves. The wave system, referred to as a pseudo-shock wave or shock train, establishes the combustion chamber entrance conditions, and therefore influences the performance of the entire propulsion system. The characteristics of the pseudo-shock depend on a number of variables which make this flow phenomenon particularly challenging to be analysed. Difficulties in experimentally obtaining accurate flow quantities at high speeds and discrepancies of numerical approaches with measured data have been readily reported. Understanding the flow physics in the presence of the interaction of numerous shock waves with the boundary layer in internal flows is essential to developing methods and control strategies. To counteract the negative effects of shock wave/boundary layer interactions, which are responsible for the engine unstart process, multiple flow control methodologies have been proposed. Improved analytical models, advanced experimental methodologies and numerical simulations have allowed a more in-depth analysis of the flow physics. The present paper aims to bring together the main results, on the shock train structure and its associated phenomena inside isolators, studied using the aforementioned tools. Several promising flow control techniques that have more recently been applied to manipulate the shock wave/boundary layer interaction are also examined in this review.

  17. In vitro study of the mechanical effects of shock-wave lithotripsy.

    PubMed

    Howard, D; Sturtevant, B

    1997-01-01

    Impulsive stress in repeated shock waves administered during extracorporeal shock-wave lithotripsy (ESWL) causes injury to kidney tissue. In a study of the mechanical input of ESWL, the effects of focused shock waves on thin planar polymeric membranes immersed in a variety of tissue-mimicking fluids have been examined. A direct mechanism of failure by shock compression and an indirect mechanism by bubble collapse have been observed. Thin membranes are easily damaged by bubble collapse. After propagating through cavitation-free acoustically heterogeneous media (liquids mixed with hollow glass spheres, and tissue) shock waves cause membranes to fail in fatigue by a shearing mechanism. As is characteristic of dynamic fatigue, the failure stress increases with strain rate, determined by the amplitude and rise time of the attenuated shock wave. Shocks with large amplitude and short rise time (i.e., in uniform media) cause no damage. Thus the inhomogeneity of tissue is likely to contribute to injury in ESWL. A definition of dose is proposed which yields a criterion for damage based on measurable shock wave properties.

  18. Burnett-Cattaneo Continuum Theory for Shock Waves

    NASA Astrophysics Data System (ADS)

    Holian, B. L.; Mareschal, M.; Ravelo, R.

    2011-03-01

    We model strong shockwave propagation, both in the ideal gas and in the dense Lennard-Jones fluid, using a refinement of earlier work, which accounts for the cold compression by a nonlinear, Burnett-like, strain-rate dependence of the thermal conductivity, and relaxation of temperature components on the hot, compressed side of the shock front. The relaxation of the disequilibrium among the three components of the kinetic temperature, namely, the difference between the temperature in the direction of a planar shock wave and those in the transverse directions, particularly in the region near the shock front, is accomplished by a rigorous application of the Cattaneo-Maxwell relaxation equation to a reference state, namely, the steady shockwave solution of linear Navier-Stokes-Fourier theory, along with the nonlinear Burnett heat-flux term. Our new continuum theory is in nearly quantitative agreement with non-equilibrium molecular-dynamics simulations under strong shockwave conditions. Part of this work supported by the U.S. Department of Energy under contract DE-AC5206NA25396.

  19. Fluid dynamics of the shock wave reactor

    NASA Astrophysics Data System (ADS)

    Masse, Robert Kenneth

    2000-10-01

    High commercial incentives have driven conventional olefin production technologies to near their material limits, leaving the possibility of further efficiency improvements only in the development of entirely new techniques. One strategy known as the Shock Wave Reactor, which employs gas dynamic processes to circumvent limitations of conventional reactors, has been demonstrated effective at the University of Washington. Preheated hydrocarbon feedstock and a high enthalpy carrier gas (steam) are supersonically mixed at a temperature below that required for thermal cracking. Temperature recovery is then effected via shock recompression to initiate pyrolysis. The evolution to proof-of-concept and analysis of experiments employing ethane and propane feedstocks are presented. The Shock Wave Reactor's high enthalpy steam and ethane flows severely limit diagnostic capability in the proof-of-concept experiment. Thus, a preliminary blow down supersonic air tunnel of similar geometry has been constructed to investigate recompression stability and (especially) rapid supersonic mixing necessary for successful operation of the Shock Wave Reactor. The mixing capabilities of blade nozzle arrays are therefore studied in the air experiment and compared with analytical models. Mixing is visualized through Schlieren imaging and direct photography of condensation in carbon dioxide injection, and interpretation of visual data is supported by pressure measurement and flow sampling. The influence of convective Mach number is addressed. Additionally, thermal behavior of a blade nozzle array is analyzed for comparison to data obtained in the course of succeeding proof-of-concept experiments. Proof-of-concept is naturally succeeded by interest in industrial adaptation of the Shock Wave Reactor, particularly with regard to issues involving the scaling and refinement of the shock recompression. Hence, an additional, variable geometry air tunnel has been constructed to study the parameter

  20. Compressible turbulence and shock-capturing using a variational multiscale method

    NASA Astrophysics Data System (ADS)

    Garai, Anirban; Burgess, Nicholas; Murman, Scott; Diosady, Laslo

    2016-11-01

    We have previously developed a dynamic extension of Hughes' variational multiscale method which is implemented in an entropy-stable Discontinuous-Galerkin spectral-element solver. This solver and sub-grid model have been examined on standard low-speed benchmark flows, e.g. homogeneous turbulence, channel flow, etc. Here we extend the approach to higher speeds where compressibility effects are no longer insignificant, and the flowfields develop unsteady shocklets and shock waves. Homogeneous isotropic turbulence at high turbulent Mach number is tested for two cases - decaying and passing through a normal shock. Numerical simulations using the multiscale sub-grid model, no sub-grid model, and a variation of Barter and Darmofal's shock-capturing scheme are examined in isolation and combination. The computed results are compared against theoretical observations and previous computational results.

  1. Gas turbine power plant with supersonic shock compression ramps

    DOEpatents

    Lawlor, Shawn P.; Novaresi, Mark A.; Cornelius, Charles C.

    2008-10-14

    A gas turbine engine. The engine is based on the use of a gas turbine driven rotor having a compression ramp traveling at a local supersonic inlet velocity (based on the combination of inlet gas velocity and tangential speed of the ramp) which compresses inlet gas against a stationary sidewall. The supersonic compressor efficiently achieves high compression ratios while utilizing a compact, stabilized gasdynamic flow path. Operated at supersonic speeds, the inlet stabilizes an oblique/normal shock system in the gasdynamic flow path formed between the rim of the rotor, the strakes, and a stationary external housing. Part load efficiency is enhanced by use of a lean pre-mix system, a pre-swirl compressor, and a bypass stream to bleed a portion of the gas after passing through the pre-swirl compressor to the combustion gas outlet. Use of a stationary low NOx combustor provides excellent emissions results.

  2. Material Point Methods for Shock Waves

    NASA Astrophysics Data System (ADS)

    Zhang, Duan; Dhakal, Tilak

    2016-11-01

    Particle methods are often the choice for problems involving large material deformation with history dependent material models. Often large deformation of a material is caused by shock loading, therefore accurate calculation of shock waves is important for particle methods. In this work, we study four major versions (original MPM, GIMP, CPDI, and DDMP) of material point methods, using a weak one-dimensional isothermal shock of ideal gas as an example. The original MPM fails. With a small number of particles, the GIMP and the CPDI methods produce reasonable results. However, as the number of particles increases these methods do not converge and produce pressure spikes. With sparse particles, DDMP results are unsatisfactory. As the number of particles increases, DDMP results converge to correct solutions, but the large number of particles needed for an accurate result makes the method very expensive to use in shock wave problems. To improve the numerical accuracy while preserving the convergence, conservation, and smoothness of the DDMP method, a new numerical integration scheme is introduced. The improved DDMP method is only slightly more expensive than the original DDMP method, but accuracy improvements are significant as shown by numerical examples. This work was performed under the auspices of the United States Department of Energy.

  3. Symmetry of spherically converging shock waves through reflection, relating to the shock ignition fusion energy scheme.

    PubMed

    Davie, C J; Evans, R G

    2013-05-03

    We examine the properties of perturbed spherically imploding shock waves in an ideal fluid through the collapse, bounce, and development into an outgoing shock wave. We find broad conservation of the size and shape of ingoing and outgoing perturbations when viewed at the same radius. The outgoing shock recovers the velocity of the unperturbed shock outside the strongly distorted core. The results are presented in the context of the robustness of the shock ignition approach to inertial fusion energy.

  4. Three-dimensional shock-wave/boundary-layer interactions with bleed through a circular hole

    NASA Technical Reports Server (NTRS)

    Rimlinger, M. J.; Shih, T. I.-P.; Chyu, W. J.

    1992-01-01

    Computations were performed to study three-dimensional (3-D), shock-wave/boundary-layer interactions on a flat plate in which fluid in the boundary layer was bled through a circular hole into a plenum to control shock-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 shock-wave impingement affect upstream, spanwise, and downstream influence lengths. This study revealed an underlying mechanisms by which bleed holes can affect shock-wave/boundary-layer 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.

  5. Measurements of the equations of state and spectrum of nonideal xenon plasma under shock compression.

    PubMed

    Zheng, J; Gu, Y J; Chen, Z Y; Chen, Q F

    2010-08-01

    Experimental equations of state on generation of nonideal xenon plasma by intense shock wave compression was presented in the ranges of pressure of 2-16 GPa and temperature of 31-50 kK, and the xenon plasma with the nonideal coupling parameter Γ range from 0.6-2.1 was generated. The shock wave was produced using the flyer plate impact and accelerated up to ∼6 km/s with a two-stage light gas gun. Gaseous specimens were shocked from two initial pressures of 0.80 and 4.72 MPa at room temperature. Time-resolved spectral radiation histories were recorded by using a multiwavelength channel pyrometer. The transient spectra with the wavelength range of 460-700 nm were recorded by using a spectrometer to evaluate the shock temperature. Shock velocity was measured and particle velocity was determined by the impedance matching methods. The equations of state of xenon plasma and ionization degree have been discussed in terms of the self-consistent fluid variational theory.

  6. Shock Waves and Commutation Speed of Memristors

    NASA Astrophysics Data System (ADS)

    Tang, Shao; Tesler, Federico; Marlasca, Fernando Gomez; Levy, Pablo; Dobrosavljević, V.; Rozenberg, Marcelo

    2016-01-01

    Progress of silicon-based technology is nearing its physical limit, as the minimum feature size of components is reaching a mere 10 nm. The resistive switching behavior of transition metal oxides and the associated memristor device is emerging as a competitive technology for next-generation electronics. Significant progress has already been made in the past decade, and devices are beginning to hit the market; however, this progress has mainly been the result of empirical trial and error. Hence, gaining theoretical insight is of the essence. In the present work, we report the striking result of a connection between the resistive switching and shock-wave formation, a classic topic of nonlinear dynamics. We argue that the profile of oxygen vacancies that migrate during the commutation forms a shock wave that propagates through a highly resistive region of the device. We validate the scenario by means of model simulations and experiments in a manganese-oxide-based memristor device, and we extend our theory to the case of binary oxides. The shock-wave scenario brings unprecedented physical insight and enables us to rationalize the process of oxygen-vacancy-driven resistive change with direct implications for a key technological aspect—the commutation speed.

  7. Innovations in shock wave lithotripsy technology

    NASA Astrophysics Data System (ADS)

    Zhong, Pei; Zhou, Yufeng; Zhu, Songlin; Cocks, Franklin; Preminger, Glenn

    2003-10-01

    Since its introduction in early 1980s, shock wave lithotripsy (SWL) has been used widely in clinic for the treatment of kidney and upper urinary stones. Although a variety of methods have been developed for shock wave generation, coupling, and focusing, the core of SWL technology has not changed significantly. In this talk, we will present a summary of our research efforts, aiming to provide innovations in SWL technology. Our strategy is to first better understand the mechanisms by which stone comminution and tissue injury are produced in SWL using various experimental and theoretical techniques. Based on this knowledge, we then developed novel techniques that can optimize the effect of cavitation in SWL via modification of the waveform profile, pressure distribution, and pulse sequence of lithotripter-generated shock waves. These new techniques were upgraded on a Dornier HM-3 lithotripter, the gold standard in SWL. Both in vitro phantom and in vivo animal experiments were carried out which demonstrated that the performance and safety of the upgraded HM-3 lithotripter is superior to the original HM-3 lithotripter. Finally, strategies to improve stone comminution efficiency while reducing tissue injury in SWL will be presented. [Work supported by NIH DK52985 and DK58266.

  8. Hugoniot equation of state of rock materials under shock compression

    NASA Astrophysics Data System (ADS)

    Zhang, Q. B.; Braithwaite, C. H.; Zhao, J.

    2017-01-01

    Two sets of shock compression tests (i.e. conventional and reverse impact) were conducted to determine the shock response of two rock materials using a plate impact facility. Embedded manganin stress gauges were used for the measurements of longitudinal stress and shock velocity. Photon Doppler velocimetry was used to capture the free surface velocity of the target. Experimental data were obtained on a fine-grained marble and a coarse-grained gabbro over a shock pressure range of approximately 1.5-12 GPa. Gabbro exhibited a linear Hugoniot equation of state (EOS) in the pressure-particle velocity (P-up) plane, while for marble a nonlinear response was observed. The EOS relations between shock velocity (US) and particle velocity (up) are linearly fitted as US = 2.62 + 3.319up and US = 5.4 85 + 1.038up for marble and gabbro, respectively. This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

  9. Hugoniot equation of state of rock materials under shock compression.

    PubMed

    Zhang, Q B; Braithwaite, C H; Zhao, J

    2017-01-28

    Two sets of shock compression tests (i.e. conventional and reverse impact) were conducted to determine the shock response of two rock materials using a plate impact facility. Embedded manganin stress gauges were used for the measurements of longitudinal stress and shock velocity. Photon Doppler velocimetry was used to capture the free surface velocity of the target. Experimental data were obtained on a fine-grained marble and a coarse-grained gabbro over a shock pressure range of approximately 1.5-12 GPa. Gabbro exhibited a linear Hugoniot equation of state (EOS) in the pressure-particle velocity (P-up) plane, while for marble a nonlinear response was observed. The EOS relations between shock velocity (US) and particle velocity (up) are linearly fitted as US = 2.62 + 3.319up and US = 5.4 85 + 1.038up for marble and gabbro, respectively.This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

  10. Oxy-acetylene driven laboratory scale shock tubes for studying blast wave effects

    NASA Astrophysics Data System (ADS)

    Courtney, Amy C.; Andrusiv, Lubov P.; Courtney, Michael W.

    2012-04-01

    This paper describes the development and characterization of modular, oxy-acetylene driven laboratory scale shock tubes. Such tools are needed to produce realistic blast waves in a laboratory setting. The pressure-time profiles measured at 1 MHz using high-speed piezoelectric pressure sensors have relevant durations and show a true shock front and exponential decay characteristic of free-field blast waves. Descriptions are included for shock tube diameters of 27-79 mm. A range of peak pressures from 204 kPa to 1187 kPa (with 0.5-5.6% standard error of the mean) were produced by selection of the driver section diameter and distance from the shock tube opening. The peak pressures varied predictably with distance from the shock tube opening while maintaining both a true blast wave profile and relevant pulse duration for distances up to about one diameter from the shock tube opening. This shock tube design provides a more realistic blast profile than current compression-driven shock tubes, and it does not have a large jet effect. In addition, operation does not require specialized personnel or facilities like most blast-driven shock tubes, which reduces operating costs and effort and permits greater throughput and accessibility. It is expected to be useful in assessing the response of various sensors to shock wave loading; assessing the reflection, transmission, and absorption properties of candidate armor materials; assessing material properties at high rates of loading; assessing the response of biological materials to shock wave exposure; and providing a means to validate numerical models of the interaction of shock waves with structures. All of these activities have been difficult to pursue in a laboratory setting due in part to lack of appropriate means to produce a realistic blast loading profile.

  11. Oxy-acetylene driven laboratory scale shock tubes for studying blast wave effects.

    PubMed

    Courtney, Amy C; Andrusiv, Lubov P; Courtney, Michael W

    2012-04-01

    This paper describes the development and characterization of modular, oxy-acetylene driven laboratory scale shock tubes. Such tools are needed to produce realistic blast waves in a laboratory setting. The pressure-time profiles measured at 1 MHz using high-speed piezoelectric pressure sensors have relevant durations and show a true shock front and exponential decay characteristic of free-field blast waves. Descriptions are included for shock tube diameters of 27-79 mm. A range of peak pressures from 204 kPa to 1187 kPa (with 0.5-5.6% standard error of the mean) were produced by selection of the driver section diameter and distance from the shock tube opening. The peak pressures varied predictably with distance from the shock tube opening while maintaining both a true blast wave profile and relevant pulse duration for distances up to about one diameter from the shock tube opening. This shock tube design provides a more realistic blast profile than current compression-driven shock tubes, and it does not have a large jet effect. In addition, operation does not require specialized personnel or facilities like most blast-driven shock tubes, which reduces operating costs and effort and permits greater throughput and accessibility. It is expected to be useful in assessing the response of various sensors to shock wave loading; assessing the reflection, transmission, and absorption properties of candidate armor materials; assessing material properties at high rates of loading; assessing the response of biological materials to shock wave exposure; and providing a means to validate numerical models of the interaction of shock waves with structures. All of these activities have been difficult to pursue in a laboratory setting due in part to lack of appropriate means to produce a realistic blast loading profile.

  12. 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.

  13. Addressing the problem of uniform converging spherical shock wave in water

    NASA Astrophysics Data System (ADS)

    Nitishinskiy, M.; Efimov, S.; Yanuka, D.; Gurovich, V. Tz.; Krasik, Ya. E.

    2016-10-01

    Time-resolved parameters of plasma compressed by a shock wave generated by the underwater electrical explosion of a spherical wire array are presented. The plasma was preliminarily formed inside a capillary placed at the equatorial plane along the axis of the array. Temporal evolution analysis of Hα and C II spectral lines showed that the plasma density increases from its initial value of ˜3 × 1017 cm-3 up to ˜5.5 × 1017 cm-3 within 300 ± 25 ns. These results were found to be in agreement with those of the model that considers the adiabatic compression of the plasma by the converging capillary walls caused by interaction with the incident shock wave with a pressure of ˜3 × 109 Pa at a radius of 1.5 mm. The latter results coincide well with those of the 1D hydrodynamic modeling, which assumes uniformity of the converging shock wave.

  14. Amorphization and nanocrystallization of silcon under shock compression

    DOE PAGES

    Remington, B. A.; Wehrenberg, C. E.; Zhao, S.; ...

    2015-11-06

    High-power, short-duration, laser-driven, shock compression and recovery experiments on [001] silicon unveiled remarkable structural changes above a pressure threshold. Two distinct amorphous regions were identified: (a) a bulk amorphous layer close to the surface and (b) amorphous bands initially aligned with {111} slip planes. Further increase of the laser energy leads to the re-crystallization of amorphous silicon into nanocrystals with high concentration of nano-twins. This amorphization is produced by the combined effect of high magnitude hydrostatic and shear stresses under dynamic shock compression. Shock-induced defects play a very important role in the onset of amorphization. Calculations of the free energymore » changes with pressure and shear, using the Patel-Cohen methodology, are in agreement with the experimental results. Molecular dynamics simulation corroborates the amorphization, showing that it is initiated by the nucleation and propagation of partial dislocations. As a result, the nucleation of amorphization is analyzed qualitatively by classical nucleation theory.« less

  15. Control and reduction of unsteady pressure loads in separated shock wave turbulent boundary layer interaction

    NASA Technical Reports Server (NTRS)

    Dolling, David S.; Barter, John W.

    1995-01-01

    The focus was on developing means of controlling and reducing unsteady pressure loads in separated shock wave turbulent boundary layer 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-layer separators' on the same interaction.

  16. Direct Visualization of Shock Waves in Supersonic Space Shuttle Flight

    NASA Technical Reports Server (NTRS)

    OFarrell, J. M.; Rieckhoff, T. J.

    2011-01-01

    Direct observation of shock boundaries is rare. This Technical Memorandum describes direct observation of shock waves produced by the space shuttle vehicle during STS-114 and STS-110 in imagery provided by NASA s tracking cameras.

  17. EXPERIMENTAL STUDY OF SHOCK WAVE DYNAMICS IN MAGNETIZED PLASMAS

    SciTech Connect

    Nirmol K. Podder

    2009-03-17

    In this four-year project (including one-year extension), the project director and his research team built a shock-wave-plasma apparatus to study shock wave dynamics in glow discharge plasmas in nitrogen and argon at medium pressure (1–20 Torr), carried out various plasma and shock diagnostics and measurements that lead to increased understanding of the shock wave acceleration phenomena in plasmas. The measurements clearly show that in the steady-state dc glow discharge plasma, at fixed gas pressure the shock wave velocity increases, its amplitude decreases, and the shock wave disperses non-linearly as a function of the plasma current. In the pulsed discharge plasma, at fixed gas pressure the shock wave dispersion width and velocity increase as a function of the delay between the switch-on of the plasma and shock-launch. In the afterglow plasma, at fixed gas pressure the shock wave dispersion width and velocity decrease as a function of the delay between the plasma switch-off and shock-launch. These changes are found to be opposite and reversing towards the room temperature value which is the initial condition for plasma ignition case. The observed shock wave properties in both igniting and afterglow plasmas correlate well with the inferred temperature changes in the two plasmas.

  18. Modeling Propagation of Shock Waves in Metals

    SciTech Connect

    Howard, W M; Molitoris, J D

    2005-08-19

    We present modeling results for the propagation of strong shock waves in metals. In particular, we use an arbitrary Lagrange Eulerian (ALE3D) code to model the propagation of strong pressure waves (P {approx} 300 to 400 kbars) generated with high explosives in contact with aluminum cylinders. The aluminum cylinders are assumed to be both flat-topped and have large-amplitude curved surfaces. We use 3D Lagrange mechanics. For the aluminum we use a rate-independent Steinberg-Guinan model, where the yield strength and shear modulus depend on pressure, density and temperature. The calculation of the melt temperature is based on the Lindermann law. At melt the yield strength and shear modulus is set to zero. The pressure is represented as a seven-term polynomial as a function of density. For the HMX-based high explosive, we use a JWL, with a program burn model that give the correct detonation velocity and C-J pressure (P {approx} 390 kbars). For the case of the large-amplitude curved surface, we discuss the evolving shock structure in terms of the early shock propagation experiments by Sakharov.

  19. Mechanochemistry for Shock Wave Energy Dissipation

    NASA Astrophysics Data System (ADS)

    Shaw, William; Ren, Yi; Su, Zhi; Moore, Jeffrey; Suslick, Kenneth; Dlott, Dana

    2015-06-01

    Using our laser-driven flyer-plate apparatus we have developed a technique for detecting mechanically driven chemical reactions that attenuate shock waves. In these experiments 75 μm laser-driven flyer-plates travel at speeds of up to 2.8 km/s. Photonic Doppler velocimetry is used to monitor both the flight speed and the motions of an embedded mirror behind the sample on the supporting substrate. Since the Hugoniot of the substrate is known, mirror motions can be converted into the transmitted shock wave flux and fluence through a sample. Flux shows the shock profile whereas fluence represents the total energy transferred per unit area, and both are measured as a function of sample thickness. Targets materials are micrograms of carefully engineered organic and inorganic compounds selected for their potential to undergo negative volume, endothermic reactions. In situ fluorescence measurements and a suite of post mortem analytical methods are used to detect molecular chemical reactions that occur due to impact.

  20. Underwater Shock Wave Research Applied to Therapeutic Device Developments

    NASA Astrophysics Data System (ADS)

    Takayama, K.; Yamamoto, H.; Shimokawa, H.

    2013-07-01

    The chronological development of underwater shock wave research performed at the Shock Wave Research Center of the Institute of Fluid Science at the Tohoku University is presented. Firstly, the generation of planar underwater shock waves in shock tubes and their visualization by using the conventional shadowgraph and schlieren methods are described. Secondly, the generation of spherical underwater shock waves by exploding lead azide pellets weighing from several tens of micrograms to 100 mg, that were ignited by irradiating with a Q-switched laser beam, and their visualization by using double exposure holographic interferometry are presented. The initiation, propagation, reflection, focusing of underwater shock waves, and their interaction with various interfaces, in particular, with air bubbles, are visualized quantitatively. Based on such a fundamental underwater shock wave research, collaboration with the School of Medicine at the Tohoku University was started for developing a shock wave assisted therapeutic device, which was named an extracorporeal shock wave lithotripter (ESWL). Miniature shock waves created by irradiation with Q-switched HO:YAG laser beams are studied, as applied to damaged dysfunctional nerve cells in the myocardium in a precisely controlled manner, and are effectively used to design a catheter for treating arrhythmia.

  1. A numerical study of shock wave diffraction by a circular cylinder

    NASA Technical Reports Server (NTRS)

    Yang, J.-Y.; Liu, Y.; Lomax, H.

    1986-01-01

    The nonstationary shock wave diffraction patterns generated by a blast wave impinging on a circular cylinder are numerically simulated using a second-order hybrid upwind method for solving the two-dimensional inviscid compressible Euler equations of gasdynamics. The complete diffraction patterns, including the transition from regular to Mach reflection, trajectory of the Mach triple point and the complex shock-on-shock interaction at the wake region resulting from the Mach shocks collision behind the cylinder are reported in detail. Pressure-time history and various contour plots are also included. Comparison between the work of Bryson and Gross (1961) which included both experimental schlieren pictures and theoretical calculations using Whitham's ray-shock theory and results of the present finite difference computation indicate good agreement in every aspect except for some nonideal gas and viscous effects which are not accounted for by the Euler equations.

  2. Particle Acceleration in SN1006 Shock Waves

    NASA Technical Reports Server (NTRS)

    Raymond, John C.; Ghavamian, Parviz; Sonneborn, George (Technical Monitor)

    2003-01-01

    This grant is for the analysis of FUSE observations of particle acceleration in supernova remnant SN1006 shock waves. We have performed quick look analysis of the data, but because the source is faint and because the O VI emission lines on SN1006 are extremely broad, extreme care is needed for background subtraction and profile fitting. Moreover, the bulk of the analysis in will consist of model calculations. The Ly beta and O VI lines are clearly detected at the position in the NW filament of SN1006, but not in the NE position where non-thermal X-rays are strong. The lack of O VI emission in the NE places an upper limit on the pre-shock density there.

  3. Nonplanar electrostatic shock waves in dense plasmas

    SciTech Connect

    Masood, W.; Rizvi, H.

    2010-02-15

    Two-dimensional quantum ion acoustic shock waves (QIASWs) are studied in an unmagnetized plasma consisting of electrons and ions. In this regard, a nonplanar quantum Kadomtsev-Petviashvili-Burgers (QKPB) equation is derived using the small amplitude perturbation expansion method. Using the tangent hyperbolic method, an analytical solution of the planar QKPB equation is obtained and subsequently used as the initial profile to numerically solve the nonplanar QKPB equation. It is observed that the increasing number density (and correspondingly the quantum Bohm potential) and kinematic viscosity affect the propagation characteristics of the QIASW. The temporal evolution of the nonplanar QIASW is investigated both in Cartesian and polar planes and the results are discussed from the numerical stand point. The results of the present study may be applicable in the study of propagation of small amplitude localized electrostatic shock structures in dense astrophysical environments.

  4. Electrohydraulic shock wave generation as a means to increase intrinsic permeability of mortar

    SciTech Connect

    Maurel, O.; Reess, T.; Matallah, M.; De Ferron, A.; Chen, W.; La Borderie, C.; Pijaudier-Cabot, G.; Jacques, A.; Rey-Bethbeder, F.

    2010-12-15

    This article discusses the influence of compressive shock waves on the permeability of cementitious materials. Shock waves are generated in water by Pulsed Arc Electrohydraulic Discharges (PAED). The practical aim is to increase the intrinsic permeability of the specimens. The maximum pressure amplitude of the shock wave is 250 MPa. It generates damage in the specimens and the evolution of damage is correlated with the intrinsic permeability of the mortar. A threshold of pressure is observed. From this threshold, the increase of permeability is linear in a semi-log plot. The influence of repeated shocks on permeability is also discussed. Qualitative X Ray Tomography illustrates the evolution of the microstructure of the material leading to the increase of permeability. Comparative results from mercury intrusion porosimetry (MIP) show that the micro-structural damage process starts at the sub-micrometric level and that the characteristic size of pores of growing volume increases.

  5. Planar and nonplanar ion acoustic shock waves in relativistic degenerate astrophysical electron-positron-ion plasmas

    SciTech Connect

    Ata-ur-Rahman,; Qamar, A.; Ali, S.; Mirza, Arshad M.

    2013-04-15

    We have studied the propagation of ion acoustic shock waves involving planar and non-planar geometries in an unmagnetized plasma, whose constituents are non-degenerate ultra-cold ions, relativistically degenerate electrons, and positrons. By using the reductive perturbation technique, Korteweg-deVries Burger and modified Korteweg-deVries Burger equations are derived. It is shown that only compressive shock waves can propagate in such a plasma system. The effects of geometry, the ion kinematic viscosity, and the positron concentration are examined on the ion acoustic shock potential and electric field profiles. It is found that the properties of ion acoustic shock waves in a non-planar geometry significantly differ from those in planar geometry. The present study has relevance to the dense plasmas, produced in laboratory (e.g., super-intense laser-dense matter experiments) and in dense astrophysical objects.

  6. Detonation wave compression in gas turbines

    NASA Technical Reports Server (NTRS)

    Wortman, A.

    1986-01-01

    A study was made of the concept of augmenting the performance of low pressure ratio gas turbines by detonation wave compression of part of the flow. The concept exploits the constant volume heat release of detonation waves to increase the efficiency of the Brayton cycle. In the models studied, a fraction of the compressor output was channeled into detonation ducts where it was processed by transient transverse detonation waves. Gas dynamic studies determined the maximum cycling frequency of detonation ducts, proved that upstream propagation of pressure pulses represented no problems and determined the variations of detonation duct output with time. Mixing and wave compression were used to recombine the combustor and detonation duct flows and a concept for a spiral collector to further smooth the pressure and temperature pulses was presented as an optional component. The best performance was obtained with a single firing of the ducts so that the flow could be re-established before the next detonation was initiated. At the optimum conditions of maximum frequency of the detonation ducts, the gas turbine efficiency was found to be 45 percent while that of a corresponding pressure ratio 5 conventional gas turbine was only 26%. Comparable improvements in specific fuel consumption data were found for gas turbines operating as jet engines, turbofans, and shaft output machines. Direct use of the detonation duct output for jet propulsion proved unsatisfactory. Careful analysis of the models of the fluid flow phenomena led to the conclusion that even more elaborate calculations would not diminish the uncertainties in the analysis of the system. Feasibility of the concept to work as an engine now requires validation in an engineering laboratory experiment.

  7. Electrostatic waves in the bow shock at Uranus

    SciTech Connect

    Moses, S.L.; Coroniti, F.V.; Kennel, C.F.; Scarf, F.L. ); Bagenal, F. ); Lepping, R.P. ); Quest, K.B. ); Kurth, W.S. )

    1989-10-01

    Electrostatic emissions measured by the Voyager 2 plasma wave detector (PWS) during the inbound crossing of the Uranian bow shock are shown to differ in some aspects from the waves measured during bow shock crossings at Jupiter and Saturn. The wave amplitudes in the foot of the bow shock at Uranus are in general much lower than those detected at the other out planets due to the unusually enhanced solar wind ion temperature during the crossing. This reduces the effectiveness of wave-particle interactions in heating the incoming electrons. Strong wave emissions are observed in the shock ramp that possibly arise from currents producing a Buneman mode instability. Plasma instrument (PLS) and magnetometer (MAG) measurements reveal a complicated shock structure reminiscent of computer simulations of high-Mach number shocks when the effects of anomalous resistivity are reduced, and are consistent with high ion temperatures restricting the growth of electrostatic waves.

  8. Tension of Liquids by Shock Waves

    NASA Astrophysics Data System (ADS)

    Utkin, Alexander V.; Sosikov, Vasiliy A.; Bogach, Andrey A.; Fortov, Vladimir E.

    2004-07-01

    The influences of strain rate and initial temperature on the negative pressure in distillate water, hexane, glycerol and methyl alcohol under shock waves have been investigated. The wave profiles were registered by laser interferometer VISAR. Shock waves were produced by aluminum plates accelerated by high explosive up to 600 m/s. At initial temperature 19 °C spall strength of water, hexane, and methyl alcohol is equal to 45, 15, and 47 MPa respectively and not depend on the strain rate in interval from 10-4 to 10-5 1/s. A strong dependence of negative pressure on strain rate was observed only for glycerol. The reason is that the initial temperature of glycerol was equal to the freezing point, and in the vicinity of it the relaxation properties are usually very much more pronounced. To confirm this assumption the experiments with water an initial temperature 0.7 °C were made and strong influence of strain rate on spall strength was observed close to freezing temperature too. Moreover expansion isentropes intersected the melting curve at negative pressure and double metastable state was realized in water. Theory of homogeneous bubble nucleation was used to explain the experimental results.

  9. Local stability analysis for a planar shock wave

    NASA Technical Reports Server (NTRS)

    Salas, M. D.

    1984-01-01

    A procedure to study the local stability of planar shock waves is presented. The procedure is applied to a Rankine-Hugoniot shock in a divergent/convergent nozzle, to an isentropic shock in a divergent/convergent nozzle, and to Rankine-Hugoniot shocks attached to wedges and cones. It is shown that for each case, the equation governing the shock motion is equivalent to the damped harmonic oscillator equation.

  10. Supersonic shock wave/vortex interaction

    NASA Technical Reports Server (NTRS)

    Settles, G. S.; Cattafesta, L.

    1993-01-01

    Although shock wave/vortex interaction is a basic and important fluid dynamics problem, very little research has been conducted on this topic. Therefore, a detailed experimental study of the interaction between a supersonic streamwise turbulent vortex and a shock wave was carried out at the Penn State Gas Dynamics Laboratory. A vortex is produced by replaceable swirl vanes located upstream of the throat of various converging-diverging nozzles. The supersonic vortex is then injected into either a coflowing supersonic stream or ambient air. The structure of the isolated vortex is investigated in a supersonic wind tunnel using miniature, fast-response, five-hole and total temperature probes and in a free jet using laser Doppler velocimetry. The cases tested have unit Reynolds numbers in excess of 25 million per meter, axial Mach numbers ranging from 2.5 to 4.0, and peak tangential Mach numbers from 0 (i.e., a pure jet) to about 0.7. The results show that the typical supersonic wake-like vortex consists of a non-isentropic, rotational core, where the reduced circulation distribution is self similar, and an outer isentropic, irrotational region. The vortex core is also a region of significant turbulent fluctuations. Radial profiles of turbulent kinetic energy and axial-tangential Reynolds stress are presented. The interactions between the vortex and both oblique and normal shock waves are investigated using nonintrusive optical diagnostics (i.e. schlieren, planar laser scattering, and laser Doppler velocimetry). Of the various types, two Mach 2.5 overexpanded-nozzle Mach disc interactions are examined in detail. Below a certain vortex strength, a 'weak' interaction exists in which the normal shock is perturbed locally into an unsteady 'bubble' shock near the vortex axis, but vortex breakdown (i.e., a stagnation point) does not occur. For stronger vortices, a random unsteady 'strong' interaction results that causes vortex breakdown. The vortex core reforms downstream of

  11. DDT modeling and shock compression experiments of porous or damaged energetic materials

    SciTech Connect

    Baer, M.R.; Anderson, M.U.; Graham, R.A.

    1994-05-01

    In this presentation, we present modeling of DDT in porous energetic materials and experimental studies of a time-resolved, shock compression of highly porous inert and reactive materials. This combined theoretical and experimental studies explore the nature of the microscale processes of consolidation, deformation and reaction which are key features of the shock response of porous or damaged energetic materials. The theoretical modeling is based on the theory of mixtures in which multiphase mixtures are treated in complete nonequilibrium allowing for internal boundary effects associated mass/momentum and energy exchange between phases, relative flow, rate-dependent compaction behavior, multistage chemistry and interphase boundary effects. Numerous studies of low-velocity impacts using a high resolution adaptive finite element method are presented which replicate experimental observations. The incorporation of this model into multi-material hydrocode analysis will be discussed to address the effects of confinement and its influence on accelerated combustion behavior. The experimental studies will focus on the use of PVDF piezoelectric polymer stress-rate gauge to precisely measure the input and propagating shock stress response of porous materials. In addition to single constituent porous materials, such as granular HMX, we have resolved shock waves in porous composite intermetallic powders that confirm a dispersive wave nature which is highly morphologically and material dependent. This document consists of viewgraphs from the poster session.

  12. Shock waves and nucleosynthesis in type II supernovae

    NASA Technical Reports Server (NTRS)

    Aufderheide, M. B.; Baron, E.; Thielemann, F.-K.

    1991-01-01

    In the study of nucleosynthesis in type II SN, shock waves are initiated artificially, since collapse calculations do not, as yet, give self-consistent shock waves strong enough to produce the SN explosion. The two initiation methods currently used by light-curve modelers are studied, with a focus on the peak temperatures and the nucleosynthetic yields in each method. The various parameters involved in artificially initiating a shock wave and the effects of varying these parameters are discussed.

  13. Current topics in shock waves; Proceedings of the International Symposium on Shock Waves and Shock Tubes, 17th, Lehigh University, Bethlehem, PA, July 17-21, 1989

    SciTech Connect

    Kim, Y.W.

    1990-01-01

    Various papers on shock waves are presented. The general topics addressed include: shock formation, focusing, and implosion; shock reflection and diffraction; turbulence; laser-produced plasmas and waves; ionization and shock-plasma interaction; chemical kinetics, pyrolysis, and soot formation; experimental facilities, techniques, and applications; ignition of detonation and combustion; particle entrainment and shock propagation through particle suspension; boundary layers and blast simulation; computational methods and numerical simulation.

  14. Current topics in shock waves; Proceedings of the International Symposium on Shock Waves and Shock Tubes, 17th, Lehigh University, Bethlehem, PA, July 17-21, 1989

    NASA Astrophysics Data System (ADS)

    Kim, Yong W.

    Various papers on shock waves are presented. The general topics addressed include: shock formation, focusing, and implosion; shock reflection and diffraction; turbulence; laser-produced plasmas and waves; ionization and shock-plasma interaction; chemical kinetics, pyrolysis, and soot formation; experimental facilities, techniques, and applications; ignition of detonation and combustion; particle entrainment and shock propagation through particle suspension; boundary layers and blast simulation; computational methods and numerical simulation.

  15. Internal energy relaxation in shock wave structure

    SciTech Connect

    Josyula, Eswar Suchyta, Casimir J.; Boyd, Iain D.; Vedula, Prakash

    2013-12-15

    The Wang Chang-Uhlenbeck (WCU) equation is numerically integrated to characterize the internal structure of Mach 3 and Mach 5 shock waves in a gas with excitation in the internal energy states for the treatment of inelastic collisions. Elastic collisions are modeled with the hard sphere collision model and the transition rates for the inelastic collisions modified appropriately using probabilities based on relative velocities of the colliding particles. The collision integral is evaluated by the conservative discrete ordinate method [F. Tcheremissine, “Solution of the Boltzmann kinetic equation for high-speed flows,” Comput. Math. Math. Phys. 46, 315–329 (2006); F. Cheremisin, “Solution of the Wang Chang-Uhlenbeck equation,” Dokl. Phys. 47, 487–490 (2002)] developed for the Boltzmann equation. For the treatment of the diatomic molecules, the internal energy modes in the Boltzmann equation are described quantum mechanically given by the WCU equation. As a first step in the treatment of the inelastic collisions by the WCU equation, a two- and three-quantum system is considered to study the effect of the varying of (1) the inelastic cross section and (2) the energy gap between the quantum energy states. An alternative method, the direct simulation Monte Carlo method, is used for the Mach 3 shock wave to ensure the consistency of implementation in the two methods and there is an excellent agreement between the two methods. The results from the WCU implementation showed consistent trends for the Mach 3 and Mach5 standing shock waves simulations. Inelastic contributions change the downstream equilibrium state and allow the flow to transition to the equilibrium state further upstream.

  16. Confinement effects of shock waves on laser-induced plasma from a graphite target

    SciTech Connect

    Huang, Feiling; Liang, Peipei; Yang, Xu; Cai, Hua; Wu, Jiada; Xu, Ning; Ying, Zhifeng; Sun, Jian

    2015-06-15

    The spatial confinement effects of shock waves on the laser-induced plasma (LIP) from a graphite target in air were studied by probe beam deflection (PBD) measurements and optical emission spectroscopy (OES). A clear relationship between the confinement of the LIP by the shock wave and the effects on the LIP emission was observed, and the underlying mechanisms are discussed. PBD monitoring revealed that the laser-ablation induced shock wave could be well analogized to the shock wave generated by a point explosion and would be reflected by a block. OES measurements indicated that the optical emission of the LIP exhibited significant variations with the block placement. A first enhancement and then a fast decay of CN molecular emission as well as a suppression of carbon atomic emission were observed in the presence of the block. The results revealed that the reflected shock wave spatially confined the expansion of the LIP and compressed the LIP after encountering it, pushing back the species of the LIP and changing the density of the LIP species including luminous carbon atoms and CN molecules. It is suggested that the change of the LIP emission is attributed to the density variation of the LIP species due to the compression of the LIP and the reactions occurring in the plasma.

  17. Compression dynamics and lattice kinetics in laser driven shocks of BCC metals using dynamic Laue diffraction

    NASA Astrophysics Data System (ADS)

    Wehrenberg, Christopher

    2013-10-01

    Laue diffraction experiments were used to directly observe the strain relaxation process in Ta shock compressed along the [001] direction. The unit cell aspect ratio was measured from Laue patterns at times ranging 0.1 to 1.6 ns relative to the shock wave entering the Ta sample. For 50 GPa shocks, the aspect ratio increases asymptotically to a value of 0.95 over the course of ~1 ns. The 1 ns time scale is on the order of predictions of the relaxation time scale made using the Livermore multiscale strength model [Rudd, R SCCM 2011]. In contrast, ultra-fast (less than 10 ps) relaxation times are expected above the homogeneous nucleation threshold. Consistent with this behavior, Ta subjected to shocks at 90 GPa relaxes faster than the resolution of the diffraction experiments (approximately 150 ps). As the relaxation time will be dependent on the dislocation density, one can infer a dislocation density behind the 50 GPa shock front. Dislocation densities estimated in this manner agree with in an order of magnitude both with predictions by the multiscale model and with residual dislocation densities observed in post-mortem samples. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  18. Biodamage via shock waves initiated by irradiation with ions.

    PubMed

    Surdutovich, Eugene; Yakubovich, Alexander V; Solov'yov, Andrey V

    2013-01-01

    Radiation damage following the ionising radiation of tissue has different scenarios and mechanisms depending on the projectiles or radiation modality. We investigate the radiation damage effects due to shock waves produced by ions. We analyse the strength of the shock wave capable of directly producing DNA strand breaks and, depending on the ion's linear energy transfer, estimate the radius from the ion's path, within which DNA damage by the shock wave mechanism is dominant. At much smaller values of linear energy transfer, the shock waves turn out to be instrumental in propagating reactive species formed close to the ion's path to large distances, successfully competing with diffusion.

  19. Data compression for the Cassini radio and plasma wave instrument

    NASA Technical Reports Server (NTRS)

    Farrell, W. M.; Gurnett, D. A.; Kirchner, D. L.; Kurth, W. S.; Woolliscroft, L. J. C.

    1993-01-01

    The Cassini Radio and Plasma Wave Science experiment will employ data compression to make effective use of the available data telemetry bandwidth. Some compression will be achieved by use of a lossless data compression chip and some by software in a dedicated 80C85 processor. A description of the instrument and data compression system are included in this report. Also, the selection of data compression systems and acceptability of data degradation is addressed.

  20. Expansion shock waves in regularized shallow-water theory

    NASA Astrophysics Data System (ADS)

    El, Gennady A.; Hoefer, Mark A.; Shearer, Michael

    2016-05-01

    We identify a new type of shock wave by constructing a stationary expansion shock solution of a class of regularized shallow-water equations that include the Benjamin-Bona-Mahony and Boussinesq equations. An expansion shock exhibits divergent characteristics, thereby contravening the classical Lax entropy condition. The persistence of the expansion shock in initial value problems is analysed and justified using matched asymptotic expansions and numerical simulations. The expansion shock's existence is traced to the presence of a non-local dispersive term in the governing equation. We establish the algebraic decay of the shock as it is gradually eroded by a simple wave on either side. More generally, we observe a robustness of the expansion shock in the presence of weak dissipation and in simulations of asymmetric initial conditions where a train of solitary waves is shed from one side of the shock.

  1. Cylindrically converging shock and detonation waves

    NASA Astrophysics Data System (ADS)

    Matsuo, H.

    1983-07-01

    The non-self-similar implosion of cylindrical shock and detonation waves generated by an instantaneous energy release at a cylindrical wall is analyzed theoretically by the method of integral relations. The analysis shows that as the wave propagates towards the axis, the solutions tend to approach but never reach the self-similar implosion limit. The rate of approach appears to be slower than expected, and the region of applicability of the self-similar solution appears to be restricted to a very small region behind the front. This tendency is more pronounced for the detonation case. It is also demonstrated that for detonations where the initiation energy is negligible in comparison with the chemical energy, the Chapman-Jouguet detonation jump conditions apply at the front except near the axis and near the outer wall. The chemical heating in the detonation process increases the pressure and the temperature but considerably reduces the density near the front.

  2. Augmented Shock Wave Severance of Materials

    NASA Technical Reports Server (NTRS)

    Bement, Laurence J.; Schimmel, Morry L.

    1995-01-01

    This paper describes a new approach for severing or weakening a variety of materials. The technique employs embedding explosive cords into parallel grooves that are cut into a surface of a material. The cords are initiated simultaneously to produce shock waves that progress toward the centerline between the cords and the lower surface of the material. Intersecting incident and reflected waves augment at the centerline to fail or weaken the material in tension. No harmful debris is produced on the opposite side of the material from the explosive cords. The primary focus of the effort described in this paper was to fracture the F-16 aircraft trilaminate canopy. Also, complete severance was achieved in 2024-T4 aluminum plate stock. Possible applications are through canopy egress and crew module severance from military aircraft and separation of rocket vehicle stages and payloads. This approach offers important advantages over explosive methods currently in use.

  3. Radial Shock Wave Devices Generate Cavitation

    PubMed Central

    Császár, Nikolaus B. M.; Angstman, Nicholas B.; Milz, Stefan; Sprecher, Christoph M.; Kobel, Philippe; Farhat, Mohamed; Furia, John P.; Schmitz, Christoph

    2015-01-01

    Background Conflicting reports in the literature have raised the question whether radial extracorporeal shock wave therapy (rESWT) devices and vibrating massage devices have similar energy signatures and, hence, cause similar bioeffects in treated tissues. Methods and Findings We used laser fiber optic probe hydrophone (FOPH) measurements, high-speed imaging and x-ray film analysis to compare fundamental elements of the energy signatures of two rESWT devices (Swiss DolorClast; Electro Medical Systems, Nyon, Switzerland; D-Actor 200; Storz Medical, Tägerwillen, Switzerland) and a vibrating massage device (Vibracare; G5/General Physiotherapy, Inc., Earth City, MO, USA). To assert potential bioeffects of these treatment modalities we investigated the influence of rESWT and vibrating massage devices on locomotion ability of Caenorhabditis elegans (C. elegans) worms. Results FOPH measurements demonstrated that both rESWT devices generated acoustic waves with comparable pressure and energy flux density. Furthermore, both rESWT devices generated cavitation as evidenced by high-speed imaging and caused mechanical damage on the surface of x-ray film. The vibrating massage device did not show any of these characteristics. Moreover, locomotion ability of C. elegans was statistically significantly impaired after exposure to radial extracorporeal shock waves but was unaffected after exposure of worms to the vibrating massage device. Conclusions The results of the present study indicate that both energy signature and bioeffects of rESWT devices are fundamentally different from those of vibrating massage devices. Clinical Relevance Prior ESWT studies have shown that tissues treated with sufficient quantities of acoustic sound waves undergo cavitation build-up, mechanotransduction, and ultimately, a biological alteration that “kick-starts” the healing response. Due to their different treatment indications and contra-indications rESWT devices cannot be equated to vibrating

  4. Particle Acceleration in SN1006 Shock Waves

    NASA Technical Reports Server (NTRS)

    Sonneborn, George (Technical Monitor); Raymond, John C.

    2004-01-01

    The FUSE data have been reduced, and a paper on the results is in progress. The main results have been presented in a poster at the January 2004 AAS meeting and an ApJ paper in press. The primary result is that the widths of the 0 VI lines in the NW filament are a bit less than the width expected if the oxygen kinetic temperature is 16 times the proton temperature (mass proportional heating). This is at variance with measurements of shocks in the heliosphere, where preferential heating of oxygen and other heavy species is observed. The paper discusses the theoretical implications for collisionless shock wave physics. A secondary result is that no O VI emission was observed from the NE filament. While the very different particle distribution in that region can partially account for the weakness of the O VI lines, the simplest interpretation is that the pre-shock density in the NE is less than 0.22 times the density in the NW.

  5. Optical pin apparatus for measuring the arrival time and velocity of shock waves and particles

    DOEpatents

    Benjamin, R.F.

    1983-10-18

    An apparatus for the detection of the arrival and for the determination of the velocity of disturbances such as shock-wave fronts and/or projectiles. Optical pins using fluid-filled microballoons as the light source and an optical fiber as a link to a photodetector have been used to investigate shock-waves and projectiles. A microballoon filled with a noble gas is affixed to one end of a fiber-optic cable, and the other end of the cable is attached to a high-speed streak camera. As the shock-front or projectile compresses the microballoon, the gas inside is heated and compressed producing a bright flash of light. The flash of light is transmitted via the optic cable to the streak camera where it is recorded. One image-converter streak camera is capable of recording information from more than 100 microballoon-cable combinations simultaneously.

  6. Optical pin apparatus for measuring the arrival time and velocity of shock waves and particles

    DOEpatents

    Benjamin, R.F.

    1987-03-10

    An apparatus is disclosed for the detection of the arrival and for the determination of the velocity of disturbances such as shock-wave fronts and/or projectiles. Optical pins using fluid-filled microballoons as the light source and an optical fiber as a link to a photodetector have been used to investigate shock-waves and projectiles. A microballoon filled with a noble gas is affixed to one end of a fiber-optic cable, and the other end of the cable is attached to a high-speed streak camera. As the shock-front or projectile compresses the microballoon, the gas inside is heated and compressed producing a bright flash of light. The flash of light is transmitted via the optic cable to the streak camera where it is recorded. One image-converter streak camera is capable of recording information from more than 100 microballoon-cable combinations simultaneously. 3 figs.

  7. Optical pin apparatus for measuring the arrival time and velocity of shock waves and particles

    DOEpatents

    Benjamin, Robert F.

    1987-01-01

    An apparatus for the detection of the arrival and for the determination of the velocity of disturbances such as shock-wave fronts and/or projectiles. Optical pins using fluid-filled microballoons as the light source and an optical fiber as a link to a photodetector have been used to investigate shock-waves and projectiles. A microballoon filled with a noble gas is affixed to one end of a fiber-optic cable, and the other end of the cable is attached to a high-speed streak camera. As the shock-front or projectile compresses the microballoon, the gas inside is heated and compressed producing a bright flash of light. The flash of light is transmitted via the optic cable to the streak camera where it is recorded. One image-converter streak camera is capable of recording information from more than 100 microballoon-cable combinations simultaneously.

  8. Smart structures for shock wave attenuation using ER inserts

    NASA Astrophysics Data System (ADS)

    Kim, Jaehwan; Kim, Jung-Yup; Choi, Seung-Bok; Kim, Kyung-Su

    2001-08-01

    This Paper demonstrates the possibility of shock wave attenuation propagating through a smart structure that incorporates ER insert. The wave transmission of ER inserted beam is theoretically derived using Mead & Markus model and the theoretical results are compared with the finite element analysis results. To experimentally verify the shock wave attenuation, ER insert in an aluminum plate is made and two piezoceramic disks are used as transmitter and receiver of the wave. The transmitter sends a sine pulse signal such that a component of shock wave travels through the plate structure and the receiver gets the transmitted wave signal. Wave propagation of the ER insert can be adjusted by changing the applied electric field on the ER insert. Details of the experiment are addressed and the possibility of shock wave attenuation is experimentally verified. This kind of smart structure can be used for warship and submarine hull structures to protect fragile and important equipment.

  9. Spatiotemporal dynamics of underwater conical shock wave focusing

    NASA Astrophysics Data System (ADS)

    Hoffer, P.; Lukes, P.; Akiyama, H.; Hosseini, H.

    2016-12-01

    The paper presents an experimental study on spatiotemporal dynamics of conical shock waves focusing in water. A multichannel pulsed electrohydraulic discharge source with a cylindrical ceramic-coated electrode was used. Time-resolved visualizations revealed that cylindrical pressure waves were focused to produce conical shock wave reflection over the axis of symmetry in water. Positive and negative pressures of 372 MPa and -17 MPa at the focus with 0.48 mm lateral and 22 mm axial extension (-6 dB) were measured by a fiber-optic probe hydrophone. The results clearly show the propagation process leading to the high-intensity underwater shock wave. Such strong and sharp shock wave focusing offers better localization for extracorporeal lithotripsy or other non-invasive medical shock wave procedures.

  10. Waves in low-beta plasmas - Slow shocks

    NASA Technical Reports Server (NTRS)

    Steinolfson, R. S.; Hundhausen, A. J.

    1989-01-01

    Results from wave theory and numerical simulation of the nonlinear MHD equations are used to study the response of a conducting fluid containing an embedded magnetic field with beta less than 1 to the sudden injection of material along the field lines. It is shown that the injection produces slow shocks with configurations which are concave toward the ejecta driver. Fast-mode waves which have not steepened into the shock precede the slow shock and alter the ambient medium. When beta equals 0.1, the fast mode becomes a transverse wave for parallel propagation, while the slow wave approaches a longitudinal, or sound, wave.

  11. Shock waves in a long-period optical fiber

    NASA Astrophysics Data System (ADS)

    Adamova, M. S.; Zolotovskiĭ, I. O.; Sementsov, D. I.

    2008-12-01

    The possibility of forming a shock wave of the pulse envelope has been investigated in a long-period or Bragg optical fiber with a system of two unidirectional linearly coupled waves. It has been demonstrated that, in principle, the possibility exists of forming a shock wave in a nonlinear optical fiber not only at the trailing edge but also at the leading edge of the wave packet. The origin of the formation of a shock wave depends substantially on the initial conditions providing excitation of the optical fiber.

  12. Shock wave propagation in semi-crystalline polyethylene: An atomic-scale investigation

    NASA Astrophysics Data System (ADS)

    Elder, Robert M.; O'Connor, Thomas C.; Yeh, In-Chul; Chantawansri, Tanya L.; Sirk, Timothy W.; Robbins, Mark O.; Andzelm, Jan W.

    Highly oriented polyethylene (PE) fibers are used in protection applications, therefore elucidation of their response under high strain-rate impact events is vital. Although PE fibers can have high crystallinity (>95%), they also contain defects such as amorphous domains. Using molecular dynamics simulations, we investigate shock propagation through crystalline, amorphous, and semi-crystalline PE. We generate compressive shock waves of varying strength, quantify their dynamics, and characterize their effect on material properties at the atomic scale. In the semi-crystalline PE model, the differing density and molecular order of amorphous PE and crystalline PE result in differing shock impedances, which causes reflection and refraction of shock waves at interfaces between the phases. We quantify the properties (e.g. pressure, velocity) of the reflected and refracted waves, which differ from those of the incident wave, and compare with results from impedance matching. We also examine the reflection, absorption, and transmission of energy at the crystalline-amorphous interface. Depending on shock strength, amorphous defects can dissipate shock energy, which attenuates the shock and leads to effects such as localized heating.

  13. Response of magnesium single crystals to shock-wave loading at normal and elevated temperatures

    NASA Astrophysics Data System (ADS)

    Garkushin, G.; Kanel, G.; Savinykh, A.; Razorenov, S.; Jones, D.; Proud, W.

    2013-06-01

    Magnesium single crystals, 0.2 mm to 3 mm thick, were shock loaded along the two axes, a, c and the direction at 45 degrees to the c-axis. At the room temperature the response is very similar to that observed by Pope and Johnson for beryllium single crystals (1974). Shock compression along the c-axis causes inelastic deformation by means of pyramidal slip and twinning and is associated with the largest HEL. The easiest basal slip was activated by shock loading along the inclined, off-axis direction and is associated with smallest HEL value. For all orientations, we observed elastic precursor decay and growth of the HEL values with increasing temperature. However, for the c-orientation the growth is caused by decrease of elastic constants and not with an increase of resolved shear stress along the pyramidal slip planes. In the other orientations the resolved shear stresses in slip planes at the HEL increased with temperature. At inclined shock compression we found two plastic shock waves for which the stress behind the first depends on the peak stress associated with the second plastic wave. The crystals demonstrate the largest spall strength at shock loading along the a-axis and smallest one at shock loading in off-axis direction.

  14. One-Dimensional Shock Wave Formation by an Accelerating Piston. Ph.D. Thesis - Ohio State Univ.

    NASA Technical Reports Server (NTRS)

    Mann, M. J.

    1970-01-01

    The formation of a shock wave by a solid accelerating piston was studied. A theoretical solution using the method of characteristics for a perfect gas showed that a complex wave system exists, and that the compressed gas can have large gradients in temperature, density and entropy. Experiments were performed with a piston tube where piston speed, shock speed and pressure were measured. The comparison of theory and experiment was good.

  15. Analytical solution of the problem of a shock wave in the collapsing gas in Lagrangian coordinates

    NASA Astrophysics Data System (ADS)

    Kuropatenko, V. F.; Shestakovskaya, E. S.

    2016-10-01

    It is proposed the exact solution of the problem of a convergent shock wave and gas dynamic compression in a spherical vessel with an impermeable wall in Lagrangian coordinates. At the initial time the speed of cold ideal gas is equal to zero, and a negative velocity is set on boundary of the sphere. When t > t0 the shock wave spreads from this point into the gas. The boundary of the sphere will move under the certain law correlated with the motion of the shock wave. The trajectories of the gas particles in Lagrangian coordinates are straight lines. The equations determining the structure of the gas flow between the shock front and gas border have been found as a function of time and Lagrangian coordinate. The dependence of the entropy on the velocity of the shock wave has been found too. For Lagrangian coordinates the problem is first solved. It is fundamentally different from previously known formulations of the problem of the self-convergence of the self-similar shock wave to the center of symmetry and its reflection from the center, which was built up for the infinite area in Euler coordinates.

  16. Steady state risetimes of shock waves in the atmosphere

    NASA Technical Reports Server (NTRS)

    Raspet, Richard; Bass, Henry; Yao, Lixin; Wu, Wenliang

    1992-01-01

    A square wave shape is used in the Pestorius algorithm to calculate the risetime of a step shock in the atmosphere. These results agree closely with steady shock calculations. The healing distance of perturbed shocks due to finite wave effects is then investigated for quasi-steady shocks. Perturbed 100 Pa shocks require on the order of 1.0 km travel distance to return to within 10 percent of their steady shock risetime. For 30 Pa shocks, 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 layer.

  17. Interplanetary shock waves and the structure of solar wind disturbances

    NASA Technical Reports Server (NTRS)

    Hundhausen, A. J.

    1972-01-01

    Observations and theoretical models of interplanetary shock waves are reviewed, with emphasis on the large-scale characteristics of the associated solar wind disturbances and on the relationship of these disturbances to solar activity. The sum of observational knowledge indicates that shock waves propagate through the solar wind along a broad, roughly spherical front, ahead of plasma and magnetic field ejected from solar flares. Typically, the shock front reaches 1 AU about two days after its flare origin, and is of intermediate strength. Not all large flares produce observable interplanetary shock waves; the best indicator of shock production appears to be the generation of both type 2 and type 4 radio bursts by a flare. Theoretical models of shock propagation in the solar wind can account for the typically observed shock strength, transit time, and shape.

  18. Laser measurements of bacterial endospore destruction from shock waves

    NASA Astrophysics Data System (ADS)

    Lappas, Petros P.; McCartt, A. Daniel; Gates, Sean D.; Jeffries, Jay B.; Hanson, Ronald K.

    2013-12-01

    The effects of shock waves on bioaerosols containing endospores were measured by combined laser absorption and scattering. Experiments were conducted in the Stanford aerosol shock tube for post-shock temperatures ranging from 400 K to 1100 K. Laser intensity measurements through the test section of the shock tube at wavelengths of 266 and 665 nm provided real-time monitoring of the morphological changes (includes changes in shape, structure and optical properties) in the endospores. Scatter of the visible light measured the integrity of endospore structure, while absorption of the UV light provided a measure of biochemicals released when endospores ruptured. For post-shock temperatures above 750 K the structural breakdown of Bacillus atrophaeus (BA) endospores was observed. A simple theoretical model using laser extinction is presented for determining the fraction of endospores that are ruptured by the shock waves. In addition, mechanisms of endospore mortality preceding their disintegration due to shock waves are discussed.

  19. Generation of Pc 1 waves by the ion temperature anisotropy associated with fast shocks caused by sudden impulses

    NASA Technical Reports Server (NTRS)

    Mandt, M. E.; Lee, L. C.

    1991-01-01

    The high correlation of Pc 1 events with magnetospheric compressions is known. A mechanism is proposed which leads to the generation of Pc 1 waves. The interaction of a dynamic pressure pulse with the earth's bow shock leads to the formation of a weak fast-mode shock propagating into the magnetoshealth. The shock wave can pass right through a tangential discontinuity (magnetopause) and into the magnetosphere, without disturbing either of the structures. In a quasiperpendicular geometry, the shock wave exhibits anisotropic heating. This anisotropy drives unstable ion-cyclotron waves which can contribute to the generation of the Pc 1 waves which are detected. The viability of the mechanism is demonstrated with simulations. This mechanism could explain the peak in the occurrence of observed Pc 1 waves in the postnoon sector where a field-aligned discontinuity in the solar wind would most often be parallel to the magnetopause surface due to the average Parker-spiral magnetic-field configuration.

  20. MD simulation of steady shock-wave fronts with phase transition in single-crystal iron

    NASA Astrophysics Data System (ADS)

    Zhakhovsky, V. V.; Migdal, K. P.; Inogamov, N. A.; Anisimov, S. I.

    2017-01-01

    Overdriven shock waves propagating in main crystallographic directions of single-crystal bcc iron were studied with moving-window molecular dynamics (MD) technique. To simulate correctly the shock-induced bcc-to-hcp phase transition in iron a new EAM potential fitted to the cold pressure curves and pressure transition at 13 GPa was developed with the stress matching method. We demonstrate that structure of shock fronts depends on orientation of crystal. A peculiar structure of steady shock-wave front in [100] direction is observed. While the ultra-fast α → ɛ transition initiated in uniaxially compressed crystal along [100] in elastic zone transforms bcc completely to hcp phase, transformation in other directions is performed only partially with production of metastable composition of nanometer-sized bcc-hcp-fcc grains.

  1. Tandem shock wave cavitation enhancement for extracorporeal lithotripsy

    NASA Astrophysics Data System (ADS)

    Loske, Achim M.; Prieto, Fernando E.; Fernández, Francisco; van Cauwelaert, Javier

    2002-11-01

    Extracorporeal shock wave lithotripsy (ESWL) has been successful for more than twenty years in treating patients with kidney stones. Hundreds of underwater shock waves are generated outside the patient's body and focused on the kidney stone. Stones fracture mainly due to spalling, cavitation and layer separation. Cavitation bubbles are produced in the vicinity of the stone by the tensile phase of each shock wave. Bubbles expand, stabilize and finally collapse violently, creating stone-damaging secondary shock waves and microjets. Bubble collapse can be intensified by sending a second shock wave a few hundred microseconds after the first. A novel method of generating two piezoelectrically generated shock waves with an adjustable time delay between 50 and 950 µs is described and tested. The objective is to enhance cavitation-induced damage to kidney stones during ESWL in order to reduce treatment time. In vitro kidney stone model fragmentation efficiency and pressure measurements were compared with those for a standard ESWL system. Results indicate that fragmentation efficiency was significantly enhanced at a shock wave delay of about 400 and 250 µs using rectangular and spherical stone phantoms, respectively. The system presented here could be installed in clinical devices at relatively low cost, without the need for a second shock wave generator.

  2. Temperature maxima in stable two-dimensional shock waves

    NASA Astrophysics Data System (ADS)

    Kum, Oyeon; Hoover, Wm. G.; Hoover, C. G.

    1997-07-01

    We use molecular dynamics to study the structure of moderately strong shock waves in dense two-dimensional fluids, using Lucy's pair potential. The stationary profiles show relatively broad temperature maxima, for both the longitudinal and the average kinetic temperatures, just as does Mott-Smith's model for strong shock waves in dilute three-dimensional gases.

  3. Shock Waves for Possible Application in Regenerative Medicine

    NASA Astrophysics Data System (ADS)

    Hosseini, S. H. R.; Nejad, S. Moosavi; Akiyama, H.

    The paper reports experimental study of underwater shock waves effects in modification and possible control of embryonic stem cell differentiation and proliferation. The study is motivated by its application in regenerativemedicine. Underwater shock waves have been of interest for various scientific, industrial, and medical applications.

  4. The mechanism of shock wave treatment in bone healing

    NASA Astrophysics Data System (ADS)

    Wang, Ching-Jen

    2005-04-01

    The purpose of this study was to investigate the biological mechanism of shock wave treatment in bone healing in rabbits. A closed fracture of the right femur was created with a three-point bend method and the fracture was stabilized with an intra-medullary pin. Shock waves were applied one week after the fracture. Twenty-four New Zealand white rabbits were randomly divided into 3 groups. Group 1 (the control) received no shock waves; group 2 received low-energy and group 3 high-energy shock waves. The animals were sacrificed at 24 weeks, and a 5-cm segment of the femur bone including the callus was harvested. The specimens were studied with histomorphological examination, biomechanical analysis and immunohistochemical stains. The results showed that high-energy shock waves improved bone healing with significant increases in cortical bone formation and the number neovascularization in histomorphology, better bone strength and bone mass in biomechanics, and increased expressions of angiogenic growth markers including BMP-2, eNOS, VEGF and PCNA than the control and low-energy shock wave groups. The effect of shock wave treatment appears to be dose-dependent. In conclusion, high-energy shock waves promote bone healing associated with ingrowth of neovascularization and increased expressions of angiogenic growth factors.

  5. Interaction of Isotropic Turbulence with a Shock Wave

    DTIC Science & Technology

    1992-03-01

    5 1.3 Objectives and Overview....................................... 6 2. Linear Analysis...Length Scales .................................. 74 4.1.5 Thermodynamic Properties ................................ 75 5 4.1.6 M odeling Issues...78 4.2 Modification of a Shock Wave ...................................... 82 5 4.2.1 Statistics of a Shock Wave

  6. Shock Compression of Metal Crystals: A Comparison of Eulerian and Lagrangian Elastic-Plastic Theories

    DTIC Science & Technology

    2014-11-01

    Shock Compression of Metal Crystals: A Comparison of Eulerian and Lagrangian Elastic- Plastic Theories by JD Clayton ARL-RP-0513...of Metal Crystals: A Comparison of Eulerian and Lagrangian Elastic- Plastic Theories JD Clayton Weapons and Materials Research Directorate, ARL...SUBTITLE Shock Compression of Metal Crystals: A Comparison of Eulerian and Lagrangian Elastic- Plastic Theories 5a. CONTRACT NUMBER 5b. GRANT

  7. Formation of Chondrules by Shock Waves

    NASA Astrophysics Data System (ADS)

    Morris, M. A.; Boley, A. C.

    2017-02-01

    We describe and assess current shock models for chondrule formation, particularly those driven by gravitational disk instabilities and bow shocks. We discuss predictions made by shock models and further work needed.

  8. IPShocks: Database of Interplanetary Shock Waves

    NASA Astrophysics Data System (ADS)

    Isavnin, Alexey; Lumme, Erkka; Kilpua, Emilia; Lotti, Mikko; Andreeova, Katerina; Koskinen, Hannu; Nikbakhsh, Shabnam

    2016-04-01

    Fast collisionless shocks are one of the key interplanetary structures, which have also paramount role for solar-terrestrial physics. In particular, coronal mass ejection driven shocks accelerate particles to high energies and turbulent post-shock flows may drive intense geomagnetic storms. We present comprehensive Heliospheric Shock Database (ipshocks.fi) developed and hosted at University of Helsinki. The database contains currently over 2000 fast forward and fast reverse shocks observed by Wind, ACE, STEREO, Helios, Ulysses and Cluster spacecraft. In addition, the database has search and sort tools based on the spacecraft, time range, and several key shock parameters (e.g., shock type, shock strength, shock angle), data plots for each shock and data download options. These features allow easy access to shocks and quick statistical analyses. All current shocks are identified visually and analysed using the same procedure.

  9. Biomechanical and Biochemical Cellular Response Due to Shock Waves

    DTIC Science & Technology

    2008-12-01

    using shock- wave-induced cavitation . Ultrasound in Medicine and Biology, 29, 1769-1776. Lew, H. L., J. H. Poole, S. Alvarez, and W. Moore, 2005...sheets of adipose derived stem cells to shock waves. A key guideline in the experimental design was to suppress cavitation . To this end we...shock-exposed cells and controls. We attribute this to the absence of cavitation . Time-resolved gene expression revealed that a large

  10. Radiant properties of strong shock waves in argon.

    PubMed

    Taylor, W H; Kane, J W

    1967-09-01

    Measurements of the visible radiation emitted by one dimensional, explosively generated, shock waves in argon initially at 1 atm are reported. A time-resolved spectrograph and calibrated photodetectors were used to measure the intensity of the source at 5450 A and 4050 A. The results show that explosive induced shock waves in argon having shock velocities in the range 8-9 mm/microusec radiate at these wavelengths like a blackbody having a temperature of approximately 23,000 degrees K.

  11. Dispersive shock waves in nematic liquid crystals

    NASA Astrophysics Data System (ADS)

    Smyth, Noel F.

    2016-10-01

    The propagation of coherent light with an initial step intensity profile in a nematic liquid crystal is studied using modulation theory. The propagation of light in a nematic liquid crystal is governed by a coupled system consisting of a nonlinear Schrödinger equation for the light beam and an elliptic equation for the medium response. In general, the intensity step breaks up into a dispersive shock wave, or undular bore, and an expansion fan. In the experimental parameter regime for which the nematic response is highly nonlocal, this nematic bore is found to differ substantially from the standard defocusing nonlinear Schrödinger equation structure due to the effect of the nonlocality of the nematic medium. It is found that the undular bore is of Korteweg-de Vries equation-type, consisting of bright waves, rather than of nonlinear Schrödinger equation-type, consisting of dark waves. In addition, ahead of this Korteweg-de Vries bore there can be a uniform wavetrain with a short front which brings the solution down to the initial level ahead. It is found that this uniform wavetrain does not exist if the initial jump is below a critical value. Analytical solutions for the various parts of the nematic bore are found, with emphasis on the role of the nonlocality of the nematic medium in shaping this structure. Excellent agreement between full numerical solutions of the governing nematicon equations and these analytical solutions is found.

  12. Optical observation of shock waves and cavitation bubbles in high intensity laser-induced shock processes.

    PubMed

    Martí-López, L; Ocaña, R; Porro, J A; Morales, M; Ocaña, J L

    2009-07-01

    We report an experimental study of the temporal and spatial dynamics of shock waves, cavitation bubbles, and sound waves generated in water during laser shock processing by single Nd:YAG laser pulses of nanosecond duration. A fast ICCD camera (2 ns gate time) was employed to record false schlieren photographs, schlieren photographs, and Mach-Zehnder interferograms of the zone surrounding the laser spot site on the target, an aluminum alloy sample. We recorded hemispherical shock fronts, cylindrical shock fronts, plane shock fronts, cavitation bubbles, and phase disturbance tracks.

  13. Optical observation of shock waves and cavitation bubbles in high intensity laser-induced shock processes

    SciTech Connect

    Marti-Lopez, L.; Ocana, R.; Porro, J. A.; Morales, M.; Ocana, J. L.

    2009-07-01

    We report an experimental study of the temporal and spatial dynamics of shock waves, cavitation bubbles, and sound waves generated in water during laser shock processing by single Nd:YAG laser pulses of nanosecond duration. A fast ICCD camera (2 ns gate time) was employed to record false schlieren photographs, schlieren photographs, and Mach-Zehnder interferograms of the zone surrounding the laser spot site on the target, an aluminum alloy sample. We recorded hemispherical shock fronts, cylindrical shock fronts, plane shock fronts, cavitation bubbles, and phase disturbance tracks.

  14. Plasma Shock Wave Modification Experiments in a Temperature Compensated Shock Tube

    NASA Technical Reports Server (NTRS)

    Vine, Frances J.; Mankowski, John J.; Saeks, Richard E.; Chow, Alan S.

    2003-01-01

    A number of researchers have observed that the intensity of a shock wave is reduced when it passes through a weakly ionized plasma. While there is little doubt that the intensity of a shock is reduced when it propagates through a weakly ionized plasma, the major question associated with the research is whether the reduction in shock wave intensity is due to the plasma or the concomitant heating of the flow by the plasma generator. The goal of this paper is to describe a temperature compensated experiment in a "large" diameter shock tube with an external heating source, used to control the temperature in the shock tube independently of the plasma density.

  15. Shock waves in noble gases and their mixtures

    NASA Astrophysics Data System (ADS)

    Bratos, M.; Herczynski, R.

    The shock wave structures in pure monatomic gases and in binary gas mixtures are investigated in this paper using a variational approach. The idea of Mott-Smith's distribution function (generalized in the case of a gas mixture) was combined with Tamm's method of solving the Boltzmann equation. The intermolecular potential used is of the Lennard-Jones type. The relation between the dimensionless shock wave thickness and Mach number in front of the shock wave is analyzed. Special attention was paid to the determination of shock wave structures in mixtures of gases with disparate molecular masses. The calculation performed for the shock wave in the binary gas mixture, xenon-helium, confirm the existence of a 'hump' of the density profile of the lighter component. The heavy gas component temperature overshoots its downstream equilibrium value in the case of a mixture of gases with disparate molecular masses and for a small mole fraction of the heavy gas component.

  16. Schlieren imaging of loud sounds and weak shock waves in air near the limit of visibility

    NASA Astrophysics Data System (ADS)

    Hargather, Michael John; Settles, Gary S.; Madalis, Matthew J.

    2010-02-01

    A large schlieren system with exceptional sensitivity and a high-speed digital camera are used to visualize loud sounds and a variety of common phenomena that produce weak shock waves in the atmosphere. Frame rates varied from 10,000 to 30,000 frames/s with microsecond frame exposures. Sound waves become visible to this instrumentation at frequencies above 10 kHz and sound pressure levels in the 110 dB (6.3 Pa) range and above. The density gradient produced by a weak shock wave is examined and found to depend upon the profile and thickness of the shock as well as the density difference across it. Schlieren visualizations of weak shock waves from common phenomena include loud trumpet notes, various impact phenomena that compress a bubble of air, bursting a toy balloon, popping a champagne cork, snapping a wooden stick, and snapping a wet towel. The balloon burst, snapping a ruler on a table, and snapping the towel and a leather belt all produced readily visible shock-wave phenomena. In contrast, clapping the hands, snapping the stick, and the champagne cork all produced wave trains that were near the weak limit of visibility. Overall, with sensitive optics and a modern high-speed camera, many nonlinear acoustic phenomena in the air can be observed and studied.

  17. Optical Radiation from Shock-Compressed Materials. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Svendsen, Robert F., Jr.

    1987-01-01

    Recent observations of shock-induced radiation from oxides, silicates, and metals of geophysical interest constrain the shock-compressed temperature of these materials. The relationships between the temperature inferred from the observed radiation and the temperature of the shock-compressed film or foil and/or window were investigated. Changes of the temperature field in each target component away from that of their respective shock-compressed states occur because of: shock-impedance mismatch between target components; thermal mismatch between target components; surface roughness at target interfaces; and conduction within and between target components. In particular, conduction may affect the temperature of the film/foil window interface on the time scale of the experiments, and so control the intensity and history of the dominant thermal radiation sources in the target. This type of model was used to interpret the radiation emitted by a variety of shock-compressed materials and interfaces.

  18. Viscous Shear Layers Formed by Non-Bifurcating Shock Waves in Shock-Tubes

    NASA Astrophysics Data System (ADS)

    Grogan, Kevin; Ihme, Matthias

    2015-11-01

    Shock-tubes are test apparatuses that are used extensively for chemical kinetic measurements. Under ideal conditions, shock-tubes provide a quiescent region behind a reflected shock wave where combustion may take place without complications arising from gas-dynamic effects. However, due to the reflected shock wave encountering a boundary layer, significant inhomogeneity may be introduced into the test region. The bifurcation of the reflected shock-wave is well-known to occur under certain conditions; however, a viscous shear layer may form behind a non-bifurcating reflected shock wave as well and may affect chemical kinetics and ignition of certain fuels. The focus of this talk is on the development of the viscous shear layer and the coupling to the ignition in the regime corresponding to the negative temperature conditions.

  19. Shock Wave-Induced Damage of a Protein by Void Collapse

    PubMed Central

    Lau, Edmond Y.; Berkowitz, Max L.; Schwegler, Eric

    2016-01-01

    In this study, we report on a series of molecular dynamics simulations that were used to examine the effects of shock waves on a membrane-bound ion channel. A planar shock wave was found to compress the ion channel upon impact, but the protein geometry resembles the crystal structure as soon as the solvent density begins to dissipate. When a void was placed in close proximity to the membrane, the shock wave proved to be more destructive to the protein due to formation of a nanojet that results from the asymmetric collapse of the void. The nanojet was able to cause significant structural changes to the protein even at low piston velocities that are not able to directly cause poration of the membrane. PMID:26745418

  20. Augmented shock wave fracture/severance of materials

    NASA Technical Reports Server (NTRS)

    Schimmel, Morry L. (Inventor); Bement, Laurence J. (Inventor)

    1995-01-01

    The present invention related generally to severing materials, and more particularly to severing or weakening materials through explosively induced, augmented shock waves. Explosive cords are placed in grooves on the upper surface of the material to be severed or weakened. The explosive cords are initiated simultaneously to introduce explosive shock waves into the material. These shock waves progress toward the centerline between the explosive cords and the lower surface of the material. Intersecting and reflected waves produce a rarefaction zone on the centerline to fail the material in tension. A groove may also be cut in the lower surface of the material to aid in severing or weakening the material.

  1. Investigations of Compression Shocks and Boundary Layers in Gases Moving at High Speed

    NASA Technical Reports Server (NTRS)

    Ackeret, J.; Feldmann, F.; Rott, N.

    1947-01-01

    The mutual influences of compression shocks and friction boundary layers were investigated by means of high speed wind tunnels.Schlieren optics provided a clear picture of the flow phenomena and were used for determining the location of the compression shocks, measurement of shock angles, and also for Mach angles. Pressure measurement and humidity measurements were also taken into consideration.Results along with a mathematical model are described.

  2. Simplified laser-driven flyer plates for shock compression science

    SciTech Connect

    Brown, Kathryn E.; Shaw, William L.; Zheng Xianxu; Dlott, Dana D.

    2012-10-15

    We describe a simplified system of laser-driven flyer plates for shock compression science and shock spectroscopy. We used commercially available one-box Nd:YAG lasers and beam homogenization solutions to create two launch systems, one based on a smaller (400 mJ) YAG laser and an inexpensive diffusive optic, and one based on a larger (2500 mJ) laser and a diffractive beam homogenizer. The flyer launch, flight, and impact processes were characterized by an 8 GHz fiberoptic photon Doppler velocimeter. We investigated effects of different substrates, adhesives, absorbers, ablative layers, and punching out disks from continuous foils versus fabricating individual foil disks, and found that a simple metal foil epoxied to a glass window was satisfactory in almost all cases. Our simplified system launched flyer plates with velocities up to 4.5 km s{sup -1} and kinetic energies up to 250 mJ that can drive sustained steady shocks for up to 25 ns. The factor that limits these velocities and energies is the laser fluence that can be transmitted through the glass substrate to the flyer surface without optical damage. Methods to increase this transmission are discussed. Reproducible flyer launches were demonstrated with velocity variations of 0.06% and impact time variations of 1 ns. The usefulness of this flyer plate system is demonstrated by Hugoniot equation of state measurements of a polymer film, emission spectroscopy of a dye embedded in the polymer, and impact initiation and emission spectroscopy of a reactive material consisting of nanoscopic fuel and oxidizer particles.

  3. Simplified laser-driven flyer plates for shock compression science.

    PubMed

    Brown, Kathryn E; Shaw, William L; Zheng, Xianxu; Dlott, Dana D

    2012-10-01

    We describe a simplified system of laser-driven flyer plates for shock compression science and shock spectroscopy. We used commercially available one-box Nd:YAG lasers and beam homogenization solutions to create two launch systems, one based on a smaller (400 mJ) YAG laser and an inexpensive diffusive optic, and one based on a larger (2500 mJ) laser and a diffractive beam homogenizer. The flyer launch, flight, and impact processes were characterized by an 8 GHz fiberoptic photon Doppler velocimeter. We investigated effects of different substrates, adhesives, absorbers, ablative layers, and punching out disks from continuous foils versus fabricating individual foil disks, and found that a simple metal foil epoxied to a glass window was satisfactory in almost all cases. Our simplified system launched flyer plates with velocities up to 4.5 km s(-1) and kinetic energies up to 250 mJ that can drive sustained steady shocks for up to 25 ns. The factor that limits these velocities and energies is the laser fluence that can be transmitted through the glass substrate to the flyer surface without optical damage. Methods to increase this transmission are discussed. Reproducible flyer launches were demonstrated with velocity variations of 0.06% and impact time variations of 1 ns. The usefulness of this flyer plate system is demonstrated by Hugoniot equation of state measurements of a polymer film, emission spectroscopy of a dye embedded in the polymer, and impact initiation and emission spectroscopy of a reactive material consisting of nanoscopic fuel and oxidizer particles.

  4. Simplified laser-driven flyer plates for shock compression science

    NASA Astrophysics Data System (ADS)

    Brown, Kathryn E.; Shaw, William L.; Zheng, Xianxu; Dlott, Dana D.

    2012-10-01

    We describe a simplified system of laser-driven flyer plates for shock compression science and shock spectroscopy. We used commercially available one-box Nd:YAG lasers and beam homogenization solutions to create two launch systems, one based on a smaller (400 mJ) YAG laser and an inexpensive diffusive optic, and one based on a larger (2500 mJ) laser and a diffractive beam homogenizer. The flyer launch, flight, and impact processes were characterized by an 8 GHz fiberoptic photon Doppler velocimeter. We investigated effects of different substrates, adhesives, absorbers, ablative layers, and punching out disks from continuous foils versus fabricating individual foil disks, and found that a simple metal foil epoxied to a glass window was satisfactory in almost all cases. Our simplified system launched flyer plates with velocities up to 4.5 km s-1 and kinetic energies up to 250 mJ that can drive sustained steady shocks for up to 25 ns. The factor that limits these velocities and energies is the laser fluence that can be transmitted through the glass substrate to the flyer surface without optical damage. Methods to increase this transmission are discussed. Reproducible flyer launches were demonstrated with velocity variations of 0.06% and impact time variations of 1 ns. The usefulness of this flyer plate system is demonstrated by Hugoniot equation of state measurements of a polymer film, emission spectroscopy of a dye embedded in the polymer, and impact initiation and emission spectroscopy of a reactive material consisting of nanoscopic fuel and oxidizer particles.

  5. Small scales formation via Alfven wave propagation in compressible nonuniform media

    NASA Technical Reports Server (NTRS)

    Malara, F.; Primavera, L.; Veltri, P.

    1995-01-01

    In weakly dissipative media governed by the magnetohydrodynamics (MHD) equations, any efficient mechanism of energy dissipation requires the formation of small scales. The possibility to produce small scales has been studied by Malara et al. in the case of MHD disturbances propagating in an incompressible and inhomogeneous medium, for a strictly 2D geometry. We extend the work of Malara et al. to include both compressibility and the third component for vector quantities. Using numerical simulations we show that, when an Alfven wave propagates in a compressible nonuniform medium, the two dynamical effects responsible for the small scales formation in the incompressible case are still at work: energy pinching and phase-mixing. Moreover, the interaction between the initial Alfven wave and the inhomogeneity gives rise to the formation of compressible perturbations (fast and slow waves or a static entropy wave). Some of these compressive fluctuations are subject to the steepening of the wave front and become shock waves, which are extremely efficient in dissipating their energy, their dissipation being independent of the Reynolds number. A rough estimate of the typical times which the various dynamical processes take to produce small scales and then to dissipate the energy show that these times are consistent with those required to dissipate inside the solar corona the energy of Alfven waves of photospheric origin.

  6. Cytoplasmic molecular delivery with shock waves: importance of impulse.

    PubMed Central

    Kodama, T; Hamblin, M R; Doukas, A G

    2000-01-01

    Cell permeabilization using shock waves may be a way of introducing macromolecules and small polar molecules into the cytoplasm, and may have applications in gene therapy and anticancer drug delivery. The pressure profile of a shock wave indicates its energy content, and shock-wave propagation in tissue is associated with cellular displacement, leading to the development of cell deformation. In the present study, three different shock-wave sources were investigated; argon fluoride excimer laser, ruby laser, and shock tube. The duration of the pressure pulse of the shock tube was 100 times longer than the lasers. The uptake of two fluorophores, calcein (molecular weight: 622) and fluorescein isothiocyanate-dextran (molecular weight: 71,600), into HL-60 human promyelocytic leukemia cells was investigated. The intracellular fluorescence was measured by a spectrofluorometer, and the cells were examined by confocal fluorescence microscopy. A single shock wave generated by the shock tube delivered both fluorophores into approximately 50% of the cells (p < 0.01), whereas shock waves from the lasers did not. The cell survival fraction was >0.95. Confocal microscopy showed that, in the case of calcein, there was a uniform fluorescence throughout the cell, whereas, in the case of FITC-dextran, the fluorescence was sometimes in the nucleus and at other times not. We conclude that the impulse of the shock wave (i.e., the pressure integrated over time), rather than the peak pressure, was a dominant factor for causing fluorophore uptake into living cells, and that shock waves might have changed the permeability of the nuclear membrane and transferred molecules directly into the nucleus. PMID:11023888

  7. The influence of incident shock Mach number on radial incident shock wave focusing

    NASA Astrophysics Data System (ADS)

    Chen, Xin; Tan, Sheng; He, Liming; Rong, Kang; Zhang, Qiang; Zhu, Xiaobin

    2016-04-01

    Experiments and numerical simulations were carried out to investigate radial incident shock focusing on a test section where the planar incident shock wave was divided into two identical ones. A conventional shock tube was used to generate the planar shock. Incident shock Mach number of 1.51, 1.84 and 2.18 were tested. CCD camera was used to obtain the schlieren photos of the flow field. Third-order, three step strong-stability-preserving (SSP) Runge-Kutta method, third-order weighed essential non-oscillation (WENO) scheme and adaptive mesh refinement (AMR) algorithm were adopted to simulate the complicated flow fields characterized by shock wave interaction. Good agreement between experimental and numerical results was observed. Complex shock wave configurations and interactions (such as shock reflection, shock-vortex interaction and shock focusing) were observed in both the experiments and numerical results. Some new features were observed and discussed. The differences of structure of flow field and the variation trends of pressure were compared and analyzed under the condition of different Mach numbers while shock wave focusing.

  8. August Toepler — The first who visualized shock waves

    NASA Astrophysics Data System (ADS)

    Krehl, P.; Engemann, S.

    1995-06-01

    The scientific investigation of the nature of shock waves started 130 years ago with the advent of the schlieren method which was developed in the period 1859 1864 by August Toepler. At the very beginning applied to the visualization of heat and flow phenomena, he immediately turned to air shock waves generated by electric sparks, and subjectively studied the propagation, reflection and refraction of shock waves. His new delay circuit in the microsecond time regime for the first time made it possible to vary electrically the delay time between a spark generating a shock wave and a second spark acting as a flash light source in his chlieren setup. In 1870 Toepler, together with Boltzmann, applied Jamin's interferometric refractometer and extended the visualization to very weak sound waves at the threshold of hearing. Toepler's pioneering schlieren method stimulated Ernst Mach and his team to objectively investigate the nature of shock waves: they improved Toepler's time delay circuit; continued the study on the reflection of shock waves; introduced shadowgraphy as a modification of the schlieren method; photographed the propagation of shock waves generated by an electric spark and by supersonic projectiles, and improved interferometry. Based on a large number of original documents the paper illuminates the concomitant circumstances of the invention of the schlieren method and its first applications by others.

  9. Melting and band gap-dynamics of shock-compressed graphite diagnosed by x-ray scattering at the LCLS

    NASA Astrophysics Data System (ADS)

    Zastrau, Ulf; Lee, Hae Ja

    2015-11-01

    The diversity of the electronic properties of carbon makes it of key interest to the material science community; By contrast, at the high pressures typical of planetary and stellar interiors, the behavior of carbon is poorly understood with large uncertainties in the conductivity and even the material phase. Tremendous efforts have been made to measure properties of warm dense matter (WDM) in extreme conditions, e.g. temperatures in excess of 1000 K of temperature and pressures in the Mbar regime. In laboratory experiments, practical issues with gradients in the temperature and density of shock compressed matter have hindered accurate measurement and further from distinguishing theoretical models. Here, we present measurements of melting of graphite upon coalescence of two counter-propagating shocks using combinations of spatially and spectrally resolved x-ray scattering methods at the LCLS free electron laser. The MEC nanosecond lasers launch counter-propagating shock waves into graphite. At shock coalescence, pressures in excess of 1 Mbar are reached. At given time delay, we measure scattering from the sample using 5070 eV x-ray pulses. We employed curved mosaic and perfect imaging crystals for spatially resolved x-ray scattering. Compared with hydrodynamics simulations, we present data on plasmon dispersion, axial compression gradients and finally carbon melting at shock coalescence. We have indication for a widening of the band gap during compression of the solid, while the band gab fully closes in the melt. UZ was supported by the German Volkswagen Foundation.

  10. Molecular dynamics simulations of shock waves in hydroxyl-terminated polybutadiene melts: Mechanical and structural responses

    SciTech Connect

    Fröhlich, Markus G. E-mail: ThompsonDon@missouri.edu; Sewell, Thomas D. Thompson, Donald L. E-mail: ThompsonDon@missouri.edu

    2014-01-14

    The mechanical and structural responses of hydroxyl-terminated cis-1,4-polybutadiene melts to shock waves were investigated by means of all-atom non-reactive molecular dynamics simulations. The simulations were performed using the OPLS-AA force field but with the standard 12-6 Lennard-Jones potential replaced by the Buckingham exponential-6 potential to better represent the interactions at high compression. Monodisperse systems containing 64, 128, and 256 backbone carbon atoms were studied. Supported shock waves were generated by impacting the samples onto stationary pistons at impact velocities of 1.0, 1.5, 2.0, and 2.5 km s{sup −1}, yielding shock pressures between approximately 2.8 GPa and 12.5 GPa. Single-molecule structural properties (squared radii of gyration, asphericity parameters, and orientational order parameters) and mechanical properties (density, shock pressure, shock temperature, and shear stress) were analyzed using a geometric binning scheme to obtain spatio-temporal resolution in the reference frame centered on the shock front. Our results indicate that while shear stress behind the shock front is relieved on a ∼0.5 ps time scale, a shock-induced transition to a glass-like state occurs with a concomitant increase of structural relaxation times by several orders of magnitude.

  11. Molecular dynamics simulations of shock waves in hydroxyl-terminated polybutadiene melts: Mechanical and structural responses

    NASA Astrophysics Data System (ADS)

    Fröhlich, Markus G.; Sewell, Thomas D.; Thompson, Donald L.

    2014-01-01

    The mechanical and structural responses of hydroxyl-terminated cis-1,4-polybutadiene melts to shock waves were investigated by means of all-atom non-reactive molecular dynamics simulations. The simulations were performed using the OPLS-AA force field but with the standard 12-6 Lennard-Jones potential replaced by the Buckingham exponential-6 potential to better represent the interactions at high compression. Monodisperse systems containing 64, 128, and 256 backbone carbon atoms were studied. Supported shock waves were generated by impacting the samples onto stationary pistons at impact velocities of 1.0, 1.5, 2.0, and 2.5 km s-1, yielding shock pressures between approximately 2.8 GPa and 12.5 GPa. Single-molecule structural properties (squared radii of gyration, asphericity parameters, and orientational order parameters) and mechanical properties (density, shock pressure, shock temperature, and shear stress) were analyzed using a geometric binning scheme to obtain spatio-temporal resolution in the reference frame centered on the shock front. Our results indicate that while shear stress behind the shock front is relieved on a ˜0.5 ps time scale, a shock-induced transition to a glass-like state occurs with a concomitant increase of structural relaxation times by several orders of magnitude.

  12. Microstructure and Mechanical Properties After Shock Wave Loading of Cast CrMnNi TRIP Steel

    NASA Astrophysics Data System (ADS)

    Eckner, Ralf; Krüger, L.; Ullrich, C.; Rafaja, D.; Schlothauer, T.; Heide, G.

    2016-10-01

    The mechanical response of shock wave-prestrained high-alloy Cr16-Mn7-Ni6 TRIP steel was investigated under compressive and tensile loading at room temperature. Previous shock wave loading was carried out using a flyer-plate assembly with different amounts of explosives in order to achieve shock pressures of 0.3, 0.6, 0.9, and 1.2 Mbar. A significant increase in hardness and strength was observed as compared with the initial as-cast condition. In contrast, a slight decrease in strain hardening rates was measured together with a decrease in fracture elongation in the tensile test. Microstructural analyses of the shock-loaded samples were performed by light optical and scanning electron microscopy. The microstructure revealed a high density of deformation bands consisting of separated stacking faults, ɛ-martensite, or twins. Significant amounts of deformation-induced α'-martensite were only present at the highest shock pressure of 1.2 Mbar. The thickness of the deformation bands and the number of martensite nuclei at their intersections increased with increasing shock pressure. In all shock-loaded specimens, pronounced phase transformation occurred during subsequent mechanical testing. Consequently, the amount of the deformation-induced α'-martensite in the shock-loaded specimens was higher than in the unshocked as-cast samples.

  13. Molecular dynamics simulations of shock waves in hydroxyl-terminated polybutadiene melts: mechanical and structural responses.

    PubMed

    Fröhlich, Markus G; Sewell, Thomas D; Thompson, Donald L

    2014-01-14

    The mechanical and structural responses of hydroxyl-terminated cis-1,4-polybutadiene melts to shock waves were investigated by means of all-atom non-reactive molecular dynamics simulations. The simulations were performed using the OPLS-AA force field but with the standard 12-6 Lennard-Jones potential replaced by the Buckingham exponential-6 potential to better represent the interactions at high compression. Monodisperse systems containing 64, 128, and 256 backbone carbon atoms were studied. Supported shock waves were generated by impacting the samples onto stationary pistons at impact velocities of 1.0, 1.5, 2.0, and 2.5 km s(-1), yielding shock pressures between approximately 2.8 GPa and 12.5 GPa. Single-molecule structural properties (squared radii of gyration, asphericity parameters, and orientational order parameters) and mechanical properties (density, shock pressure, shock temperature, and shear stress) were analyzed using a geometric binning scheme to obtain spatio-temporal resolution in the reference frame centered on the shock front. Our results indicate that while shear stress behind the shock front is relieved on a ∼0.5 ps time scale, a shock-induced transition to a glass-like state occurs with a concomitant increase of structural relaxation times by several orders of magnitude.

  14. Shock waves in cosmic space and planetary materials

    NASA Astrophysics Data System (ADS)

    Miura, Y.; Kato, T.

    1993-08-01

    Shock waves can be produced in the Earth's atmosphere and near vacuum of cosmic space as ``collision (as shock metamorphism)'' and ``collisionless (as plasma)'' shock events, respectively. Collisionless shock forms when the ``solar wind'' hits the ``magnetic fields'' of all the planets and comets which were found by many spacecrafts and Voyager missions as intense Alfven plasma waves. Main causes to generate the collision shock waves are bombardments of the meteorites (or asteroids) against the meteorite itself (including interplanetary dust particles), the Earth, the Moon, and Mars. Material evidence of the collision shock has been studied by shock metamorphism. Because of randomly distributed fragments of meteorites and lunar regolith, shock metamorphic study to the planetary materials should require the standard impact materials from artificial and terrestrial impact craters. Collision and collisionless shocks onto the airless lunar surface produce the regolith soils with agglutinates and solar wind components. Shock waves (including space debris) are considered to play a significant role in space environments of the Space Station and the Lunar and Martian Base projects for human (or robot) activities.

  15. Dispersive radiation induced by shock waves in passive resonators.

    PubMed

    Malaguti, Stefania; Conforti, Matteo; Trillo, Stefano

    2014-10-01

    We show that passive Kerr resonators pumped close to zero dispersion wavelengths on the normal dispersion side can develop the resonant generation of linear waves driven by cavity (mixed dispersive-dissipative) shock waves. The resonance mechanism can be successfully described in the framework of the generalized Lugiato-Lefever equation with higher-order dispersive terms. Substantial differences with radiation from cavity solitons and purely dispersive shock waves dispersion are highlighted.

  16. Experimental investigation on aero-optical aberration of shock wave/boundary layer interactions

    NASA Astrophysics Data System (ADS)

    Ding, Haolin; Yi, Shihe; Fu, Jia; He, Lin

    2016-10-01

    After streaming through the flow field which including the expansion, shock wave, boundary, etc., the optical wave would be distorted by fluctuations in the density field. Interactions between laminar/turbulent boundary layer and shock wave contain large number complex flow structures, which offer a condition for studying the influences that different flow structures of the complex flow field have on the aero-optical aberrations. Interactions between laminar/turbulent boundary layer and shock wave are investigated in a Mach 3.0 supersonic wind tunnel, based on nanoparticle-tracer planar laser scattering (NPLS) system. Boundary layer separation/attachment, induced suppression waves, induced shock wave, expansion fan and boundary layer are presented by NPLS images. Its spatial resolution is 44.15 μm/pixel. Time resolution is 6ns. Based on the NPLS images, the density fields with high spatial-temporal resolution are obtained by the flow image calibration, and then the optical path difference (OPD) fluctuations of the original 532nm planar wavefront are calculated using Ray-tracing theory. According to the different flow structures in the flow field, four parts are selected, (1) Y=692 600pixel; (2) Y=600 400pixel; (3) Y=400 268pixel; (4) Y=268 0pixel. The aerooptical effects of different flow structures are quantitatively analyzed, the results indicate that: the compressive waves such as incident shock wave, induced shock wave, etc. rise the density, and then uplift the OPD curve, but this kind of shock are fixed in space position and intensity, the aero-optics induced by it can be regarded as constant; The induced shock waves are induced by the coherent structure of large size vortex in the interaction between turbulent boundary layer, its unsteady characteristic decides the induced waves unsteady characteristic; The space position and intensity of the induced shock wave are fixed in the interaction between turbulent boundary layer; The boundary layer aero-optics are

  17. OBSERVATIONS AND INTERPRETATION OF A LOW CORONAL SHOCK WAVE OBSERVED IN THE EUV BY THE SDO/AIA

    SciTech Connect

    Ma Suli; Raymond, John C.; Golub, Leon; Grigis, Paolo; Testa, Paola; Long, David; Lin Jun; Chen Huadong

    2011-09-10

    Taking advantage of both the high temporal and spatial resolutions of the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory, we studied a limb coronal shock wave and its associated extreme ultraviolet (EUV) wave that occurred on 2010 June 13. Our main findings are: (1) the shock wave appeared clearly only in the channels centered at 193 A and 211 A as a dome-like enhancement propagating ahead of its associated semi-spherical coronal mass ejection (CME) bubble; (2) the density compression of the shock is 1.56 according to radio data and the temperature of the shock is around 2.8 MK; (3) the shock wave first appeared at 05:38 UT, 2 minutes after the associated flare has started and 1 minute after its associated CME bubble appeared; (4) the top of the dome-like shock wave set out from about 1.23 R{sub sun} and the thickness of the shocked layer is {approx}2 x 10{sup 4} km; (5) the speed of the shock wave is consistent with a slight decrease from about 600 km s{sup -1} to 550 km s{sup -1}; and (6) the lateral expansion of the shock wave suggests a constant speed around 400 km s{sup -1}, which varies at different heights and directions. Our findings support the view that the coronal shock wave is driven by the CME bubble, and the on-limb EUV wave is consistent with a fast wave or at least includes the fast wave component.

  18. Medical applications and bioeffects of extracorporeal shock waves

    NASA Astrophysics Data System (ADS)

    Delius, M.

    1994-09-01

    Lithotripter shock waves are pressure pulses of microsecond duration with peak pressures of 35 120 MPa followed by a tensile wave. They are an established treatment modality for kidney and gallstone disease. Further applications are pancreatic and salivary stones, as well as delayed fracture healing. The latter are either on their way to become established treatments or are currently under investigation. Shock waves generate tissue damage as a side effect which has been extensively investigated in the kidney, the liver, and the gallbladder. The primary adverse effects are local destruction of blood vessels, bleedings, and formation of blood clots in vessels. Investigations on the mechanism of shock wave action revealed that lithotripters generate cavitation both in vitro and in vivo. An increase in tissue damage at higher pulse administration rates, and also at shock wave application with concomitant gas bubble injection suggested that cavitation is a major mechanism of tissue damage. Disturbances of the heart rhythm and excitation of nerves are further biological effects of shock waves; both are probably also mediated by cavitation. On the cellular level, shock waves induce damage to cell organelles; its extent is related to their energy density. They also cause a transient increase in membrane permeability which does not lead to cell death. Administered either alone or in combination with drugs, shock waves have been shown to delay the growth of small animal tumors and even induce tumor remissions. While the role of cavitation in biological effects is widely accepted, the mechanism of stone fragmentation by shock waves is still controversial. Cavitation is detected around the stone and hyperbaric pressure suppresses fragmentation; yet major cracks are formed early before cavitation bubble collapse is observed. The latter has been regarded as evidence for a direct shock wave effect.

  19. Dynamics of concerted bubble cluster collapse in shock wave lithotripsy

    NASA Astrophysics Data System (ADS)

    Pishchalnikov, Yuri A.; McAteer, James A.; Evan, Andrew P.; Sapozhnikov, Oleg A.; Cleveland, Robin O.; Colonius, Tim; Bailey, Michael R.; Crum, Lawrence A.

    2003-10-01

    Cavitation bubble cluster collapse at the surface of artificial kidney stones during shock wave lithotripsy was investigated in vitro by means of multiframe high-speed photography, passive cavitation detection (PCD), and pressure waveform measurements using a fiber-optic probe hydrophone (FOPH). It was observed that after the passage of the lithotripter shock pulse the stone was covered by numerous individual bubbles. During their growth phase the bubbles coalesced into bubble clusters, with the biggest cluster at the proximal face of the stone. High-speed camera images suggested that cluster collapse started at the periphery and ended with a violent collapse in a small region in the center of the surface of the stone. Shadowgraphy resolved numerous secondary shock waves emitted during this focused collapse. Shock wave emission during cluster collapse was confirmed by PCD. Measurement with the FOPH showed that these shock waves were typically of short duration (0.2 μs). The majority of the shock waves emanating from cluster collapse were low amplitude but some shock waves registered amplitudes on the order of the incident shock pulse (tens of MPa). [Work supported by NIH DK43881, DK55674.

  20. The Observational Consequences of Proton-Generated Waves at Shocks

    NASA Technical Reports Server (NTRS)

    Reames, Donald V.

    2000-01-01

    In the largest solar energetic particle (SEP) events, acceleration takes place at shock waves driven out from the Sun by fast coronal mass ejections. Protons streaming away from strong shocks generate Alfven waves that trap particles in the acceleration region, limiting outflowing intensities but increasing the efficiency of acceleration to higher energies. Early in the events, with the shock still near the Sun, intensities at 1 AU are bounded and spectra are flattened at low energies. Elements with different charge-to-mass ratios, Q/A, differentially probe the wave spectra near shocks, producing abundance ratios that vary in space and time. An initial rise in He/H, while Fe/O declines, is a typical symptom of the non-Kolmogorov wave spectra in the largest events. Strong wave generation can cause cross-field scattering near the shock and unusually rapid reduction in anisotropies even far from the shock. At the highest energies, shock spectra steepen to form a "knee." For protons, this spectral knee can vary from approx. 10 MeV to approx. 1 GeV depending on shock conditions for wave growth. In one case, the location of the knee scales approximately as Q/A in the energy/nucleon spectra of other species.

  1. Nonlinear waves and shocks in relativistic two-fluid hydrodynamics

    NASA Astrophysics Data System (ADS)

    Haim, L.; Gedalin, M.; Spitkovsky, A.; Krasnoselskikh, V.; Balikhin, M.

    2012-06-01

    Relativistic shocks are present in a number of objects where violent processes are accompanied by relativistic outflows of plasma. The magnetization parameter σ = B2/4πnmc2 of the ambient medium varies in wide range. Shocks with low σ are expected to substantially enhance the magnetic fields in the shock front. In non-relativistic shocks the magnetic compression is limited by nonlinear effects related to the deceleration of flow. Two-fluid analysis of perpendicular relativistic shocks shows that the nonlinearities are suppressed for σ<<1 and the magnetic field reaches nearly equipartition values when the magnetic energy density is of the order of the ion energy density, Beq2 ~ 4πnmic2γ. A large cross-shock potential eφ/mic2γ0 ~ B2/Beq2 develops across the electron-ion shock front. This potential is responsible for electron energization.

  2. Analysis of shock-wave propagation in aqueous foams using shock tube experiments

    NASA Astrophysics Data System (ADS)

    Jourdan, G.; Mariani, C.; Houas, L.; Chinnayya, A.; Hadjadj, A.; Del Prete, E.; Haas, J.-F.; Rambert, N.; Counilh, D.; Faure, S.

    2015-05-01

    This paper reports experimental results of planar shock waves interacting with aqueous foams in a horizontal conventional shock tube. Four incident shock wave Mach numbers are considered, ranging from 1.07 to 1.8, with two different foam columns of one meter thickness and expansion ratios of 30 and 80. High-speed flow visualizations are used along with pressure measurements to analyse the main physical mechanisms that govern shock wave mitigation in foams. During the shock/foam interaction, a precursor leading pressure jump was identified as the trace of the liquid film destruction stage in the foam fragmentation process. The corresponding pressure threshold is found to be invariant for a given foam. Regarding the mitigation effect, the results show that the speed of the shock is drastically reduced and that wetter is the foam, slower are the transmitted waves. The presence of the foam barrier attenuates the induced pressure impulse behind the transmitted shock, while the driest foam appears to be more effective, as it limits the pressure induced by the reflected shock off the foam front. Finally, it was found that the pressure histories in the two-phase gas-liquid mixture are different from those previously obtained within a cloud of droplets. The observed behavior is attributed to the process of foam fragmentation and to the modification of the flow topology past the shock. These physical phenomena occurring during the shock/foam interaction should be properly accounted for when elaborating new physical models.

  3. Numerical simulation of MHD shock waves in the solar wind

    NASA Technical Reports Server (NTRS)

    Steinolfson, R. S.; Dryer, M.

    1978-01-01

    The effects of the interplanetary magnetic field on the propagation speed of shock waves through an ambient solar wind are examined by numerical solutions of the time-dependent nonlinear equations of motion. The magnetic field always increases the velocity of strong shocks. Although the field may temporarily slow down weak shocks inside 1 AU, it eventually also causes weak shocks to travel faster than they would without the magnetic field at larger distances. Consistent with the increase in the shock velocity, the gas pressure ratio across a shock is reduced considerably in the presence of the magnetic field. The numerical method is used to simulate (starting at 0.3 AU) the large deceleration of a shock observed in the lower corona by ground-based radio instrumentation and the more gradual deceleration of the shock in the solar wind observed by the Pioneer 9 and Pioneer 10 spacecraft.

  4. Temperature measurements of explosively driven strong shock waves in gases

    NASA Astrophysics Data System (ADS)

    Nakayama, Yoshio; Yoshida, Masatake; Kakudate, Yozo; Usuba, Shu; Yamawaki, Hiroaki; Aoki, Katsutoshi; Tanaka, Katsumi; Fujiwara, Shuzo

    1992-03-01

    Two types of explosively driven shock tube; one-dimensional shock tube, and cumulative shock tube were used to generate strong shock waves in gases. Temperature measurements were made by using a spectroscope with eight-PIN photodiode system over the visible wavelength range (440-740 nm). The color temperature as well as the brightness temperature for one-dimensional shock tube with atmospheric pressure argon agreed fairly well with theoretical calculations; the brightness temperature was 18,000 K and 19,200 K for shock velocity of 4.8 km/s and 5.7 km/s respectively with an accuracy of +/- 500 K. The brightness temperature in the cumulative shock tube was 62,200 +/- 2,010 K at shock velocity of 27 km/s for atmospheric pressure air and agreed with theoretical values.

  5. Shock Formation of Slow Magnetosonic Waves in Coronal Plumes

    NASA Technical Reports Server (NTRS)

    Cuntz, Manfred; Suess, Steve; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    We investigate the height of shock formation in coronal plumes for slow magnetosonic waves. The models take into account plume geometric spreading, heat conduction, and radiative damping. The wave parameters as well as the spreading functions of the plumes and the base magnetic field strengths are given by empirical constraints mostly from Solar and Heliospheric Observatory (SOHO)/ Ultraviolet Coronograph Spectrometer (UVCS), Extreme Ultraviolet Imaging Telescope (EIT), Michelson Doppler Imager (MDI), and Large Angle Spectrometric Coronagraph (LASCO). Our models show that shock formation occurs at relatively low coronal heights, typically within 1.2 RsuN, depending on the model parameters. The shock formation is calculated using the well-established wave breaking criterion given by the intersection of C+ characteristics in the space-time plane. Our models show that shock heating by slow magnetosonic waves is expected to be relevant at most heights in solar coronal plumes, although such waves are probably not the main energy supply mechanism.

  6. Shear waves in inhomogeneous, compressible fluids in a gravity field.

    PubMed

    Godin, Oleg A

    2014-03-01

    While elastic solids support compressional and shear waves, waves in ideal compressible fluids are usually thought of as compressional waves. Here, a class of acoustic-gravity waves is studied in which the dilatation is identically zero, and the pressure and density remain constant in each fluid particle. These shear waves are described by an exact analytic solution of linearized hydrodynamics equations in inhomogeneous, quiescent, inviscid, compressible fluids with piecewise continuous parameters in a uniform gravity field. It is demonstrated that the shear acoustic-gravity waves also can be supported by moving fluids as well as quiescent, viscous fluids with and without thermal conductivity. Excitation of a shear-wave normal mode by a point source and the normal mode distortion in realistic environmental models are considered. The shear acoustic-gravity waves are likely to play a significant role in coupling wave processes in the ocean and atmosphere.

  7. Convection of a pattern of vorticity through a shock wave

    NASA Technical Reports Server (NTRS)

    Ribner, H S

    1954-01-01

    An arbitrary weak spatial distribution of vorticity can be represented in terms of plane sinusoidal shear waves of all orientations and wave lengths (Fourier integral). The analysis treats the passage of a single representative weak shear wave through a plane shock and shows refraction and modification of the shear wave with simultaneous generation of an acoustically intense sound wave. Applications to turbulence and to noise in supersonic wind tunnels are indicated.

  8. Shock Waves in a Bose-Einstein Condensate

    NASA Technical Reports Server (NTRS)

    Kulikov, Igor; Zak, Michail

    2005-01-01

    A paper presents a theoretical study of shock waves in a trapped Bose-Einstein condensate (BEC). The mathematical model of the BEC in this study is a nonlinear Schroedinger equation (NLSE) in which (1) the role of the wave function of a single particle in the traditional Schroedinger equation is played by a space- and time-dependent complex order parameter (x,t) proportional to the square root of the density of atoms and (2) the atoms engage in a repulsive interaction characterized by a potential proportional to | (x,t)|2. Equations that describe macroscopic perturbations of the BEC at zero temperature are derived from the NLSE and simplifying assumptions are made, leading to equations for the propagation of sound waves and the transformation of sound waves into shock waves. Equations for the speeds of shock waves and the relationships between jumps of velocity and density across shock fronts are derived. Similarities and differences between this theory and the classical theory of sound waves and shocks in ordinary gases are noted. The present theory is illustrated by solving the equations for the example of a shock wave propagating in a cigar-shaped BEC.

  9. Shock wave-boundary layer interactions in rarefied gas flows

    NASA Technical Reports Server (NTRS)

    Bird, G. A.

    1991-01-01

    A numerical study is presented, using the direct simulation Monte Carlo (DSMC) method, of shock wave-boundary layer interactions in low density supersonic flows. Test cases include two-dimensional, axially-symmetric and three-dimensional flows. The effective displacement angle of the boundary layer is calculated for representative flat plate, wedge, and cone flows. The maximum pressure, shear stress, and heat transfer in the shock formation region is determined in each case. The two-dimensional reflection of an oblique shock wave from a flat plate is studied, as is the three-dimensional interaction of such a wave with a sidewall boundary layer.

  10. First experience with a modified Siemens Lithostar shock wave system.

    PubMed

    Volmer, K D; Köhler, G; Folberth, W; Planz, K

    1991-01-01

    A Siemens Lithostar shock wave system was modified and investigated clinically. The modified system yields increased focal pressure and energy density. The first clinical experience in renal calculi shows a significant reduction in shock wave numbers per treatment. Higher energy output enables better treatment results for difficult stones such as staghorn and infections calculi. Despite the higher energy output more than 90% of treatments could be performed without anesthesia or analgesia. No significant side effects could be detected. The service life of the modified shock wave system increased by a factor of two.

  11. Generation of shear waves as an effective mechanism of dynamic load of the lithotripter shock wave on the kidney stone

    NASA Astrophysics Data System (ADS)

    Sapozhnikov, Oleg A.; Cleveland, Robin O.; Bailey, Michael R.; Crum, Lawrence A.

    2003-10-01

    A number of stone comminution mechanisms have been studied in lithotripsy. Except cavitation erosion, these mechanisms (namely, spallation, dynamic fatigue, shear, and circumferential compression) are associated with stresses generated in the stone by the shock wave. The mechanical load on the stone depends on the waveform and stone structure, size, and shape. We modeled the propagation of lithotripter shock waves through a cylindrical stone with a finite differences simulation based on Lame's equation. The stone parameters were similar to those of natural kidney stones. A new mechanism of tensile stress generation is predicted that may be 5-10 times more efficient than spalling. Shear elasticity of the stone gave rise to the peak tensile strain in the bulk of the stone; this strain occurs near the stone axis due to coherent arrival of shear waves from the front edges of the stone. The position of the region of maximum strain and direction of corresponding tensile forces is similar to those predicted by the spalling mechanism. The modeling also showed that circumferential compression is not activated by the dynamic load produced by a short shock wave typical for lithotripsy. [Work supported by NIH PO1 DK43881, RO1 DK55674 and FOGARTY, CDRF, ONRIFO, and NSBRI.

  12. Entropy jump across an inviscid shock wave

    NASA Technical Reports Server (NTRS)

    Salas, Manuel D.; Iollo, Angelo

    1995-01-01

    The shock jump conditions for the Euler equations in their primitive form are derived by using generalized functions. The shock profiles for specific volume, speed, and pressure are shown to be the same, however density has a different shock profile. Careful study of the equations that govern the entropy shows that the inviscid entropy profile has a local maximum within the shock layer. We demonstrate that because of this phenomenon, the entropy, propagation equation cannot be used as a conservation law.

  13. Laser interferometer measurements of refractive index in shock-compressed materials

    NASA Astrophysics Data System (ADS)

    Wise, J. L.; Chhabildas, L. C.

    Laser interferometer systems provide a means for probing the refractive index of transparent specimens subjected to dynamic compression. Previous interferometer measurements of optical properties under shock loading are reviewed for polymethyl methacrylate, fused silica, sapphire, nitromethane, and an aqueous solution of zinc chloride; various degrees of departure from Gladstone-Dale behavior are noted for these materials. In addition, a detailed summary of recent optical studies of lithium fluoride (LiF) is provided. Interferometer data from plate-impact experiments verify sustained LiF transparency for Hugoniot stresses to at least 115 GPa, and establish the variation of LiF refractive index for shock amplitudes ranging from 1.58 to 115 GPa. The refractive-index data for LiF agree with earlier static and shock-wave data, and exhibit a pronounced deviation from predictions based on the Gladstone-Dale, Lorentz-Lorenz, and Drude relations. A modified form of the Gladstone-Dale relation is presented which correctly models the latest LiF measurements. Potential applications of LiF and other window materials to dynamic high-pressure experimentation are discussed.

  14. Propagation of impact-induced shock waves in porous sandstone using mesoscale modeling

    NASA Astrophysics Data System (ADS)

    GÜLdemeister, Nicole; WÜNnemann, Kai; Durr, Nathanael; Hiermaier, Stefan

    2013-01-01

    Abstract-Generation and propagation of <span class="hlt">shock</span> <span class="hlt">waves</span> by meteorite impact is significantly affected by material properties such as porosity, water content, and strength. The objective of this work was to quantify processes related to the <span class="hlt">shock</span>-induced compaction of pore space by numerical modeling, and compare the results with data obtained in the framework of the Multidisciplinary Experimental and Modeling Impact Research Network (MEMIN) impact experiments. We use mesoscale models resolving the collapse of individual pores to validate macroscopic (homogenized) approaches describing the bulk behavior of porous and water-saturated materials in large-scale models of crater formation, and to quantify localized <span class="hlt">shock</span> amplification as a result of pore space crushing. We carried out a suite of numerical models of planar <span class="hlt">shock</span> <span class="hlt">wave</span> propagation through a well-defined area (the "sample") of porous and/or water-saturated material. The porous sample is either represented by a homogeneous unit where porosity is treated as a state variable (macroscale model) and water content by an equation of state for mixed material (ANEOS) or by a defined number of individually resolved pores (mesoscale model). We varied porosity and water content and measured thermodynamic parameters such as <span class="hlt">shock</span> <span class="hlt">wave</span> velocity and particle velocity on meso- and macroscales in separate simulations. The mesoscale models provide additional data on the heterogeneous distribution of peak <span class="hlt">shock</span> pressures as a consequence of the complex superposition of reflecting rarefaction <span class="hlt">waves</span> and <span class="hlt">shock</span> <span class="hlt">waves</span> originating from the crushing of pores. We quantify the bulk effect of porosity, the reduction in <span class="hlt">shock</span> pressure, in terms of Hugoniot data as a function of porosity, water content, and strength of a quartzite matrix. We find a good agreement between meso-, macroscale models and Hugoniot data from <span class="hlt">shock</span> experiments. We also propose a combination of a porosity compaction model (ɛ-α model) that was</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993ders.conf..283T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993ders.conf..283T"><span id="translatedtitle">Simulations for detonation initiation behind reflected <span class="hlt">shock</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Takano, Yasunari</p> <p></p> <p>Numerical simulations are carried out for detonation initiation behind reflected <span class="hlt">shock</span> <span class="hlt">waves</span> in a <span class="hlt">shock</span> tube. The two-dimensional thin-layer Navier-Stokes equations with chemical effects are numerically solved by use of a combined method consisting of the Flux-Corrected Transport scheme, the Crank-Nicolson scheme, and a chemical calculation step. Effects of chemical reactions occurring in a <span class="hlt">shock</span>-heated hydrogen, oxygen, and argon mixture are estimated by using a simplified reaction model: two progress parameters are introduced to take account of induction reactions as well as exothermic reactions. Simulations are carried out referring to several experiments: generation of multidimensional and unstable reaction <span class="hlt">shock</span> <span class="hlt">waves</span>; strong and mild ignitions; and reacting <span class="hlt">shock</span> <span class="hlt">waves</span> in hydrogen and oxygen diluted in argon mixture.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850060847&hterms=temper&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dtemper','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850060847&hterms=temper&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dtemper"><span id="translatedtitle">Nonlinear <span class="hlt">shock</span> acceleration. III - Finite <span class="hlt">wave</span> velocity, <span class="hlt">wave</span> pressure, and entropy generation via <span class="hlt">wave</span> damping</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Eichler, D.</p> <p>1985-01-01</p> <p>The nonlinear theory of <span class="hlt">shock</span> acceleration developed in earlier papers, which treated the <span class="hlt">waves</span> as being completely frozen into the fluid, is generalized to include <span class="hlt">wave</span> dynamics. In the limit where damping keeps the <span class="hlt">wave</span> amplitude small, it is found that a finite phase velocity (V sub ph) of the scattering <span class="hlt">waves</span> through the background fluid, tempers the acceleration generated by high Mach number <span class="hlt">shocks</span>. Asymptotic spectra proportional to 1/E sq are possible only when the ratio of <span class="hlt">wave</span> velocity to <span class="hlt">shock</span> velocity is less than 0.13. For a given asymptotic spectrum, the efficiency of relativistic particle production is found to be practically independent of the value of V sub ph, so that earlier results concerning its value remain valid for finite V sub ph. In the limit where there is no <span class="hlt">wave</span> damping, it is shown that for modest Alfven Mach numbers, approximately greater than 4 and less than 6, the magnetic field is amplified by the energetic particles to the point of being in rough equipartition with them, as models of synchrotron emission frequently take the field to be. In this case, the disordering and amplification of field energy may play a major role in the <span class="hlt">shock</span> transition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApPhL.110b3701L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApPhL.110b3701L"><span id="translatedtitle">Molecular modeling of transmembrane delivery of paclitaxel by <span class="hlt">shock</span> <span class="hlt">waves</span> with nanobubbles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lu, Xue-mei; Yuan, Bing; Zhang, Xian-ren; Yang, Kai; Ma, Yu-qiang</p> <p>2017-01-01</p> <p>The development of advanced delivery strategies for anticancer drugs that can permeate through cellular membranes is urgently required for biomedical applications. In this work, we investigated the dynamic transmembrane behavior of paclitaxel (PTX), a powerful anticancer drug, under the combined impact of <span class="hlt">shock</span> <span class="hlt">waves</span> and nanobubbles, by using atomistic molecular dynamics simulations. Our simulations show that the PTX molecule experiences complicated motion modes during the action process with the membrane, as a consequence of its interplay with the lipid bilayer and water, under the joint effect of the <span class="hlt">shock</span> <span class="hlt">wave</span> and nanobubble. Moreover, it was found that the transmembrane movement of PTX is closely associated with the conformation changes of PTX, as well as the structural changes of the membrane (e.g., <span class="hlt">compression</span> and poration in membrane). The nanobubble collapse induced by the <span class="hlt">shock</span> <span class="hlt">wave</span>, the proper PTX location with respect to the nanobubble, and a suitable nanobubble size and <span class="hlt">shock</span> impulse are all necessary for the delivery of PTX into the cell. This work provides a molecular understanding of the interaction mechanism between drug molecules and cell membranes under the influence of <span class="hlt">shock</span> <span class="hlt">waves</span> and nanobubbles, and paves the way for exploiting targeted drug delivery systems that combine nanobubbles and ultrasound.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JAP...112f3529J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JAP...112f3529J"><span id="translatedtitle">Effect of compositional variation on the <span class="hlt">shock</span> <span class="hlt">wave</span> response of bulk amorphous alloys</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jaglinski, T.; Turneaure, Stefan J.; Gupta, Y. M.</p> <p>2012-09-01</p> <p>The objective of this work was to determine how variations in composition influence the <span class="hlt">shock</span> <span class="hlt">wave</span> response of bulk amorphous alloys (BAAs). Toward this end, (Hf,Zr)-based bulk amorphous alloy specimens (nominal composition of (Hf0.5Zr0.5)56.7Cu15.3Ni12.5Nb5.0Al10.0Y0.5) were subjected to peak stresses of 4-16 GPa in plate impact experiments and their response was compared to a previously studied Zr-based BAA (nominal composition of Zr56.7Cu15.3Ni12.5Nb5.0Al10.0Y0.5). The (Hf,Zr)-based BAA displayed a Hugoniot elastic limit (HEL) of ˜7.4 GPa corresponding to an elastic strain of 4.3%. (Hf,Zr)-based BAAs <span class="hlt">shock</span> <span class="hlt">compressed</span> above the HEL exhibited distinct two <span class="hlt">wave</span> structures, small elastic precursor relaxation, non-steady plastic <span class="hlt">waves</span>, and strength loss. All of these features are qualitatively similar to previous observations in various Zr-based BAAs. One dimensional <span class="hlt">wave</span> propagation simulations incorporating a strain-softening strength model, developed previously for a Zr-based BAA, showed excellent agreement between measured and simulated particle velocity histories for the (Hf,Zr)-based BAA. The only significant differences in the <span class="hlt">shock</span> <span class="hlt">wave</span> responses of the (Hf,Zr)-based alloy and the Zr-based alloy are elastic <span class="hlt">shock</span> velocity and plastic <span class="hlt">shock</span> velocity differences which are due to the different ambient densities and different elastic moduli for the two alloy compositions. These findings demonstrate that, apart from differences related to ambient density and elastic stiffness, the substitution of Hf for 50% of the Zr did not significantly alter the <span class="hlt">shock</span> <span class="hlt">compression</span> response of the (Hf,Zr)-based BAA as compared to the previously examined Zr-based BAA. Based on the results of this study and other relevant data in the literature, it is expected that monolithic BAAs displaying brittle quasi-static <span class="hlt">compression</span> behavior will likely display <span class="hlt">shock</span> <span class="hlt">compression</span> response that is comparable to Zr-based and (Hf,Zr)-based BAAs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhyD..333...11E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhyD..333...11E"><span id="translatedtitle">Dispersive <span class="hlt">shock</span> <span class="hlt">waves</span> and modulation theory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>El, G. A.; Hoefer, M. A.</p> <p>2016-10-01</p> <p>There is growing physical and mathematical interest in the hydrodynamics of dissipationless/dispersive media. Since G.B. Whitham's seminal publication fifty years ago that ushered in the mathematical study of dispersive hydrodynamics, there has been a significant body of work in this area. However, there has been no comprehensive survey of the field of dispersive hydrodynamics. Utilizing Whitham's averaging theory as the primary mathematical tool, we review the rich mathematical developments over the past fifty years with an emphasis on physical applications. The fundamental, large scale, coherent excitation in dispersive hydrodynamic systems is an expanding, oscillatory dispersive <span class="hlt">shock</span> <span class="hlt">wave</span> or DSW. Both the macroscopic and microscopic properties of DSWs are analyzed in detail within the context of the universal, integrable, and foundational models for uni-directional (Korteweg-de Vries equation) and bi-directional (Nonlinear Schrödinger equation) dispersive hydrodynamics. A DSW fitting procedure that does not rely upon integrable structure yet reveals important macroscopic DSW properties is described. DSW theory is then applied to a number of physical applications: superfluids, nonlinear optics, geophysics, and fluid dynamics. Finally, we survey some of the more recent developments including non-classical DSWs, DSW interactions, DSWs in perturbed and inhomogeneous environments, and two-dimensional, oblique DSWs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008ShWav..18..393M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008ShWav..18..393M"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">wave</span> driven microparticles for pharmaceutical applications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Menezes, V.; Takayama, K.; Gojani, A.; Hosseini, S. H. R.</p> <p>2008-10-01</p> <p>Ablation created by a Q-switched Nd:Yttrium Aluminum Garnet (Nd:YAG) laser beam focusing on a thin aluminum foil surface spontaneously generates a <span class="hlt">shock</span> <span class="hlt">wave</span> that propagates through the foil and deforms it at a high speed. This high-speed foil deformation can project dry micro- particles deposited on the anterior surface of the foil at high speeds such that the particles have sufficient momentum to penetrate soft targets. We used this method of particle acceleration to develop a drug delivery device to deliver DNA/drug coated microparticles into soft human-body targets for pharmaceutical applications. The device physics has been studied by observing the process of particle acceleration using a high-speed video camera in a shadowgraph system. Though the initial rate of foil deformation is over 5 km/s, the observed particle velocities are in the range of 900-400 m/s over a distance of 1.5-10 mm from the launch pad. The device has been tested by delivering microparticles into liver tissues of experimental rats and artificial soft human-body targets, modeled using gelatin. The penetration depths observed in the experimental targets are quite encouraging to develop a future clinical therapeutic device for treatments such as gene therapy, treatment of cancer and tumor cells, epidermal and mucosal immunizations etc.</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://www.osti.gov/scitech/servlets/purl/1262247','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1262247"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">wave</span> perturbation decay in granular materials</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Vogler, Tracy J.</p> <p>2015-11-05</p> <p>A technique in which the evolution of a perturbation in a <span class="hlt">shock</span> <span class="hlt">wave</span> front is monitored as it travels through a sample is applied to granular materials. Although the approach was originally conceived as a way to measure the viscosity of the sample, here it is utilized as a means to probe the deviatoric strength of the material. Initial results for a tungsten carbide powder are presented that demonstrate the approach is viable. Simulations of the experiments using continuum and mesoscale modeling approaches are used to better understand the experiments. The best agreement with the limited experimental data is obtained for the mesoscale model, which has previously been shown to give good agreement with planar impact results. The continuum simulations indicate that the decay of the perturbation is controlled by material strength but is insensitive to the compaction response. Other sensitivities are assessed using the two modeling approaches. The simulations indicate that the configuration used in the preliminary experiments suffers from certain artifacts and should be modified to remove them. As a result, the limitations of the current instrumentation are discussed, and possible approaches to improve it are suggested.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1262247-shock-wave-perturbation-decay-granular-materials','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1262247-shock-wave-perturbation-decay-granular-materials"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">wave</span> perturbation decay in granular materials</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Vogler, Tracy J.</p> <p>2015-11-05</p> <p>A technique in which the evolution of a perturbation in a <span class="hlt">shock</span> <span class="hlt">wave</span> front is monitored as it travels through a sample is applied to granular materials. Although the approach was originally conceived as a way to measure the viscosity of the sample, here it is utilized as a means to probe the deviatoric strength of the material. Initial results for a tungsten carbide powder are presented that demonstrate the approach is viable. Simulations of the experiments using continuum and mesoscale modeling approaches are used to better understand the experiments. The best agreement with the limited experimental data is obtainedmore » for the mesoscale model, which has previously been shown to give good agreement with planar impact results. The continuum simulations indicate that the decay of the perturbation is controlled by material strength but is insensitive to the compaction response. Other sensitivities are assessed using the two modeling approaches. The simulations indicate that the configuration used in the preliminary experiments suffers from certain artifacts and should be modified to remove them. As a result, the limitations of the current instrumentation are discussed, and possible approaches to improve it are suggested.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005ASAJ..117.2371B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005ASAJ..117.2371B"><span id="translatedtitle">Observation of cavitation during <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bailey, Michael R.; Crum, Lawrence A.; Pishchalnikov, Yuri A.; McAteer, James A.; Pishchalnikova, Irina V.; Evan, Andrew P.; Sapozhnikov, Oleg A.; Cleveland, Robin O.</p> <p>2005-04-01</p> <p>A system was built to detect cavitation in pig kidney during <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy (SWL) with a Dornier HM3 lithotripter. Active detection, using echo on B-mode ultrasound, and passive cavitation detection (PCD), using coincident signals on confocal, orthogonal receivers, were equally sensitive and were used to interrogate the renal collecting system (urine) and the kidney parenchyma (tissue). Cavitation was detected in urine immediately upon SW administration in urine or urine plus X-ray contrast agent, but in tissue, cavitation required hundreds of SWs to initiate. Localization of cavitation was confirmed by fluoroscopy, sonography, and by thermally marking the kidney using the PCD receivers as high intensity focused ultrasound sources. Cavitation collapse times in tissue and native urine were about the same but less than in urine after injection of X-ray contrast agent. Cavitation, especially in the urine space, was observed to evolve from a sparse field to a dense field with strong acoustic collapse emissions to a very dense field that no longer produced detectable collapse. The finding that cavitation occurs in kidney tissue is a critical step toward determining the mechanisms of tissue injury in SWL. [Work sup ported by NIH (DK43881, DK55674, FIRCA), ONRIFO, CRDF and NSBRI SMS00203.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996ShWav...6..249Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996ShWav...6..249Y"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">waves</span> from an open-ended <span class="hlt">shock</span> tube with different shapes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yu, Q.; Grönig, H.</p> <p>1996-11-01</p> <p>A new method for decreasing the attenuation of a <span class="hlt">shock</span> <span class="hlt">wave</span> emerging from an open-ended <span class="hlt">shock</span> tube exit into a large free space has been developed to improve the <span class="hlt">shock</span> <span class="hlt">wave</span> technique for cleaning deposits on the surfaces in industrial equipments by changing the tube exit geometry. Three tube exits (the simple tube exit, a tube exit with ring and a coaxial tube exit) were used to study the propagation processes of the <span class="hlt">shock</span> <span class="hlt">waves</span>. The detailed flow features were experimentally investigated by use of a two-dimensional color schlieren method and by pressure measurements. By comparing the results for different tube exits, it is shown that the expansion of the <span class="hlt">shock</span> <span class="hlt">waves</span> near the mouth can be restricted by using the tube exit with ring or the coaxial tube exit. Thus, the attenuation of the <span class="hlt">shock</span> <span class="hlt">waves</span> is reduced. The time histories of overpressure have illustrated that the best results are obtained for the coaxial tube exit. But the pressure signals for the tube exit with ring showed comparable results with the advantage of a relatively simple geometry. The flow structures of diffracting <span class="hlt">shock</span> <span class="hlt">waves</span> have also been simulated by using an upwind finite volume scheme based on a high order extension of Godunov's method as well as an adaptive unstructured triangular mesh refinement/unrefinement algorithm. The numerical results agree remarkably with the experimental ones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15812285','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15812285"><span id="translatedtitle">Acetabular augmentation induced by extracorporeal <span class="hlt">shock</span> <span class="hlt">waves</span> in rabbits.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Saisu, Takashi; Kamegaya, Makoto; Wada, Yuichi; Takahashi, Kenji; Mitsuhashi, Shigeru; Moriya, Hideshige; Maier, Markus</p> <p>2005-05-01</p> <p>We conducted this animal study to demonstrate whether exposing the acetabulum in immature rabbits to extracorporeal <span class="hlt">shock</span> <span class="hlt">waves</span> induces bone formation in the acetabulum. Five thousand <span class="hlt">shock</span> <span class="hlt">waves</span> of 100 MPa each were directed, from outside, at the acetabular roof of eight immature rabbits. At each of two time points (4 and 8 weeks) after treatment, the pelvises of four rabbits were removed and evaluated morphologically. Woven bone formation was observed on the lateral margin of the acetabular roof at 4 weeks after treatment, and the breadth of the acetabular roof in the coronal plane was significantly increased. Eight weeks after treatment, the woven bone disappeared; the breadth of the acetabular roof, however, was significantly increased. These findings demonstrated that extracorporeal <span class="hlt">shock</span> <span class="hlt">waves</span> induced acetabular augmentation in rabbits. We conclude that extracorporeal <span class="hlt">shock</span> <span class="hlt">waves</span>, perhaps, could be applied clinically for the treatment of acetabular dysplasia.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/948551','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/948551"><span id="translatedtitle">Nonstandard jump functions for radially symmetric <span class="hlt">shock</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Baty, Roy S.; Tucker, Don H.; Stanescu, Dan</p> <p>2008-10-01</p> <p>Nonstandard analysis is applied to derive generalized jump functions for radially symmetric, one-dimensional, magnetogasdynamic <span class="hlt">shock</span> <span class="hlt">waves</span>. It is assumed that the <span class="hlt">shock</span> <span class="hlt">wave</span> jumps occur on infinitesimal intervals, and the jump functions for the physical parameters occur smoothly across these intervals. Locally integrable predistributions of the Heaviside function are used to model the flow variables across a <span class="hlt">shock</span> <span class="hlt">wave</span>. The equations of motion expressed in nonconservative form are then applied to derive unambiguous relationships between the jump functions for the physical parameters for two families of self-similar flows. It is shown that the microstructures for these families of radially symmetric, magnetogasdynamic <span class="hlt">shock</span> <span class="hlt">waves</span> coincide in a nonstandard sense for a specified density jump function</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22525461','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22525461"><span id="translatedtitle">PARTICLE ACCELERATION AT LOW CORONAL <span class="hlt">COMPRESSION</span> REGIONS AND <span class="hlt">SHOCKS</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Schwadron, N. A.; Lee, M. A.; Gorby, M; Lugaz, N.; Spence, H. E.; Desai, M.; Török, T.; Downs, C.; Linker, J.; Lionello, R.; Mikić, Z.; Riley, P.; Giacalone, J.; Jokipii, J. R.; Kota, J.; Kozarev, K.</p> <p>2015-09-10</p> <p>We present a study on particle acceleration in the low corona associated with the expansion and acceleration of coronal mass ejections (CMEs). Because CME expansion regions low in the corona are effective accelerators over a finite spatial region, we show that there is a rigidity regime where particles effectively diffuse away and escape from the acceleration sites using analytic solutions to the Parker transport equation. This leads to the formation of broken power-law distributions. Based on our analytic solutions, we find a natural ordering of the break energy and second power-law slope (above the break energy) as a function of the scattering characteristics. These relations provide testable predictions for the particle acceleration from low in the corona. Our initial analysis of solar energetic particle observations suggests a range of <span class="hlt">shock</span> <span class="hlt">compression</span> ratios and rigidity dependencies that give rise to the solar energetic particle (SEP) events studied. The wide range of characteristics inferred suggests competing mechanisms at work in SEP acceleration. Thus, CME expansion and acceleration in the low corona may naturally give rise to rapid particle acceleration and broken power-law distributions in large SEP events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1208837-imaging-shock-waves-diamond-both-high-temporal-spatial-resolution-xfel','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1208837-imaging-shock-waves-diamond-both-high-temporal-spatial-resolution-xfel"><span id="translatedtitle">Imaging <span class="hlt">shock</span> <span class="hlt">waves</span> in diamond with both high temporal and spatial resolution at an XFEL</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Schropp, Andreas; Hoppe, Robert; Meier, Vivienne; ...</p> <p>2015-06-18</p> <p>The advent of hard x-ray free-electron lasers (XFELs) has opened up a variety of scientific opportunities in areas as diverse as atomic physics, plasma physics, nonlinear optics in the x-ray range, and protein crystallography. In this article, we access a new field of science by measuring quantitatively the local bulk properties and dynamics of matter under extreme conditions, in this case by using the short XFEL pulse to image an elastic <span class="hlt">compression</span> <span class="hlt">wave</span> in diamond. The elastic <span class="hlt">wave</span> was initiated by an intense optical laser pulse and was imaged at different delay times after the optical pump pulse using magnifiedmore » x-ray phase-contrast imaging. The temporal evolution of the <span class="hlt">shock</span> <span class="hlt">wave</span> can be monitored, yielding detailed information on <span class="hlt">shock</span> dynamics, such as the <span class="hlt">shock</span> velocity, the <span class="hlt">shock</span> front width, and the local <span class="hlt">compression</span> of the material. The method provides a quantitative perspective on the state of matter in extreme conditions.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140013351','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140013351"><span id="translatedtitle">Grain Destruction in a Supernova Remnant <span class="hlt">Shock</span> <span class="hlt">Wave</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Raymond, John C.; Ghavamian, Parviz; Williams, Brian J.; Blair, William P.; Borkowski, Kazimierz J.; Gaetz, Terrance J.; Sankrit, Ravi</p> <p>2014-01-01</p> <p>Dust grains are sputtered away in the hot gas behind <span class="hlt">shock</span> fronts in supernova remnants, gradually enriching the gas phase with refractory elements. We have measured emission in C IV (lambda)1550 from C atoms sputtered from dust in the gas behind a non-radiative <span class="hlt">shock</span> <span class="hlt">wave</span> in the northern Cygnus Loop. Overall, the intensity observed behind the <span class="hlt">shock</span> agrees approximately with predictions from model calculations that match the Spitzer 24 micron and the X-ray intensity profiles. Thus these observations confirm the overall picture of dust destruction in SNR <span class="hlt">shocks</span> and the sputtering rates used in models. However, there is a discrepancy in that the CIV intensity 10'' behind the <span class="hlt">shock</span> is too high compared to the intensities at the <span class="hlt">shock</span> and 25'' behind it. Variations in the density, hydrogen neutral fraction and the dust properties over parsec scales in the pre- <span class="hlt">shock</span> medium limit our ability to test dust destruction models in detail.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900037939&hterms=asterisk&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dasterisk','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900037939&hterms=asterisk&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dasterisk"><span id="translatedtitle">A new class of solutions for interstellar magnetohydrodynamic <span class="hlt">shock</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Roberge, W. G.; Draine, B. T.</p> <p>1990-01-01</p> <p>An analysis is presented of the equations of motion for steady MHD <span class="hlt">shock</span> <span class="hlt">waves</span> proopagating in interstellar clouds, for boundary conditions that preclude C <span class="hlt">shocks</span>. In addition to J <span class="hlt">shocks</span>, in which the neutral fluid component becomes subsonic at an adiabatic jump front, the equations admit a new class of solutions, called C-asterisk <span class="hlt">shocks</span>, in which the transition to subsonic flow occurs continuously at a sonic point. Numerical methods are developed for computing the structure of J and C-asterisk <span class="hlt">shocks</span> propagating in diffuse interstellar clouds. The effects of chemical, ionization, and recombination processes are included in this treatment. An alternative numerical method, which uses artificial viscosity to facilitate integration through sonic points, is analyzed and shown to be invalid. A set of exemplary solutions, computed for realistic <span class="hlt">shock</span> parameters, shows that C-asterisk <span class="hlt">shocks</span> occur for a broad range of conditions relevant to diffuse interstellar clouds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22341891','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22341891"><span id="translatedtitle">Grain destruction in a supernova remnant <span class="hlt">shock</span> <span class="hlt">wave</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Raymond, John C.; Gaetz, Terrance J.; Ghavamian, Parviz; Williams, Brian J.; Blair, William P.; Borkowski, Kazimierz J.; Sankrit, Ravi</p> <p>2013-12-01</p> <p>Dust grains are sputtered away in the hot gas behind <span class="hlt">shock</span> fronts in supernova remnants (SNRs), gradually enriching the gas phase with refractory elements. We have measured emission in C IV λ1550 from C atoms sputtered from dust in the gas behind a non-radiative <span class="hlt">shock</span> <span class="hlt">wave</span> in the northern Cygnus Loop. Overall, the intensity observed behind the <span class="hlt">shock</span> agrees approximately with predictions from model calculations that match the Spitzer 24 μm and the X-ray intensity profiles. Thus, these observations confirm the overall picture of dust destruction in SNR <span class="hlt">shocks</span> and the sputtering rates used in models. However, there is a discrepancy in that the C IV intensity 10'' behind the <span class="hlt">shock</span> is too high compared with the intensities at the <span class="hlt">shock</span> and 25'' behind it. Variations in the density, hydrogen neutral fraction, and the dust properties over parsec scales in the pre-<span class="hlt">shock</span> medium limit our ability to test dust destruction models in detail.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013ApJ...778..161R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013ApJ...778..161R"><span id="translatedtitle">Grain Destruction in a Supernova Remnant <span class="hlt">Shock</span> <span class="hlt">Wave</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Raymond, John C.; Ghavamian, Parviz; Williams, Brian J.; Blair, William P.; Borkowski, Kazimierz J.; Gaetz, Terrance J.; Sankrit, Ravi</p> <p>2013-12-01</p> <p>Dust grains are sputtered away in the hot gas behind <span class="hlt">shock</span> fronts in supernova remnants (SNRs), gradually enriching the gas phase with refractory elements. We have measured emission in C IV λ1550 from C atoms sputtered from dust in the gas behind a non-radiative <span class="hlt">shock</span> <span class="hlt">wave</span> in the northern Cygnus Loop. Overall, the intensity observed behind the <span class="hlt">shock</span> agrees approximately with predictions from model calculations that match the Spitzer 24 μm and the X-ray intensity profiles. Thus, these observations confirm the overall picture of dust destruction in SNR <span class="hlt">shocks</span> and the sputtering rates used in models. However, there is a discrepancy in that the C IV intensity 10'' behind the <span class="hlt">shock</span> is too high compared with the intensities at the <span class="hlt">shock</span> and 25'' behind it. Variations in the density, hydrogen neutral fraction, and the dust properties over parsec scales in the pre-<span class="hlt">shock</span> medium limit our ability to test dust destruction models in detail.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFMMR53D..08D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFMMR53D..08D"><span id="translatedtitle">On the Concordance of Static High Pressure Phase Transformation Data on Minerals With <span class="hlt">Shock</span> <span class="hlt">Wave</span> Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>de Carli, P. S.; El Goresy, A.; Xie, Z.; Sharp, T. G.</p> <p>2006-12-01</p> <p>About 50 years ago, <span class="hlt">shock</span> <span class="hlt">wave</span> researchers were confounded by the apparent rapidity of <span class="hlt">shock</span>-induced phase transformations and invoked special mechanisms as an explanation. Some workers speculatively interpret <span class="hlt">shock</span> <span class="hlt">wave</span> data as indicative of very rapid reconstructive phase transformations of minerals at modest temperatures. The belief that kinetic effects are negligible has justified the use of microsecond duration <span class="hlt">shock</span> recovery experiments to interpret much longer duration <span class="hlt">shock</span> effects in terrestrial impact craters and in meteorites. Here we summarize the extensive evidence that phase transformations under <span class="hlt">shock</span> <span class="hlt">compression</span> are governed by the same kinetics as phase transitions under static <span class="hlt">compression</span>. Hugoniot measurements on quartz and feldspars have been interpreted as indicating phase transitions to dense phases at pressures near 35 GPa. Release adiabat measurements imply that these phases persist on release of pressure down to about 7 GPa, below which there is expansion to a final density appropriate to a glass. Microsecond-duration <span class="hlt">shock</span> recovery experiments support this interpretation; a low density amorphous phase (diaplectic glass) is recovered. A similar effect is observed in static <span class="hlt">compression</span> experiments conducted at room temperature at a lower pressure, 12-15 GPa. The pressure difference is a kinetic effect; the transition requires higher <span class="hlt">shock</span> pressures (implying higher <span class="hlt">shock</span> temperatures) to run to completion on a microsecond time scale. Direct evidence for kinetic effects on the tectosilicate transformation is found in studies of naturally <span class="hlt">shocked</span> meteorites that contain melt veins. When the melt veins solidify under pressure, the resultant mineralogy together with vein cooling calculations constrains the <span class="hlt">shock</span> pressure-time history. In some samples, in which the <span class="hlt">shock</span> pressure is constrained by vein mineralogy to a range of 17-25 Gpa, one may observe the presence of diaplectic glass in only near-vein regions heated by conduction from the vein</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhyD..310...19W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhyD..310...19W"><span id="translatedtitle">A geometric singular perturbation approach for planar stationary <span class="hlt">shock</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Zhuopu; Zhang, Jiazhong; Ren, Junheng; Aslam, Muhammad Nauman</p> <p>2015-08-01</p> <p>The non-linear non-equilibrium nature of <span class="hlt">shock</span> <span class="hlt">waves</span> in gas dynamics is investigated for the planar case. Along each streamline, the Euler equations with non-equilibrium pressure are reduced to a set of ordinary differential equations defining a slow-fast system, and geometric singular perturbation theory is applied. The proposed theory shows that an orbit on the slow manifold corresponds to the smooth part of the solution to the Euler equation, where non-equilibrium effects are negligible; and a relaxation motion from the unsteady to the steady branch of the slow manifold corresponds to a <span class="hlt">shock</span> <span class="hlt">wave</span>, where the flow relaxes from non-equilibrium to equilibrium. Recognizing the <span class="hlt">shock</span> <span class="hlt">wave</span> as a fast motion is found to be especially useful for <span class="hlt">shock</span> <span class="hlt">wave</span> detection when post-processing experimental measured or numerical calculated flow fields. Various existing <span class="hlt">shock</span> detection methods can be derived from the proposed theory in a rigorous mathematical manner. The proposed theory provides a new <span class="hlt">shock</span> detection method based on its non-linear non-equilibrium nature, and may also serve as the theoretical foundation for many popular <span class="hlt">shock</span> <span class="hlt">wave</span> detection techniques.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA409784','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA409784"><span id="translatedtitle">Statistical Case Study of Extracorporeal <span class="hlt">Shock</span> <span class="hlt">Wave</span> Lithotripsy</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2007-11-02</p> <p><span class="hlt">Shock</span> <span class="hlt">Wave</span> Lithotripsy (ESWL) is one of the recent, most common ways of treating patients with urinary (renal and ureteric) stones through non...Page 1 of 3 Statistical Case Study of Extracorporeal <span class="hlt">Shock</span> <span class="hlt">Wave</span> Lithotripsy Hani M. Amasha1 and Basel M. Al-Eideh2 1Department of...invasive destruction of stones [1]. Many reports and studies have shown its safety and success. It offers the patient less pain; much less discomfort and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA600899','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA600899"><span id="translatedtitle">Observation and Control of <span class="hlt">Shock</span> <span class="hlt">Waves</span> in Individual Nanoplasmas</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2014-03-18</p> <p>Observation and Control of <span class="hlt">Shock</span> <span class="hlt">Waves</span> in Individual Nanoplasmas Daniel D. Hickstein,1 Franklin Dollar,1 Jim A. Gaffney,2 Mark E. Foord,2 George M...distribution of individual, isolated 100-nm-scale plasmas, we make the first experimental observation of <span class="hlt">shock</span> <span class="hlt">waves</span> in nanoplasmas . We demonstrate that...i Nanoscale plasmas ( nanoplasmas ) offer enhanced laser absorption compared to solid or gas targets [1], enabling high-energy physics with tabletop</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhDT.........6K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT.........6K"><span id="translatedtitle">Tracking kidney stones with sound during <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kracht, Jonathan M.</p> <p></p> <p>The prevalence of kidney stones has increased significantly over the past decades. One of the primary treatments for kidney stones is <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy which focuses acoustic <span class="hlt">shock</span> <span class="hlt">waves</span> onto the stone in order to fragment it into pieces that are small enough to pass naturally. This typically requires a few thousand <span class="hlt">shock</span> <span class="hlt">waves</span> delivered at a rate of about 2 Hz. Although lithotripsy is the only non-invasive treatment option for kidney stories, both acute and chronic complications have been identified which could be reduced if fewer <span class="hlt">shock</span> <span class="hlt">waves</span> were used. One factor that could be used to reduce the number of <span class="hlt">shock</span> <span class="hlt">waves</span> is accounting for the motion of the stone which causes a portion of the delivered <span class="hlt">shock</span> <span class="hlt">waves</span> to miss the stone, yielding no therapeutic benefit. Therefore identifying when the stone is not in focus would allow tissue to be spared without affecting fragmentation. The goal of this thesis is to investigate acoustic methods to track the stone in real-time during lithotripsy in order to minimize poorly-targeted <span class="hlt">shock</span> <span class="hlt">waves</span>. A relatively small number of low frequency ultrasound transducers were used in pulse-echo mode and a novel optimization routine based on time-of-flight triangulation is used to determine stone location. It was shown that the accuracy of the localization may be estimated without knowing the true stone location. This method performed well in preliminary experiments but the inclusion of tissue-like aberrating layers reduced the accuracy of the localization. Therefore a hybrid imaging technique employing DORT (Decomposition of the Time Reversal Operator) and the MUSIC (Multiple Signal Classification) algorithm was developed. This method was able to localize kidney stories to within a few millimeters even in the presence of an aberrating layer. This would be sufficient accuracy for targeting lithotripter <span class="hlt">shock</span> <span class="hlt">waves</span>. The conclusion of this work is that tracking kidney stones with low frequency ultrasound should be effective clinically.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22047096','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22047096"><span id="translatedtitle">Dust acoustic <span class="hlt">shock</span> <span class="hlt">waves</span> in two temperatures charged dusty grains</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>El-Shewy, E. K.; Abdelwahed, H. G.; Elmessary, M. A.</p> <p>2011-11-15</p> <p>The reductive perturbation method has been used to derive the Korteweg-de Vries-Burger equation and modified Korteweg-de Vries-Burger for dust acoustic <span class="hlt">shock</span> <span class="hlt">waves</span> in a homogeneous unmagnetized plasma having electrons, singly charged ions, hot and cold dust species with Boltzmann distributions for electrons and ions in the presence of the cold (hot) dust viscosity coefficients. The behavior of the <span class="hlt">shock</span> <span class="hlt">waves</span> in the dusty plasma has been investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AIPC..593...99L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AIPC..593...99L"><span id="translatedtitle">More efficient focusing for extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Loske, Achim M.; Prieto, Fernando E.</p> <p>2001-10-01</p> <p>The purpose of this study was to generate alternative pressure waveforms in order to increase efficiency during non-invasive treatments of nephrolithiasis. Two new systems for electrohydraulic <span class="hlt">shock</span> <span class="hlt">wave</span> generators were tested. These devices generate two pressure pulses, instead of only one positive peak, followed by a trough, as in conventional systems. Pressure measurements and stone fragmentation efficiency were compared to that of conventional <span class="hlt">shock</span> <span class="hlt">wave</span> generators, using needle hydrophones and kidney-stone models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18442965','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18442965"><span id="translatedtitle">T-<span class="hlt">wave</span> oversensing and inappropriate <span class="hlt">shocks</span>: a case report.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Srivathsan, Komandoor; Scott, Luis R; Altemose, Gregory T</p> <p>2008-05-01</p> <p>A 27-year-old male with congenital long QT syndrome, SCN5A mutation experienced recurrent inappropriate exercise-related implantable cardioverter defibrillator (ICD) <span class="hlt">shocks</span>. This device showed T-<span class="hlt">wave</span> oversensing with double, which lead to these device discharges. Dynamic T-<span class="hlt">wave</span> oversensing was reproducibly provoked at exercise treadmill testing and was confirmed as the mechanism leading to double counting. The insertion of a new pacing and sensing lead with increased R-<span class="hlt">wave</span> amplitude did not solve the problem. Exchanging the existing ICD generator with one capable of automatic sensitivity control (Biotronik, Lexos DR, Biotronik, Berlin, Germany) completely eliminated T-<span class="hlt">wave</span> oversensing and inappropriate <span class="hlt">shocks</span>.</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('https://www.ncbi.nlm.nih.gov/pubmed/22554068','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22554068"><span id="translatedtitle">Ultrafast <span class="hlt">shock</span> <span class="hlt">compression</span> and <span class="hlt">shock</span>-induced decomposition of 1,3,5-triamino-2,4,6-trinitrobenzene subjected to a subnanosecond-duration <span class="hlt">shock</span>: an analysis of decomposition products.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Carter, Jeffrey A; Zaug, Joseph M; Nelson, A J; Armstrong, Michael R; Manaa, M Riad</p> <p>2012-05-24</p> <p><span class="hlt">Shock</span> <span class="hlt">compression</span> studies of pressed and confined ultrafine 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) powder were conducted using ultrashort ~300 ps, ~50 GPa <span class="hlt">shock</span> <span class="hlt">waves</span>. The recovered decomposition products were characterized using X-ray photoelectron spectroscopy, infrared spectroscopy, and Raman spectroscopy. A substantial amount of <span class="hlt">shock</span>-related chemistry was observed. Approximately 75% of the nitrogen atoms were liberated as gas-phase species, along with ~33% of the oxygen atoms, as a result of the applied <span class="hlt">shock</span>. Furthermore, we observe C 1s binding energies suggesting the formation of sp(3) hybridized amorphous carbon. For comparison, a carbon nitride material was also prepared and characterized by thermally pyrolizing TATB. The <span class="hlt">shock-compressed</span> TATB and the thermally pyrolized TATB are qualitatively different, suggesting that, carbon nitrides, a possible indicator of nitrogen-rich heterocycles precursors, are not a major product class for strongly overdriven <span class="hlt">shock</span> conditions. These experimental conditions were, however, not detonation conditions, and the possible formation of nitrogen-rich heterocycles in actual detonations still exists.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012IAUS..279..335I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012IAUS..279..335I"><span id="translatedtitle">Turbulent Magnetic Field Amplification behind Strong <span class="hlt">Shock</span> <span class="hlt">Waves</span> in GRB and SNR</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Inoue, Tsuyoshi</p> <p>2012-09-01</p> <p>Using three-dimensional (special relativistic) magnetohydrodynamics simulations, the amplification of magnetic field behind strong <span class="hlt">shock</span> <span class="hlt">wave</span> is studied. In supernova remnants and gamma-ray bursts, strong <span class="hlt">shock</span> <span class="hlt">waves</span> propagate through an inhomogeneous density field. When the <span class="hlt">shock</span> <span class="hlt">wave</span> hit a density bump or density dent, the Richtmyer-Meshkov instability is induced that cause a deformation of the <span class="hlt">shock</span> front. The deformed <span class="hlt">shock</span> leaves vorticity behind the <span class="hlt">shock</span> <span class="hlt">wave</span> that amplifies the magnetic field due to the stretching of field lines.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MNRAS.463.1026L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MNRAS.463.1026L"><span id="translatedtitle">SHOCKFIND - an algorithm to identify magnetohydrodynamic <span class="hlt">shock</span> <span class="hlt">waves</span> in turbulent clouds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lehmann, Andrew; Federrath, Christoph; Wardle, Mark</p> <p>2016-11-01</p> <p>The formation of stars occurs in the dense molecular cloud phase of the interstellar medium. Observations and numerical simulations of molecular clouds have shown that supersonic magnetized turbulence plays a key role for the formation of stars. Simulations have also shown that a large fraction of the turbulent energy dissipates in <span class="hlt">shock</span> <span class="hlt">waves</span>. The three families of MHD <span class="hlt">shocks</span> - fast, intermediate and slow - distinctly <span class="hlt">compress</span> and heat up the molecular gas, and so provide an important probe of the physical conditions within a turbulent cloud. Here, we introduce the publicly available algorithm, SHOCKFIND, to extract and characterize the mixture of <span class="hlt">shock</span> families in MHD turbulence. The algorithm is applied to a three-dimensional simulation of a magnetized turbulent molecular cloud, and we find that both fast and slow MHD <span class="hlt">shocks</span> are present in the simulation. We give the first prediction of the mixture of turbulence-driven MHD <span class="hlt">shock</span> families in this molecular cloud, and present their distinct distributions of sonic and Alfvénic Mach numbers. Using subgrid one-dimensional models of MHD <span class="hlt">shocks</span> we estimate that ˜0.03 per cent of the volume of a typical molecular cloud in the Milky Way will be <span class="hlt">shock</span> heated above 50 K, at any time during the lifetime of the cloud. We discuss the impact of this <span class="hlt">shock</span> heating on the dynamical evolution of molecular clouds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020080810','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020080810"><span id="translatedtitle">Energetic Particle Abundances as Probes of an Interplanetary <span class="hlt">Shock</span> <span class="hlt">Wave</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Reames, D. V.; Tylka, A. J.; White, Nicholas E. (Technical Monitor)</p> <p>2002-01-01</p> <p>We examine the unique abundance variations of Fe/O and He/H in solar energetic particles from a W09 event of 2001 April 10, that have leaked through the flank of an interplanetary <span class="hlt">shock</span> launched from W04 on April 9. <span class="hlt">Shock</span> <span class="hlt">waves</span> from both events reach the Wind spacecraft on April 11. During the second event, both Fe/O and He/H begin at low values and rise to maxima near the time of passage of the <span class="hlt">shock</span> <span class="hlt">waves</span>, indicating greater scattering for the species with the highest rigidity at a given velocity. Strong modulation of Fe/O suggests preferential scattering and trapping of Fe by the <span class="hlt">wave</span> spectrum near and behind the intermediate <span class="hlt">shock</span>. A significant factor may be the residual proton-generated <span class="hlt">waves</span> from the very hard proton spectrum accelerated by the early <span class="hlt">shock</span> <span class="hlt">wave</span> prior to the onset of the second event. Thus, ion abundances from the later event probe the residual <span class="hlt">wave</span> spectrum at the earlier <span class="hlt">shock</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040065781&hterms=harvard&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dharvard','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040065781&hterms=harvard&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dharvard"><span id="translatedtitle">The <span class="hlt">Shock</span> <span class="hlt">Compression</span> Laboratory at Harvard: A New Facility for Planetary Impact Processes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stewart, S. T.</p> <p>2004-01-01</p> <p>The <span class="hlt">Shock</span> <span class="hlt">Compression</span> Laboratory in the Department of Earth and Planetary Sciences at Harvard is a new facility for the study of impact and collisional phenomena. The following describes the experimental capabilities of the laboratory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001PhyU...44..371T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001PhyU...44..371T"><span id="translatedtitle">REVIEWS OF TOPICAL PROBLEMS: <span class="hlt">Shock</span> <span class="hlt">compression</span> of condensed materials (laboratory studies)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Trunin, Ryurik F.</p> <p>2001-04-01</p> <p>Laboratory <span class="hlt">shock</span> <span class="hlt">compression</span> data obtained in Russia since 1948 are reviewed, including those for elements and alloys, organic compounds, minerals, rocks, and liquids as well as the hydrides, carbides, and nitrides of metals.</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> <span class="hlt">Wave</span>/Turbulent Boundary Layer 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 <span class="hlt">compressible</span> turbulence modeling for high speed flows with <span class="hlt">shock</span> <span class="hlt">wave</span> / turbulent boundary layer 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 layers because of the very large and variable adverse pressure gradients caused by the <span class="hlt">shock</span> <span class="hlt">waves</span>. 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('https://ntrs.nasa.gov/search.jsp?R=19960009429&hterms=Bls&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DBls','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960009429&hterms=Bls&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DBls"><span id="translatedtitle">Reduction of fluctuating pressure loads in <span class="hlt">shock</span> <span class="hlt">wave</span> turbulent boundary layer interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Barter, John W.; Dolling, David S.</p> <p>1995-01-01</p> <p>Fluctuating surface pressure measurements have been made to investigate the effectiveness of boundary layer separators (BLS's) in reducing the fluctuating pressure loads produced by separated <span class="hlt">shock</span> <span class="hlt">wave</span> turbulent boundary layer interactions. Measurements have been made under unswept and swept <span class="hlt">compression</span> corner interactions in a Mach 5 flow. BLS's fix the separation location and eliminate the large-amplitude, low-frequency fluctuating pressure loads upstream of the <span class="hlt">compression</span> corners. The loads on the unswept <span class="hlt">compression</span> corner face are reduced by as much as 59%. The BLS's also shift the mean pressure distribution on the unswept corner face in the streamwise direction. Results show that the loads on the corner face vary with the BLS height and the distance between the BLS and the <span class="hlt">compression</span> corner. Suggestions for the optimum placement and the use of the BLS's are also made.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22227876','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22227876"><span id="translatedtitle">Oblique ion acoustic <span class="hlt">shock</span> <span class="hlt">waves</span> in a magnetized plasma</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Shahmansouri, M.; Mamun, A. A.</p> <p>2013-08-15</p> <p>Ion acoustic (IA) <span class="hlt">shock</span> <span class="hlt">waves</span> are studied in a magnetized plasma consisting of a cold viscous ion fluid and Maxwellian electrons. The Korteweg–de Vries–Burgers equation is derived by using the reductive perturbation method. It is shown that the combined effects of external magnetic field and obliqueness significantly modify the basic properties (viz., amplitude, width, speed, etc.) of the IA <span class="hlt">shock</span> <span class="hlt">waves</span>. It is observed that the ion-viscosity is a source of dissipation, and is responsible for the formation of IA <span class="hlt">shock</span> structures. The implications of our results in some space and laboratory plasma situations are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EUCAS...7..437G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EUCAS...7..437G"><span id="translatedtitle">A new configuration of irregular reflection of <span class="hlt">shock</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gvozdeva, L. G.; Gavrenkov, S. A.</p> <p>2015-06-01</p> <p>A new configuration of <span class="hlt">shock</span> <span class="hlt">waves</span> has been found in the reflection of <span class="hlt">shock</span> <span class="hlt">waves</span> in a stationary supersonic gas flow in addition to the wellknown regular and Mach reflections. This new three-<span class="hlt">shock</span> configuration occurs with a negative angle of reflection and Mach numbers greater than 3 and an adiabatic index smaller than 1.4. It has been shown that this new configuration is unstable and leads to a radical change of the total flow pattern. The emergence of this new kind of instability can negatively affect operation of aircraft and rocket engines due to the failure of the flow to be as conventionally predicted.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4530210','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4530210"><span id="translatedtitle">Fractionated Repetitive Extracorporeal <span class="hlt">Shock</span> <span class="hlt">Wave</span> Therapy: A New Standard in <span class="hlt">Shock</span> <span class="hlt">Wave</span> Therapy?</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kisch, Tobias; Sorg, Heiko; Forstmeier, Vinzent; Mailaender, Peter; Kraemer, Robert</p> <p>2015-01-01</p> <p>Background. ESWT has proven clinical benefit in dermatology and plastic surgery. It promotes wound healing and improves tissue regeneration, connective tissue disorders, and inflammatory skin diseases. However, a single treatment session or long intervals between sessions may reduce the therapeutic effect. The present study investigated the effects of fractionated repetitive treatment in skin microcirculation. Methods. 32 rats were randomly assigned to two groups and received either fractionated repetitive high-energy ESWT every ten minutes or placebo <span class="hlt">shock</span> <span class="hlt">wave</span> treatment, applied to the dorsal lower leg. Microcirculatory effects were continuously assessed by combined laser Doppler imaging and photospectrometry. Results. In experimental group, cutaneous tissue oxygen saturation was increased 1 minute after the first application and until the end of the measuring period at 80 minutes after the second treatment (P < 0.05). The third ESWT application boosted the effect to its highest extent. Cutaneous capillary blood flow showed a significant increase after the second application which was sustained for 20 minutes after the third application (P < 0.05). Placebo group showed no statistically significant differences. Conclusions. Fractionated repetitive extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> therapy (frESWT) boosts and prolongs the effects on cutaneous hemodynamics. The results indicate that frESWT may provide greater benefits in the treatment of distinct soft tissue disorders compared with single-session ESWT. PMID:26273619</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JOM....65b.185A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JOM....65b.185A"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">Waves</span> Impacting Composite Material Plates: The Mutual Interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Andreopoulos, Yiannis</p> <p>2013-02-01</p> <p>High-performance, fiber-reinforced polymer composites have been extensively used in structural applications in the last 30 years because of their light weight combined with high specific stiffness and strength at a rather low cost. The automotive industry has adopted these materials in new designs of lightweight vehicles. The mechanical response and characterization of such materials under transient dynamic loading caused with <span class="hlt">shock</span> impact induced by blast is not well understood. Air blast is associated with a fast traveling <span class="hlt">shock</span> front with high pressure across followed by a decrease in pressure behind due to expansion <span class="hlt">waves</span>. The time scales associated with the <span class="hlt">shock</span> front are typically 103 faster than those involved in the expansion <span class="hlt">waves</span>. Impingement of blast <span class="hlt">waves</span> on structures can cause a reflection of the <span class="hlt">wave</span> off the surface of the structure followed by a substantial transient aerodynamic load, which can cause significant deformation and damage of the structure. These can alter the overpressure, which is built behind the reflected <span class="hlt">shock</span>. In addition, a complex aeroelastic interaction between the blast <span class="hlt">wave</span> and the structure develops that can induce reverberation within an enclosure, which can cause substantial overpressure through multiple reflections of the <span class="hlt">wave</span>. Numerical simulations of such interactions are quite challenging. They usually require coupled solvers for the flow and the structure. The present contribution provides a physics-based analysis of the phenomena involved, a critical review of existing computational techniques together with some recent results involving face-on impact of <span class="hlt">shock</span> <span class="hlt">waves</span> on thin composite plates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012pbdm.book..403L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012pbdm.book..403L"><span id="translatedtitle">Generation of Focused <span class="hlt">Shock</span> <span class="hlt">Waves</span> in Water for Biomedical Applications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lukeš, Petr; Šunka, Pavel; Hoffer, Petr; Stelmashuk, Vitaliy; Beneš, Jiří; Poučková, Pavla; Zadinová, Marie; Zeman, Jan</p> <p></p> <p>The physical characteristics of focused two-successive (tandem) <span class="hlt">shock</span> <span class="hlt">waves</span> (FTSW) in water and their biological effects are presented. FTSW were ­generated by underwater multichannel electrical discharges in a highly conductive saline solution using two porous ceramic-coated cylindrical electrodes of different diameter and surface area. The primary cylindrical pressure <span class="hlt">wave</span> generated at each composite electrode was focused by a metallic parabolic reflector to a common focal point to form two strong <span class="hlt">shock</span> <span class="hlt">waves</span> with a variable time delay between the <span class="hlt">waves</span>. The pressure field and interaction between the first and the second <span class="hlt">shock</span> <span class="hlt">waves</span> at the focus were investigated using schlieren photography and polyvinylidene fluoride (PVDF) <span class="hlt">shock</span> gauge sensors. The largest interaction was obtained for a time delay of 8-15 μs between the <span class="hlt">waves</span>, producing an amplitude of the negative pressure phase of the second <span class="hlt">shock</span> <span class="hlt">wave</span> down to -80 MPa and a large number of cavitations at the focus. The biological effects of FTSW were demonstrated in vitro on damage to B16 melanoma cells, in vivo on targeted lesions in the thigh muscles of rabbits and on the growth delay of sarcoma tumors in Lewis rats treated in vivo by FTSW, compared to untreated controls.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFD.G5001Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFD.G5001Q"><span id="translatedtitle">Optimization on the focusing of multiple <span class="hlt">shock</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Qiu, Shi; Eliasson, Veronica</p> <p>2016-11-01</p> <p>Focusing of multiple <span class="hlt">shock</span> <span class="hlt">waves</span> can lead to extreme thermodynamic conditions, which are desired for applications like <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy and inertial confinement fusion. To study <span class="hlt">shock</span> focusing effects, multiple energy sources have been placed in a circular pattern around an intended target, while the distance between each source and the target is fixed. All the sources are set to release the same amount of energy at the same time in order to create multiple identical <span class="hlt">shock</span> <span class="hlt">waves</span>. The object is to optimize the thermodynamic conditions at the target by rearranging the initial placement of each source. However, dealing with this optimization problem can be challenging due to the high computational cost introduced by solving the Euler equations. To avoid this issue, both numerical and analytical methods have been applied to handle <span class="hlt">shock</span> focusing more efficiently. A numerical method, an approximate theory named Geometrical <span class="hlt">Shock</span> Dynamics (GSD), has been utilized to describe the motion of <span class="hlt">shock</span>. Using an analytical method, a transition curve between regular and irregular reflection has been employed to predict <span class="hlt">shock</span> interactions. Results show that computational cost can be reduced dramatically by combining GSD and a transition curve. In addition, optimization results based on varying initial setups is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ShWav..26..851G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ShWav..26..851G"><span id="translatedtitle">Explosive-driven <span class="hlt">shock</span> <span class="hlt">wave</span> and vortex ring interaction with a propane flame</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Giannuzzi, P. M.; Hargather, M. J.; Doig, G. C.</p> <p>2016-11-01</p> <p>Experiments were performed to analyze the interaction of an explosively driven <span class="hlt">shock</span> <span class="hlt">wave</span> and a propane flame. A 30 g explosive charge was detonated at one end of a 3-m-long, 0.6-m-diameter <span class="hlt">shock</span> tube to produce a <span class="hlt">shock</span> <span class="hlt">wave</span> which propagated into the atmosphere. A propane flame source was positioned at various locations outside of the <span class="hlt">shock</span> tube to investigate the effect of different strength <span class="hlt">shock</span> <span class="hlt">waves</span>. High-speed retroreflective shadowgraph imaging visualized the <span class="hlt">shock</span> <span class="hlt">wave</span> motion and flame response, while a synchronized color camera imaged the flame directly. The explosively driven <span class="hlt">shock</span> tube was shown to produce a repeatable <span class="hlt">shock</span> <span class="hlt">wave</span> and vortex ring. Digital streak images show the <span class="hlt">shock</span> <span class="hlt">wave</span> and vortex ring propagation and expansion. The shadowgrams show that the <span class="hlt">shock</span> <span class="hlt">wave</span> extinguishes the propane flame by pushing it off of the fuel source. Even a weak <span class="hlt">shock</span> <span class="hlt">wave</span> was found to be capable of extinguishing the flame.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AIPC..706.1203T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AIPC..706.1203T"><span id="translatedtitle">Development of an Explosively Driven Sustained <span class="hlt">Shock</span> Generator for <span class="hlt">Shock</span> <span class="hlt">Wave</span> Studies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Taylor, P.; Cook, I. T.; Salisbury, D. A.</p> <p>2004-07-01</p> <p>Investigation of explosive initiation phenomena close to the initiation threshold with explosively driven <span class="hlt">shock</span> <span class="hlt">waves</span> is difficult due to the attenuative nature of the pressure input. The design and experimental testing of a sustained <span class="hlt">shock</span> <span class="hlt">wave</span> generator based on an explosive plane <span class="hlt">wave</span> lens and impedance mismatched low density foam and high impedance layers is described. Calibration experiments to develop a 1-D calculational model for the plane <span class="hlt">wave</span> lens and booster charge were performed. A calculational study was undertaken to determine the sensitivity of the output pulse to plate and foam thicknesses and foam density. A geometry which generates a 24kb almost flat topped <span class="hlt">shock</span> <span class="hlt">wave</span> with a duration of over 4μs into the HMX based plastic explosive EDC37 was defined and tested. Experimental <span class="hlt">shock</span> profile data is compared with pre-shot predictions from the PETRA Eulerian hydrocode incorporating a "snowplough" or simple locking model for the foam. A reasonable match to the observed magnitude and profile of the initial <span class="hlt">shock</span> is achieved, although the timing of subsequent <span class="hlt">shock</span> <span class="hlt">waves</span> is less well matched.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ShWav..26..709S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ShWav..26..709S"><span id="translatedtitle">Growth and decay of weak <span class="hlt">shock</span> <span class="hlt">waves</span> in magnetogasdynamics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Singh, L. P.; Singh, D. B.; Ram, S. D.</p> <p>2016-11-01</p> <p>The purpose of the present study is to investigate the problem of the propagation of weak <span class="hlt">shock</span> <span class="hlt">waves</span> in an inviscid, electrically conducting fluid under the influence of a magnetic field. The analysis assumes the following two cases: (1) a planar flow with a uniform transverse magnetic field and (2) cylindrically symmetric flow with a uniform axial or varying azimuthal magnetic field. A system of two coupled nonlinear transport equations, governing the strength of a <span class="hlt">shock</span> <span class="hlt">wave</span> and the first-order discontinuity induced behind it, are derived that admit a solution that agrees with the classical decay laws for a weak <span class="hlt">shock</span>. An analytic expression for the determination of the <span class="hlt">shock</span> formation distance is obtained. How the magnetic field strength, whether axial or azimuthal, influences the <span class="hlt">shock</span> formation is also assessed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19720035837&hterms=effect+temperature+gas+absorption&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Deffect%2Btemperature%2Bgas%2Babsorption','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19720035837&hterms=effect+temperature+gas+absorption&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Deffect%2Btemperature%2Bgas%2Babsorption"><span id="translatedtitle">Radiative transfer effects on reflected <span class="hlt">shock</span> <span class="hlt">waves</span>. II - Absorbing gas.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Su, F. Y.; Olfe, D. B.</p> <p>1972-01-01</p> <p>Radiative cooling effects behind a reflected <span class="hlt">shock</span> <span class="hlt">wave</span> are calculated for an absorbing-emitting gas by means of an expansion procedure in the small density ratio across the <span class="hlt">shock</span> front. For a gray gas <span class="hlt">shock</span> layer with an optical thickness of order unity or less the absorption integral is simplified by use of the local temperature approximation, whereas for larger optical thicknesses a Rosseland diffusion type of solution is matched with the local temperature approximation solution. The calculations show that the <span class="hlt">shock</span> <span class="hlt">wave</span> will attenuate at first and then accelerate to a constant velocity. Under appropriate conditions the gas enthalpy near the wall may increase at intermediate times before ultimately decreasing to zero. A two-band absorption model yields end-wall radiant-heat fluxes which agree well with available <span class="hlt">shock</span>-tube measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPC.1786l0001R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1786l0001R"><span id="translatedtitle">Plane <span class="hlt">shock</span> <span class="hlt">wave</span> structure in a dilute granular gas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Reddy, M. H. Lakshminarayana; Alam, Meheboob</p> <p>2016-11-01</p> <p>We analyse the early time evolution of the Riemann problem of planar <span class="hlt">shock</span> <span class="hlt">wave</span> structures for a dilute granular gas by solving Navier-Stokes equations numerically. The one-dimensional reduced Navier-Stokes equations for plane <span class="hlt">shock</span> <span class="hlt">wave</span> problem are solved numerically using a relaxation-type numerical scheme. The results on the <span class="hlt">shock</span> structures in granular gases are presented for different Mach numbers and restitution coefficients. Based on our analysis on early time <span class="hlt">shock</span> dynamics we conclude that the density and temperature profiles are "asymmetric"; the density maximum and the temperature maximum occur within the <span class="hlt">shock</span> layer; the absolute magnitudes of longitudinal stress and heat flux which are initially zero at both end states attain maxima in a very short time and thereafter decrease with time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009APS..DPPNO6002M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009APS..DPPNO6002M"><span id="translatedtitle">Laboratory observations of self-excited dust acoustic <span class="hlt">shock</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Merlino, Robert L.; Heinrich, Jonathon R.; Kim, Su-Hyun</p> <p>2009-11-01</p> <p>Dust acoustic <span class="hlt">waves</span> have been discussed in connection with dust density structures in Saturn's rings and the Earth's mesosphere, and as a possible mechanism for triggering condensation of small grains in dust molecular clouds. Dust acoustic <span class="hlt">waves</span> are a ubiquitous occurrence in laboratory dusty plasmas formed in glow discharges. We report observations of repeated, self-excited dust acoustic <span class="hlt">shock</span> <span class="hlt">waves</span> in a dc glow discharge dusty plasma using high-speed video imaging. Two major observations will be presented: (1) The self-steepening of a nonlinear dust acoustic <span class="hlt">wave</span> into a saw-tooth <span class="hlt">wave</span> with sharp gradient in dust density, very similar to those found in numerical solutions [1] of the fully nonlinear fluid equations for nondispersive dust acoustic <span class="hlt">waves</span>, and (2) the collision and confluence of two dust acoustic <span class="hlt">shock</span> <span class="hlt">waves</span>. [4pt] [1] B. Eliasson and P. K. Shukla, Phys. Rev. E 69, 067401 (2004).</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://adsabs.harvard.edu/abs/2012PhRvL.108b5002S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012PhRvL.108b5002S"><span id="translatedtitle">Dispersive Nature of High Mach Number Collisionless Plasma <span class="hlt">Shocks</span>: Poynting Flux of Oblique Whistler <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sundkvist, David; Krasnoselskikh, V.; Bale, S. D.; Schwartz, S. J.; Soucek, J.; Mozer, F.</p> <p>2012-01-01</p> <p>Whistler <span class="hlt">wave</span> trains are observed in the foot region of high Mach number quasiperpendicular <span class="hlt">shocks</span>. The <span class="hlt">waves</span> are oblique with respect to the ambient magnetic field as well as the <span class="hlt">shock</span> normal. The Poynting flux of the <span class="hlt">waves</span> is directed upstream in the <span class="hlt">shock</span> normal frame starting from the ramp of the <span class="hlt">shock</span>. This suggests that the <span class="hlt">waves</span> are an integral part of the <span class="hlt">shock</span> structure with the dispersive <span class="hlt">shock</span> as the source of the <span class="hlt">waves</span>. These observations lead to the conclusion that the <span class="hlt">shock</span> ramp structure of supercritical high Mach number <span class="hlt">shocks</span> is formed as a balance of dispersion and nonlinearity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014APS..DFDD20001R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APS..DFDD20001R"><span id="translatedtitle">Schlieren imaging of <span class="hlt">shock</span> <span class="hlt">waves</span> radiated by a trumpet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rendon, Pablo L.; Velasco-Segura, Roberto; Echeverria, Carlos; Porta, David; Vazquez, Teo; Perez-Lopez, Antonio; Stern, Catalina</p> <p>2014-11-01</p> <p>The flaring bell section of modern trumpets is known to be critical in determining a wide variety of properties associated with the sound radiated by these instruments. We are particularly interested in the shape of the radiated wavefront, which clearly depends on the bell profile. A horn loudspeaker is used to drive high-intensity sound at different frequencies through a B-flat concert trumpet. The sound intensity is high enough to produce <span class="hlt">shock</span> <span class="hlt">waves</span> inside the instrument resonator, and the radiated <span class="hlt">shocks</span> are then visualised using Schlieren imaging. Through these images we are able to study the geometry of the <span class="hlt">shock</span> <span class="hlt">waves</span> radiated by the instrument bell, and also to calculate their propagation speed. The results show that propagation outside the bell is very nearly spherical, and that, as expected, the frequency of the driving signal affects the point at which the <span class="hlt">shock</span> <span class="hlt">waves</span> separate from the instrument. We acknowledge financial support from PAPIIT IN109214 and PAPIIT IN117712.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015shw2.conf..855Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015shw2.conf..855Y"><span id="translatedtitle">Development of a Novel <span class="hlt">Shock</span> <span class="hlt">Wave</span> Catheter Ablation System</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yamamoto, H.; Hasebe, Yuhi; Kondo, Masateru; Fukuda, Koji; Takayama, Kazuyoshi; Shimokawa, Hiroaki</p> <p></p> <p>Although radio-frequency catheter ablation (RFCA) is quite effective for the treatment tachyarrhythmias, it possesses two fundamental limitations, including limited efficacy for the treatment of ventricular tachyarrhythmias of epicardial origin and the risk of thromboembolism. Consequently, new method is required, which can eradicate arrhythmia source in deep part of cardiac muscle without heating. On the other hand, for a medical application of <span class="hlt">shock</span> <span class="hlt">waves</span>, extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripter (ESWL) has been established [1]. It was demonstrated that the underwater <span class="hlt">shock</span> focusing is one of most efficient method to generate a controlled high pressure in a small region [2]. In order to overcome limitations of existing methods, we aimed to develop a new catheter ablation system with underwater <span class="hlt">shock</span> <span class="hlt">waves</span> that can treat myocardium at arbitrary depth without causing heat.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005shwa.book..725N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005shwa.book..725N"><span id="translatedtitle">A novel method to transform prokaryotic cells using <span class="hlt">shock</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nataraja, K. N.; Udayakumar, M.; Jagadeesh, G.</p> <p></p> <p>The transgenic approach that is being used to study gene function or to improve the efficiency of crop plants/organisms involves transformation of a wide range of cells, tissues, and organisms with nucleic acid. In this study we report a new micro- <span class="hlt">shock</span> assisted prokaryotic cell transformation technique. An underwater electric discharge based <span class="hlt">shock</span> <span class="hlt">wave</span> generator (25 kV; 150 m A; high voltage capacitor) has been designed and fabricated to carry out the prokaryotic cell transformation experiments. Test tubes with bacterial cell suspension with appropriate plasmid DNA, immersed in water are exposed to <span class="hlt">shock</span> <span class="hlt">wave</span> loading (typical overpressure 130 bar). The transformation efficiency of samples of the prokaryotic cells exposed to <span class="hlt">shock</span> <span class="hlt">waves</span> is very high compared to conventional methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940007618','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940007618"><span id="translatedtitle">Initiating solar system formation through stellar <span class="hlt">shock</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Boss, A. P.; Myhill, E. A.</p> <p>1993-01-01</p> <p>Isotopic anomalies in presolar grains and other meteoritical components require nucleosynthesis in stellar interiors, condensation into dust grains in stellar envelopes, transport of the grains through the interstellar medium by stellar outflows, and finally injection of the grains into the presolar nebula. The proximity of the presolar cloud to these energetic stellar events suggests that a <span class="hlt">shock</span> <span class="hlt">wave</span> from a stellar outflow might have initiated the collapse of an otherwise stable presolar cloud. We have begun to study the interactions of stellar <span class="hlt">shock</span> <span class="hlt">waves</span> with thermally supported, dense molecular cloud cores, using a three spatial dimension (3D) radiative hydrodynamics code. Supernova <span class="hlt">shock</span> <span class="hlt">waves</span> have been shown by others to destroy quiescent clouds, so we are trying to determine if the much smaller <span class="hlt">shock</span> speeds found in, e.g., asymptotic giant branch (AGB) star winds, are strong enough to initiate collapse in an otherwise stable, rotating, solar-mass cloud core, without leading to destruction of the cloud.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22252090','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22252090"><span id="translatedtitle">Traveling <span class="hlt">waves</span> in Hall-magnetohydrodynamics and the ion-acoustic <span class="hlt">shock</span> structure</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hagstrom, George I.; Hameiri, Eliezer</p> <p>2014-02-15</p> <p>Hall-magnetohydrodynamics (HMHD) is a mixed hyperbolic-parabolic partial differential equation that describes the dynamics of an ideal two fluid plasma with massless electrons. We study the only <span class="hlt">shock</span> <span class="hlt">wave</span> family that exists in this system (the other discontinuities being contact discontinuities and not <span class="hlt">shocks</span>). We study planar traveling <span class="hlt">wave</span> solutions and we find solutions with discontinuities in the hydrodynamic variables, which arise due to the presence of real characteristics in Hall-MHD. We introduce a small viscosity into the equations and use the method of matched asymptotic expansions to show that solutions with a discontinuity satisfying the Rankine-Hugoniot conditions and also an entropy condition have continuous <span class="hlt">shock</span> structures. The lowest order inner equations reduce to the <span class="hlt">compressible</span> Navier-Stokes equations, plus an equation which implies the constancy of the magnetic field inside the <span class="hlt">shock</span> structure. We are able to show that the current is discontinuous across the <span class="hlt">shock</span>, even as the magnetic field is continuous, and that the lowest order outer equations, which are the equations for traveling <span class="hlt">waves</span> in inviscid Hall-MHD, are exactly integrable. We show that the inner and outer solutions match, which allows us to construct a family of uniformly valid continuous composite solutions that become discontinuous when the diffusivity vanishes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5462554','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5462554"><span id="translatedtitle">Attenuation of <span class="hlt">shock</span> <span class="hlt">waves</span> in copper and stainless steel</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Harvey, W.B.</p> <p>1986-06-01</p> <p>By using <span class="hlt">shock</span> pins, data were gathered on the trajectories of <span class="hlt">shock</span> <span class="hlt">waves</span> in stainless steel (SS-304L) and oxygen-free-high-conductivity copper (OFHC-Cu). <span class="hlt">Shock</span> pressures were generated in these materials by impacting the appropriate target with thin (approx.1.5 mm) flying plates. The flying plates in these experiments were accelerated to high velocities (approx.4 km/s) by high explosives. Six experiments were conducted, three using SS-304L as the target material and three experiments using OFHC-Cu as the target material. Peak <span class="hlt">shock</span> pressures generated in the steel experiments were approximately 109, 130, and 147 GPa and in the copper experiments, the peak <span class="hlt">shock</span> pressures were approximately 111, 132, and 143 GPa. In each experiment, an attenuation of the <span class="hlt">shock</span> <span class="hlt">wave</span> by a following release <span class="hlt">wave</span> was clearly observed. An extensive effort using two characteristic codes (described in this work) to theoretically calculate the attenuation of the <span class="hlt">shock</span> <span class="hlt">waves</span> was made. The efficacy of several different constitutive equations to successfully model the experiments was studied by comparing the calculated <span class="hlt">shock</span> trajectories to the experimental data. Based on such comparisons, the conclusion can be drawn that OFHC-Cu enters a melt phase at about 130 GPa on the principal Hugoniot. There was no sign of phase changes in the stainless-steel experiments. In order to match the observed attenuation of the <span class="hlt">shock</span> <span class="hlt">waves</span> in the SS-304L experiments, it was necessary to include strength effects in the calculations. It was found that the values for the parameters in the strength equations were dependent on the equation of state used in the modeling of the experiments. 66 refs., 194 figs., 77 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19750050112&hterms=anatomy+anatomy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Danatomy%2Banatomy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19750050112&hterms=anatomy+anatomy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Danatomy%2Banatomy"><span id="translatedtitle">The anatomy of floating <span class="hlt">shock</span> fitting. [<span class="hlt">shock</span> <span class="hlt">waves</span> computation for flow field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Salas, M. D.</p> <p>1975-01-01</p> <p>The floating <span class="hlt">shock</span> fitting technique is examined. Second-order difference formulas are developed for the computation of discontinuities. A procedure is developed to compute mesh points that are crossed by discontinuities. The technique is applied to the calculation of internal two-dimensional flows with arbitrary number of <span class="hlt">shock</span> <span class="hlt">waves</span> and contact surfaces. A new procedure, based on the coalescence of characteristics, is developed to detect the formation of <span class="hlt">shock</span> <span class="hlt">waves</span>. Results are presented to validate and demonstrate the versatility of the technique.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013APS..SHK.F1019F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013APS..SHK.F1019F"><span id="translatedtitle">Recording of Phase Transition in Tin in <span class="hlt">Shock</span> and Release <span class="hlt">Waves</span> Using Laser Interferometer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Finyushin, Stanislav; Fedorov, Alexey; Mikhailov, Anatoliy; Nazarov, Dmitriy; Chudakov, Evgeniy; Kalashnikov, Denis; Trunin, Ivan; Tereshkina, Irina</p> <p>2013-06-01</p> <p>In this paper the authors present results of experiments, concerning the recording of free surface velocity and particle velocity of tin/LiF window interface of tin sample at the dynamic pressure in the range 10 to 70 GPa, using laser interferometry methods Fabry-Perot and PDV. The features of recorded velocity histories interpreted the polymorphous transitions (the direct β - γ phase transition, the reverse γ - β phase transition) and some points on tin melting curve. The tin samples were loaded by impactor accelerated by explosion products of HE cartridge (the <span class="hlt">wave</span> with the rectangular profile) or by direct detonation <span class="hlt">wave</span> of HE layer (the <span class="hlt">wave</span> with the decaying profile). With the help of PDV method, velocity of particles cloud was recorded with the free surface velocity at the moment when the <span class="hlt">shock</span> <span class="hlt">wave</span> front arrived to the tin free surface with the pressure amplitude of P >= 19 GPa. This could is corresponded to appearing of the liquid-solid phase at the release <span class="hlt">wave</span>. The tin melting in the <span class="hlt">shock</span> <span class="hlt">wave</span> is recorded at the loading pressure of P >= 51 GPa. The pressure and temperature numerical simulations were performed for <span class="hlt">shock</span> <span class="hlt">compression</span> and the further releasing of tin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhRvE..92b3028N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvE..92b3028N"><span id="translatedtitle">Passage of a <span class="hlt">shock</span> <span class="hlt">wave</span> through inhomogeneous media and its impact on gas-bubble deformation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nowakowski, A. F.; Ballil, A.; Nicolleau, F. C. G. A.</p> <p>2015-08-01</p> <p>The paper investigates <span class="hlt">shock</span>-induced vortical flows within inhomogeneous media of nonuniform thermodynamic properties. Numerical simulations are performed using a Eulerian type mathematical model for <span class="hlt">compressible</span> multicomponent flow problems. The model, which accounts for pressure nonequilibrium and applies different equations of state for individual flow components, shows excellent capabilities for the resolution of interfaces separating <span class="hlt">compressible</span> fluids as well as for capturing the baroclinic source of vorticity generation. The developed finite volume Godunov type computational approach is equipped with an approximate Riemann solver for calculating fluxes and handles numerically diffused zones at flow component interfaces. The computations are performed for various initial conditions and are compared with available experimental data. The initial conditions promoting a <span class="hlt">shock</span>-bubble interaction process include weak to high planar <span class="hlt">shock</span> <span class="hlt">waves</span> with a Mach number ranging from 1.2 to 3 and isolated cylindrical bubble inhomogeneities of helium, argon, nitrogen, krypton, and sulphur hexafluoride. The numerical results reveal the characteristic features of the evolving flow topology. The impulsively generated flow perturbations are dominated by the reflection and refraction of the <span class="hlt">shock</span>, the <span class="hlt">compression</span>, and acceleration as well as the vorticity generation within the medium. The study is further extended to investigate the influence of the ratio of the heat capacities on the interface deformation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhDT........42L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhDT........42L"><span id="translatedtitle">Implications of heterogeneity in the <span class="hlt">shock</span> <span class="hlt">wave</span> propagation of dynamically <span class="hlt">shocked</span> materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>LaJeunesse, Jeff</p> <p></p> <p>The field of <span class="hlt">shock</span> physics as a whole has only recently begun to pay particular attention to modeling heterogeneous materials under <span class="hlt">shock</span> loading. These materials are important because of their practicality in terms of creating stronger, more <span class="hlt">shock</span> resistant materials. To understand why they absorb <span class="hlt">shock</span> impact energy better than homogeneous materials means that the small-scale processes that occur during the <span class="hlt">shock</span> loading of these heterogeneous materials needs to be understood. Recent computational experiments, called mesoscale simulations, have shown that explicitly incorporating small-scale heterogeneous features into hydrocode simulations allows the bulk <span class="hlt">shock</span> response of the heterogeneous material to be observed while not requiring the use of empirically determined constitutive equations. Including these features in simulations can offer insights into the irreversible mechanisms that dominate the propagation of <span class="hlt">shock</span> <span class="hlt">waves</span> in heterogeneous materials. Three cases where the mesoscale approach for modeling the dynamic <span class="hlt">shock</span> loading of heterogeneous materials are presented. These materials fall into three categories: granular - dry sand, granular with binder - concrete, and granular contained in a metal foam with a binder - granular explosive contained in an aluminum foam. The processes in which <span class="hlt">shock</span> <span class="hlt">waves</span> propagate through each material are addressed and relationships between the three materials are discussed. Particle velocity profiles for dry sand and concrete was obtained from Harvard University and Eglin Air Force Base, respectively. Mesoscale simulations using CTH are conducted for each type of heterogeneous material and the results are compared to the experimental data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19880009175','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19880009175"><span id="translatedtitle">Fluctuations and massive separation in three-dimensional <span class="hlt">shock-wave</span>/boundary-layer interactions</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.; Brown, J. D.; Brown, J. L.; Lockman, W. K.; Horstman, C. C.</p> <p>1988-01-01</p> <p><span class="hlt">Shock-wave</span> unsteadiness was observed in rapidly <span class="hlt">compressed</span> supersonic turbulent boundary layer flows with significant separation. A Mach 2.85 <span class="hlt">shock-wave</span>/turbulent boundary layer flow was set up over a series of cylinder-flare bodies in the High Reynolds Number Channel 1. The transition from fully attached to fully separated flow was studied using axisymmetric flares with increasing <span class="hlt">compression</span> angles. In the second phase, the 30 deg flare was inclined relative to the cylinder axis, so that the effect on a separated flow of increasing 3 dimensionality could be observed. Two 3-D separated cases are examined. A simple conditional sampling technique is applied to the data to group them according to an associated <span class="hlt">shock</span> position. Mean velocities and turbulent kinetic energies, computed from the conditionally samples data, are compared to those from the unsorted data and to computed values. Three basic questions were addressed: can conditional sampling be used to provide snapshots of the flow; are averaged turbulence quantities dominated by the bimodal nature of the interaction; and is the <span class="hlt">shock</span> unsteadiness really important to computational accuracy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21367305','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21367305"><span id="translatedtitle">Visualization of <span class="hlt">Shock</span> <span class="hlt">Wave</span> Driven by Millimeter <span class="hlt">Wave</span> Plasma in a Parabolic Thruster</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Yamaguchi, Toshikazu; Shimada, Yutaka; Shiraishi, Yuya; Shibata, Teppei; Komurasaki, Kimiya; Oda, Yasuhisa; Kajiwara, Ken; Takahashi, Koji; Kasugai, Atsushi; Sakamoto, Keishi; Arakawa, Yoshihiro</p> <p>2010-05-06</p> <p>By focusing a high-power millimeter <span class="hlt">wave</span> beam generated by a 170 GHz gyrotron, a breakdown occurred and a <span class="hlt">shock</span> <span class="hlt">wave</span> was driven by plasma heated by following microwave energy. The <span class="hlt">shock</span> <span class="hlt">wave</span> and the plasma around a focal point of a parabolic thruster were visualized by a shadowgraph method, and a transition of structures between the <span class="hlt">shock</span> <span class="hlt">wave</span> and the plasma was observed. There was a threshold local power density to make the transition, and the propagation velocity at the transition was around 800 m/s.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AIPC.1195.1395H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AIPC.1195.1395H"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">Compression</span> and Recovery of Microorganism-Loaded Broths and AN Emulsion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hazell, P. J.; Beveridge, C.; Groves, K.; Stennett, C.</p> <p>2009-12-01</p> <p>The microorganisms Escherichia coli, Enterococcus faecalis and Zygosaccharomyces bailii and an oil-based emulsion, have been subjected to <span class="hlt">shock</span> <span class="hlt">compression</span> using the flyer-plate technique to initial pressures of 0.8 GPa (in the suspension). In each experiment, a stainless steel capsule was used to contain the broths and allow for recovery without contamination. Where cavitation was mostly suppressed by virtue of simultaneous <span class="hlt">shock</span> and dynamic <span class="hlt">compression</span>, no kill was observed. By introducing an air gap behind the suspension, limited kill was measured in the yeast. Results also suggest that stable emulsification occurs in coarse oil-based emulsions that are subjected to <span class="hlt">shock</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009APS..SHK.C2005H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009APS..SHK.C2005H"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">compression</span> and recovery of microorganism-loaded broths and an emulsion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hazell, Paul; Beveridge, Cliff; Groves, Kathy</p> <p>2009-06-01</p> <p>The microorganisms Escherichia coli, Enterococcus feacalis and Zygosaccharomyces bailii and an oil-based emulsion, have been subjected to <span class="hlt">shock</span> <span class="hlt">compression</span> using the flyer-plate technique to initial pressures of 0.8 GPa (in the suspension). In each experiment, a stainless steel capsule was used to contain the broths and allow for recovery without contamination. Where cavitation was suppressed by virtue of simultaneous <span class="hlt">shock</span> and quasi-static <span class="hlt">compression</span>, no kill was observed. By introducing an air gap behind the suspension, limited kill was measured in the yeast. Results also suggest that emulsification occurs in oil-based emulsions that are subjected to <span class="hlt">shock</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JGRA..117.8223I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JGRA..117.8223I"><span id="translatedtitle">Hybrid simulation of the <span class="hlt">shock</span> <span class="hlt">wave</span> trailing the Moon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Israelevich, P.; Ofman, L.</p> <p>2012-08-01</p> <p>A standing <span class="hlt">shock</span> <span class="hlt">wave</span> behind the Moon was predicted by Michel (1967) but never observed nor simulated. We use 1D hybrid code in order to simulate the collapse of the plasma-free cavity behind the Moon and for the first time to model the formation of this <span class="hlt">shock</span>. Starting immediately downstream of the obstacle we consider the evolution of plasma expansion into the cavity in the frame of reference moving along with the solar wind. Well-known effects as electric charging of the cavity affecting the plasma flow and counterstreaming ion beams in the wake are reproduced. Near the apex of the inner Mach cone where the plasma flows from the opposite sides of the obstacle meet, a <span class="hlt">shock</span> <span class="hlt">wave</span> arises. We expect the <span class="hlt">shock</span> to be produced at periods of high electron temperature solar wind streams (Ti ≪ Te ˜ 100 eV). The <span class="hlt">shock</span> is produced by the interaction of oppositely directed proton beams in the plane containing solar wind velocity and interplanetary magnetic field vectors. In the direction across the magnetic field and the solar wind velocity, the <span class="hlt">shock</span> results from the interaction of the plasma flow with the region of the enhanced magnetic field inside the cavity that plays the role of the magnetic barrier. The appearance of the standing <span class="hlt">shock</span> <span class="hlt">wave</span> is expected at the distance of ˜7RM downstream of the Moon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140010226','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140010226"><span id="translatedtitle">Hybrid Simulation of the <span class="hlt">Shock</span> <span class="hlt">Wave</span> Trailing the Moon</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Israelevich, P.; Ofman, Leon</p> <p>2012-01-01</p> <p>A standing <span class="hlt">shock</span> <span class="hlt">wave</span> behind the Moon was predicted by Michel (1967) but never observed nor simulated. We use 1D hybrid code in order to simulate the collapse of the plasma-free cavity behind the Moon and for the first time to model the formation of this <span class="hlt">shock</span>. Starting immediately downstream of the obstacle we consider the evolution of plasma expansion into the cavity in the frame of reference moving along with the solar wind. Well-known effects as electric charging of the cavity affecting the plasma flow and counterstreaming ion beams in the wake are reproduced. Near the apex of the inner Mach cone where the plasma flows from the opposite sides of the obstacle meet, a <span class="hlt">shock</span> <span class="hlt">wave</span> arises. We expect the <span class="hlt">shock</span> to be produced at periods of high electron temperature solar wind streams (T(sub i) much less than T(sub e) approximately 100 eV). The <span class="hlt">shock</span> is produced by the interaction of oppositely directed proton beams in the plane containing solar wind velocity and interplanetary magnetic field vectors. In the direction across the magnetic field and the solar wind velocity, the <span class="hlt">shock</span> results from the interaction of the plasma flow with the region of the enhanced magnetic field inside the cavity that plays the role of the magnetic barrier. The appearance of the standing <span class="hlt">shock</span> <span class="hlt">wave</span> is expected at the distance of approximately 7R(sub M) downstream of the Moon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012epsc.conf...39I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012epsc.conf...39I"><span id="translatedtitle">Hybrid simulation of the <span class="hlt">shock</span> <span class="hlt">wave</span> formation behind the Moon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Israelevich, P.; Ofman, L.</p> <p>2012-09-01</p> <p>A standing <span class="hlt">shock</span> <span class="hlt">wave</span> behind the Moon was predicted by Michel (1967) but never observed nor simulated. We use 1D hybrid code in order to simulate the collapse of the plasma-free cavity behind the Moon and for the first time to model the formation of this <span class="hlt">shock</span>. Starting immediately downstream of the obstacle we consider the evolution of plasma expansion into the cavity in the frame of reference moving along with the solar wind. Wellknown effects as electric charging of the cavity affecting the plasma flow and counter streaming ion beams in the wake are reproduced. Near the apex of the inner Mach cone where the plasma flows from the opposite sides of the obstacle meet, a <span class="hlt">shock</span> <span class="hlt">wave</span> arises. The <span class="hlt">shock</span> is produced by the interaction of oppositely directed proton beams in the plane containing solar wind velocity and interplanetary magnetic field vectors. In the direction across the magnetic field and the solar wind velocity, the <span class="hlt">shock</span> results from the interaction of the plasma flow with the region of the enhanced magnetic field inside the cavity that plays the role of the magnetic barrier. Simulations with lower electron temperatures (Te~20eV) show weakened <span class="hlt">shock</span> formation behind the moon at much greater distances. The <span class="hlt">shock</span> disappears for typical solar wind conditions (Ti ~ Te) Therefore, in order to observe the trailing <span class="hlt">shock</span>, a satellite should have a trajectory passing very close to the wake axis during the period of hot solar wind streams. We expect the <span class="hlt">shock</span> to be produced at periods of high electron temperature solar wind streams (Ti<<Te~100eV). The appearance of the standing <span class="hlt">shock</span> <span class="hlt">wave</span> is expected at the distance of ~ 7RM downstream of the Moon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22370055','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22370055"><span id="translatedtitle">Radial distribution of <span class="hlt">compressive</span> <span class="hlt">waves</span> in the solar corona revealed by Akatsuki radio occultation observations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Miyamoto, Mayu; Imamura, Takeshi; Ando, Hiroki; Toda, Tomoaki; Nakamura, Masato; Tokumaru, Munetoshi; Shiota, Daikou; Isobe, Hiroaki; Asai, Ayumi; Häusler, Bernd; Pätzold, Martin; Nabatov, Alexander</p> <p>2014-12-10</p> <p>Radial variations of the amplitude and the energy flux of <span class="hlt">compressive</span> <span class="hlt">waves</span> in the solar corona were explored for the first time using a spacecraft radio occultation technique. By applying wavelet analysis to the frequency time series taken at heliocentric distances of 1.5-20.5 R{sub S} (solar radii), quasi-periodic density disturbances were detected at almost all distances. The period ranges from 100 to 2000 s. The amplitude of the fractional density fluctuation increases with distance and reaches ∼30% around 5 R{sub S} , implying that nonlinearity of the <span class="hlt">wave</span> field is potentially important. We further estimate the <span class="hlt">wave</span> energy flux on the assumption that the observed periodical fluctuations are manifestations of acoustic <span class="hlt">waves</span>. The energy flux increases with distance below ∼6 R{sub S} and seems to saturate above this height, suggesting that the acoustic <span class="hlt">waves</span> do not propagate from the low corona but are generated in the extended corona, probably through nonlinear dissipation of Alfvén <span class="hlt">waves</span>. The <span class="hlt">compressive</span> <span class="hlt">waves</span> should eventually dissipate through <span class="hlt">shock</span> generation to heat the corona.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007PhyU...50..333F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007PhyU...50..333F"><span id="translatedtitle">ORAL ISSUE OF THE JOURNAL "USPEKHI FIZICHESKIKH NAUK": Intense <span class="hlt">shock</span> <span class="hlt">waves</span> and extreme states of matter</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fortov, Vladimir E.</p> <p>2007-04-01</p> <p>The physical properties of hot dense matter over a broad domain of the phase diagram are of immediate interest in astrophysics, planetary physics, power engineering, controlled thermonuclear fusion, impulse technologies, enginery, and several special applications. The use of intense <span class="hlt">shock</span> <span class="hlt">waves</span> in dynamic physics and high-pressure chemistry has made the exotic high-energy-density states of matter a subject of laboratory experiments and enabled advancing by many orders of magnitude along the pressure scale to range into the megabars and even gigabars. The present report reviews the latest experimental research involving <span class="hlt">shock</span> <span class="hlt">waves</span> in nonideal plasmas under conditions of strong collective interparticle interaction. The results of investigations into the thermodynamic, transport, and optical properties of strongly <span class="hlt">compressed</span> hot matter, as well as into its composition and conductivity, are discussed. Experimental techniques for high energy density cumulation, the drivers of intense <span class="hlt">shock</span> <span class="hlt">waves</span>, and methods for the fast diagnostics of high-energy plasma are considered. Also discussed are <span class="hlt">compression</span>-stimulated physical effects: pressure-induced ionization, plasma phase transitions, the deformation of bound states, plasma blooming ('transparentization' of plasma), etc. Suggestions for future research are put forward.</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://adsabs.harvard.edu/abs/2015APS..DPPUP2096N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DPPUP2096N"><span id="translatedtitle">Collisionless <span class="hlt">shock</span> <span class="hlt">waves</span> mediated by Weibel Instability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Naseri, Neda; Ruan, Panpan; Zhang, Xi; Khudik, Vladimir; Shvets, Gennady</p> <p>2015-11-01</p> <p>Relativistic collisionless <span class="hlt">shocks</span> are common events in astrophysical environments. They are thought to be responsible for generating ultra-high energy particles via the Fermi acceleration mechanism. It has been conjectured that the formation of collisionless <span class="hlt">shocks</span> is mediated by the Weibel instability that takes place when two initially cold, unmagnetized plasma shells counter-propagate into each other with relativistic drift velocities. Using a PIC code, VLPL, which is modified to suppress numerical Cherenkov instabilities, we study the <span class="hlt">shock</span> formation and evolution for asymmetric colliding shells with different densities in their own proper reference frame. Plasma instabilities in the region between the <span class="hlt">shock</span> and the precursor are also investigated using a moving-window simulation that advances the computational domain at the <span class="hlt">shock</span>'s speed. This method helps both to save computation time and avoid severe numerical Cherenkov instabilities, and it allows us to study the <span class="hlt">shock</span> evolution in a longer time period. Project is supported by US DOE grants DE-FG02-04ER41321 and DE-FG02-07ER54945.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011APS..SHK.F1099B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011APS..SHK.F1099B"><span id="translatedtitle">Rock-forming Minerals Transformations in Conditions of Stepwise <span class="hlt">Shock</span> <span class="hlt">Compression</span> of Qwartz-feldspar-biotite-garnet Schist from Southern Ural</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Belyatinskaya, Irina; Feldman, Vilen; Milyavskiy, Vladimir; Borodina, Tatiana</p> <p>2011-06-01</p> <p>Samples for experiments with use of recovery assemblies of planar geometry have been taken from Southern Ural (Russia). The maximal <span class="hlt">shock</span> pressures in the samples were attained upon a few reverberations of the <span class="hlt">waves</span> between the walls of the recovery ampoule (stepwise <span class="hlt">shock</span> <span class="hlt">compression</span>) and were equal 26, 36 and 52 GPa. <span class="hlt">Shock</span>-metamorphic transformations of rock-forming minerals (garnet, biotite, quartz, potash feldspar and plagioclase) have been studied with the use of optical and scanning electron microscopy (SEM) methods, microprobe analysis, and X-ray phase analysis (XPA). The strongest transformations (mechanical and chemical) were observed in potash feldspar and plagioclase. These minerals undergo strong amorphization at 26 GPa already. Plagioclase chemical transformations are equal to results of earlier stepwise <span class="hlt">shock</span> <span class="hlt">compression</span> experiments. Biotite also reveals strong mechanical (kink-bands, partial melting) and chemical (for melted biotites only) transformations. Garnet reveals mechanical transformations only. The work was supported by RFBR (09-05-00211).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860026497&hterms=Sound+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DSound%2Bwaves','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860026497&hterms=Sound+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DSound%2Bwaves"><span id="translatedtitle">Cylindrical sound <span class="hlt">wave</span> generated by <span class="hlt">shock</span>-vortex interaction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ribner, H. S.</p> <p>1985-01-01</p> <p>The passage of a columnar vortex broadside through a <span class="hlt">shock</span> is investigated. This has been suggested as a crude, but deterministic, model of the generation of '<span class="hlt">shock</span> noise' by the turbulence in supersonic jets. The vortex is decomposed by Fourier transform into plane sinusoidal shear <span class="hlt">waves</span> disposed with radial symmetry. The plane sound <span class="hlt">waves</span> produced by each shear <span class="hlt">wave/shock</span> interaction are recombined in the Fourier integral. The <span class="hlt">waves</span> possess an envelope that is essentially a growing cylindrical sound <span class="hlt">wave</span> centered at the transmitted vortex. The pressure jump across the nominal radius R = ct attenuates with time as 1/(square root of R) and varies around the arc in an antisymmetric fashion resembling a quadrupole field. Very good agreement, except near the <span class="hlt">shock</span>, is found with the antisymmetric component of reported interferometric measurements in a <span class="hlt">shock</span> tube. Beyond the front r approximately equals R is a precursor of opposite sign, that decays like 1/R, generated by the 1/r potential flow around the vortex core. The present work is essentially an extension and update of an early approximate study at M = 1.25. It covers the range (R/core radius) = 10, 100, 1000, and 10,000 for M = 1.25 and (in part) for M = 1.29 and, for fixed (R/core radius) = 1000, the range M = 1.01 to infinity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003ASAJ..114.2463W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003ASAJ..114.2463W"><span id="translatedtitle">Treatment of nonunions of long bone fractures with <span class="hlt">shock</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Ching-Jen</p> <p>2003-10-01</p> <p>A prospective clinical study investigated the effectiveness of <span class="hlt">shock</span> <span class="hlt">waves</span> in the treatment of 72 patients with 72 nonunions of long bone fractures (41 femurs, 19 tibias, 7 humeri, 1 radius, 3 ulnas and 1 metatarsal). The doses of <span class="hlt">shock</span> <span class="hlt">waves</span> were 6000 impulses at 28 kV for the femur and tibia, 3000 impulses at 28 kV for the humerus, 2000 impulses at 24 kV for the radius and ulna, and 1000 impulses at 20 kV for the metatarsal. The results of treatment were assessed clinically, and fracture healing was assessed with plain x-rays and tomography. The rate of bony union was 40% at 3 months, 60.9% at 6 months and 80% at 12 months followup. <span class="hlt">Shock</span> <span class="hlt">wave</span> treatment was most successful in hypertrophic nonunions and nonunions with a defect and was least effective in atrophic nonunions. There were no systemic complications or device-related problems. Local complications included petechiae and hematoma formation that resolved spontaneously. In the author's experience, the results of the <span class="hlt">shock</span> <span class="hlt">wave</span> treatment were similar to the results of surgical treatment for chronic nonunions with no surgical risks. <span class="hlt">Shock</span> <span class="hlt">wave</span> treatment is a safe and effective alternative method in the treatment of chronic nonunions of long bones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AIPC.1503....2K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AIPC.1503....2K"><span id="translatedtitle">Effects of low-dose extracorporeal <span class="hlt">shock</span> <span class="hlt">waves</span> on microcirculation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khaled, Walaa; Goertz, Ole; Lauer, Henrik; Lehnhardt, Marcus; Hauser, Jörg</p> <p>2012-11-01</p> <p>The extended wounds of burn patients remain a challenge due to wound infection and following septicemia. The aim of this study was to analyze microcirculation, angiogenesis and leukocyte endothelium interaction after burn injury with and without extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> application (ESWA). A novel shockwave system was developed based on a commercially available device for orthopedics (Dornier Aries®) that was equipped with a newly developed applicator. This system is based on the electromagnetic <span class="hlt">shock</span> <span class="hlt">wave</span> emitter (EMSE) technology and was introduced to accomplish a localized treatment for wound healing. The system includes a novel field of focus for new applications, with high precision and ease of use. In the animal study, full-thickness burns were inflicted on to the ears of hairless mice (n=51). Intravital fluorescent microscopy was used to assess microcirculatory parameters, angiogenesis and leukocyte behavior. ESWA was performed on day 1, 3 and 7. Values were obtained immediately after burn, as well as at days 1, 3, 7, and 12 post burn. All shockwave treated groups showed an accelerated angiogenesis with a less non-perfused area and an improved blood flow after burn injury compared to the placebo control group. After three treatments, the <span class="hlt">shock</span> <span class="hlt">waves</span> increased the number of rolling leukocytes significantly compared to the non-treated animals. <span class="hlt">Shock</span> <span class="hlt">waves</span> seem to have a positive effect on several parameters of wound healing after burn injury. However, further investigations are necessary to detect positive influence of <span class="hlt">shock</span> <span class="hlt">waves</span> on microcirculation after burn injuries.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PThPS.187...96K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PThPS.187...96K"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">Wave</span> Collisions and Thermalization in AdS_5</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kovchegov, Y. V.</p> <p></p> <p>We study heavy ion collisions at strong 't Hooft coupling usingAdS/CFT correspondence. According to the AdS/CFT dictionary heavy ion collisions correspond to gravitational <span class="hlt">shock</span> <span class="hlt">wave</span> collisions in AdS_5. We construct the metric in the forward light cone after the collision perturbatively through expansion of Einstein equations in graviton exchanges. We obtain an analytic expression for the metric including all-order graviton exchanges with one <span class="hlt">shock</span> <span class="hlt">wave</span>, while keeping the exchanges with another <span class="hlt">shock</span> <span class="hlt">wave</span> at the lowest order. We read off the corresponding energy-momentum tensor of the produced medium. Unfortunately this energy-momentum tensor does not correspond to ideal hydrodynamics, indicating that higher order graviton exchanges are needed to construct the full solution of the problem. We also show that <span class="hlt">shock</span> <span class="hlt">waves</span> must completely stop almost immediately after the collision in AdS_5, which, on the field theory side, corresponds to complete nuclear stopping due to strong coupling effects, likely leading to Landau hydrodynamics. Finally, we perform trapped surface analysis of the <span class="hlt">shock</span> <span class="hlt">wave</span> collisions demonstrating that a bulk black hole, corresponding to ideal hydrodynamics on the boundary, has to be created in such collisions, thus constructing a proof of thermalization in heavy ion collisions at strong coupling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930064552&hterms=Parviz&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DParviz','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930064552&hterms=Parviz&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DParviz"><span id="translatedtitle">Direct numerical simulation of isotropic turbulence interacting with a weak <span class="hlt">shock</span> <span class="hlt">wave</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lee, Sangsan; Lele, Sanjiva K.; Moin, Parviz</p> <p>1993-01-01</p> <p>Direct numerical simulations are used to investigate the interaction of isotropic quasi-incompressible turbulence with a weak <span class="hlt">shock</span> <span class="hlt">wave</span>. A linear analysis of the interaction is conducted for comparison with the simulations. Both the simulations and the analysis show that turbulence is enhanced during the interaction. Turbulent kinetic energy and transverse vorticity components are amplified, and turbulent lengthscales are decreased. It is suggested that the amplification mechanism is primarily linear. Simulations also showed a rapid evolution of turbulent kinetic energy just downstream of the <span class="hlt">shock</span>, a behavior not reproduced by the linear analysis. Analysis of the budget of the turbulent kinetic energy transport equation shows that this behavior can be attributed to the pressure transport term. Multiple <span class="hlt">compression</span> peaks were found along the mean streamlines at locations where the local <span class="hlt">shock</span> thickness had increased significantly.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10183615','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10183615"><span id="translatedtitle">Characteristics of <span class="hlt">shock-compressed</span> configuration of Ti and Si powder mixtures</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Thadhani, N.N.; Dunbar, E.; Graham, R.A.</p> <p>1993-08-01</p> <p><span class="hlt">Shock-compression</span> recovery experiments were performed on mixtures of Ti and Si powders of fine, medium, and coarse morphology, and packed at different initial densities, using the Sandia Momma and Poppa Bear fixtures with Baratol explosive. The <span class="hlt">shock-compressed</span> configuration revealed characteristics typical of either chemically reacted material with fine equiaxed grains, or unreacted material with densely packed Ti and Si particles. The unreacted configuration showed that Ti particles were extensively deformed, irrespective of powder morphology and <span class="hlt">shock</span> conditions generated by either fixture. In contrast Si particles showed different characteristics depending on the powder morphology, packing density, and <span class="hlt">shock</span> conditions. The microstructural characteristics of unreacted configuration of Ti and Si powder mixtures were investigated. Mechanistic processes occurring prior to the inception of <span class="hlt">shock</span>-induced chemical reactions in this system are described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011MNRAS.416.1284G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011MNRAS.416.1284G"><span id="translatedtitle"><span class="hlt">Shock</span> formation in stellar perturbations and tidal <span class="hlt">shock</span> <span class="hlt">waves</span> in binaries</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gundlach, Carsten; Murphy, Jeremiah W.</p> <p>2011-09-01</p> <p>We investigate whether tidal forcing can result in sound <span class="hlt">waves</span> steepening into <span class="hlt">shocks</span> at the surface of a star. To model the sound <span class="hlt">waves</span> and <span class="hlt">shocks</span>, we consider adiabatic non-spherical perturbations of a Newtonian perfect fluid star. Because tidal forcing of sound <span class="hlt">waves</span> is naturally treated with linear theory, but the formation of <span class="hlt">shocks</span> is necessarily non-linear, we consider the perturbations in two regimes. In most of the interior, where tidal forcing dominates, we treat the perturbations as linear, while in a thin layer near the surface we treat them in full non-linearity but in the approximation of plane symmetry, fixed gravitational field and a barotropic equation of state. Using a hodograph transformation, this non-linear regime is also described by a linear equation. We show that the two regimes can be matched to give rise to a single-mode equation which is linear but models non-linearity in the outer layers. This can then be used to obtain an estimate for the critical mode amplitude at which a <span class="hlt">shock</span> forms near the surface. As an application, we consider the tidal <span class="hlt">waves</span> raised by the companion in an irrotational binary system in circular orbit. We find that <span class="hlt">shocks</span> form at the same orbital separation where Roche lobe overflow occurs, and so <span class="hlt">shock</span> formation is unlikely to occur.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/970576','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/970576"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">wave</span> structure for a fully ionized plasma</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Masser, Thomas O; Wohibier, John G; Lowrie, Robert B</p> <p>2009-01-01</p> <p>We study the structure of planar <span class="hlt">shock</span> <span class="hlt">waves</span> in a two-temperature model of a fully ionized plasma that includes electron heat conduction and energy exchange between electrons and ions. For steady flow in a reference frame moving with the <span class="hlt">shock</span>, the model reduces to an autonomous system of ordinary differential equations which can be numerically integrated. A phase space analysis of the ODEs provides additional insight into the structure of the solutions. For example, below a threshold mach number the model produces fully dispersed <span class="hlt">shocks</span>; while above another threshold mach number, the solutions contain embedded hydrodynamic <span class="hlt">shocks</span>. Between these two threshold values, the appearance of embedded <span class="hlt">shocks</span> depends on the electron diffusivity and the electron-ion coupling term. We also find that the ion temperature may continue to increase after the <span class="hlt">shock</span> and reaches a maximum near the isothermal sonic point. We summarize the methodology for solving for two-temperature <span class="hlt">shocks</span>, and show results for several values of <span class="hlt">shock</span> strength and material parameters to quantify the <span class="hlt">shock</span> structure and explore the range of possible solutions. Such solutions may be used to verify hydrodynamic codes that use similar plasma physics models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001APS..SHK.N3005N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001APS..SHK.N3005N"><span id="translatedtitle">Transient bond scission of polytetrafluoroethylene under laser-induced <span class="hlt">shock</span> <span class="hlt">compression</span> studied by nanosecond time-resolved Raman spectroscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nakamura, Kazutaka; Wakabayashi, Kunihiko; Konodo, Ken-Ichi</p> <p>2001-06-01</p> <p>Nanosecond time-resolved Raman spectroscopy has been performed to study polymer films, polytetrafluoroethylene (PTFE), under laser driven <span class="hlt">shock</span> <span class="hlt">compression</span> at laser power density of 4.0 GW/cm^2. The overtone-mode line of PTFE showed red shift (18 cm-1) at delay time of 9.3 ns due to the <span class="hlt">shock</span> <span class="hlt">compression</span> and corresponding pressure was estimated to be approximately 2.7 GPa by analyzing static and <span class="hlt">shock</span> <span class="hlt">compression</span> data. The estimated pressure was in good agreement with that estimated by ablation pressure in glass-confined geometry. A new vibrational line at 1900 cm-1 appeared only under <span class="hlt">shock</span> <span class="hlt">compression</span> and was assigned to the C=C streching in transient species such as a monomer (C_2F_4) produced by the <span class="hlt">shock</span>-induced bond scission. Intensity of the new line increased with increasing delay time along propagation of the <span class="hlt">shock</span> <span class="hlt">compression</span> with a <span class="hlt">shock</span> velocity of 2.5 km/s.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20854065','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20854065"><span id="translatedtitle">Inertial-Fusion-Related Hydrodynamic Instabilities in a Spherical Gas Bubble Accelerated by a Planar <span class="hlt">Shock</span> <span class="hlt">Wave</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Niederhaus, John; Ranjan, Devesh; Anderson, Mark; Oakley, Jason; Bonazza, Riccardo; Greenough, Jeff</p> <p>2005-05-15</p> <p>Experiments studying the <span class="hlt">compression</span> and unstable growth of a dense spherical bubble in a gaseous medium subjected to a strong planar <span class="hlt">shock</span> <span class="hlt">wave</span> (2.8 < M < 3.4) are performed in a vertical <span class="hlt">shock</span> tube. The test gas is initially contained in a free-falling spherical soap-film bubble, and the <span class="hlt">shocked</span> bubble is imaged using planar laser diagnostics. Concurrently, simulations are carried out using a <span class="hlt">compressible</span> hydrodynamics code in r-z axisymmetric geometry.Experiments and computations indicate the formation of characteristic vortical structures in the post-<span class="hlt">shock</span> flow, due to Richtmyer-Meshkov and Kelvin-Helmholtz instabilities, and smaller-scale vortices due to secondary effects. Inconsistencies between experimental and computational results are examined, and the usefulness of the current axisymmetric approach is evaluated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3699325','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3699325"><span id="translatedtitle"><span class="hlt">Wave</span>-breaking-extended fiber supercontinuum generation for high <span class="hlt">compression</span> ratio transform-limited pulse <span class="hlt">compression</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Liu, Yuan; Tu, Haohua; Boppart, Stephen A.</p> <p>2013-01-01</p> <p><span class="hlt">Wave</span>-breaking often occurs when a short intense optical pulse propagates in a long normally dispersive optical fiber. This effect has conventionally been avoided in fiber (super-)continuum-based pulse <span class="hlt">compression</span> because the accumulated frequency chirp of the output pulse cannot be fully compensated by a standard prism (or grating) pair. Thus, the spectral extending capability of the <span class="hlt">wave</span>-breaking has not been utilized to shorten the <span class="hlt">compressed</span> pulse. We demonstrate that <span class="hlt">wave</span>-breaking-free operation is not necessary if a 4f pulse shaper-based compressor is employed to remove both the linear and nonlinear chirp of the output pulse. By propagating a 180 fs (FWHM) input pulse in a nonlinear photonic crystal fiber beyond the <span class="hlt">wave</span>-breaking limit, we <span class="hlt">compress</span> the <span class="hlt">wave</span>-breaking-extended supercontinuum output pulse to the bandwidth-limited duration of 6.4 fs (FWHM). The combination of high <span class="hlt">compression</span> ratio (28×) and short pulse width represents a significant improvement over that attained in the <span class="hlt">wave</span>-breaking-free regime. PMID:22739845</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1981swan.rept.....D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1981swan.rept.....D"><span id="translatedtitle">A <span class="hlt">shock</span> <span class="hlt">wave</span> approach to the noise of supersonic propellers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dittmar, J. H.; Rice, E. J.</p> <p>1981-12-01</p> <p>To model propeller noise expected for a turboprop aircraft, the pressure ratio across the <span class="hlt">shock</span> at the propeller tip was calculated and compared with noise data from three propellers. At helical tip Mach numbers over 1.0, using only the tip <span class="hlt">shock</span> <span class="hlt">wave</span>, the model gave a fairly good prediction of the noise for a bladed propeller and for a propeller swept for aerodynamic purposes. However for another propeller, which was highly swept and designed to have noise cancellations from the inboard propeller sections, the <span class="hlt">shock</span> strength from the tip over predicted the noise. In general the good agreement indicates that <span class="hlt">shock</span> theory is a viable method for predicting the noise from these supersonic propellers but that the <span class="hlt">shock</span> strengths from all of the blade sections need to be properly included.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011APS..SHK.U6002J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011APS..SHK.U6002J"><span id="translatedtitle">Resolving the <span class="hlt">Shock</span> <span class="hlt">Wave</span> Profile in Viscous Fluids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jordan, Kenneth; Borg, John</p> <p>2011-06-01</p> <p>Capturing and modeling <span class="hlt">shock</span> <span class="hlt">wave</span> profiles has a long history in computational analysis. Often artificial irreversibilities and/or smearing schemes are implemented in order to stabilize and resolve the <span class="hlt">shock</span>. This work presents a direct numeric simulation of the full Navier-Stokes equations where the <span class="hlt">shock</span> profile is completely resolved without the use of artificial viscosity or <span class="hlt">shock</span> smearing techniques. Several viscosity models are employed to study the role of viscosity on this second order accurate finite difference scheme. The results are compared to an analytic solutions and experimental results. The results indicated that the <span class="hlt">shock</span> front thickness and entropy production are in good agreement with simple analytic solutions and experimental results. The extension of this technique to solid and granular materials will be discussed.</p> </li> <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> <span class="hlt">wave</span> 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 parallel 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 parallel <span class="hlt">shocks</span>. It was found that unstable <span class="hlt">waves</span> 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> layer 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://adsabs.harvard.edu/abs/1982Natur.300..237M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1982Natur.300..237M"><span id="translatedtitle">Measurements on a <span class="hlt">shock</span> <span class="hlt">wave</span> generated by a solar flare</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maxwell, A.; Dryer, M.</p> <p>1982-11-01</p> <p><span class="hlt">Shock</span> <span class="hlt">waves</span> generated by intense solar flares may be driven by a large amount of ejected mass, about 5 x 10 to the 16th g, and the total energy involved may be of the order of 10 to the 32nd erg. The <span class="hlt">shocks</span> may have initial velocities of the order of 2,000 km/s and, in their exodus through the corona, may be accompanied by fast-moving optical transients, the emission of highly characteristic radio signatures and the acceleration of particles to quasi-relativistic velocities. Here, a review is presented of data on a high-velocity <span class="hlt">shock</span> generated by a flare on 18 August 1979, 1400 UT, and comments are provided on some previously deduced velocities for the <span class="hlt">shock</span>. Attention is given to a model, based on current computer programs to account for the overall characteristics of the <span class="hlt">shock</span> as it propagated through the corona and the interplanetary plasma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19830033736&hterms=exodus&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dexodus','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830033736&hterms=exodus&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dexodus"><span id="translatedtitle">Measurements on a <span class="hlt">shock</span> <span class="hlt">wave</span> generated by a solar flare</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Maxwell, A.; Dryer, M.</p> <p>1982-01-01</p> <p><span class="hlt">Shock</span> <span class="hlt">waves</span> generated by intense solar flares may be driven by a large amount of ejected mass, about 5 x 10 to the 16th g, and the total energy involved may be of the order of 10 to the 32nd erg. The <span class="hlt">shocks</span> may have initial velocities of the order of 2,000 km/s and, in their exodus through the corona, may be accompanied by fast-moving optical transients, the emission of highly characteristic radio signatures and the acceleration of particles to quasi-relativistic velocities. Here, a review is presented of data on a high-velocity <span class="hlt">shock</span> generated by a flare on 18 August 1979, 1400 UT, and comments are provided on some previously deduced velocities for the <span class="hlt">shock</span>. Attention is given to a model, based on current computer programs to account for the overall characteristics of the <span class="hlt">shock</span> as it propagated through the corona and the interplanetary plasma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Ap%26SS.362...58G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Ap%26SS.362...58G"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">waves</span> in dusty plasma with two temperature superthermal ions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ghai, Yashika; Saini, N. S.</p> <p>2017-03-01</p> <p>An investigation of dust acoustic <span class="hlt">shock</span> <span class="hlt">waves</span> in dusty plasma containing two temperature ions is presented. The present investigation is motivated by the observations of Geotail spacecraft that report the occurrence of two temperature ion populations in Earth's magnetotail. We have derived Burgers equation to study dust acoustic <span class="hlt">shock</span> structures in an unmagnetized plasma with two temperature superthermal ions. We have also derived the modified Burgers equation at critical values of physical parameters for which nonlinear coefficient (A) of Burgers equation vanishes. The numerical analysis is performed in context with observations in Earth's magnetotail and the influence of various plasma parameters viz. ions temperature ratio, superthermality of hot and cold ions, kinematic viscosity etc. has been observed on characteristics of DA <span class="hlt">shocks</span>. It is observed that the amplitude of positive <span class="hlt">shocks</span> via Burgers equation decreases whereas that of modified <span class="hlt">shocks</span> with higher order nonlinearity increases with increase in superthermality of cold ions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016InJPh..90.1055N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016InJPh..90.1055N"><span id="translatedtitle">Propagation of exponential <span class="hlt">shock</span> <span class="hlt">wave</span> in an axisymmetric rotating non-ideal dusty gas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nath, G.</p> <p>2016-09-01</p> <p>One-dimensional unsteady isothermal and adiabatic flow behind a strong exponential <span class="hlt">shock</span> <span class="hlt">wave</span> propagating in a rotational axisymmetric mixture of non-ideal gas and small solid particles, which has variable azimuthal and axial fluid velocities, is analyzed. The <span class="hlt">shock</span> <span class="hlt">wave</span> is driven out by a piston moving with time according to exponential law. The azimuthal and axial components of the fluid velocity in the ambient medium are assumed to be varying and obeying exponential laws. In the present work, small solid particles are considered as pseudo-fluid with the assumption that the equilibrium flow-conditions are maintained in the flow-field, and the viscous-stress and heat conduction of the mixture are negligible. Solutions are obtained in both the cases, when the flow between the <span class="hlt">shock</span> and the piston is isothermal or adiabatic by taking into account the components of vorticity vector and <span class="hlt">compressibility</span>. It is found that the assumption of zero temperature gradient brings a profound change in the density, axial component of vorticity vector and <span class="hlt">compressibility</span> distributions as compared to that of the adiabatic case. To investigate the behavior of the flow variables and the influence on the <span class="hlt">shock</span> <span class="hlt">wave</span> propagation by the parameter of non-idealness of the gas overline{b} in the mixture as well as by the mass concentration of solid particles in the mixture Kp and by the ratio of the density of solid particles to the initial density of the gas G1 are worked out in detail. It is interesting to note that the <span class="hlt">shock</span> strength increases with an increase in G1 ; whereas it decreases with an increase in overline{b} . Also, a comparison between the solutions in the cases of isothermal and adiabatic flows is made.</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('https://www.osti.gov/scitech/biblio/372295','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/372295"><span id="translatedtitle">Numerical simulation of heat transfer in chemically reacting <span class="hlt">shock</span> <span class="hlt">wave</span>-turbulent boundary layer interactions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Moon, S.Y.; Yoon, K.T.; Chung, T.J.</p> <p>1996-07-01</p> <p>The flow field of a transverse jet in a supersonic airstream subjected to <span class="hlt">shock</span> <span class="hlt">wave</span>-turbulent boundary layer interactions is simulated numerically by adaptive mixed explicit-implicit generalized-Galerkin finite element methods. In this scheme, convection and diffusion implicitness parameters are introduced to resolve <span class="hlt">shock</span> <span class="hlt">wave</span> discontinuities and widely disparate time and length scales of turbulence and finite rate chemistry. These parameters are flow field dependent, calculated from local Mach, Reynolds, and Damkohler numbers for each element. Effects of turbulence are taken into account with a two-equation ({kappa}-{epsilon}) model with a <span class="hlt">compressibility</span> correction. Various cases of mixing, slot widths, and total pressure ratios with and without chemical reactions are examined. Favorable comparisons with experimental measurements are demonstrated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990AIPC..208..831L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990AIPC..208..831L"><span id="translatedtitle">Air bubble-<span class="hlt">shock</span> <span class="hlt">wave</span> interaction adjacent to gelantine surface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lush, P. A.; Tomita, Y.; Onodera, O.; Takayama, K.; Sanada, N.; Kuwahara, M.; Ioritani, N.; Kitayama, O.</p> <p>1990-07-01</p> <p>The interaction between a <span class="hlt">shock</span> <span class="hlt">wave</span> and an air bubble-adjacent to a gelatine surface is investigated in order to simulate human tissue damage resulting from extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy. Using high speed cine photography it is found that a <span class="hlt">shock</span> <span class="hlt">wave</span> of strength 11 MPa causes 1-3 mm diameter bubbles to produce high velocity microjets with penetration rates of approximately 110 m/s and penetration depths approximately equal to twice the initial bubble diameter. Theoretical considerations for liquid impact on soft solid of similar density indicate that microjet velocities will be twice the penetration rate, i.e. 220 m/s in the present case. Such events are the probable cause of observed renal tissue damage.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10025241','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10025241"><span id="translatedtitle">[High energy <span class="hlt">shock</span> <span class="hlt">wave</span> treatment of the painful heel spur].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Perlick, L; Boxberg, W; Giebel, G</p> <p>1998-12-01</p> <p>Extracorporal <span class="hlt">shock</span> <span class="hlt">wave</span> application (ESWA) has been used in the treatment of stones located in kidneys, bile, pancreas and the glandula parotis. In the last 2 years several studies have shown the benefit of the ESWA on the treatment of soft tissue disorders. The aim of this study was to explore the effect of high energy extracorporal <span class="hlt">shock</span> <span class="hlt">waves</span> in patients with painful calcaneus spurs. 83 patients who underwent medicophysical treatment without benefit were treated with 3000 impulses of 0.30 mj/mm2. Follow-ups after 12 weeks and 12 months showed that 51 of 83 patients became pain-free and 20 patients improved from the treatment. The results are showing the benefit of the high energy extracorporal <span class="hlt">shock</span> <span class="hlt">wave</span> application in the treatment of chronic plantar fasciitis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14733349','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14733349"><span id="translatedtitle">Effect of extracorporeal <span class="hlt">shock</span> <span class="hlt">waves</span> on calcaneal bone spurs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lee, Gregory P; Ogden, John A; Cross, G Lee</p> <p>2003-12-01</p> <p>In a prospective study of 435 patients with chronic proximal plantar fasciitis, 283 (65%) had an inferior calcaneal bone spur of variable size evident prior to treatment with electrohydraulic high-energy extracorporeal <span class="hlt">shock</span> <span class="hlt">waves</span> (ESW). This included 308 patients who received extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> treatments and 127 placebo (sham control) patients. At both initial (3 months) and final (12 months) evaluations after receiving ESW, no patient who received <span class="hlt">shock</span> <span class="hlt">wave</span> applications had significant disappearance or change in the radiographic appearance of the heel spur. Clinical outcome after ESW was satisfactory in 168 patients (82%) with a radiographically demonstrable inferior heel spur and in 81 patients (79%) without such a heel spur. The results showed no correlation between the presence or absence of the heel spur and the eventual treatment outcome.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19830044689&hterms=PROBLEMS+RESOLVED+ACOUSTICS&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DPROBLEMS%2BRESOLVED%2BACOUSTICS','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830044689&hterms=PROBLEMS+RESOLVED+ACOUSTICS&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DPROBLEMS%2BRESOLVED%2BACOUSTICS"><span id="translatedtitle">Finite difference solutions to <span class="hlt">shocked</span> acoustic <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Walkington, N. J.; Eversman, W.</p> <p>1983-01-01</p> <p>The MacCormack, Lambda and split flux finite differencing schemes are used to solve a one dimensional acoustics problem. Two duct configurations were considered, a uniform duct and a converging-diverging nozzle. Asymptotic solutions for these two ducts are compared with the numerical solutions. When the acoustic amplitude and frequency are sufficiently high the acoustic signal <span class="hlt">shocks</span>. This condition leads to a deterioration of the numerical solutions since viscous terms may be required if the <span class="hlt">shock</span> is to be resolved. A continuous uniform duct solution is considered to demonstrate how the viscous terms modify the solution. These results are then compared with a <span class="hlt">shocked</span> solution with and without viscous terms. Generally it is found that the most accurate solutions are those obtained using the minimum possible viscosity coefficients. All of the schemes considered give results accurate enough for acoustic power calculations with no one scheme performing significantly better than the others.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.2121I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.2121I"><span id="translatedtitle">Hybrid simulation of the <span class="hlt">shock</span> <span class="hlt">wave</span> trailing the Moon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Israelevich, P.; Ofman, L.</p> <p>2012-04-01</p> <p>Standing <span class="hlt">shock</span> <span class="hlt">wave</span> behind the Moon was predicted be Michel (1967) but never observed nor simulated. We use 1D hybrid code in order to simulate the collapse of the plasma-free cavity behind the Moon and for the first time to model the formation of this <span class="hlt">shock</span>. Starting immediately downstream of the obstacle we consider the evolution of plasma expansion into the cavity in the frame of reference moving along with the solar wind. Well-known effects as electric charging of the cavity affecting the plasma flow and counter streaming ion beams in the wake are reproduced. Near the apex of the inner Mach cone where the plasma flows from the opposite sides of the obstacle meet, a <span class="hlt">shock</span> <span class="hlt">wave</span> arises. The <span class="hlt">shock</span> is produced by the interaction of oppositely directed proton beams in the plane containing solar wind velocity and interplanetary magnetic field vectors. In the direction across the magnetic field and the solar wind velocity, the <span class="hlt">shock</span> results from the interaction of the plasma flow with the region of the enhanced magnetic field inside the cavity that plays the role of magnetic barrier. The appearance of the standing <span class="hlt">shock</span> <span class="hlt">wave</span> is expected at the distance of ~ 7RM downstream of the Moon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950052353&hterms=Ryszard&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DRyszard','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950052353&hterms=Ryszard&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DRyszard"><span id="translatedtitle">Supernova remnants and the physics of strong <span class="hlt">shock</span> <span class="hlt">waves</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.; Reynolds, Stephen P.; Borkowski, Kazimierz; Chevalier, Roger; Cox, Donald P.; Dickel, John R.; Pisarski, Ryszard; Raymond, John; Spangler, Stephen R.; Volk, Heinrich J.</p> <p>1994-01-01</p> <p>This paper reports on a Workshop on Supernova Remnants and the Physics of Strong <span class="hlt">Shock</span> <span class="hlt">Waves</span> hosted by North Carolina State University at Raleigh, North Carolina, September 16-18, 1993. The workshop brought together observers, <span class="hlt">shock</span> theorists, cosmic-ray specialists, and simulators to address the role supernova remnants can play in furthering our understanding of the complex plasma physics associated with collisionless <span class="hlt">shocks</span> and particle acceleration. Over fifty scientists presented papers on various aspects of supernova remnants. In lieu of a proceedings volume, we present here a synopsis of the workshop, in the form of brief summaries of each workshop session.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980223576','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980223576"><span id="translatedtitle">Effect of Surface Roughness on Characteristics of Spherical <span class="hlt">Shock</span> <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Huber, Paul W.; McFarland, Donald R.</p> <p>1959-01-01</p> <p>Measurements of peak overpressure and Mach stem height were made at four burst heights. Data were obtained with instrumentation capable of directly observing the variation of <span class="hlt">shock</span> <span class="hlt">wave</span> movement with time. Good similarity of free air <span class="hlt">shock</span> peak overpressure with larger scale data was found to exist. The net effect of surface roughness on <span class="hlt">shock</span> peak overpressures slightly. Surface roughness delayed the Mach stem formation at the greatest charge height and lowered the growth at all burst heights. A similarity parameter was found which approximately correlates the triple point path at different burst heights.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860041641&hterms=ohms+law&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dohms%2Blaw','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860041641&hterms=ohms+law&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dohms%2Blaw"><span id="translatedtitle">Hybrid simulation codes with application to <span class="hlt">shocks</span> and upstream <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Winske, D.</p> <p>1985-01-01</p> <p>Hybrid codes in which part of the plasma is represented as particles and the rest as a fluid are discussed. In the past few years such codes with particle ions and massless, fluid electrons have been applied to space plasmas, especially to collisionless <span class="hlt">shocks</span>. All of these simulation codes are one-dimensional and similar in structure, except for how the field equations are solved. The various approaches that are used (resistive Ohm's law, predictor-corrector, Hamiltonian) are described in detail and results from the various codes are compared with examples taken from collisionless <span class="hlt">shocks</span> and low frequency <span class="hlt">wave</span> phenomena upstream of <span class="hlt">shocks</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000086187&hterms=ortho&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dortho','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000086187&hterms=ortho&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dortho"><span id="translatedtitle">Far-Infrared Water Emissions from Magnetohydrodynamic <span class="hlt">Shock</span> <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kaufman, Michael J.; Neufeld, David A.</p> <p>1996-01-01</p> <p>Nondissociative, magnetohydrodynamic, C-type <span class="hlt">shock</span> <span class="hlt">waves</span> are expected to be a prodigious source of far-infrared water emissions in dense interstellar regions. We have constructed a model to calculate the farinfrared H20 line spectra that emerge from such <span class="hlt">shocks</span>. Using the best estimates currently available for the radiative cooling rate and the degree of ion-neutral coupling within the <span class="hlt">shocked</span> gas, we modeled the temperature structure of MHD <span class="hlt">shocks</span> using standard methods in which the charged and neutral particles are treated separately as two weakly coupled, interpenetrating fluids. Then we solved the equations of statistical equilibrium to find the populations of the lowest 179 and 170 rotational states of ortho- and para-H2O We have completed an extensive parameter study to determine the emergent H2O line luminosities as a function of preshock density in the range n(H2) equals 10(exp 4) - 10(sup 6.5)/cc and <span class="hlt">shock</span> velocity in the range upsilon(sub s) = 5 - 40 km/ s. We find that numerous rotational transitions of water are potentially observable using the Infrared Space Observatory and the Submillimeter <span class="hlt">Wave</span> Astronomy Satellite and may be used as diagnostics of the <span class="hlt">shocked</span> gas. We have also computed the rotational and ro-vibrational emissions expected from H2, CO, and OH, and we discuss how complementary observations of such emissions may be used to further constrain the <span class="hlt">shock</span> conditions. In common with previous studies, we come close to matching the observed H2, and high-J CO emissions from the Orion-KL star-forming region on the basis of a single <span class="hlt">shock</span> model. We present our predictions for the strengths of H2O line emission from the Orion <span class="hlt">shock</span>, and we show how our results may be scaled to other regions where molecular <span class="hlt">shocks</span> are likely to be present.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFD.L5004W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFD.L5004W"><span id="translatedtitle">Numerical Study of <span class="hlt">Shock</span> <span class="hlt">Wave</span> Attenuation Using Logarithmic Spiral Liquid Sheet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wan, Qian; Deiterding, Ralf; Eliasson, Veronica</p> <p>2016-11-01</p> <p>Research of <span class="hlt">shock</span> <span class="hlt">wave</span> attenuation has drawn much attention due to its military and civilian applications. One method to attenuate <span class="hlt">shock</span> <span class="hlt">waves</span> is to use water to block the <span class="hlt">shock</span> <span class="hlt">wave</span> propagation path and allow the <span class="hlt">shock</span> <span class="hlt">wave</span> to lose energy by breaking up the water sheet. We propose a way by holding a water sheet in logarithmic spiral shape, which has the ability of focusing the incident <span class="hlt">shock</span> <span class="hlt">wave</span> to its focal region. In addition, the <span class="hlt">shock</span> <span class="hlt">wave</span> will break up the bulk water and thus lose energy. The process of <span class="hlt">shock</span> <span class="hlt">wave</span> reflecting off and transmitting through the water sheet is numerically modeled using Euler equations and stiffened gas equation of state. In this study, the <span class="hlt">shock</span> focusing ability of a logarithmic spiral water sheet is compared for various logarithmic spiral sheets. Further, the attenuation effect is quantified by the measurement of pressure impulse and peak pressure behind the transmitted and reflected <span class="hlt">shock</span> <span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19770036939&hterms=DCW&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DDCW','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19770036939&hterms=DCW&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DDCW"><span id="translatedtitle">Reynolds number effects on <span class="hlt">shock-wave</span> turbulent boundary-layer interactions - A comparison of numerical and experimental results</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.; Settles, G. S.; Vas, I. E.; Bogdonoff, S. M.; Hung, C. M.</p> <p>1977-01-01</p> <p>An experiment is described that tests and guides computations of a <span class="hlt">shock-wave</span> turbulent boundary-layer interaction flow over a 20-deg <span class="hlt">compression</span> corner at Mach 2.85. Numerical solutions of the time-averaged Navier-Stokes equations for the entire flow field, employing various turbulence models, are compared with the data. Each model is critically evaluated by comparisons with the details of the experimental data. Experimental results for the extent of upstream pressure influence and separation location are compared with numerical predictions for a wide range of Reynolds numbers and <span class="hlt">shock-wave</span> strengths.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19880027234&hterms=KIN&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DKIN','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19880027234&hterms=KIN&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DKIN"><span id="translatedtitle">Experimental study of three <span class="hlt">shock</span> <span class="hlt">wave</span>/turbulent boundary layer interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smits, Alexander J.; Muck, Kin-Choong</p> <p>1987-01-01</p> <p>The paper presents a systematic study of the supersonic flow of a turbulent boundary layer over several <span class="hlt">compression</span>-corner models. The wind tunnel and the <span class="hlt">compression</span>-corner models (ramps fitted with aerodynamic fences to minimize three-dimensional effects) were identical with those used by Settles et al. (1979); constant-temperature hot-wire anemometry was used for the mass-flow measurements. The turning angles used for the <span class="hlt">compression</span> corners were 8, 16, and 20 deg. In all three flow cases, the <span class="hlt">shock</span> <span class="hlt">wave</span>/turbulent flow interaction did amplify the turbulent stresses dramatically, with amplification increasing with increasing turning angle. However, different stress components were amplified by different amounts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..SHK.M1024B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..SHK.M1024B"><span id="translatedtitle">Tabletop Optical Diagnostics for <span class="hlt">Shock</span> <span class="hlt">Compression</span> of Liquids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bassett, Will</p> <p>2015-06-01</p> <p>A novel platform for probing chemical properties in <span class="hlt">shocked</span> liquids has recently been developed. A target cell consisting of around two hundred cuvettes roughly fifty microns deep for use with the laser-launched flyer plate apparatus developed in our group which takes advantage of our ability to perform more than a hundred launches per day. Modeling of the <span class="hlt">shock</span> events suggests that we can access pressures between two and thirty GPa and temperatures as high as 1500 kelvin in liquid phase materials through impact driven <span class="hlt">shocks</span> lasting tens of nanoseconds. The tabletop scale of our laser-launched flyer apparatus allows for a variety of techniques for optical diagnostics of <span class="hlt">shocked</span> states such as fluorescence emission, infrared absorption, and Raman scattering. Preliminary results on Rhodamine 6G in glycerol <span class="hlt">shocked</span> to 4 GPa show fluorescence red shifts of tens of nanometers. Initially, fluorescence emission of pH-indicator dyes will be used to monitor dissociation of water under <span class="hlt">shock</span>. Future efforts will include temperature measurements during <span class="hlt">shocks</span> using the Stokes:anti-Stokes ratios in Raman scattering and chemical compositions of reacting liquids determined through infrared absorption.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910046931&hterms=polish&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dpolish','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910046931&hterms=polish&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dpolish"><span id="translatedtitle">Plasma <span class="hlt">wave</span> generation near the inner heliospheric <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>Macek, W. M.; Cairns, I. H.; Kurth, W. S.; Gurnett, D. A.</p> <p>1991-01-01</p> <p>There is mounting evidence that the Voyager 1 and 2 and Pioneer 11 spacecraft may approach the inner (termination) heliospheric <span class="hlt">shock</span> near the end of this century. It is argued here, by analogy with planetary bow <span class="hlt">shocks</span>, that energetic electrons backstreaming from the heliospheric <span class="hlt">shock</span> along the magnetic field should be unstable to the generation of Langmuir <span class="hlt">waves</span> by the electron beam instability. Analytic expressions for the cutoff velocity, corresponding to the beam speed of the electrons backstreaming from the <span class="hlt">shock</span>, are derived for a standard solar wind model. At the front side of the heliosphere the maximum beam velocity is expected to be at the meridian passing through the nose of the <span class="hlt">shock</span>, which is assumed to be aligned with the Very Local Inter-Stellar Medium flow. This foreshock region and the associated Langmuir <span class="hlt">waves</span> are relevant to both the expected in situ observations of the heliospheric boundaries, and to the low-frequency (2-3 kHz) radio emissions observed by the Voyager spacecraft in the outer heliosphere. Provided that these radio emissions are generated by Langmuir <span class="hlt">waves</span>, the minimum Langmuir <span class="hlt">wave</span> electric fields at the remote source are estimated to be greater than about 3 - 30 microV/m.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990008041&hterms=Uranus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DUranus','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990008041&hterms=Uranus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DUranus"><span id="translatedtitle">A Study of Uranus' Bow <span class="hlt">Shock</span> Motions Using Langmuir <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Xue, S.; Cairns, I. H.; Smith, C. W.; Gurnett, D. A.</p> <p>1996-01-01</p> <p>During the Voyager 2 flyby of Uranus, strong electron plasma oscillations (Langmuir <span class="hlt">waves</span>) were detected by the plasma <span class="hlt">wave</span> instrument in the 1.78-kHz channel on January 23-24, 1986, prior to the inbound bow <span class="hlt">shock</span> crossing. Langmuir <span class="hlt">waves</span> are excited by energetic electrons streaming away from the bow <span class="hlt">shock</span>. The goal of this work is to estimate the location and motion of Uranus' bow <span class="hlt">shock</span> using Langmuir <span class="hlt">wave</span> data, together with the spacecraft positions and the measured interplanetary magnetic field. The following three remote sensing analyses were performed: the basic remote sensing method, the lag time method, and the trace-back method. Because the interplanetary magnetic field was highly variable, the first analysis encountered difficulties in obtaining a realistic estimation of Uranus' bow <span class="hlt">shock</span> motion. In the lag time method developed here, time lags due to the solar wind's finite convection speed are taken into account when calculating the <span class="hlt">shock</span>'s standoff distance. In the new trace-back method, limits on the standoff distance are obtained as a function of time by reconstructing electron paths. Most of the results produced by the latter two analyses are consistent with predictions based on the standard theoretical model and the measured solar wind plasma parameters. Differences between our calculations and the theoretical model are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997APS..SHK..G203B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997APS..SHK..G203B"><span id="translatedtitle">Effect of Shear on Failure <span class="hlt">Waves</span> in <span class="hlt">Shocked</span> Soda Lime Glass</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brar, N. S.; Mello, M.; Clifton, R. J.</p> <p>1997-07-01</p> <p>Failure <span class="hlt">waves</span> in <span class="hlt">shock-compressed</span> soda lime glass are thought to involve a loss of shearing resistance because in-material stress gauges have shown a marked increase in the transverse stress, and consequent reduction in the shear stress on arrival of the failure <span class="hlt">wave</span>. To explore the relation between failure <span class="hlt">waves</span> and shearing resistance, a series of pressure-shear (oblique impact) are being performed in the 4-inch gas gun at Brown University. These experiments involve the impact of a glass plate by a steel flyer plate or vice versa. The former configuration is designed to relate failure <span class="hlt">wave</span> phenomena in oblique impact to those reported for normal impact, whereas the latter configuration is designed to allow direct measurements of the shearing resistance of the failed material. In both configurations, the normal and transverse motion of the free surface of the target is monitored using laser interferometery. Initial results from these experiments will be reported.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4523845','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4523845"><span id="translatedtitle">The electrical conductivity of Al2O3 under <span class="hlt">shock-compression</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Liu, Hanyu; Tse, John S.; Nellis, W. J.</p> <p>2015-01-01</p> <p>Sapphire (Al2O3) crystals are used below 100 GPa as anvils and windows in dynamic-<span class="hlt">compression</span> experiments because of their transparency and high density. Above 100 GPa <span class="hlt">shock</span> pressures, sapphire becomes opaque and electrically conducting because of <span class="hlt">shock</span>-induced defects. Such effects prevent temperature and dc conductivity measurements of materials <span class="hlt">compressed</span> quasi-isentropically. Opacities and electrical conductivities at ~100 GPa are non-equilibrium, rather than thermodynamic parameters. We have performed electronic structure calculations as a guide in predicting and interpreting <span class="hlt">shock</span> experiments and possibly to discover a window up to ~200 GPa. Our calculations indicate <span class="hlt">shocked</span> sapphire does not metallize by band overlap at ~300 GPa, as suggested previously by measured non-equilibrium data. <span class="hlt">Shock-compressed</span> Al2O3 melts to a metallic liquid at ~500 GPa and 10,000 K and its conductivity increases rapidly to ~2000 Ω−1cm−1 at ~900 GPa. At these high <span class="hlt">shock</span> temperatures and pressures sapphire is in thermal equilibrium. Calculated conductivity of Al2O3 is similar to those measured for metallic fluid H, N, O, Rb, and Cs. Despite different materials, pressures and temperatures, and <span class="hlt">compression</span> techniques, both experimental and theoretical, conductivities of all these poor metals reach a common end state typical of strong-scattering disordered materials. PMID:26239369</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1328805-directional-amorphization-boron-carbide-subjected-laser-shock-compression','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1328805-directional-amorphization-boron-carbide-subjected-laser-shock-compression"><span id="translatedtitle">Directional amorphization of boron carbide subjected to laser <span class="hlt">shock</span> <span class="hlt">compression</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Zhao, Shiteng; Kad, Bimal; Remington, Bruce A.; ...</p> <p>2016-10-12</p> <p>When crystalline solids are stressed quasi-statically, dislocation slip, twinning, and phase transformations are the predominant mechanisms to dissipate the imparted elastic energy. Under <span class="hlt">shock</span>, high hydrostatic and shear stresses promptly build up at the <span class="hlt">shock</span> front, favoring fast energy dissipation mechanisms. Amorphization, which may only involve localized atomic arrangements, is therefore an additional potential candidate. <span class="hlt">Shock</span>-induced amorphization has now been reported in various materials and hence should be incorporated as a deformation/damage mechanism of crystals subjected to high-strain-rate loading.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhPl...21k2701Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhPl...21k2701Z"><span id="translatedtitle">The effect of <span class="hlt">shock</span> dynamics on <span class="hlt">compressibility</span> of ignition-scale National Ignition Facility implosions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zylstra, A. B.; Frenje, J. A.; Séguin, F. H.; Hicks, D. G.; Dewald, E. L.; Robey, H. F.; Rygg, J. R.; Meezan, N. B.; Rosenberg, M. J.; Rinderknecht, H. G.; Friedrich, S.; Bionta, R.; Olson, R.; Atherton, J.; Barrios, M.; Bell, P.; Benedetti, R.; Berzak Hopkins, L.; Betti, R.; Bradley, D.; Callahan, D.; Casey, D.; Collins, G.; Dixit, S.; Döppner, T.; Edgell, D.; Edwards, M. J.; Gatu Johnson, M.; Glenn, S.; Glenzer, S.; Grim, G.; Hatchett, S.; Jones, O.; Khan, S.; Kilkenny, J.; Kline, J.; Knauer, J.; Kritcher, A.; Kyrala, G.; Landen, O.; LePape, S.; Li, C. K.; Lindl, J.; Ma, T.; Mackinnon, A.; Macphee, A.; Manuel, M. J.-E.; Meyerhofer, D.; Moody, J.; Moses, E.; Nagel, S. R.; Nikroo, A.; Pak, A.; Parham, T.; Petrasso, R. D.; Prasad, R.; Ralph, J.; Rosen, M.; Ross, J. S.; Sangster, T. C.; Sepke, S.; Sinenian, N.; Sio, H. W.; Spears, B.; Springer, P.; Tommasini, R.; Town, R.; Weber, S.; Wilson, D.; Zacharias, R.</p> <p>2014-11-01</p> <p>The effects of <span class="hlt">shock</span> dynamics on <span class="hlt">compressibility</span> of indirect-drive ignition-scale surrogate implosions, CH shells filled with D3He gas, have been studied using charged-particle spectroscopy. Spectral measurements of D3He protons produced at the <span class="hlt">shock</span>-bang time probe the <span class="hlt">shock</span> dynamics and in-flight characteristics of an implosion. The proton <span class="hlt">shock</span> yield is found to vary by over an order of magnitude. A simple model relates the observed yield to incipient hot-spot adiabat, suggesting that implosions with rapid radiation-power increase during the main drive pulse may have a 2× higher hot-spot adiabat, potentially reducing <span class="hlt">compressibility</span>. A self-consistent 1-D implosion model was used to infer the areal density (ρR) and the shell center-of-mass radius (Rcm) from the downshift of the <span class="hlt">shock</span>-produced D3He protons. The observed ρR at <span class="hlt">shock</span>-bang time is substantially higher for implosions, where the laser drive is on until near the <span class="hlt">compression</span> bang time ("short-coast"), while longer-coasting implosions have lower ρR. This corresponds to a much larger temporal difference between the <span class="hlt">shock</span>- and <span class="hlt">compression</span>-bang time in the long-coast implosions (˜800 ps) than in the short-coast (˜400 ps); this will be verified with a future direct bang-time diagnostic. This model-inferred differential bang time contradicts radiation-hydrodynamic simulations, which predict constant 700-800 ps differential independent of coasting time; this result is potentially explained by uncertainties in modeling late-time ablation drive on the capsule. In an ignition experiment, an earlier <span class="hlt">shock</span>-bang time resulting in an earlier onset of shell deceleration, potentially reducing <span class="hlt">compression</span> and, thus, fuel ρR.</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://www.osti.gov/scitech/servlets/purl/1164241','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1164241"><span id="translatedtitle">The effect of <span class="hlt">shock</span> dynamics on <span class="hlt">compressibility</span> of ignition-scale National Ignition Facility implosions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zylstra, A. B.; Frenje, J. A.; Séguin, F. H.; Hicks, D. G.; Dewald, E. L.; Robey, H. F.; Rygg, J. R.; Meezan, N. B.; Rosenberg, M. J.; Rinderknecht, H. G.; Friedrich, S.; Bionta, R.; Olson, R.; Atherton, J.; Barrios, M.; Bell, P.; Benedetti, R.; Hopkins, L. Berzak; Betti, R.; Bradley, D.; Callahan, D.; Casey, D.; Collins, G.; Dixit, S.; Döppner, T.; Edgell, D.; Edwards, M. J.; Johnson, M. Gatu; Glenn, S.; Glenzer, S.; Grim, G.; Hatchett, S.; Jones, O.; Khan, S.; Kilkenny, J.; Kline, J.; Knauer, J.; Kritcher, A.; Kyrala, G.; Landen, O.; LePape, S.; Li, C. K.; Lindl, J.; Ma, T.; Mackinnon, A.; Macphee, A.; Manuel, M. J.-E.; Meyerhofer, D.; Moody, J.; Moses, E.; Nagel, S. R.; Nikroo, A.; Pak, A.; Parham, T.; Petrasso, R. D.; Prasad, R.; Ralph, J.; Rosen, M.; Ross, J. S.; Sangster, T. C.; Sepke, S.; Sinenian, N.; Sio, H. W.; Spears, B.; Springer, P.; Tommasini, R.; Town, R.; Weber, S.; Wilson, D.; Zacharias, R.</p> <p>2014-11-03</p> <p>The effects of <span class="hlt">shock</span> dynamics on <span class="hlt">compressibility</span> of indirect-drive ignition-scale surrogate implosions, CH shells filled with D<sup>3</sup>He gas, have been studied using charged-particle spectroscopy. Spectral measurements of D<sup>3</sup>He protons produced at the <span class="hlt">shock</span>-bang time probe the <span class="hlt">shock</span> dynamics and in-flight characteristics of an implosion. The proton <span class="hlt">shock</span> yield is found to vary by over an order of magnitude. A simple model relates the observed yield to incipient hot-spot adiabat, suggesting that implosions with rapid radiation-power increase during the main drive pulse may have a 2x higher hot-spot adiabat, potentially reducing <span class="hlt">compressibility</span>. A self-consistent 1-D implosion model was used to infer the areal density (pR) and the shell center-of-mass radius (R<sub>cm</sub>) from the downshift of the <span class="hlt">shock</span>-produced D<sup>3</sup>He protons. The observed pR at <span class="hlt">shock</span>-bang time is substantially higher for implosions, where the laser drive is on until near the <span class="hlt">compression</span> bang time ('short-coast'), while longer-coasting implosions have lower pR. This corresponds to a much larger temporal difference between the <span class="hlt">shock</span>- and <span class="hlt">compression</span>-bang time in the long-coast implosions (~800 ps) than in the short-coast (~400 ps); this will be verified with a future direct bang-time diagnostic. This model-inferred differential bang time contradicts radiation-hydrodynamic simulations, which predict constant 700–800 ps differential independent of coasting time. This result is potentially explained by uncertainties in modeling late-time ablation drive on the capsule. In an ignition experiment, an earlier <span class="hlt">shock</span>-bang time resulting in an earlier onset of shell deceleration, potentially reducing <span class="hlt">compression</span> and, thus, fuel pR.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1164241-effect-shock-dynamics-compressibility-ignition-scale-national-ignition-facility-implosions','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1164241-effect-shock-dynamics-compressibility-ignition-scale-national-ignition-facility-implosions"><span id="translatedtitle">The effect of <span class="hlt">shock</span> dynamics on <span class="hlt">compressibility</span> of ignition-scale National Ignition Facility implosions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Zylstra, A. B.; Frenje, J. A.; Séguin, F. H.; ...</p> <p>2014-11-03</p> <p>The effects of <span class="hlt">shock</span> dynamics on <span class="hlt">compressibility</span> of indirect-drive ignition-scale surrogate implosions, CH shells filled with D3He gas, have been studied using charged-particle spectroscopy. Spectral measurements of D3He protons produced at the <span class="hlt">shock</span>-bang time probe the <span class="hlt">shock</span> dynamics and in-flight characteristics of an implosion. The proton <span class="hlt">shock</span> yield is found to vary by over an order of magnitude. A simple model relates the observed yield to incipient hot-spot adiabat, suggesting that implosions with rapid radiation-power increase during the main drive pulse may have a 2x higher hot-spot adiabat, potentially reducing <span class="hlt">compressibility</span>. A self-consistent 1-D implosion model was used to infermore » the areal density (pR) and the shell center-of-mass radius (Rcm) from the downshift of the <span class="hlt">shock</span>-produced D3He protons. The observed pR at <span class="hlt">shock</span>-bang time is substantially higher for implosions, where the laser drive is on until near the <span class="hlt">compression</span> bang time ('short-coast'), while longer-coasting implosions have lower pR. This corresponds to a much larger temporal difference between the <span class="hlt">shock</span>- and <span class="hlt">compression</span>-bang time in the long-coast implosions (~800 ps) than in the short-coast (~400 ps); this will be verified with a future direct bang-time diagnostic. This model-inferred differential bang time contradicts radiation-hydrodynamic simulations, which predict constant 700–800 ps differential independent of coasting time. This result is potentially explained by uncertainties in modeling late-time ablation drive on the capsule. In an ignition experiment, an earlier <span class="hlt">shock</span>-bang time resulting in an earlier onset of shell deceleration, potentially reducing <span class="hlt">compression</span> and, thus, fuel pR.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22299749','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22299749"><span id="translatedtitle">The effect of <span class="hlt">shock</span> dynamics on <span class="hlt">compressibility</span> of ignition-scale National Ignition Facility implosions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zylstra, A. B. Frenje, J. A.; Séguin, F. H.; Rosenberg, M. J.; Rinderknecht, H. G.; Gatu Johnson, M.; Li, C. K.; Manuel, M. J.-E.; Petrasso, R. D.; Sinenian, N.; Sio, H. W.; Hicks, D. G.; Dewald, E. L.; Robey, H. F.; Rygg, J. R.; Meezan, N. B.; Friedrich, S.; Bionta, R.; Atherton, J.; Barrios, M.; and others</p> <p>2014-11-15</p> <p>The effects of <span class="hlt">shock</span> dynamics on <span class="hlt">compressibility</span> of indirect-drive ignition-scale surrogate implosions, CH shells filled with D{sup 3}He gas, have been studied using charged-particle spectroscopy. Spectral measurements of D{sup 3}He protons produced at the <span class="hlt">shock</span>-bang time probe the <span class="hlt">shock</span> dynamics and in-flight characteristics of an implosion. The proton <span class="hlt">shock</span> yield is found to vary by over an order of magnitude. A simple model relates the observed yield to incipient hot-spot adiabat, suggesting that implosions with rapid radiation-power increase during the main drive pulse may have a 2× higher hot-spot adiabat, potentially reducing <span class="hlt">compressibility</span>. A self-consistent 1-D implosion model was used to infer the areal density (ρR) and the shell center-of-mass radius (R{sub cm}) from the downshift of the <span class="hlt">shock</span>-produced D{sup 3}He protons. The observed ρR at <span class="hlt">shock</span>-bang time is substantially higher for implosions, where the laser drive is on until near the <span class="hlt">compression</span> bang time (“short-coast”), while longer-coasting implosions have lower ρR. This corresponds to a much larger temporal difference between the <span class="hlt">shock</span>- and <span class="hlt">compression</span>-bang time in the long-coast implosions (∼800 ps) than in the short-coast (∼400 ps); this will be verified with a future direct bang-time diagnostic. This model-inferred differential bang time contradicts radiation-hydrodynamic simulations, which predict constant 700–800 ps differential independent of coasting time; this result is potentially explained by uncertainties in modeling late-time ablation drive on the capsule. In an ignition experiment, an earlier <span class="hlt">shock</span>-bang time resulting in an earlier onset of shell deceleration, potentially reducing <span class="hlt">compression</span> and, thus, fuel ρR.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22403239','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22403239"><span id="translatedtitle">Dynamics of cylindrical converging <span class="hlt">shock</span> <span class="hlt">waves</span> interacting with aerodynamic obstacle arrays</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Vignati, F.; Guardone, A.</p> <p>2015-06-15</p> <p>Cylindrical converging <span class="hlt">shock</span> <span class="hlt">waves</span> interacting with an array of aerodynamic obstacles are investigated numerically for diverse <span class="hlt">shock</span> strengths and for different obstacle configurations in air in standard conditions. The considered number of obstacles N is 4, 6, 8, 16, and 24. Obstacles are lenticular airfoils with thickness-to-chord ratios t/c of 0.07, 0.14, and 0.21. The distances of the airfoil leading edge from the <span class="hlt">shock</span> focus point (r{sub LE})/(r{sub LE}{sup ref}) are 1, 2, and 2.5, where r{sub LE}{sup ref}=7 is the dimensionless reference distance from the origin. Considered impinging <span class="hlt">shock</span> Mach numbers M{sub s} are 2.2, 2.7, and 3.2 at the reference distance from the origin. The reference experimental configuration (N=8,t/c =0.14,r{sub LE}=7,M{sub s}=2.7) was proposed by Kjellander et al. [“Thermal radiation from a converging <span class="hlt">shock</span> implosion,” Phys. Fluids 22, 046102 (2010)]. Numerical results compare fairly well to available one-dimensional models for <span class="hlt">shock</span> propagation and to available experimental results in the reference configuration. Local reflection types are in good agreement with the classical criteria for planar <span class="hlt">shock</span> <span class="hlt">waves</span>. The main <span class="hlt">shock</span> reshaping patterns are identified and their dependence on the <span class="hlt">shock</span> strength and obstacle configuration is exposed. In particular, different <span class="hlt">shock</span> patterns are observed after the leading edge reflection, which results in polygonal <span class="hlt">shock</span> <span class="hlt">wave</span> with N, 2N, 3N, and 4N sides. The largest temperature peak at the origin is obtained for the 8- and the 16-obstacle configurations and for the smallest thickness to length ratio, 0.07, located at distance from the origin of 2r{sub LE}{sup ref}. In terms of <span class="hlt">compression</span> efficiency at the origin, the 16-obstacle configuration is found to perform slightly better than the reference 8-obstacle configuration—with an efficiency increase of about 2%-3%, which is well within the model accuracy—thus confirming the goodness of the obstacle arrangement proposed by Kjellander and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870025302&hterms=berkeley&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dberkeley','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870025302&hterms=berkeley&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dberkeley"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">waves</span> and <span class="hlt">shock</span> tubes; Proceedings of the Fifteenth International Symposium, Berkeley, CA, July 28-August 2, 1985</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bershader, D. (Editor); Hanson, R. (Editor)</p> <p>1986-01-01</p> <p>A detailed survey is presented of <span class="hlt">shock</span> tube experiments, theoretical developments, and applications being carried out worldwide. The discussions explore <span class="hlt">shock</span> tube physics and the related chemical, physical and biological science and technology. Extensive attention is devoted to <span class="hlt">shock</span> <span class="hlt">wave</span> phenomena in dusty gases and other multiphase and heterogeneous systems, including chemically reactive mixtures. Consideration is given to techniques for measuring, visualizing and theoretically modeling flowfield, <span class="hlt">shock</span> <span class="hlt">wave</span> and rarefaction <span class="hlt">wave</span> characteristics. Numerical modeling is explored in terms of the application of computational fluid dynamics techniques to describing flowfields in <span class="hlt">shock</span> tubes. <span class="hlt">Shock</span> interactions and propagation, in both solids, fluids, gases and mixed media are investigated, along with the behavior of <span class="hlt">shocks</span> in condensed matter. Finally, chemical reactions that are initiated as the result of passage of a <span class="hlt">shock</span> <span class="hlt">wave</span> are discussed, together with methods of controlling the evolution of laminar separated flows at concave corners on advanced reentry vehicles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ShWav..26..385G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ShWav..26..385G"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">wave</span> emission during the collapse of cavitation bubbles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Garen, W.; Hegedűs, F.; Kai, Y.; Koch, S.; Meyerer, B.; Neu, W.; Teubner, U.</p> <p>2016-07-01</p> <p><span class="hlt">Shock</span> <span class="hlt">wave</span> emission induced by intense laser pulses is investigated experimentally. The present work focuses on the conditions of <span class="hlt">shock</span> <span class="hlt">wave</span> emission in glycerine and distilled water during the first bubble collapse. Experimental investigations are carried out in liquids as a function of temperature and viscosity. Comparison is made with the theoretical work of Poritsky (Proc 1st US Natl Congress Appl Mech 813-821, 1952) and Brennen (Cavitation and bubble dynamics, Oxford University Press 1995). To the best knowledge of the authors, this is the first experimental verification of those theories.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20655341','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20655341"><span id="translatedtitle">The importance of microjet vs <span class="hlt">shock</span> <span class="hlt">wave</span> formation in sonophoresis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wolloch, Lior; Kost, Joseph</p> <p>2010-12-01</p> <p>Low-frequency ultrasound application has been shown to greatly enhance transdermal drug delivery. Skin exposed to ultrasound is affected in a heterogeneous manner, thus mass transport through the stratum corneum occurs mainly through highly permeable localized transport regions (LTRs). <span class="hlt">Shock</span> <span class="hlt">waves</span> and microjets generated during inertial cavitations are responsible for the transdermal permeability enhancement. In this study, we evaluated the effect of these two phenomena using direct and indirect methods, and demonstrated that the contribution of microjets to skin permeability enhancement is significantly higher than <span class="hlt">shock</span> <span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19730050328&hterms=embedded+type&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dembedded%2Btype','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19730050328&hterms=embedded+type&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dembedded%2Btype"><span id="translatedtitle">Analysis of embedded <span class="hlt">shock</span> <span class="hlt">waves</span> calculated by relaxation methods.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Murman, E. M.</p> <p>1973-01-01</p> <p>The requirements for uniqueness of the calculated jump conditions across embedded <span class="hlt">shock</span> <span class="hlt">waves</span> are investigated for type-dependent difference systems used in transonic flow studies. A mathematical analysis shows that sufficient conditions are (1) the equations should be differenced in conservative form and (2) a special difference operator should be used when switching from a hyperbolic to an elliptic operator. The latter results in a consistency condition on the integral equations, rather than the differential, at these points. Calculated jump conditions for several embedded and detached <span class="hlt">shock</span> <span class="hlt">waves</span> are analyzed in the physical and hodograph planes. Comparisons are made with previous results, a time-dependent calculation, and data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760016856','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760016856"><span id="translatedtitle"><span class="hlt">Wave</span> theory of turbulence in <span class="hlt">compressible</span> media</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kentzer, C. P.</p> <p>1975-01-01</p> <p>An acoustical theory of turbulence was developed to aid in the study of the generation of sound in turbulent flows. The statistical framework adopted is a quantum-like <span class="hlt">wave</span> dynamical formulation in terms of complex distribution functions. This formulation results in nonlinear diffusion-type transport equations for the probability densities of the five modes of <span class="hlt">wave</span> propagation: two vorticity modes, one entropy mode, and two acoustic modes. This system of nonlinear equations is closed and complete. The technique of analysis was chosen such that direct applications to practical problems can be obtained with relative ease.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980228372','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980228372"><span id="translatedtitle">Structure of Weak <span class="hlt">Shock</span> <span class="hlt">Waves</span> in a Monatomic Gas</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sherman, F. S.; Talbot, L.</p> <p>1959-01-01</p> <p>The profiles and thicknesses of normal <span class="hlt">shock</span> <span class="hlt">waves</span> in argon at Mach numbers of 1.335, 1.454, 1.576, and 1-713 were determined experimentally by means of a free-molecule probe whose equilibrium temperature is related by kinetic theory to the local flow properties and their gradients. Comparisons were made between the experimental <span class="hlt">shock</span> profiles and the theoretical profiles calculated from the Navier-Stokes equations, the Grad 13-moment equations, and the Burnett equations. New, very accurate numerical integrations of the Burnett equations were obtained for this purpose with results quite different from those found by Zoller, to whom the solution of this problem is frequently attributed. The experimental <span class="hlt">shock</span> profiles were predicted with approximately equal success by the Navier-Stokes and Burnett theories, while the 13-moment method was definitely less satisfactory. A surprising feature of the theoretical results is the relatively small difference in predictions between the Navier-Stokes and Burnett theories in the present range of <span class="hlt">shock</span> strengths and the contrastingly large difference between predictions of Burnett and the 13-moment theories. It is concluded that the Navier-Stokes equations are correct for weak <span class="hlt">shocks</span> and that within the present <span class="hlt">shock</span> strength range the Burnett equations make no improvement which merits the trouble of solving them. For <span class="hlt">shocks</span> of noticeably greater strength, say with a <span class="hlt">shock</span> Mach number of more than 2.5, it remains fundamentally doubtful that any of these theories can be correct.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AIPC.1793l0003C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AIPC.1793l0003C"><span id="translatedtitle">Fluorescent probes for <span class="hlt">shock</span> <span class="hlt">compression</span> spectroscopy of microstructured materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Christensen, James M.; Banishev, Alexandr A.; Dlott, Dana D.</p> <p>2017-01-01</p> <p>We are developing fluorescent probes to obtain dynamic two-dimensional pressure maps of <span class="hlt">shocked</span> microstructured materials. We have fabricated silica nano-or micro-spheres doped with rhodamine 6G dye (R6G) which fluoresce strongly, and which may be dispersed throughout a microstructured sample. Alternatively we can grow thin skin layers of dye-doped silica on the surface of particles. The emissive microspheres were embedded in poly-methyl methacrylate (PMMA) and were excited by a quasi-continuous laser. When the samples were <span class="hlt">shocked</span> to 3-8.4 GPa using laser-driven flyer plates, the emission redshifted and lost intensity. When encapsulating the dye in silica, the emission became brighter and the intensity-loss response became fast enough to monitor nanosecond <span class="hlt">shock</span> effects. Preliminary data are reported showing the intensity loss in a <span class="hlt">shocked</span> microstructured medium, an artificial sand, consisting of dye-coated silica microspheres.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20875777','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20875777"><span id="translatedtitle">Evolution of <span class="hlt">Shock</span> <span class="hlt">Waves</span> in Silicon Carbide Rods</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Balagansky, I. A.; Balagansky, A. I.; Razorenov, S. V.; Utkin, A. V.</p> <p>2006-07-28</p> <p>Evolution of <span class="hlt">shock</span> <span class="hlt">waves</span> in self-bonded silicon carbide bars in the shape of 20 mm x 20 mm square prisms of varying lengths (20 mm, 40 mm, and 77.5 mm) is investigated. The density and porosity of the test specimens were 3.08 g/cm3 and 2%, respectively. <span class="hlt">Shock</span> <span class="hlt">waves</span> were generated by detonating a cylindrical shaped (d=40 mm and 1=40 mm) stabilized RDX high explosive charge of density 1.60 g/cm3. Embedded manganin gauges at various distances from the impact face were used to monitor the amplitude of <span class="hlt">shock</span> pressure profiles. Propagation velocity of the stress pulse was observed to be equal to the elastic bar <span class="hlt">wave</span> velocity of 11 km/s and was independent of the amplitude of the impact pulse. Strong fuzziness of the stress <span class="hlt">wave</span> front is observed. This observation conforms to the theory on the instability of the <span class="hlt">shock</span> formation in a finite size elastic body. This phenomenon of <span class="hlt">wave</span> front fuzziness may be useful for desensitization of heterogeneous high explosives.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/12173','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/12173"><span id="translatedtitle">The equation of state of HF under <span class="hlt">shock</span> <span class="hlt">compression</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fried, L E; Howard, W M</p> <p>1999-06-01</p> <p>We develop a model of chemical equilibrium mixtures containing the elements H, C, F. We show that the <span class="hlt">shock</span> response of a wide variety of molecular and polymeric fluorocarbons can be modeled as a chemical equilibrium mixture of a small number of dissociation product molecules. HF is known to strongly associate in the supercritical fluid phase. We predict that such an association also occurs under <span class="hlt">shock</span> conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5248985','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5248985"><span id="translatedtitle"><span class="hlt">Compressible</span> gas properties of UF/sub 6/ for isentropic, normal <span class="hlt">shock</span>, and oblique <span class="hlt">shock</span> conditions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Harloff, G.J.</p> <p>1984-11-01</p> <p>Isentropic, normal <span class="hlt">shock</span>, and oblique <span class="hlt">shock</span> tables are given for the real gas UF/sub 6/ for Mach numbers up to 22. An evaluation of the real gas effects is given. A computer program listing is included.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SPIE.9894E..0TL','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SPIE.9894E..0TL"><span id="translatedtitle">Traveling solitary <span class="hlt">wave</span> induced by nonlocality in dispersive <span class="hlt">shock</span> <span class="hlt">wave</span> generation (Conference Presentation)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Louis, Hélène; Odent, Vincent; Louvergneaux, Eric</p> <p>2016-04-01</p> <p><span class="hlt">Shock</span> <span class="hlt">waves</span> are well-known nonlinear <span class="hlt">waves</span>, displaying an abrupt discontinuity. Observation can be made in a lot of physical fields, as in water <span class="hlt">wave</span>, plasma and nonlinear optics. <span class="hlt">Shock</span> <span class="hlt">waves</span> can either break or relax through either catastrophic or regularization phenomena. In this work, we restrain our study to dispersive <span class="hlt">shock</span> <span class="hlt">waves</span>. This regularization phenomenon implies the emission of dispersive <span class="hlt">waves</span>. We demonstrate experimentally and numerically the generation of spatial dispersive <span class="hlt">shock</span> <span class="hlt">waves</span> in a nonlocal focusing media. The generation of dispersive <span class="hlt">shock</span> <span class="hlt">wave</span> in a focusing media is more problematic than in a defocusing one. Indeed, the modulational instability has to be frustrated to observe this phenomenon. In 2010, the dispersive <span class="hlt">shock</span> <span class="hlt">wave</span> was demonstrated experimentally in a focusing media with a partially coherent beam [1]. Another way is to use a nonlocal media [2]. The impact of nonlocality is more important than the modulational instability frustration. Here, we use nematic liquid crystals (NLC) as Kerr-like nonlocal medium. To achieve <span class="hlt">shock</span> formation, we use the Riemann condition as initial spatial condition (edge at the beam entrance of the NLC cell). In these experimental conditions, we generate, experimentally and numerically, <span class="hlt">shock</span> <span class="hlt">waves</span> that relax through the emission of dispersive <span class="hlt">waves</span>. Associated with this phenomenon, we evidence the emergence of a localized <span class="hlt">wave</span> that travels through the transverse beam profile. The beam steepness, which is a good indicator of the <span class="hlt">shock</span> formation, is maximal at the <span class="hlt">shock</span> point position. This latter follows a power law versus the injected power as in [3]. Increasing the injected power, we found multiple <span class="hlt">shock</span> points. We have good agreements between the numerical simulations and the experimental results. [1] W. Wan, D. V Dylov, C. Barsi, and J. W. Fleischer, Opt. Lett. 35, 2819 (2010). [2] G. Assanto, T. R. Marchant, and N. F. Smyth, Phys. Rev. A - At. Mol. Opt. Phys. 78, 1 (2008). [3] N. Ghofraniha, L. S</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840008422','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840008422"><span id="translatedtitle"><span class="hlt">Shock</span> conditions and <span class="hlt">shock</span> <span class="hlt">wave</span> structures in a steady flow in a dissipative fluid</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Germain, P.; Guiraud, J. P.</p> <p>1983-01-01</p> <p>More precisely, calling xi the reciprocal of the Reynolds number based on the <span class="hlt">shock</span> <span class="hlt">wave</span> curvature radius, the xi terms of the first order are systematically taken into account. The most important result is a system of formulas giving a correction of order xi for the various RANKINE-HUGONIOT conditions. The suggested formulas may for instance have to be used instead of the conventional ones to evaluate the loss of the total pressure across the detached <span class="hlt">shock</span> <span class="hlt">wave</span> which is found at the nose of a very small probe in supersonic flow.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010PhRvE..82e1915S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010PhRvE..82e1915S"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">wave</span> initiated by an ion passing through liquid water</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Surdutovich, Eugene; Solov'Yov, Andrey V.</p> <p>2010-11-01</p> <p>We investigate the <span class="hlt">shock</span> <span class="hlt">wave</span> produced by an energetic ion in liquid water. This <span class="hlt">wave</span> is initiated by a rapid energy loss when the ion moves through the Bragg peak. The energy is transferred from the ion to secondary electrons, which then transfer it to the water molecules. The pressure in the overheated water increases by several orders of magnitude and drives a cylindrical <span class="hlt">shock</span> <span class="hlt">wave</span> on a nanometer scale. This <span class="hlt">wave</span> eventually weakens as the front expands further; but before that, it may contribute to DNA damage due to large pressure gradients developed within a few nanometers from the ion’s trajectory. This mechanism of DNA damage may be a very important contribution to the direct chemical effects of low-energy electrons and holes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22252089','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22252089"><span id="translatedtitle">Solitary and <span class="hlt">shock</span> <span class="hlt">waves</span> in magnetized electron-positron plasma</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lu, Ding; Li, Zi-Liang; Abdukerim, Nuriman; Xie, Bai-Song</p> <p>2014-02-15</p> <p>An Ohm's law for electron-positron (EP) plasma is obtained. In the framework of EP magnetohydrodynamics, we investigate nonrelativistic nonlinear <span class="hlt">waves</span>' solutions in a magnetized EP plasma. In the collisionless limit, quasistationary propagating solitary <span class="hlt">wave</span> structures for the magnetic field and the plasma density are obtained. It is found that the <span class="hlt">wave</span> amplitude increases with the Mach number and the Alfvén speed. However, the dependence on the plasma temperature is just the opposite. Moreover, for a cold EP plasma, the existence range of the solitary <span class="hlt">waves</span> depends only on the Alfvén speed. For a hot EP plasma, the existence range depends on the Alfvén speed as well as the plasma temperature. In the presence of collision, the electromagnetic fields and the plasma density can appear as oscillatory <span class="hlt">shock</span> structures because of the dissipation caused by the collisions. As the collision frequency increases, the oscillatory <span class="hlt">shock</span> structure becomes more and more monotonic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1982stw..proc.....T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1982stw..proc.....T"><span id="translatedtitle"><span class="hlt">Shock</span> tubes and <span class="hlt">waves</span>; Proceedings of the Thirteenth International Symposium, Niagara Falls, NY, July 6-9, 1981</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Treanor, C. E.; Hall, J. G.</p> <p>1982-10-01</p> <p>The present conference on <span class="hlt">shock</span> tubes and <span class="hlt">waves</span> considers <span class="hlt">shock</span> tube drivers, luminous <span class="hlt">shock</span> tubes, <span class="hlt">shock</span> tube temperature and pressure measurement, <span class="hlt">shock</span> front distortion in real gases, nonlinear standing <span class="hlt">waves</span>, transonic flow <span class="hlt">shock</span> <span class="hlt">wave</span> turbulent boundary interactions, wall roughness effects on reflected <span class="hlt">shock</span> bifurcation, argon thermal conductivity, pattern generation in gaseous detonations, cylindrical resonators, <span class="hlt">shock</span> tunnel-produced high gain lasers, fluid dynamic aspects of laser-metal interaction, and the ionization of argon gas behind reflected <span class="hlt">shock</span> <span class="hlt">waves</span>. Also discussed are the ionization relaxation of <span class="hlt">shock</span>-heated plasmas and gases, discharge flow/<span class="hlt">shock</span> tube studies of singlet oxygen, rotational and vibrational relaxation, chemiluminescence thermal and <span class="hlt">shock</span> <span class="hlt">wave</span> decomposition of hydrogen cyanide and hydrogen azide, <span class="hlt">shock</span> <span class="hlt">wave</span> structure in gas-particle mixtures at low Mach numbers, binary nucleation in a Ludwieg tube, <span class="hlt">shock</span> liquefaction experiments, pipeline explosions, the <span class="hlt">shock</span> <span class="hlt">wave</span> ignition of pulverized coal, and <span class="hlt">shock</span>-initiated methane combustion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23271649','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23271649"><span id="translatedtitle">Observations of ubiquitous <span class="hlt">compressive</span> <span class="hlt">waves</span> in the Sun's chromosphere.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Morton, Richard J; Verth, Gary; Jess, David B; Kuridze, David; Ruderman, Michael S; Mathioudakis, Mihalis; Erdélyi, Robertus</p> <p>2012-01-01</p> <p>The details of the mechanism(s) responsible for the observed heating and dynamics of the solar atmosphere still remain a mystery. Magnetohydrodynamic <span class="hlt">waves</span> are thought to have a vital role in this process. Although it has been shown that incompressible <span class="hlt">waves</span> are ubiquitous in off-limb solar atmospheric observations, their energy cannot be readily dissipated. Here we provide, for the first time, on-disk observation and identification of concurrent magnetohydrodynamic <span class="hlt">wave</span> modes, both <span class="hlt">compressible</span> and incompressible, in the solar chromosphere. The observed ubiquity and estimated energy flux associated with the detected magnetohydrodynamic <span class="hlt">waves</span> suggest the chromosphere is a vast reservoir of <span class="hlt">wave</span> energy with the potential to meet chromospheric and coronal heating requirements. We are also able to propose an upper bound on the flux of the observed <span class="hlt">wave</span> energy that is able to reach the corona based on observational constraints, which has important implications for the suggested mechanism(s) for quiescent coronal heating.</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('https://ntrs.nasa.gov/search.jsp?R=19910034707&hterms=Sound+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DSound%2Bwaves','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910034707&hterms=Sound+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DSound%2Bwaves"><span id="translatedtitle">Scattering of sound <span class="hlt">waves</span> by a <span class="hlt">compressible</span> vortex</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Colonius, Tim; Lele, Sanjiva K.; Moin, Parviz</p> <p>1991-01-01</p> <p>Scattering of plane sound <span class="hlt">waves</span> by a <span class="hlt">compressible</span> vortex is investigated by direct computation of the two-dimensional Navier-Stokes equations. Nonreflecting boundary conditions are utilized, and their accuracy is established by comparing results on different sized domains. Scattered <span class="hlt">waves</span> are directly measured from the computations. The resulting amplitude and directivity pattern of the scattered <span class="hlt">waves</span> is discussed, and compared to various theoretical predictions. For compact vortices (zero circulation), the scattered <span class="hlt">waves</span> directly computed are in good agreement with predictions based on an acoustic analogy. Strong scattering at about + or - 30 degrees from the direction of incident <span class="hlt">wave</span> propagation is observed. Back scattering is an order of magnitude smaller than forward scattering. For vortices with finite circulation refraction of the sound by the mean flow field outside the vortex core is found to be important in determining the amplitude and directivity of the scattered <span class="hlt">wave</span> field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JPhCS.652a2037K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JPhCS.652a2037K"><span id="translatedtitle">Generation of <span class="hlt">Shock-Wave</span> Disturbances at Plasma-Vapor Bubble Oscillation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kuznetsova, N. S.; Yudin, A. S.; Voitenko, N. V.</p> <p>2015-11-01</p> <p>The complex physical and mathematical model describing all steps of plasma-vapor bubble evolution in the system of the water-ground condensed media is presented. Discharge circuit operation, discharge plasma channel expansion, its transformation into the vapor-plasma bubble and its pulsation, pressure <span class="hlt">wave</span> generation and propagation of the mechanical stress <span class="hlt">waves</span> in the ground are self-consistently considered in the model. The model allows investigation of the basic laws of stored energy transformation into the discharge plasma channel, next to the plasma-vapor bubble and transformation of this energy to the energy of pressure <span class="hlt">wave</span> <span class="hlt">compressing</span> the surrounding ground. Power characteristics of <span class="hlt">wave</span> disturbances generated by gas-vapor bubble oscillation in liquid depending on the circuit parameters are analyzed for the prediction of the ground boundary displacement. The dynamics of the <span class="hlt">shock-wave</span> propagation in water-ground condensed media depending on the rate of the plasma channel energy release is investigated. Simulation of the <span class="hlt">shock-wave</span> phenomena at a plasma-vapor bubble oscillation in condensed media consecutively describes the physical processes underlying technology for producing piles by electro-discharge stuffing. The quantitative model verified by physical experimental tests will allow optimization of pulse generator parameters and electrode system construction of high-voltage equipment.</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> <span class="hlt">wave</span>-boundary layer 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 layer transition on an oblique <span class="hlt">shock</span> <span class="hlt">wave</span> 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 layer is only 0.2 mm, and seeding proved to be problematic as practically no seeding was recorded in the lower 40 % of the boundary layer. The top 60 % could, however, still be resolved with good accuracy and is found to be in good agreement with the <span class="hlt">compressible</span> Blasius solution. Due to the effects of turbulent mixing, the near-wall seeding deficiency disappears when the boundary layer transitions to a turbulent state. This allowed the seeding distribution to be used as an indicator for the state of the boundary layer, permitting to obtain an approximate intermittency distribution for the boundary layer transition region. This knowledge was then used for positioning the oblique <span class="hlt">shock</span> <span class="hlt">wave</span> in the laminar, transitional (50 % intermittency) or turbulent region of the boundary layer. 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 layer is lifted over the separation bubble and remains in a laminar state up to the impingement point of the <span class="hlt">shock</span> <span class="hlt">wave</span>. 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('https://ntrs.nasa.gov/search.jsp?R=19840041510&hterms=variable+compression+ratio&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dvariable%2Bcompression%2Bratio','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19840041510&hterms=variable+compression+ratio&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dvariable%2Bcompression%2Bratio"><span id="translatedtitle">On the theory of cosmic-ray-mediated <span class="hlt">shocks</span> with variable <span class="hlt">compression</span> ratio</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Eichler, D.</p> <p>1984-01-01</p> <p>Cosmic-ray-mediated <span class="hlt">shocks</span> may accelerate enough cosmic rays to high enough energies that they escape the <span class="hlt">shock</span>, carrying an appreciable amount of energy before being convected to downstream infinity. Under such conditions, it is noted, the overall <span class="hlt">compression</span> ratio cannot be determined from the conservation equations as in conventional hydrodynamic treatments, and the standard equations for <span class="hlt">shock</span> acceleration admit arbitrarily high <span class="hlt">compression</span> ratios. A procedure is outlined for obtaining the structure of high Mach number, cosmic-ray-mediated <span class="hlt">shocks</span>, including their overall compresion ratio, around a low Mach number viscous subshock. Analytic solutions are obtained by quardrature for an energy-dependent diffusion coefficient in the limit of extreme sensitivity to energy, which, unlike previous solutions, include the finite thermal pressure of the preshock gas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21266464','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21266464"><span id="translatedtitle">Density measurement of <span class="hlt">shock</span> <span class="hlt">compressed</span> foam using two-dimensional x-ray radiography</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Le Pape, Sebastien; Macphee, Andrew; Hey, Daniel; Patel, Pravesh; Mackinnon, Andrew; Key, Mike; Pasley, John; Wei, Mingsheng; Chen, Sophia; Ma, Tammy; Beg, Farhat; Alexander, N.; Stephens, Rich; Offerman, Dustin; Link, A.; Van-Woerkom, Lynn; Freeman, R.</p> <p>2008-10-15</p> <p>We have used spherically bent quartz crystal to image a laser-generated <span class="hlt">shock</span> in a foam medium. The foam targets had a density of 0.16 g/cm{sup 3} and thickness of 150 {mu}m, an aluminum/copper pusher drove the <span class="hlt">shock</span>. The experiment was performed at the Titan facility at Lawrence Livermore National Laboratory using a 2 ns, 250 J laser pulse to <span class="hlt">compress</span> the foam target, and a short pulse (10 ps, 350 J) to generate a bright Ti K{alpha} x-ray source at 4.5 keV to radiograph the <span class="hlt">shocked</span> target. The crystal used gives a high resolution ({approx}20 {mu}m) monochromatic image of the <span class="hlt">shock</span> <span class="hlt">compressed</span> foam.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ShWav..26...69H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ShWav..26...69H"><span id="translatedtitle">Response of ocean bottom dwellers exposed to underwater <span class="hlt">shock</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hosseini, S. H. R.; Kaiho, Kunio; Takayama, Kazuyoshi</p> <p>2016-01-01</p> <p>The paper reports results of experiments to estimate the mortality of ocean bottom dwellers, ostracoda, against underwater <span class="hlt">shock</span> <span class="hlt">wave</span> exposures. This study is motivated to verify the possible survival of ocean bottom dwellers, foraminifera, from the devastating underwater <span class="hlt">shock</span> <span class="hlt">waves</span> induced mass extinction of marine creatures which took place at giant asteroid impact events. Ocean bottom dwellers under study were ostracoda, the replacement of foraminifera, we readily sampled from ocean bottoms. An analogue experiment was performed on a laboratory scale to estimate the domain and boundary of over-pressures at which marine creatures' mortality occurs. Ostracods were exposed to underwater <span class="hlt">shock</span> <span class="hlt">waves</span> generated by the explosion of 100mg PETN pellets in a chamber at <span class="hlt">shock</span> over-pressures ranging up to 44MPa. Pressure histories were measured simultaneously on 113 samples. We found that bottom dwellers were distinctively killed against overpressures of 12MPa and this value is much higher than the usual <span class="hlt">shock</span> over-pressure threshold value for marine-creatures having lungs and balloons.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1810637M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1810637M"><span id="translatedtitle">Stochastic electron acceleration during turbulent reconnection in strong <span class="hlt">shock</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Matsumoto, Yosuke</p> <p>2016-04-01</p> <p>Acceleration of charged particles is a fundamental topic in astrophysical, space and laboratory plasmas. Very high energy particles are commonly found in the astrophysical and planetary <span class="hlt">shocks</span>, and in the energy releases of solar flares and terrestrial substorms. Evidence for relativistic particle production during such phenomena has attracted much attention concerning collisionless <span class="hlt">shock</span> <span class="hlt">waves</span> and magnetic reconnection, respectively, as ultimate plasma energization mechanisms. While the energy conversion proceeds macroscopically, and therefore the energy mostly flows to ions, plasma kinetic instabilities excited in a localized region have been considered to be the main electron heating and acceleration mechanisms. We present that efficient electron energization can occur in a much larger area during turbulent magnetic reconnection from the intrinsic nature of a strong collisionless <span class="hlt">shock</span> <span class="hlt">wave</span>. Supercomputer simulations have revealed a multiscale <span class="hlt">shock</span> structure comprising current sheets created via an ion-scale Weibel instability and resulting energy dissipation through magnetic reconnection. A part of the upstream electrons undergoes first-order Fermi acceleration by colliding with reconnection jets and magnetic islands, giving rise to a nonthermal relativistic population downstream. The dynamics has shed new light on magnetic reconnection as an agent of energy dissipation and particle acceleration in strong <span class="hlt">shock</span> <span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PMB....61.7031O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PMB....61.7031O"><span id="translatedtitle">Lithotripter <span class="hlt">shock</span> <span class="hlt">wave</span> interaction with a bubble near various biomaterials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ohl, S. W.; Klaseboer, E.; Szeri, A. J.; Khoo, B. C.</p> <p>2016-10-01</p> <p>Following previous work on the dynamics of an oscillating bubble near a bio-material (Ohl et al 2009 Phys. Med. Biol. 54 6313-36) and the interaction of a bubble with a shockwave (Klaseboer et al 2007 J. Fluid Mech. 593 33-56), the present work concerns the interaction of a gas bubble with a traveling <span class="hlt">shock</span> <span class="hlt">wave</span> (such as from a lithotripter) in the vicinity of bio-materials such as fat, skin, muscle, cornea, cartilage, and bone. The bubble is situated in water (to represent a water-like biofluid). The bubble collapses are not spherically symmetric, but tend to feature a high speed jet. A few simulations are performed and compared with available experimental observations from Sankin and Zhong (2006 Phys. Rev. E 74 046304). The collapses of cavitation bubbles (created by laser in the experiment) near an elastic membrane when hit by a lithotripter <span class="hlt">shock</span> <span class="hlt">wave</span> are correctly captured by the simulation. This is followed by a more systematic study of the effects involved concerning shockwave bubble biomaterial interactions. If a subsequent rarefaction <span class="hlt">wave</span> hits the collapsed bubble, it will re-expand to a very large size straining the bio-materials nearby before collapsing once again. It is noted that, for hard bio-material like bone, reflection of the <span class="hlt">shock</span> <span class="hlt">wave</span> at the bone—water interface can affect the bubble dynamics. Also the initial size of the bubble has a significant effect. Large bubbles (˜1 mm) will split into smaller bubbles, while small bubbles collapse with a high speed jet in the travel direction of the <span class="hlt">shock</span> <span class="hlt">wave</span>. The numerical model offers a computationally efficient way of understanding the complex phenomena involving the interplay of a bubble, a <span class="hlt">shock</span> <span class="hlt">wave</span>, and a nearby bio-material.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27649337','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27649337"><span id="translatedtitle">Lithotripter <span class="hlt">shock</span> <span class="hlt">wave</span> interaction with a bubble near various biomaterials.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ohl, S W; Klaseboer, E; Szeri, A J; Khoo, B C</p> <p>2016-10-07</p> <p>Following previous work on the dynamics of an oscillating bubble near a bio-material (Ohl et al 2009 Phys. Med. Biol. 54 6313-36) and the interaction of a bubble with a shockwave (Klaseboer et al 2007 J. Fluid Mech. 593 33-56), the present work concerns the interaction of a gas bubble with a traveling <span class="hlt">shock</span> <span class="hlt">wave</span> (such as from a lithotripter) in the vicinity of bio-materials such as fat, skin, muscle, cornea, cartilage, and bone. The bubble is situated in water (to represent a water-like biofluid). The bubble collapses are not spherically symmetric, but tend to feature a high speed jet. A few simulations are performed and compared with available experimental observations from Sankin and Zhong (2006 Phys. Rev. E 74 046304). The collapses of cavitation bubbles (created by laser in the experiment) near an elastic membrane when hit by a lithotripter <span class="hlt">shock</span> <span class="hlt">wave</span> are correctly captured by the simulation. This is followed by a more systematic study of the effects involved concerning shockwave bubble biomaterial interactions. If a subsequent rarefaction <span class="hlt">wave</span> hits the collapsed bubble, it will re-expand to a very large size straining the bio-materials nearby before collapsing once again. It is noted that, for hard bio-material like bone, reflection of the <span class="hlt">shock</span> <span class="hlt">wave</span> at the bone-water interface can affect the bubble dynamics. Also the initial size of the bubble has a significant effect. Large bubbles (∼1 mm) will split into smaller bubbles, while small bubbles collapse with a high speed jet in the travel direction of the <span class="hlt">shock</span> <span class="hlt">wave</span>. The numerical model offers a computationally efficient way of understanding the complex phenomena involving the interplay of a bubble, a <span class="hlt">shock</span> <span class="hlt">wave</span>, and a nearby bio-material.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26442143','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26442143"><span id="translatedtitle">Bubbles with <span class="hlt">shock</span> <span class="hlt">waves</span> and ultrasound: a review.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ohl, Siew-Wan; Klaseboer, Evert; Khoo, Boo Cheong</p> <p>2015-10-06</p> <p>The study of the interaction of bubbles with <span class="hlt">shock</span> <span class="hlt">waves</span> and ultrasound is sometimes termed 'acoustic cavitation'. It is of importance in many biomedical applications where sound <span class="hlt">waves</span> are applied. The use of <span class="hlt">shock</span> <span class="hlt">waves</span> and ultrasound in medical treatments is appealing because of their non-invasiveness. In this review, we present a variety of acoustics-bubble interactions, with a focus on <span class="hlt">shock</span> <span class="hlt">wave</span>-bubble interaction and bubble cloud phenomena. The dynamics of a single spherically oscillating bubble is rather well understood. However, when there is a nearby surface, the bubble often collapses non-spherically with a high-speed jet. The direction of the jet depends on the 'resistance' of the boundary: the bubble jets towards a rigid boundary, splits up near an elastic boundary, and jets away from a free surface. The presence of a <span class="hlt">shock</span> <span class="hlt">wave</span> complicates the bubble dynamics further. We shall discuss both experimental studies using high-speed photography and numerical simulations involving <span class="hlt">shock</span> <span class="hlt">wave</span>-bubble interaction. In biomedical applications, instead of a single bubble, often clouds of bubbles appear (consisting of many individual bubbles). The dynamics of such a bubble cloud is even more complex. We shall show some of the phenomena observed in a high-intensity focused ultrasound (HIFU) field. The nonlinear nature of the sound field and the complex inter-bubble interaction in a cloud present challenges to a comprehensive understanding of the physics of the bubble cloud in HIFU. We conclude the article with some comments on the challenges ahead.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820017213','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820017213"><span id="translatedtitle">On the acceleration of ions by interplanetary <span class="hlt">shock</span> <span class="hlt">waves</span>. 3: High time resolution observations of CIR proton events</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pesses, M. E.; Vanallen, J. A.; Tsurutani, B. T.; Smith, E. J.</p> <p>1981-01-01</p> <p>Observations within + or - 3 hours of corotating interaction region (CIR) <span class="hlt">shock</span> <span class="hlt">waves</span> of proton intensities, pitch angle distribution and crude differential energy spectra of the range of 0.6 E sub p 3.4 MeV are presented. The principle result is the evidence for the persistent flow of particles away from the <span class="hlt">shock</span>. The observations are found to be in good agreement with the hypothesis of local interplanetary <span class="hlt">shock</span> acceleration by the <span class="hlt">shock</span> drift and <span class="hlt">compression</span> mechanisms. The same set of observations strongly suggest that transit time damping does not play an important role in the acceleration of protons to 1 MeV in the immediate vicinity of CIR <span class="hlt">shocks</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960009428&hterms=vortex+generators&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dvortex%2Bgenerators','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960009428&hterms=vortex+generators&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dvortex%2Bgenerators"><span id="translatedtitle">Experimental study of the use of vortex generators to reduce fluctuating pressure loads in <span class="hlt">shock</span> <span class="hlt">wave</span> turbulent boundary layer interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Barter, John W.; Dolling, David S.</p> <p>1995-01-01</p> <p>Fluctuating wall pressure measurements have been made in a separated <span class="hlt">shock</span> <span class="hlt">wave</span>/turbulent boundary layer interaction produced by an unswept <span class="hlt">compression</span> corner in a Mach 5 flow. Wheeler doublet vortex generators were placed 15.8 boundary layer thicknesses upstream of the corner to study their effect on the fluctuating pressure loads produced by the translating separation <span class="hlt">shock</span>. The vortex generators produced significant three-dimensionality in an otherwise two-dimensional interaction. They reduced the upstream influence and the length of the region of <span class="hlt">shock</span> motion by 60% and 64%, respectively, decreased the maximum wall pressure rms by 23%, and shifted the fluctuations to a higher frequency band. The maximum fraction of energy in the 100-500 Hz frequency band is decreased by 11%. These changes are due to a fuller boundary layer profile, a weaker separation <span class="hlt">shock</span>, and increased boundary layer turbulence causing increased separation <span class="hlt">shock</span> jitter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24607758','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24607758"><span id="translatedtitle">Viscoelastic <span class="hlt">shock</span> <span class="hlt">wave</span> in ballistic gelatin behind soft body armor.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Li; Fan, Yurun; Li, Wei</p> <p>2014-06-01</p> <p>Ballistic gelatins are widely used as a surrogate of biological tissue in blunt trauma tests. Non-penetration impact tests of handgun bullets on the 10wt% ballistic gelatin block behind soft armor were carried out in which a high-speed camera recorded the crater׳s movement and pressure sensors imbedded in the gelatin block recorded the pressure <span class="hlt">waves</span> at different locations. The observed <span class="hlt">shock</span> <span class="hlt">wave</span> attenuation indicates the necessity of considering the gelatin׳s viscoelasticity. A three-element viscoelastic constitutive model was adopted, in which the relevant parameters were obtained via fitting the damping free oscillations at the beginning of the creep-mode of rheological measurement, and by examining the data of published split Hopkinson pressure bar (SHPB) experiments. The viscoelastic model is determined by a retardation time of 5.5×10(-5)s for high oscillation frequencies and a stress relaxation time of 2.0-4.5×10(-7)s for <span class="hlt">shock</span> <span class="hlt">wave</span> attenuation. Using the characteristic-line method and the spherical <span class="hlt">wave</span> assumption, the propagation of impact pressure <span class="hlt">wave</span> front and the subsequent unloading profile can be simulated using the experimental velocity boundary condition. The established viscoelastic model considerably improves the prediction of <span class="hlt">shock</span> <span class="hlt">wave</span> attenuation in the ballistic gelatin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA535019','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA535019"><span id="translatedtitle">What is a <span class="hlt">Shock</span> <span class="hlt">Wave</span> to a Molecule?</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2010-03-31</p> <p>spectrum of the very hot SAM. For high pressures , we used a diamond anvil apparatus. Prior to our work it was not possible to obtain vibrational spectra...of the SAM spectra under conditions of static high pressure and (quasi) static high temperature . Temperatures reached during <span class="hlt">shock</span> <span class="hlt">compression</span> can...also studied the response to flash heating and static high pressure up to 10 GPa. (a) Papers published in peer-reviewed journals (N/A for none) 1</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040129607','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040129607"><span id="translatedtitle">Internal <span class="hlt">Shock</span> Interactions in Propulsion/Airframe Integrated Three-Dimensional Sidewall <span class="hlt">Compression</span> Scramjet Inlets</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Holland, Scott D.; Perkins, John N.</p> <p>1992-01-01</p> <p>The advantages and design requirements of propulsion/airframe integration for high Mach number flight have led to extensive study of the three-dimensional sidewall <span class="hlt">compression</span> scramjet inlet in recent years. Recent research publications have indicated testing over a broad range of Mach number (2 to 18) in a variety of test gases, such as air, helium, and tetrafluoromethane. Multiple experimental techniques have been employed to obtain detailed internal <span class="hlt">shock</span> interaction data, performance data, and inlet starting limits. Computational fluid dynamics has been effectively used for preliminary parametric studies as well as in parallel with experiments to aid in the explanation of unusual or unexpected flow phenomena. Inlets of this genre afford a relatively simple, generic geometry while producing a highly complex, three-dimensional flow field dominated by <span class="hlt">shock/shock</span> and <span class="hlt">shock</span>/boundary layer interactions. While the importance of the viscous effects in high speed inlet interactions is recognized, the present work addresses in a parametric fashion the inviscid effects of leading edge sweep, sidewall <span class="hlt">compression</span>, and inflow Mach number on the internal <span class="hlt">shock</span> structure in terms of inlet <span class="hlt">compression</span> and mass capture. In the process, the source of the of the Mach number invariance with leading edge sweep for a constant sidewall <span class="hlt">compression</span> class of inlet is identified, and a previously undocumented spillage phenomenon in a constant effective wedge angle class of inlets is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22130476','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22130476"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">wave</span> refraction enhancing conditions on an extended interface</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Markhotok, A.; Popovic, S.</p> <p>2013-04-15</p> <p>We determined the law of <span class="hlt">shock</span> <span class="hlt">wave</span> refraction for a class of extended interfaces with continuously variable gradients. When the interface is extended or when the gas parameters vary fast enough, the interface cannot be considered as sharp or smooth and the existing calculation methods cannot be applied. The expressions we derived are general enough to cover all three types of the interface and are valid for any law of continuously varying parameters. We apply the equations to the case of exponentially increasing temperature on the boundary and compare the results for all three types of interfaces. We have demonstrated that the type of interface can increase or inhibit the <span class="hlt">shock</span> <span class="hlt">wave</span> refraction. Our findings can be helpful in understanding the results obtained in energy deposition experiments as well as for controlling the <span class="hlt">shock</span>-plasma interaction in other settings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001SPIE.4183..644K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001SPIE.4183..644K"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">wave</span> reflection over convex and concave wedge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kitade, M.; Kosugi, T.; Yada, K.; Takayama, Kazuyoshi</p> <p>2001-04-01</p> <p>It is well known that the transition criterion nearly agrees with the detachment criterion in the case of strong <span class="hlt">shocks</span>, two-dimensional, and pseudosteady flow. However, when the <span class="hlt">shock</span> <span class="hlt">wave</span> diffracts over a wedge whose angle is below the detachment criterion, that is, in the domain of Mach reflection, precursory regular reflection (PRR) appears near the leading edge and as the <span class="hlt">shock</span> <span class="hlt">wave</span> propagates, the PRR is swept away by the overtaking corner signal (cs) that forces the transition to Mach reflection. It is clear that viscosity and thermal conductivity influences transition and the triple point trajectory. On the other hand, the reflection over concave and convex wedges is truly unsteady flow, and the effect of viscosity and thermal conductivity on transition and triple point trajectory has not been reported. This paper describes that influence of viscosity over convex and concave corners investigated both experiments and numerical simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/8687173','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/8687173"><span id="translatedtitle">[Biochemical evaluation of renal lesions produced by electrohydraulic <span class="hlt">shock</span> <span class="hlt">waves</span>].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rodriguez Vela, L; Abadia Bayona, T; Lazaro Castillo, J; Guallar Labrador, A; Rioja Sanz, C; Rioja Sanz, L A</p> <p>1995-01-01</p> <p>The authors present a biochemical study of the renal lesions produced during extracorporeal electrohydraulic <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy (ESWL). The sequential variation (before and after ESWL) of various biochemical parameters of the blood and 24-hour urine was analysed in 50 patients. A significant increase of urinary N-Acetyl-Glucosaminidase (NAG), urinary NAG/urinary creatinine quotient, proteinuria, serum creatinine and potassium was detected during the 24 hours following ESWL. A significant fall in creatinine clearance, urinary osmolarity and uric acid clearance was also detected. A positive correlation was observed between these alterations, the number of <span class="hlt">shocks</span> and the kilovoltage used. On the 7th and 15th days, no significant difference was observed compared to the baseline values before ESWL. This can be explained by the fact that the lesions caused by <span class="hlt">shock</span> <span class="hlt">waves</span> are already in the repair phase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22472256','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22472256"><span id="translatedtitle">First-principles calculation of the reflectance of <span class="hlt">shock-compressed</span> xenon</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Norman, G. E.; Saitov, I. M. Stegailov, V. V.</p> <p>2015-05-15</p> <p>Within electron density functional theory (DFT), the reflectance of radiation from <span class="hlt">shock-compressed</span> xenon plasma is calculated. The dependence of the reflectance on the frequency of the incident radiation and on the plasma density is considered. The Fresnel formula is used. The expression for the longitudinal dielectric tensor in the long-wavelength limit is used to calculate the imaginary part of the dielectric function (DF). The real part of the DF is determined by the Kramers-Kronig transformation. The results are compared with experimental data. An approach is proposed to estimate the plasma frequency in <span class="hlt">shock-compressed</span> xenon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910067030&hterms=1092&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D%2526%25231092','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910067030&hterms=1092&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D%2526%25231092"><span id="translatedtitle">The optical emission from oscillating white dwarf radiative <span class="hlt">shock</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Imamura, James N.; Rashed, Hussain; Wolff, Michael T.</p> <p>1991-01-01</p> <p>The hypothesis that quasi-periodic oscillations (QPOs) are due to the oscillatory instability of radiative <span class="hlt">shock</span> <span class="hlt">waves</span> discovered by Langer et al. (1981, 1092) is examined. The time-dependent optical spectra of oscillating radiative <span class="hlt">shocks</span> produced by flows onto magnetic white dwarfs are calculated. The results are compared with the observations of the AM Her QPO sources V834 Cen, AN UMa, EF Eri, and VV Pup. It is found that the <span class="hlt">shock</span> oscillation model has difficulties with aspects of the observations for each of the sources. For VV Pup, AN UMa, and V834 Cen, the cyclotron luminosities for the observed magnetic fields of these systems, based on our calculations, are large. The strong cyclotron emission probably stabilizes the <span class="hlt">shock</span> oscillations. For EF Eri, the mass of the white dwarf based on hard X-ray observations is greater than 0.6 solar mass.</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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