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Sample records for reflected shock waves

  1. Weak shock wave reflection from concave surfaces

    NASA Astrophysics Data System (ADS)

    Gruber, Sebastien; Skews, Beric

    2013-07-01

    The reflection of very weak shock waves from concave curved surfaces has not been well documented in the past, and recent studies have shown the possible existence of a variation in the accepted reflection configuration evolution as a shock wave encounters an increasing gradient on the reflecting surface. The current study set out to investigate this anomaly using high-resolution photography. Shock tube tests were done on various concave circular and parabolic geometries, all with zero initial ramp angle. Although the results have limitations due to the achievable image resolution, the results indicate that for very weak Mach numbers, M S < 1.1, there may be a region in which the reflection configuration resembles that of a regular reflection, unlike for the stronger shock wave case. This region exists after the triple point of the Mach reflection meets the reflecting surface and prior to the formation of the additional shock structures that represent a transitioned regular reflection. The Mach and transitioned regular reflections at 1.03 < M s < 1.05 also exhibit no signs of a visible shear layer, or a clear discontinuity at the triple point, and are thus also apparently different in the weak shock regime than what has been described for stronger shocks, similar to what has been shown for weak shocks reflecting off a plane wedge.

  2. A note on weak shock wave reflection

    NASA Astrophysics Data System (ADS)

    Viero, D. P.; Susin, F. M.; Defina, A.

    2013-09-01

    This work discusses the possibility of reconstructing, both numerically and experimentally, the steady state flow field and shock reflection pattern close to the triple point of von Neumann, Guderley and Vasilev reflections. First, a criterion for the orientation of shock wave fronts, even in the case of subcritical/subsonic flow downstream the front, is introduced and formalized. Then, a technique for obtaining a close view of the above reflection patterns centered about the triple point is described and a numerical example, within the framework of shallow water flow, is presented and discussed.

  3. Shock wave reflections in a liquid filled thin tube

    NASA Astrophysics Data System (ADS)

    Yamamoto, Shota; Tagawa, Yoshiyuki; Kameda, Masaharu

    2013-11-01

    We investigate a behavior of an underwater shock wave in a thin glass tube using an ultra high-speed camera up to 107 frames per second. We here focus on the pressure of the reflected shock wave at interfaces (water-glass wall / water-air). A shock wave is visualized using the Background Oriented Schlieren (BOS) technique. We measure the time evolution of the shock front position and estimate the shock velocity, pressure, and internal energy as a function of the distance from the shock center. At the water-wall interface the reflected shock pressure is lower than the incident shock pressure, which agrees well with the theoretical estimation for an acoustic pressure wave. The reflected pressure at the air-water interface is much lower than the incident shock, indicating that the shape of the air-water interface may affect this reduction of the reflected pressure.

  4. 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.

  5. Irregular Reflection of Acoustical Shock Waves and von Neumann Paradox

    NASA Astrophysics Data System (ADS)

    Baskar, S.; Coulouvrat, F.; Marchiano, R.

    2006-05-01

    We investigate the reflection of weak acoustical shock waves grazing over a rigid surface. We define a critical parameter and examine the different types of reflection structure depending on this parameter. The study of the step shock is then extended to both N-waves and periodic saw-tooth waves, which are more realistic from an acoustical point of view. The numerical simulations reveal new reflection structures for these two waves which are not observed for step shocks. The results of the model are finally compared for periodic saw-tooth waves to ultrasonic experiments.

  6. The physical nature of weak shock wave reflection

    NASA Astrophysics Data System (ADS)

    Skews, Beric W.; Ashworth, Jason T.

    2005-10-01

    For weak shock waves and small wedge angles the application of three-shock (von Neumann) theory gives no physically realistic solutions and yet experiments clearly show a pattern of reflection of three shocks meeting at a triple point. This disagreement is referred to as the von Neumann paradox, and the reflection pattern as von Neumann reflection (vNR). Some recent numerical computations have indicated the existence of an expansion wave immediately behind the reflected wave as originally suggested by Guderley over fifty years ago. Furthermore, a recent solution of the inviscid transonic equations has indicated the possible existence of a very small, multi-wave structure immediately behind the three-shock confluence. A special shock tube has been constructed which allows Mach stem lengths to be obtained which are more than an order of magnitude larger than those obtainable in conventional shock tubes. Schlieren photographs do indeed show a structure consisting of an expansion wave followed by a small shock situated behind the confluence point, with some indication of smaller scale structures in some tests. This indicates that some of the earlier models of vNR, in the parameter space tested, are incorrect. The size of the region influenced by this small wave system is about 2% of the Mach stem length and it is therefore not surprising that it has not been detected before in conventional shock tube facilities.

  7. Reflection of cylindrical converging shock wave over a plane wedge

    NASA Astrophysics Data System (ADS)

    Zhang, Fu; Si, Ting; Zhai, Zhigang; Luo, Xisheng; Yang, Jiming; Lu, Xiyun

    2016-08-01

    The cylindrical converging shock reflection over a plane wedge is investigated experimentally and numerically in a specially designed shock tube which converts a planar shock into a cylindrical one. When the converging shock is moving along the wedge, both the shock strength and the incident angle are changing, which provides the possibility for the wave transition. The results show that both regular reflection (RR) and Mach reflection (MR) are found on the wedge with different initial incident angles. The wave transitions from direct Mach reflection (DiMR) to inverse Mach reflection (InMR) and further to transitioned regular reflection (TRR) are observed with appropriate initial incident angles. The instability development in the shear layer and strong vortices formation near the wall are evident, which are ascribed not only to the interaction of two shear layers but also to the shock impact and the shock converging effect. Because of the flow unsteadiness after the converging shock, the detachment criterion provides a good estimation for the RR → MR transition, but fails to predict the DiMR → InMR transition, and MR is found to persist slightly below the mechanical equilibrium condition. A hysteresis process is found in the MR → TRR transition and becomes more apparent as the increase of the initial incident angle due to the shock converging effect.

  8. Radiative transfer effects on reflected shock waves. II - Absorbing gas.

    NASA Technical Reports Server (NTRS)

    Su, F. Y.; Olfe, D. B.

    1972-01-01

    Radiative cooling effects behind a reflected shock wave are calculated for an absorbing-emitting gas by means of an expansion procedure in the small density ratio across the shock front. For a gray gas shock 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 shock wave 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 shock-tube measurements.

  9. The Interaction of a Reflected Shock Wave with the Boundary Layer in a Shock Tube

    NASA Technical Reports Server (NTRS)

    Mark, Herman

    1958-01-01

    Ideally, the reflection of a shock from the closed end of a shock tube provides, for laboratory study, a quantity of stationary gas at extremely high temperature. Because of the action of viscosity, however, the flow in the real case is not one-dimensional, and a boundary layer grows in the fluid following the initial shock wave. In this paper simplifying assumptions are made to allow an analysis of the interaction of the shock reflected from the closed end with the boundary layer of the initial shock afterflow. The analysis predicts that interactions of several different types will exist in different ranges of initial shock Mach number. It is shown that the cooling effect of the wall on the afterflow boundary layer accounts for the change in interaction type. An experiment is carried out which verifies the existence of the several interaction regions and shows that they are satisfactorily predicted by the theory. Along with these results, sufficient information is obtained from the experiments to make possible a model for the interaction in the most complicated case. This model is further verified by measurements made during the experiment. The case of interaction with a turbulent boundary layer is also considered. Identifying the type of interaction with the state of turbulence of the interacting boundary layer allows for an estimate of the state of turbulence of the boundary layer based on an experimental investigation of the type of interaction. A method is proposed whereby the effect of the boundary-layer interaction on the strength of the reflected shock may be calculated. The calculation indicates that the reflected shock is rapidly attenuated for a short distance after reflection, and this result compares favorably with available experimental results.

  10. Auto-ignition of hydrocarbons behind reflected shock waves.

    NASA Technical Reports Server (NTRS)

    Vermeer, D. J.; Meyer, J. W.; Oppenheim, A. K.

    1972-01-01

    The paper reports on the study of auto-ignition of hydrocarbon-oxygen mixtures behind reflected shock waves. Because of their bearing on the problem of knock in internal combustion engines, n-heptane and iso-octane were chosen as the combustible species. Their stoichiometric mixtures with oxygen had to be diluted with 70% argon to reduce the influence of the boundary layer. Photographic records demonstrated the existence of two different modes of ignition, as has been previously established for the hydrogen-oxygen system. The pressure-temperature limits between these regions of mild and strong ignition were determined. From the same experimental tests, induction time data were obtained over the pressure range of 1-4 atm and the temperature interval of 1200-1700 K.

  11. Microscopic structure of the Mach-type reflection of weak shock waves

    NASA Astrophysics Data System (ADS)

    Walenta, Z. A.

    The purpose of the present work was to investigate the microscopic structure of the three-shock inter-action region generated in a low-density shock tube during the Mach-type reflection of a weak shock wave. The experimental conditions corresponded to the case when Von Neumann's theory fails to predict the existence of reflection while Guderley's theory predicts the presence of a rarefaction wave behind the reflected shock. The experiment shows that under such conditions the Mach-type reflection does exist, and no rarefaction wave is present. A possible reason for this disagreement is the influence of viscosity, neglected in Von Neumann's and Guderley's theories.

  12. On the Role of Shock Wave Reflections in Impact Cratering

    NASA Astrophysics Data System (ADS)

    Bertoglio, O.

    2015-07-01

    When the downward impact shockwave meets a rock discontinuity, an upward reflected pressure wave is created. When travelling through the crater fill deposits, this wave projects upwards the shattered rocks which so may contribute to the rim creation.

  13. Leading edge reflection patterns for cylindrical converging shock waves over convex obstacles

    NASA Astrophysics Data System (ADS)

    Vignati, F.; Guardone, A.

    2016-09-01

    The unsteady reflection of cylindrical converging shock waves over convex obstacles is investigated numerically. At the leading edge, numerical simulations show the occurrence of all types of regular and irregular reflections predicted by the pseudo-steady theory for planar shock-wave reflections over planar surfaces, although for different combinations of wedge angles and incident shock Mach number. The domain of occurrence of each reflection type and its evolution in time due to shock acceleration and to the non-planar geometry is determined and it is compared to the results of the pseudo-steady theory. The dependence of the reflection pattern on the (local) values of the wedge angle is in good agreement with the pseudo-steady theory. Less complex reflection patterns are instead observed at larger values of the leading edge shock Mach number at which the pseudo-steady theory predicts the occurrence of more complex reflection patterns.

  14. Numerical studies of shock focusing induced by reflection of detonation waves within a hemispherical implosion chamber

    NASA Astrophysics Data System (ADS)

    Hatanaka, K.; Saito, T.; Takayama, K.

    2012-11-01

    The initiation and the propagation of detonation waves in a hemispherical chamber and the imploding shock waves that are the reflected detonation waves at the chamber wall are numerically investigated. The effects of the boundary layer and the non-uniformity of the flow field induced by the detonation wave on the imploding shock stability are examined. It is found that the effect of the boundary layer separation on the chamber wall has the strongest effect on the implosion focus.

  15. Comparison of weak-shock reflection factors for wedges, cylinders and blast waves

    SciTech Connect

    Reichenbach, H.; Kuhl, A.L.

    1992-07-01

    Ernst Mach (1838--1916) was the first to discover an irregular reflection phenomenon of shock waves, as is well known in our community. In fact, this occurred in 1875 -- three years earlier than usually assumed in the literature. A facsimile of the paper in which he mentioned a special shock wave behavior is shown in a figure. However, it is correct that Mach gave the physical interpretation of this phenomenon in 1878. Since Mach`s discovery of an irregular shock reflection pattern 117 years ago, new shock configurations have been discovered -- one of the most recent examples is the so-called {open_quotes}von Neumann reflection{close_quotes} for weak shocks as reported by Colella and Henderson in 1990. Due to active research efforts related to shock reflection, especially in the last two decades, we now have a relatively detailed understanding of reflection phenomena and of transition conditions from one reflection configuration to another. The purpose of this paper is to compare reflection factors for weak shocks from various surfaces, and to focus attention on some unsolved questions. Three different cases are considered: (1) square-wave planar shock reflection from wedges, (2) square-wave planar shock reflection from cylinders and (3) spherical blast wave reflection from a planar surface. The authors restrict themselves to weak shocks. Following Henderson`s definition, shocks with a Mach number of M{sub 0} < 1.56 in air or with an overpressure of {Delta}p{sub I} < 25 psi (1.66 bar) under normal ambient conditions are called weak.

  16. Comparison of weak-shock reflection factors for wedges, cylinders and blast waves

    SciTech Connect

    Reichenbach, H. , Freiburg im Breisgau ); Kuhl, A.L. )

    1992-07-01

    Ernst Mach (1838--1916) was the first to discover an irregular reflection phenomenon of shock waves, as is well known in our community. In fact, this occurred in 1875 -- three years earlier than usually assumed in the literature. A facsimile of the paper in which he mentioned a special shock wave behavior is shown in a figure. However, it is correct that Mach gave the physical interpretation of this phenomenon in 1878. Since Mach's discovery of an irregular shock reflection pattern 117 years ago, new shock configurations have been discovered -- one of the most recent examples is the so-called [open quotes]von Neumann reflection[close quotes] for weak shocks as reported by Colella and Henderson in 1990. Due to active research efforts related to shock reflection, especially in the last two decades, we now have a relatively detailed understanding of reflection phenomena and of transition conditions from one reflection configuration to another. The purpose of this paper is to compare reflection factors for weak shocks from various surfaces, and to focus attention on some unsolved questions. Three different cases are considered: (1) square-wave planar shock reflection from wedges, (2) square-wave planar shock reflection from cylinders and (3) spherical blast wave reflection from a planar surface. The authors restrict themselves to weak shocks. Following Henderson's definition, shocks with a Mach number of M[sub 0] < 1.56 in air or with an overpressure of [Delta]p[sub I] < 25 psi (1.66 bar) under normal ambient conditions are called weak.

  17. Diffuse holographic interferometric observation of shock wave reflection from a skewed wedge

    NASA Astrophysics Data System (ADS)

    Numata, D.; Ohtani, K.; Takayama, K.

    2009-06-01

    The pattern of shock wave reflection over a wedge is, in general, either a regular reflection or a Mach reflection, depending on wedge angles, shock wave Mach numbers, and specific heat ratios of gases. However, regular and Mach reflections can coexist, in particular, over a three-dimensional wedge surface, whose inclination angles locally vary normal to the direction of shock propagation. This paper reports a result of diffuse double exposure holographic interferometric observations of shock wave reflections over a skewed wedge surface placed in a 100 × 180 mm shock tube. The wedge consists of a straight generating line whose local inclination angle varies continuously from 30° to 60°. Painting its surface with fluorescent spray paint and irradiating its surface with a collimated object beam at a time interval of a few microseconds, we succeeded in visualizing three-dimensional shock reflection over the skewed wedge surface. Experiments were performed at shock Mach numbers, 1.55, 2.02, and 2.53 in air. From reconstructed holographic images, we estimated critical transition angles at these shock wave Mach numbers and found that these were very close to those over straight wedges. This is attributable to the flow three-dimensionality.

  18. Time-resolved spectroscopic measurements behind incident and reflected shock waves in air and xenon

    NASA Technical Reports Server (NTRS)

    Yoshinaga, T.

    1973-01-01

    Time-resolved spectra have been obtained behind incident and reflected shock waves in air and xenon at initial pressures of 0.1 and 1.0 torr using a rotating drum spectrograph and the OSU (The Ohio State University) arc-driven shock tube. These spectra were used to determine the qualitative nature of the flow as well as for making estimates of the available test time. The (n+1,n) and (n,n) band spectra of N2(+) (1st negative) were observed in the test gas behind incident shock waves in air at p1=1.0 torr and Us=9-10 km/sec. Behind reflected shock waves in air, the continuum of spectra appeared to cover almost the entire wavelength of 2,500-7,000 A for the shock-heated test gas. For xenon, the spectra for the incident shock wave cases for p1=0.1 torr show an interesting structure in which two intensely bright regions are witnessed in the time direction. The spectra obtained behind reflected shock waves in xenon were also dominated by continuum radiation but included strong absorption spectra due to FeI and FeII from the moment the reflected shock passed and on.

  19. Numerical investigation of shock wave reflections near the head ends of rotating detonation engines

    NASA Astrophysics Data System (ADS)

    Zhou, R.; Wang, J.-P.

    2013-09-01

    The influence of various chamber geometries on shock wave reflections near the head end of rotating detonation engines was investigated. A hydrogen/air one-step chemical reaction model was used. The results demonstrated that the variation in flow field along the radial direction was not obvious when the chamber width was small, but became progressively more obvious as the chamber width increased. The thrust increased linearly, and the detonation height and the fuel-based gross specific impulse were almost constant as the chamber width increased. Near the head end, shock waves reflected repeatedly between the inner and outer walls. Both regular and Mach reflections were found near the head end. The length of the Mach stem increased as the chamber length increased. When the chamber width, chamber length and injection parameters were the same, the larger inner radius resulted in more shock wave reflections between the inner and outer walls. The greater the ratio of the chamber width to the inner radius, the weaker the shock wave reflection near the head end. The detonation height on the outer wall and the thrust, both increased correspondingly, while the specific impulse was almost constant as the inner radius of the chamber increased. The numerical shock wave reflection phenomena coincided qualitatively with the experimental results.

  20. An experimental study of shock wave reflection over non-Newtonian liquid wedges

    NASA Astrophysics Data System (ADS)

    Jeon, Hongjoo; Dougherty, Christopher; Miller, Ryan; Eliasson, Veronica

    2014-11-01

    An experimental investigation of the reflection of a planar shock wave over different density liquid wedges was performed by means of an angled shock tube. The goal is to find a transition criterion between regular reflection (RR) and irregular reflection (IR). The shock tube can be rotated to any angle between the horizontal and vertical planes for various impact media. The reflection of the oblique shock wave for different wedges was visualized using the shadowgraph and schlieren techniques. Previous research by Ben-Dor et al. (1987) conducted different types of reflecting solid conditions and Takayama et al. (1989) investigated a similar experiment with a nonsolid reflecting surface. Motivated by the previous work, we undertook a series of shock tube experiments where both Newtonian and non-Newtonian liquids were used to form a wedge for a shock wave to impact. Shear-thickening materials, such as a water-cornstarch mixture, or similar suspensions, could potentially be utilized to protect soldiers and other high-risk personnel from impacts. Results show that, for both a water-cornstarch and ballistic gelatin sample, the detachment angle at which the RR transitions to an IR was different from those of a solid and water. This work is funded by NSF Grant #CBET-1437412.

  1. Numerical solutions of several reflected shock-wave flow fields with nonequilibrium chemical reactions

    NASA Technical Reports Server (NTRS)

    Hanson, R. K.; Presley, L. L.; Williams, E. V.

    1972-01-01

    The method of characteristics for a chemically reacting gas is used in the construction of the time-dependent, one-dimensional flow field resulting from the normal reflection of an incident shock wave at the end wall of a shock tube. Nonequilibrium chemical reactions are allowed behind both the incident and reflected shock waves. All the solutions are evaluated for oxygen, but the results are generally representative of any inviscid, nonconducting, and nonradiating diatomic gas. The solutions clearly show that: (1) both the incident- and reflected-shock chemical relaxation times are important in governing the time to attain steady state thermodynamic properties; and (2) adjacent to the end wall, an excess-entropy layer develops wherein the steady state values of all the thermodynamic variables except pressure differ significantly from their corresponding Rankine-Hugoniot equilibrium values.

  2. Optical measurements of the mutual reflection of two-plane shock waves

    SciTech Connect

    Barbosa, F.J.; Skews, B.W.

    1995-12-31

    A bifurcated shock tube is used to create two synchronized waves of equal strength. Essentially a single shock wave is split symmetrically in two, the two waves then are later brought back together at a trailing edge of a wedge to interact, the plane of symmetry acting as an ideal rigid wall. The normal method of studying mach reflections is to allow a plane shock wave to impinge on a wedge, however the boundary layer growth on the wedge surface effectively ensures that the flow direction behind the Mach stem does not have to satisfy the boundary condition of being parallel to the surface of the wedge. Thus the transition from regular to Mach reflection occurs at higher angles of incidence than theory allows. The present experiment was initiated to generate data on the ideal cause of reflection off a plane wall. The advantage of the new system is that like classical theory and computational solutions of the inviscid Euler equations, the boundary layer no slip condition is not imposed at the plane of reflection. Optical methods are used to investigate the post-shock flow, as well as to help explain the complex interactions which occur when the two shock waves are not synchronized. These interactions show many very interesting features and clearly indicate the need for higher resolution measurements such as are obtained using holographic interferometry, and also to extend the work to different wedge angles and Mach numbers.

  3. Effect of screening layers of a suspension in a gas on shock-wave reflection

    NASA Astrophysics Data System (ADS)

    Ivandaev, A. I.; Kutushev, A. G.

    1985-02-01

    The effect of a screening layer of a suspension of finely dispersed particles in a gas on the reflection of a plane nonstationary shock wave from a rigid wall is analyzed numerically. The possibility of using limiting (equilibrium and frozen) flow schemes in the layer to calcuate the reflection process is assessed. The effect of screening-layer parameters on the maximum pressure on the wall is investigated. It is noted that the results may be of use in the design of systems of dust protection against shock waves and in the analysis of gasdynamic techniques for the deposition of powder coatings.

  4. Weak-shock reflection factors

    SciTech Connect

    Reichenbach, H.; Kuhl, A.L.

    1993-09-07

    The purpose of this paper is to compare reflection factors for weak shocks from various surfaces, and to focus attention on some unsolved questions. Three different cases are considered: square-wave planar shock reflection from wedges; square-wave planar shock reflection from cylinders; and spherical blast wave reflection from a planar surface. We restrict ourselves to weak shocks. Shocks with a Mach number of M{sub O} < 1.56 in air or with an overpressure of {Delta}{sub PI} < 25 psi (1.66 bar) under normal ambient conditions are called weak.

  5. Pseudo-stationary oblique-shock-wave reflections in frozen and equilibrium air

    NASA Astrophysics Data System (ADS)

    Lee, J.-H.; Glass, I. I.

    An analytical and numerical investigation has been undertaken concerning the reflection of oblique shock waves in pseudostationary flow, with emphasis on air (due to its importance in the determination of structural loading caused by blast). The transition boundaries between the four types of shock wave reflection (regular, single Mach, complex Mach, and double Mach; respectively, RR, SMR, CMR, and DMR) were established up to an initial shock Mach number M(S) of 20 for both frozen (perfect) and imperfect air in thermodynamic equilibrium. It is confirmed that RR persists below the frozen gas RR-MR transition line determined by the von Neumann detachment criterion, and that some SMR, CMR, and DMR occurred outside their analytically predicted domains.

  6. Ethane ignition and oxidation behind reflected shock waves

    SciTech Connect

    de Vries, Jaap; Hall, Joel M.; Simmons, Stefanie L.; Kalitan, Danielle M.; Petersen, Eric L.; Rickard, Matthew J.A.

    2007-07-15

    Several diluted C{sub 2}H{sub 6}/O{sub 2}/Ar mixtures of varying concentrations and equivalence ratios (0.5<{phi}<2.0) were studied at temperatures between 1218 and 1860 K and at pressures between 0.57 and 3.0 atm using a shock tube. The argon dilution ranged from 91 to 98% by volume. Reaction progress was monitored using chemiluminescence emission from OH{sup *} and CH{sup *} at 307 and 431 nm, respectively. The dependence of ignition delay time on temperature, activation energy, and reactant concentrations is given in a master correlation of all the experimental data. The overall activation energy was found to be 39.6 kcal/mol over the range of conditions studied. For the first time in a shock-tube C{sub 2}H{sub 6} oxidation study, detailed species profile data and quantitative OH{sup *} time histories were documented, in addition to ignition delay times, and compared against modern detailed mechanisms. Because of the comprehensive scope of the present study and the high precision of the experimental data, several conclusions can be drawn that could not have been reached from earlier studies. Although there is some discrepancy among previous ethane oxidation data, the present work clearly shows the convergence of ignition delay time measurements to those herein and the remarkable accuracy of current kinetics models over most of the parameter space explored, despite the variation in the literature data. However, two areas shown to still need more measurements and better modeling are those of higher pressures and fuel-rich ethane-air mixtures. After appropriate OH{sup *} and CH{sup *} submechanisms are added, two modern chemical kinetics mechanisms containing high-temperature ethane chemistry are compared to the data to gauge the current state of C{sub 2}H{sub 6} oxidation modeling over the conditions of this study. The reproduction of the OH{sup *} and CH{sup *} profiles, together with {tau}{sub ign} predictions by these models, are compared against the profiles

  7. Effects of trapped electrons on ion reflection in an oblique shock wave

    SciTech Connect

    Toida, Mieko; Inagaki, Junya

    2015-06-15

    A magnetosonic shock wave propagating obliquely to an external magnetic field can trap electrons and accelerate them to ultrarelativistic energies. The trapped electrons excite two-dimensional (2D) electromagnetic fluctuations with finite wavenumbers along the shock front. We study effects of the trapped electrons on ion motions through the 2D fluctuations. It is analytically shown that the fraction of ions reflected from the shock front is enhanced by the 2D fluctuations. This is confirmed by 2D (two space coordinates and three velocities) relativistic, electromagnetic particle simulations with full ion and electron dynamics and calculation of test ions in the electromagnetic fields averaged along the shock front. A comparison between 2D and one-dimensional electromagnetic particle simulations is also shown.

  8. Nonself-similar flow with a shock wave reflected from the center of symmetry and new self-similar solutions with two reflected shocks

    NASA Astrophysics Data System (ADS)

    Valiyev, Kh. F.; Kraiko, A. N.

    2013-03-01

    In some problems concerning cylindrically and spherically symmetric unsteady ideal (inviscid and nonheat-conducting) gas flows at the axis and center of symmetry (hereafter, at the center of symmetry), the gas density vanishes and the speed of sound becomes infinite starting at some time. This situation occurs in the problem of a shock wave reflecting from the center of symmetry. For an ideal gas with constant heat capacities and their ratio γ (adiabatic exponent), the solution of this problem near the reflection point is self-similar with a self-similarity exponent determined in the course of the solution construction. Assuming that γ on the reflected shock wave decreases, if this decrease exceeds a threshold value, the flow changes substantially. Assuming that the type of the solution remains unchanged for such γ, self-similarity is preserved if a piston starts expanding from the center of symmetry at the reflection time preceded by a finite-intensity reflected shock wave propagating at the speed of sound. To answer some questions arising in this formulation, specifically, to find the solution in the absence of the piston, the evolution of a close-to-self-similar solution calculated by the method of characteristics is traced. The required modification of the method of characteristics and the results obtained with it are described. The numerical results reveal a number of unexpected features. As a result, new self-similar solutions are constructed in which two (rather than one) shock waves reflect from the center of symmetry in the absence of the piston.

  9. Imploding conical shock waves

    NASA Astrophysics Data System (ADS)

    Paton, R. T.; Skews, B. W.; Rubidge, S.; Snow, J.

    2013-07-01

    The behaviour of conical shock waves imploding axisymmetrically was first studied numerically by Hornung (J Fluid Mech 409:1-12, 2000) and this prompted a limited experimental investigation into these complex flow patterns by Skews et al. (Shock Waves 11:323-326, 2002). Modification of the simulation boundary conditions, resulting in the loss of self-similarity, was necessary to image the flow experimentally. The current tests examine the temporal evolution of these flows utilising a converging conical gap of fixed width fed by a shock wave impinging at its entrance, supported by CFD simulations. The effects of gap thickness, angle and incident shock strength were investigated. The wave initially diffracts around the outer lip of the gap shedding a vortex which, for strong incident shock cases, can contain embedded shocks. The converging shock at exit reflects on the axis of symmetry with the reflected wave propagating outwards resulting in a triple point developing on the incident wave together with the associated shear layer. This axisymmetric shear layer rolls up into a mushroom-shaped toroidal vortex ring and forward-facing jet. For strong shocks, this deforms the Mach disk to the extent of forming a second triple point with the primary shock exhibiting a double bulge. Separate features resembling the Richtmeyer-Meshkov and Kelvin-Helmholtz instabilities were noted in some tests. Aside from the incident wave curvature, the reflection patterns demonstrated correspond well with the V- and DV-types identified by Hornung although type S was not clearly seen, possibly due to the occlusion of the reflection region by the outer diffraction vortex at these early times. Some additional computational work explicitly exploring the limits of the parameter space for such systems has demonstrated the existence of a possible further reflection type, called vN-type, which is similar to the von Neumann reflection for plane waves. It is recommended that the parameter space be

  10. CONTRIBUTION OF VELOCITY VORTICES AND FAST SHOCK REFLECTION AND REFRACTION TO THE FORMATION OF EUV WAVES IN SOLAR ERUPTIONS

    SciTech Connect

    Wang, Hongjuan; Liu, Siqing; Gong, Jiancun; Wu, Ning; Lin, Jun

    2015-06-01

    We numerically study the detailed evolutionary features of the wave-like disturbance and its propagation in the eruption. This work is a follow-up to Wang et al., using significantly upgraded new simulations. We focus on the contribution of the velocity vortices and the fast shock reflection and refraction in the solar corona to the formation of the EUV waves. Following the loss of equilibrium in the coronal magnetic structure, the flux rope exhibits rapid motions and invokes the fast-mode shock at the front of the rope, which then produces a type II radio burst. The expansion of the fast shock, which is associated with outward motion, takes place in various directions, and the downward expansion shows the reflection and the refraction as a result of the non-uniform background plasma. The reflected component of the fast shock propagates upward and the refracted component propagates downward. As the refracted component reaches the boundary surface, a weak echo is excited. The Moreton wave is invoked as the fast shock touches the bottom boundary, so the Moreton wave lags the type II burst. A secondary echo occurs in the area where reflection of the fast shock encounters the slow-mode shock, and the nearby magnetic field lines are further distorted because of the interaction between the secondary echo and the velocity vortices. Our results indicate that the EUV wave may arise from various processes that are revealed in the new simulations.

  11. A State-of-the-Knowledge Review on Pseudo-Steady Shock-Wave Reflections and their Transition Criteria

    NASA Astrophysics Data System (ADS)

    Ben-Dor, G.

    2006-07-01

    The distinguished philosopher Ernst Mach published the first known paper on the phenomenon of planar shock-wave reflections over straight wedges over 125 years ago in 1878. In his publication he presented two wave configurations that could result from this reflection process, a regular reflection (RR) and a configuration that was later named after him and called Mach reflection (MR) in the early 1940s. In 1945, Smith reported on an additional wave configuration, which had a reflected shock wave that was slightly different from that of the just-mentioned Mach reflection. Smith (OSRD Rep. 6271, Off. Sci. Res. Dev., 1945) did not ascribe any special importance to the wave configuration that he observed. The wave configuration that was observed and reported by Smith (OSRD Rep. 6271, Off. Sci. Res. Dev., 1945) was recognized as an independent one only about 5 years later when White (Tech. Rep. II-10, Princeton Univ. Dept. Phys., 1951) reported on the discovery of a new wave configuration that was named double-Mach reflections (DMR) because it had similar features to that of the Mach reflection wave configuration but all the features were doubled. For this reason the Mach reflection wave configuration has been re-named single-Mach reflection (SMR). (Until the late 1970s it was called simple-Mach reflection although nothing is simple about it.). The discovery of the double-Mach reflection revealed that the wave configuration that was first observed by Smith was an intermediate wave configuration between the SMR and the DMR wave configurations. For this reason it was named transitional-Mach reflection (TMR) (Until the early 1980s it was called complex-Mach reflection although it is not the most complex one.). Since the discovery of the DMR many investigations were aimed at elucidating the exact transition criteria between the above-mentioned four different wave configurations as well as some additional configurations and sub-configurations that were discovered later. In

  12. Analytical reconsideration of the von Neumann paradox in the reflection of a shock wave over a wedge

    NASA Astrophysics Data System (ADS)

    Vasilev, Eugene I.; Elperin, Tov; Ben-Dor, Gabi

    2008-04-01

    The reflection of weak shock waves has been reconsidered analytically using shock polars. Based on the boundary condition across the slipstream, the solutions of the three-shock theory (3ST) were classified as "standard-3ST solutions" and "nonstandard-3ST solutions." It was shown that there are two situations in the nonstandard case: A situation whereby the 3ST provides solutions of which at least one is physical and a situation when the 3ST provides a solution which is not physical, and hence a reflection having a three-shock confluence is not possible. In addition, it is shown that there are initial conditions for which the 3ST does not provide any solution. In these situations, a four-wave theory, which is also presented in this study, replaces the 3ST. It is shown that four different wave configurations can exist in the weak shock wave reflection domain, a Mach reflection, a von Neumann reflection, a ?R (this reflection is not named yet!), and a modified Guderley reflection (GR). Recall that the wave configuration that was hypothesized by Guderley ["Considerations of the structure of mixed subsonic-supersonic flow patterns," Air Materiel Command Technical Report No. F-TR-2168-ND, ATI No. 22780, GS-AAF-Wright Field No. 39, U.S. Wright-Patterson Air Force Base, Dayton, OH (October 1947); Theorie Schallnaher Strömungen (Springer-Verlag, Berlin, 1957)] and later termed Guderley reflection did not include a slipstream (see Fig. 7). Our numerical study revealed that the wave structure proposed by Guderley must be complemented by a slipstream (see Fig. 4) in order to be relevant for explaining the von Neumann paradox. Hereafter, for simplicity, this modified GR wave configuration will be also termed Guderley reflection. The domains and transition boundaries between these four types of reflection are elucidated.

  13. Shock wave reflection induced detonation (SWRID) under high pressure and temperature condition in closed cylinder

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Qi, Y.; Liu, H.; Zhang, P.; He, X.; Wang, J.

    2016-07-01

    Super-knock is one of the major obstacles for improving power density in advanced internal combustion engines (ICE). This work studied the mechanism of super-knock initiation using a rapid compression machine that simulated conditions relevant to ICEs and provided excellent optical accessibility. Based on the high-speed images and pressure traces of the stoichiometric iso-octane/oxygen/nitrogen combustion under high-temperature and high-pressure conditions, it was observed that detonation was first initiated in the near-wall region as a result of shock wave reflection. Before detonation was initiated, the speed of the combustion wave front was less than that of the Chapman-Jouguet (C-J) detonation speed (around 1840 m/s). In the immediate vicinity of the initiation, the detonation speed was much higher than that of the C-J detonation.

  14. Shock wave reflection induced detonation (SWRID) under high pressure and temperature condition in closed cylinder

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Qi, Y.; Liu, H.; Zhang, P.; He, X.; Wang, J.

    2016-09-01

    Super-knock is one of the major obstacles for improving power density in advanced internal combustion engines (ICE). This work studied the mechanism of super-knock initiation using a rapid compression machine that simulated conditions relevant to ICEs and provided excellent optical accessibility. Based on the high-speed images and pressure traces of the stoichiometric iso-octane/oxygen/nitrogen combustion under high-temperature and high-pressure conditions, it was observed that detonation was first initiated in the near-wall region as a result of shock wave reflection. Before detonation was initiated, the speed of the combustion wave front was less than that of the Chapman-Jouguet (C-J) detonation speed (around 1840 m/s). In the immediate vicinity of the initiation, the detonation speed was much higher than that of the C-J detonation.

  15. 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.

  16. Oxygen atom kinetics in silane-hydrogen-nitrous oxide mixtures behind reflected shock waves

    NASA Astrophysics Data System (ADS)

    Javoy, S.; Mével, R.; Dupré, G.

    2010-11-01

    Resonance Absorption Spectroscopy has been used to study the O-atom dynamics behind reflected shock waves in highly argon diluted silane-hydrogen-nitrous oxide mixtures in the temperature range 1606-2528 K and at total pressures from 234 to 584 kPa. The absorptions at 130.5 nm of N 2O, SiH 4 and Si have been taken into account to compare simulated and experimental absorption profiles. A detailed kinetic model has been also used to interpret the results and reaction pathway and sensitivity analyses have been performed to underline important elementary reactions. A comparison with the O-atom kinetic in silane-nitrous oxide and hydrogen-nitrous oxide mixtures is also proposed.

  17. Weak shock reflection

    NASA Astrophysics Data System (ADS)

    Hunter, John K.; Brio, Moysey

    2000-05-01

    We present numerical solutions of a two-dimensional inviscid Burgers equation which provides an asymptotic description of the Mach reflection of weak shocks. In our numerical solutions, the incident, reflected, and Mach shocks meet at a triple point, and there is a supersonic patch behind the triple point, as proposed by Guderley for steady weak-shock reflection. A theoretical analysis indicates that there is an expansion fan at the triple point, in addition to the three shocks. The supersonic patch is extremely small, and this work is the first time it has been resolved.

  18. Reflected-shock initiation of explosives

    SciTech Connect

    Ferm, E.N.; Hull, L.M.

    1993-08-01

    In a study of initiations caused by reflected shock from a high-impedance boundary, attempts to establish sufficient conditions for initiative are described. Shock polar analysis is used to discover the ranges of various flow regimes, general shock structures and pressure estimates of states behind the reflected wave. Using this knowledge, wave structure growth rates from hydrocode simulations are estimated and standard-shock initiation criteria are used; experiments are designed in which the initiation from a reflected-shock wave structure appears likely. Two experiments are described in which a reflected-shock wave from a uranium surface initiated PBX 9502. The experimental evidence is in good agreement with the assumptions and results of the analysis.

  19. A Hypothesis About the Role of a Reflected Shock Wave in Impact Cratering

    NASA Astrophysics Data System (ADS)

    Bertoglio, O.

    2016-08-01

    If a shockwave meets with a discontinuity, a reflected wave is created which transmits an upward impulse to the crater broken rocks, that can fly to create a circular rim. A numerical example shows how a stratigraphic inversion may be created.

  20. Shock wave interaction with turbulence: Pseudospectral simulations

    SciTech Connect

    Buckingham, A.C.

    1986-12-30

    Shock waves amplify pre-existing turbulence. Shock tube and shock wave boundary layer interaction experiments provide qualitative confirmation. However, shock pressure, temperature, and rapid transit complicate direct measurement. Computational simulations supplement the experimental data base and help isolate the mechanisms responsible. Simulations and experiments, particularly under reflected shock wave conditions, significantly influence material mixing. In these pseudospectral Navier-Stokes simulations the shock wave is treated as either a moving (tracked or fitted) domain boundary. The simulations assist development of code mix models. Shock Mach number and pre-existing turbulence intensity initially emerge as key parameters. 20 refs., 8 figs.

  1. Optical signal measurement of iso-octane autoignition behind reflected shock wave

    NASA Astrophysics Data System (ADS)

    Chen, Qisheng; Dou, Zhiguo; Li, Lan

    2015-03-01

    Ignition delay time of diluted iso-octane/Air mixtures were measured in a single pulse reflected shock tube. In this work, the onset of ignition was determined by monitoring both the pressure history and the emitted light corresponding to OH* emission. The photomultiplier tube (PMT) in specially designed housing at CaF2 window were used with 310±5nm filters to measure the ultraviolet OH* emission. Experiments were performed at temperatures between 1295K and 2487K, pressures about 1 atm. and varying equivalence ratios (Φ=0.25, 0.5, 1.0, 2.0). Long shock tube dwell time (about 15ms) was achieved by tailored contact surface operation under such conditions. To simulate real engine environment, liquid fuel aerosol was generated by the supersonic atomizer, and the size of fuel droplet in aerosol was measured. Both pressure and OH*emission histories were obtained to determine the ignition delay time and the relative strength of the ignition process. The OH* emission time history data showed that there were different behaviors of iso-octane in ignition process under varying temperatures. Several potential chemical kinetics mechanisms were used to simulated iso-octane autoignition under the same conditions. Analysis of the experiments results and simulations supported the validation of those chemical kinetics mechanisms. The experimental data was consistent with the prediction of mechanism in low temperatures and the experiment data showed that the factors of temperature and equivalent ratio have different effect on the ignition delay time

  2. Attosecond shock waves.

    PubMed

    Zhokhov, P A; Zheltikov, A M

    2013-05-01

    Shock-wave formation is a generic scenario of wave dynamics known in nonlinear acoustics, fluid dynamics, astrophysics, seismology, and detonation physics. Here, we show that, in nonlinear optics, remarkably short, attosecond shock transients can be generated through a strongly coupled spatial and temporal dynamics of ultrashort light pulses, suggesting a pulse self-compression scenario whereby multigigawatt attosecond optical waveforms can be synthesized. PMID:23683197

  3. Unsteady shock-wave reflection and interaction in viscous flow with thermal and chemical nonequilibrium

    NASA Astrophysics Data System (ADS)

    Furumoto, Gregory Hideyo

    Numerical simulations were used to study steady shock/boundary layer interactions and self-sustained unsteady hypersonic type IV shock-shock interference heating problems with nonequilibrium real gas effects. The emphasis of the investigation was on the effects of internal thermochemical excitation on surface heating rates, skin friction, and flow field unsteadiness of the viscous shock interactions. The multicomponent Navier-Stokes equations with nonequilibrium rotational, vibrational, and chemical models for five-species air were solved using a finite-volume, second-order TVD scheme together with a new third-order semi-implicit Runge-Kutta scheme. For a steady shock/boundary layer interaction on a flat plate, it was found that the real gas effects reduced the size of the shock induced separation bubble and the magnitude of the surface heating rates. For the shock-shock interference flow of nitrogen over a cylinder at Mach 8, the results showed that type IV shock-shock interference heating flows with real gas effects were inherently unsteady. The degree of the unsteadiness was related to the location of the jet impingement on the cylinder relative to the stagnation point. For certain impingement positions, vortices were generated and shed off near the jet impingement point. This periodic shedding of the vortices contributed to the self-sustained oscillations of both the jet and other parts of the flow field. The effect of thermochemical nonequilibrium was observed to be a decrease in the peak surface pressure enhancement and an increase in peak surface heating enhancement, relative to a perfect gas flow of the same freestream conditions. The nonequilibrium cases exhibited a higher oscillation frequency and wider range of variation over a cycle than did the perfect gas flows.

  4. When shock waves collide

    DOE PAGES

    Martinez, D.; Hartigan, P.; Frank, A.; Hansen, E.; Yirak, K.; Liao, A. S.; Graham, P.; Foster, J.; Wilde, B.; Blue, B.; et al

    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

  5. When Shock Waves Collide

    NASA Astrophysics Data System (ADS)

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

  6. Shock wave treatment in medicine.

    PubMed

    Shrivastava, S K; Kailash

    2005-03-01

    Extracorporeal shock wave therapy in orthopedics and traumatology is still a young therapy method. Since the last few years the development of shock wave therapy has progressed rapidly. Shock waves have changed the treatment of urolithiasis substantially. Today shock waves are the first choice to treat kidney and urethral stones. Urology has long been the only medical field for shock waves in medicine. Meanwhile shock waves have been used in orthopedics and traumatology to treat insertion tendinitis, avascular necrosis of the head of femur and other necrotic bone alterations. Another field of shock wave application is the treatment of tendons, ligaments and bones on horses in veterinary medicine. In the present paper we discuss the basic theory and application of shock waves and its history in medicine. The idea behind using shock wave therapy for orthopedic diseases is the stimulation of healing in tendons, surrounding tissue and bones. PMID:15933416

  7. Kinetics of the Thermal Decomposition of Tetramethylsilane behind the Reflected Shock Waves in a Single Pulse Shock Tube (SPST) and Modeling Study

    NASA Astrophysics Data System (ADS)

    Parandaman, A.; Sudhakar, G.; Rajakumar, B.

    Thermal reactions of Tetramethylsilane (TMS) diluted in argon were studied behind the reflected shock waves in a single-pulse shock tube (SPST) over the temperature range of 1085-1221 K and pressures varied between 10.6 and 22.8 atm. The stable products resulting from the decomposition of TMS were identified and quantified using gas chromatography and also verified with Fourier Transform Infrared (FTIR) spectrometer. The major reaction products are methane (CH4) and ethylene (C2H4). The minor reaction products are ethane (C2H6) and propylene (C3H6). The initiation of mechanism in the decomposition of TMS takes plays via the Si-C bond scission by ejecting the methyl radicals (CH3) and trimethylsilyl radicals ((CH3)3Si). The measured temperature dependent rate coefficient for the total decomposition of TMS was to be ktotal = 1.66 ×1015 exp (-64.46/RT) s-1 and for the formation of CH4 reaction channel was to be k = 2.20 × 1014 exp (-60.15/RT) s-1, where the activation energies are given in kcal mol-1. A kinetic scheme containing 17 species and 28 elementary reactions was used for the simulation using chemical kinetic simulator over the temperature range of 1085-1221 K. The agreement between the experimental and simulated results was satisfactory.

  8. 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.

  9. Dissociation of 1,1,1-trifluoroethane behind reflected shock waves :shock tube/time-of-flight mass spectrometry experiments.

    SciTech Connect

    Giri, B. R.; Tranter, R. S.; Chemistry

    2007-01-01

    The dissociation of 1,1,1,-trifluoroethane, a potential non-RRKM reaction, has been studied at 600 and 1200 Torr and high temperatures (1500-1840 K) using a new shock tube/time-of-flight mass spectrometer (ST/TOF-MS). These data obtained by an independent method are in good agreement with the laser schlieren, LS, experiments of Kiefer et al. [J. Phys. Chem. A 2004, 108, 2443-2450] and extend the range of that experimental dataset. The data have been simulated by both standard RRKM calculations and the non-RRKM model reported by Kiefer et al. but with <{Delta}E{sub down}> = 750 cm{sup -1}. Both the RRKM and non-RRKM calculations provide equally good fits to the ST/TOF-MS data. Neither model simulates the combined ST/TOF-MS and LS datasets particularly well. However, the non-RRKM model predicts a pressure dependency closer to that observed in the experiments than the RRKM model.

  10. Shock wave control using liquid curtains

    NASA Astrophysics Data System (ADS)

    Colvert, Brendan; Tao, Xingtian; Eliasson, Veronica

    2014-11-01

    The effectiveness of a planar wall of liquid as a blast mitigation device is examined using a shock tube and a custom-designed and -built shock test chamber. Experimental data collection methods being used include high-speed schlieren photography and high-frequency pressure sensors. During the relevant shock interaction time periods, the liquid-gas interface is examined to determine its effect on shock waves. The characteristic quantities that reflect these effects include reflected-to-incident shock strength ratio, transmitted-to-incident shock strength ratio, transmitted and reflected impulse, and peak pressure reduction. These parameters are examined for correlations to incident wave speed, liquid mass, liquid density, and liquid viscosity. Initial results have been obtained that show a correlation between fluid mass and peak pressure reduction. More experiments are being performed to further explore this relationship as well as examine the effects of altering the other parameters such as liquid-gas interface geometry and using dilatant fluids.

  11. Methane oxidation behind reflected shock waves: Ignition delay times measured by pressure and flame band emission

    NASA Technical Reports Server (NTRS)

    Brabbs, T. A.; Robertson, T. F.

    1986-01-01

    Ignition delay data were recorded for three methane-oxygen-argon mixtures (phi = 0.5, 1.0, 2.0) for the temperature range 1500 to 1920 K. Quiet pressure trances enabled us to obtain delay times for the start of the experimental pressure rise. These times were in good agreement with those obtained from the flame band emission at 3700 A. The data correlated well with the oxygen and methane dependence of Lifshitz, but showed a much stronger temperature dependence (phi = 0.5 delta E = 51.9, phi = 1.0 delta = 58.8, phi = 2.0 delta E = 58.7 Kcal). The effect of probe location on the delay time measurement was studied. It appears that the probe located 83 mm from the reflecting surface measured delay times which may not be related to the initial temperature and pressure. It was estimated that for a probe located 7 mm from the reflecting surface, the measured delay time would be about 10 microseconds too short, and it was suggested that delay times less than 100 microsecond should not be used. The ignition period was defined as the time interval between start of the experimental pressure rise and 50 percent of the ignition pressure. This time interval was measured for three gas mixtures and found to be similar (40 to 60 micro sec) for phi = 1.0 and 0.5 but much longer (100 to 120) microsecond for phi = 2.0. It was suggested that the ignition period would be very useful to the kinetic modeler in judging the agreement between experimental and calculated delay times.

  12. Shock Wave Application to Cell Cultures

    PubMed Central

    Holfeld, Johannes; Tepeköylü, Can; Kozaryn, Radoslaw; Mathes, Wolfgang; Grimm, Michael; Paulus, Patrick

    2014-01-01

    Shock waves nowadays are well known for their regenerative effects. Basic research findings showed that shock waves do cause a biological stimulus to target cells or tissue without any subsequent damage. Therefore, in vitro experiments are of increasing interest. Various methods of applying shock waves onto cell cultures have been described. In general, all existing models focus on how to best apply shock waves onto cells. However, this question remains: What happens to the waves after passing the cell culture? The difference of the acoustic impedance of the cell culture medium and the ambient air is that high, that more than 99% of shock waves get reflected! We therefore developed a model that mainly consists of a Plexiglas built container that allows the waves to propagate in water after passing the cell culture. This avoids cavitation effects as well as reflection of the waves that would otherwise disturb upcoming ones. With this model we are able to mimic in vivo conditions and thereby gain more and more knowledge about how the physical stimulus of shock waves gets translated into a biological cell signal (“mechanotransduction"). PMID:24747842

  13. 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.

  14. The carbon dioxide chaperon efficiency for the reaction H + O2 + M yields HO2 + M from ignition delay times behind reflected shock waves

    NASA Technical Reports Server (NTRS)

    Brabbs, Theodore A.; Robertson, Thomas F.

    1987-01-01

    Ignition delay times for stoichiometric hydrogen-oxygen in argon with and without carbon dioxide were measured behind reflected shock waves. A 20-reaction kinetic mechanism models the measured hydrogen-oxygen delay times over the temperature range 950 to 1300 K. The chaperon efficiency for carbon dioxide determined for the hydrogen-oxygen carbon dioxide mixture was 7.0. This value is in agreement with literature values but much less than a recent value obtained from flow tube experiments. Delay times measured behind a reflected shock wave were about 20% longer than those measured behind incident shock waves. The kinetic mechanism successfully modeled the high-pressure data of Skinner and the hydrogen-air data of Stack. It is suggested that the lowest temperature points for the hydrogen-air data of Slack are unreliable and that the 0.27-atm data may illustrate a case where vibrational relaxation of nitrogen is important. The reaction pathway HO2 yields H2O2 yields OH yields H was required to model the high-pressure data of Skinner. The successful modeling of the stoichiometric hydrogen-air data demonstrates the appropriateness of deriving kinetic models from data for gas mixtures highly diluted with argon. The technique of reducing a detailed kinetic mechanism to only the important reactions for a limited range of experimental data may render the mechanism useless for other test conditions.

  15. 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.

  16. Shock transmission and reflection from a material interface and subsequent reflection from a hard boundary

    SciTech Connect

    Hurricane, O A; Miller, P L

    1998-11-20

    As a shock wave passes through a material interface into a region of higher density (the receiver material), a trans- mitted and reflected shock wave are both generated and the interface is set into motion. The speeds of the transmitted shock, reflected shock, and interface are related to the ini- tial shock speed and material properties via a set of coupled nonlinear equations that, in general, cannot be easily solved analytically. In this report, we derive the equations which describe this process and we document a numerical routine which solves the nonlinear equations. We then go on to solve the problem of finding the position where the interface col- lides with the transmitted shock wave once the transmitted shock wave is reflected from an impenetrable boundary lo- cated somewhere away from the initial material interface. Fi- nally, we compare the analytical predictions with the CALE simulation running in 1-D.

  17. Imaging Supersonic Aircraft Shock Waves

    NASA Technical Reports Server (NTRS)

    Weinstein, Leonard M.; Stacy, Kathryn; Vieira, Gerald J.; Haering, Edward A., Jr.; Bowers, Albion H.

    1997-01-01

    A schlieren imaging system that uses the sun as a light source was developed it) obtain direct flow-field images of shock waves of aircraft in flight. This system was used to study how shock waves evolve to form sonic booms. The image quality obtained was limited by several optical and mechanical factors. Converting the photographs to digital images and applying digital image-processing techniques greatly improved the final quality of the images and more clearly showed the shock structures.

  18. 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.

  19. 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.

  20. A collisionless shock wave experiment

    SciTech Connect

    Winske, D.; Jones, M.E.; Sgro, A.G.; Thomas, V.A.

    1995-04-01

    Collisionless shock waves are a very important heating mechanism for plasmas and are commonly found in space and astrophysical environments. Collisionless shocks were studied in the laboratory more than 20 years ago, and more recently in space via in situ satellite measurements. The authors propose a new laboratory shock wave experiment to address unresolved issues related to the differences in the partition of plasma heating between electrons and ions in space and laboratory plasmas, which can have important implications for a number of physical systems.

  1. Solitary versus shock wave acceleration in laser-plasma interactions.

    PubMed

    Macchi, Andrea; Nindrayog, Amritpal Singh; Pegoraro, Francesco

    2012-04-01

    The excitation of nonlinear electrostatic waves, such as shock and solitons, by ultraintense laser interaction with overdense plasmas and related ion acceleration are investigated by numerical simulations. Stability of solitons and formation of shock waves is strongly dependent on the velocity distribution of ions. Monoenergetic components in ion spectra are produced by "pulsed" reflection from solitary waves. Possible relevance to recent experiments on "shock acceleration" is discussed. PMID:22680581

  2. 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

  3. 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.

  4. 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.

    2016-04-01

    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.

  5. Shock tubes and waves; Proceedings of the Thirteenth International Symposium, Niagara Falls, NY, July 6-9, 1981

    NASA Astrophysics Data System (ADS)

    Treanor, C. E.; Hall, J. G.

    1982-10-01

    The present conference on shock tubes and waves considers shock tube drivers, luminous shock tubes, shock tube temperature and pressure measurement, shock front distortion in real gases, nonlinear standing waves, transonic flow shock wave turbulent boundary interactions, wall roughness effects on reflected shock bifurcation, argon thermal conductivity, pattern generation in gaseous detonations, cylindrical resonators, shock tunnel-produced high gain lasers, fluid dynamic aspects of laser-metal interaction, and the ionization of argon gas behind reflected shock waves. Also discussed are the ionization relaxation of shock-heated plasmas and gases, discharge flow/shock tube studies of singlet oxygen, rotational and vibrational relaxation, chemiluminescence thermal and shock wave decomposition of hydrogen cyanide and hydrogen azide, shock wave structure in gas-particle mixtures at low Mach numbers, binary nucleation in a Ludwieg tube, shock liquefaction experiments, pipeline explosions, the shock wave ignition of pulverized coal, and shock-initiated methane combustion.

  6. 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.

  7. Review of methods to attenuate shock/blast waves

    NASA Astrophysics Data System (ADS)

    Igra, O.; Falcovitz, J.; Houas, L.; Jourdan, G.

    2013-04-01

    Quick and reliable shock wave attenuation is the goal of every protection facility and therefore it is not surprising that achieving this has drawn much attention during the past hundred years. Different options have been suggested; their usefulness varying from a reasonable protection to the opposite, a shock enhancement. An example for a suggestion for shock mitigation that turned out to be an enhancement of the impinging shock wave was the idea to cover a protected object with a foam layer. While the pressure behind the reflected shock wave from the foam frontal surface was smaller than that recorded in a similar reflection from a rigid wall [25], the pressure on the “protected” surface, attached to the foam's rear-surface, was significantly higher than that recorded in a similar reflection from a bare, rigid wall [11]. In protecting humans and installations from destructive shock and/or blast waves the prime goal is to reduce the wave amplitude and the rate of pressure increase across the wave front. Both measures result in reducing the wave harmful effects. During the past six decades several approaches for achieving the desired protection have been offered in the open literature. We point out in this review that while some of the suggestions offered are practical, others are impractical. In our discussion we focus on recent schemes for shock/blast wave attenuation, characterized by the availability of reliable measurements (notably pressure and optical diagnostics) as well as high-resolution numerical simulations.

  8. Model for shock wave chaos.

    PubMed

    Kasimov, Aslan R; Faria, Luiz M; Rosales, Rodolfo R

    2013-03-01

    We propose the following model equation, u(t) + 1/2(u(2)-uu(s))x = f(x,u(s)) that predicts chaotic shock waves, similar to those in detonations in chemically reacting mixtures. The equation is given on the half line, x<0, and the shock is located at x = 0 for any t ≥ 0. Here, u(s)(t) is the shock state and the source term f is taken to mimic the chemical energy release in detonations. This equation retains the essential physics needed to reproduce many properties of detonations in gaseous reactive mixtures: steady traveling wave solutions, instability of such solutions, and the onset of chaos. Our model is the first (to our knowledge) to describe chaos in shock waves by a scalar first-order partial differential equation. The chaos arises in the equation thanks to an interplay between the nonlinearity of the inviscid Burgers equation and a novel forcing term that is nonlocal in nature and has deep physical roots in reactive Euler equations. PMID:23521260

  9. Model for shock wave chaos.

    PubMed

    Kasimov, Aslan R; Faria, Luiz M; Rosales, Rodolfo R

    2013-03-01

    We propose the following model equation, u(t) + 1/2(u(2)-uu(s))x = f(x,u(s)) that predicts chaotic shock waves, similar to those in detonations in chemically reacting mixtures. The equation is given on the half line, x<0, and the shock is located at x = 0 for any t ≥ 0. Here, u(s)(t) is the shock state and the source term f is taken to mimic the chemical energy release in detonations. This equation retains the essential physics needed to reproduce many properties of detonations in gaseous reactive mixtures: steady traveling wave solutions, instability of such solutions, and the onset of chaos. Our model is the first (to our knowledge) to describe chaos in shock waves by a scalar first-order partial differential equation. The chaos arises in the equation thanks to an interplay between the nonlinearity of the inviscid Burgers equation and a novel forcing term that is nonlocal in nature and has deep physical roots in reactive Euler equations.

  10. Dual Mode Shock-Expansion/Reflected-Shock Tunnel

    NASA Technical Reports Server (NTRS)

    Erdos, John I.; Bakos, Robert J.; Castrogiovanni, Anthony; Rogers, R. Clayton

    1998-01-01

    NASA s HYPULSE facility at GASL has been reconfigured to permit free jet testing of the Hyper-X flowpath at flight Mach numbers of 7 and 10. Among the required changes are addition of a converging-diverging nozzle to permit operation in a reflected shock tunnel mode, a 7 ft. diameter test cabin and a 30 in. diameter contoured nozzle. However, none of these changes were allowed to interfere with rapid recovery of the prior shock-expansion tunnel mode of operation, and indeed certain changes should enhance facility usefulness and productivity in either mode. A previously-developed shock-induced detonation mode of driving the facility has been successfully applied to both reflected shock tunnel operation at Mach 10 flight conditions, with tailored interface operation, and shock-expansion tunnel operation at flight conditions corresponding to Mach numbers from 12 to 25. Tailored interface operation at Mach 7 has been achieved with an unheated helium driver. In the present paper, the rationale for a dual mode shock expansion/reflected shock tunnel is discussed, and the capabilities and limitations for each mode are outlined. The physical changes in the HYPULSE facility to achieve dual mode capability are also described. Limited calibration data obtained to date in the new reflected shock tunnel mode are presented and the anticipated flight simulation map with dual mode operation is also outlined.

  11. 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.

  12. 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.

  13. Corrugation of Relativistic Magnetized Shock Waves

    NASA Astrophysics Data System (ADS)

    Lemoine, Martin; Ramos, Oscar; Gremillet, Laurent

    2016-08-01

    As a shock front interacts with turbulence it develops corrugation, which induces outgoing wave modes in the downstream plasma. For a fast shock wave, the incoming wave modes can either be fast magnetosonic waves originating downstream, outrunning the shock, or eigenmodes of the upstream plasma drifting through the shock. Using linear perturbation theory in relativistic MHD, this paper provides a general analysis of the corrugation of relativistic magnetized fast shock waves resulting from their interaction with small amplitude disturbances. Transfer functions characterizing the linear response for each of the outgoing modes are calculated as a function of the magnetization of the upstream medium and as a function of the nature of the incoming wave. Interestingly, if the latter is an eigenmode of the upstream plasma, we find that there exists a resonance at which the (linear) response of the shock becomes large or even diverges. This result may have profound consequences on the phenomenology of astrophysical relativistic magnetized shock waves.

  14. Multichannel fiber-based diffuse reflectance spectroscopy for the rat brain exposed to a laser-induced shock wave: comparison between ipsi- and contralateral hemispheres

    NASA Astrophysics Data System (ADS)

    Miyaki, Mai; Kawauchi, Satoko; Okuda, Wataru; Nawashiro, Hiroshi; Takemura, Toshiya; Sato, Shunichi; Nishidate, Izumi

    2015-03-01

    Due to considerable increase in the terrorism using explosive devices, blast-induced traumatic brain injury (bTBI) receives much attention worldwide. However, little is known about the pathology and mechanism of bTBI. In our previous study, we found that cortical spreading depolarization (CSD) occurred in the hemisphere exposed to a laser- induced shock wave (LISW), which was followed by long-lasting hypoxemia-oligemia. However, there is no information on the events occurred in the contralateral hemisphere. In this study, we performed multichannel fiber-based diffuse reflectance spectroscopy for the rat brain exposed to an LISW and compared the results for the ipsilateral and contralateral hemispheres. A pair of optical fibers was put on the both exposed right and left parietal bone; white light was delivered to the brain through source fibers and diffuse reflectance signals were collected with detection fibers for both hemispheres. An LISW was applied to the left (ipsilateral) hemisphere. By analyzing reflectance signals, we evaluated occurrence of CSD, blood volume and oxygen saturation for both hemispheres. In the ipsilateral hemispheres, we observed the occurrence of CSD and long-lasting hypoxemia-oligemia in all rats examined (n=8), as observed in our previous study. In the contralateral hemisphere, on the other hand, no occurrence of CSD was observed, but we observed oligemia in 7 of 8 rats and hypoxemia in 1 of 8 rats, suggesting a mechanism to cause hypoxemia or oligemia or both that is (are) not directly associated with CSD in the contralateral hemisphere.

  15. SHOCK-WAVE THERAPY APPLICATION IN CLINICAL PRACTICE (REVIEW).

    PubMed

    Sheveleva, N; Minbayeva, L; Belyayeva, Y

    2016-03-01

    The article presents literature review on the use of extracorporeal shock-wave therapy in physiotherapeutic practice. The basic mechanisms of shock waves influence on the organism are spotlighted. Studies proving high efficacy of the method in treatment of wide variety of inflammatory diseases and traumatic genesis are presented. The data on comparative assessment of shock-wave therapy efficacy, and results of researches on possibility of extracorporeal shock-wave therapy effect potentiating in combination with other therapeutic methods are reflected. Recent years, the range of indications for shock-wave therapy application had been significantly widened. However, further study of the method is still relevant because mechanisms of action of the factor are studied insufficiently; methods of therapy parameters selection (energy flux density, number of pulses per treatment, duration of a course) are either advisory or empirical.

  16. 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.

  17. Calculating Flows With Interfering Shock Waves

    NASA Technical Reports Server (NTRS)

    Glass, Christopher E.

    1993-01-01

    Equilibrium Air Shock Interference, EASI, program takes account of dissociation of air molecules. Revives and updates older computational methods for calculating inviscid flow field and maximum heating from interference of shock waves. Expands methods to solve problems involving six shock-wave interference patterns on two-dimensional cylindrical leading edge with equilibrium, chemically-reacting gas mixture. Written in FORTRAN 77.

  18. Stationary one-dimensional dispersive shock waves.

    PubMed

    Kartashov, Yaroslav V; Kamchatnov, Anatoly M

    2012-02-01

    We address shock waves generated upon the interaction of tilted plane waves with negative refractive index defects in defocusing media with linear gain and two-photon absorption. We found that, in contrast to conservative media where one-dimensional dispersive shock waves usually exist only as nonstationary objects expanding away from a defect or generating beam, the competition between gain and two-photon absorption in a dissipative medium results in the formation of localized stationary dispersive shock waves, whose transverse extent may considerably exceed that of the refractive index defect. One-dimensional dispersive shock waves are stable if the defect strength does not exceed a certain critical value.

  19. 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.

  20. Oblique shock reflection from an axis of symmetry

    NASA Astrophysics Data System (ADS)

    Hornung, H. G.

    2000-04-01

    An exploratory computational study of the reflection of an inward-facing conical shock wave from its axis of symmetry is presented. This is related to more complex practical situations in both steady and unsteady flows. The absence of a length scale in the problem studied makes features grow linearly with time. The ensuing flow is related to the Guderley singularity in a cylindrical imploding shock. The problem is explored by making a large number of computations of the Euler equations. Distinct reflection configurations are identified, and the regions of parameter space in which they occur are delineated.

  1. Mach reflection of a ZND detonation wave

    NASA Astrophysics Data System (ADS)

    Li, J.; Ning, J.; Lee, J. H. S.

    2015-05-01

    The Mach reflection of a ZND detonation wave on a wedge is investigated numerically. A two-step chain-branching reaction model is used giving a thermally neutral induction zone followed by a chemical reaction zone for the detonation wave. The presence of a finite reaction zone thickness renders the Mach reflection process non-self-similar. The variation of the height of the Mach stem with distance of propagation does not correspond to a straight curve from the wedge apex as governed by self-similar three-shock theory. However, the present results indicate that in the near field around the wedge apex, and in the far field where the reaction zone thickness is small compared to the distance of travel of the Mach stem, the behavior appears to be self-similar. This corresponds to the so-called frozen and equilibrium limit pointed out by Hornung and Sanderman for strong discontinuity shock waves and by Shepherd et al. for cellular detonations. The critical wedge angle for the transition from regular to Mach reflection is found to correspond to the value determined by self-similar three-shock theory, but not by reactive three-shock theory for a discontinuous detonation front.

  2. Shock wave formation in the collapse of a vapor nanobubble.

    PubMed

    Magaletti, F; Marino, L; Casciola, C M

    2015-02-13

    In this Letter, the dynamics of a collapsing vapor bubble is addressed by means of a diffuse-interface formulation. The model cleanly captures, through a unified approach, all the critical features of the process, such as phase change, transition to supercritical conditions, thermal conduction, compressibility effects, and shock wave formation and propagation. Rather unexpectedly for pure vapor bubbles, the numerical experiments show that the process consists in the oscillation of the bubble associated with the emission of shock waves in the liquid, and with the periodic disappearance and reappearance of the liquid-vapor interface due to transition to super- or subcritical conditions. The results identify the mechanism of shock wave formation as strongly related to the transition of the vapor to the supercritical state, with a progressive steepening of a focused compression wave evolving into a shock which is eventually reflected as an outward propagating wave in the liquid. PMID:25723223

  3. Electron physics in shock waves

    NASA Astrophysics Data System (ADS)

    Kilian, Patrick

    2014-05-01

    The non-relativistic shocks that we find in the solar wind (no matter if driven by CMEs or encounters with planets) are dominated by ion dynamics. Therefore a detailed treatment of electrons is often neglegted to gain significant reductions in computational effort. With recent super computers and massively parallel codes it is possible to perform self-consistent kinetic simulations using particle in cell code. This allows to study the heating of the electrons as well as the acceleration to superthermal energies. These energetic electrons are interesting for couple of reasons. e.g. as an influence on plasma instabilities or for the generation of plasma waves.

  4. Interplanetary shock waves associated with solar flares

    NASA Technical Reports Server (NTRS)

    Chao, J. K.; Sakurai, K.

    1974-01-01

    The interaction of the earth's magnetic field with the solar wind is discussed with emphasis on the influence of solar flares. The geomagnetic storms are considerered to be the result of the arrival of shock wave generated by solar flares in interplanetary space. Basic processes in the solar atmosphere and interplanetary space, and hydromagnetic disturbances associated with the solar flares are discussed along with observational and theoretical problems of interplanetary shock waves. The origin of interplanetary shock waves is also discussed.

  5. On the generation of dispersive shock waves

    NASA Astrophysics Data System (ADS)

    Miller, Peter D.

    2016-10-01

    We review various methods for the analysis of initial-value problems for integrable dispersive equations in the weak-dispersion or semiclassical regime. Some methods are sufficiently powerful to rigorously explain the generation of modulated wavetrains, so-called dispersive shock waves, as the result of shock formation in a limiting dispersionless system. They also provide a detailed description of the solution near caustic curves that delimit dispersive shock waves, revealing fascinating universal wave patterns.

  6. A study of slipstreams in triple shock wave configurations

    NASA Astrophysics Data System (ADS)

    Gvozdeva, L.; Gavrenkov, S.; Nesterov, A.

    2015-05-01

    A shock wave appearing in supersonic gas flow reflects in different ways depending on flow conditions. It can take the form of regular or irregular reflection. For the irregular reflection configuration of three shock waves and a slipstream arises. Mathematical investigations of the development of parameters across slipstream in triple shock configuration have been made with variation of the angle of incidence of the shock wave, the shock wave Mach number and the adiabatic index of the gas. It has been shown that the characteristic mixing parameters of the slipstream increase with the increase of Mach number of the flow and the decrease of the heat capacity ratio. This leads to an increase of vortex formation and an increase of the angular spread of the slipstream. It also has been shown that the angle between the reflected wave and the slipstream diminishes with the decrease in heat capacity ratio so that the value may become of the same order as the spread angle. This may lead to quantitative changes in the whole reflection pattern near the triple point. The evident dependence of slipstream instability magnitude on the physical and chemical transformation intensity in the fluid was previously experimentally observed. The results of an analytical investigation appeared to be in good agreement with the experimental data.

  7. Shock Waves Impacting Composite Material Plates: The Mutual Interaction

    NASA Astrophysics Data System (ADS)

    Andreopoulos, Yiannis

    2013-02-01

    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 shock impact induced by blast is not well understood. Air blast is associated with a fast traveling shock front with high pressure across followed by a decrease in pressure behind due to expansion waves. The time scales associated with the shock front are typically 103 faster than those involved in the expansion waves. Impingement of blast waves on structures can cause a reflection of the wave 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 shock. In addition, a complex aeroelastic interaction between the blast wave and the structure develops that can induce reverberation within an enclosure, which can cause substantial overpressure through multiple reflections of the wave. 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 shock waves on thin composite plates.

  8. The role of shock waves in expansion tube accelerators

    NASA Astrophysics Data System (ADS)

    Olson, G.; Peterson, Richard; Pulford, B.; Seaberg, M.; Stein, K.; Stelter, C.; Weber, R.

    2006-12-01

    Simulations are combined with laboratory measurements to show the important role of shock waves in a popular physics demonstration, the "ping pong cannon." The simulation and measurements confirm a developing shock wave that reflects from the end of the closed tube and approaching ball and the eventual formation of a transient localized pressure build-up near the exit tape barrier. This 2atm burst of pressure peaks within a few microseconds of the ball's arrival, resulting from the combination of near ambient gas density and shock heating to about 1200K. Pulsed schlieren images beyond the exit confirm the sequence of internally reflected shock waves and the intense, hot air pressure pulse that explosively removes the exit tape just prior to the ball arrival.

  9. Gigabar shock wave in a laboratory experiment

    NASA Astrophysics Data System (ADS)

    Gus'kov, S. Yu.

    2016-03-01

    The current status of research on generating a powerful shock wave with a pressure of up to several gigabars in a laboratory experiment is reviewed. The focus is on results which give a possibility of shock-wave experiments to study an equation of state of matter (EOS) at the level of gigabar pressure. The proposals are discussed to achieve a plane record-pressure shock wave driven by laser-accelerated fast electrons with respect to EOS-experiment as well as to prospective method of inertial fusion target (ICF) ignition as shock ignition.

  10. 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.

  11. 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].

  12. Raman spectroscopy of hypersonic shock waves

    PubMed

    Ramos; Mate; Tejeda; Fernandez; Montero

    2000-10-01

    Raman spectroscopy is shown to be an efficient diagnostic methodology for the study of hypersonic shock waves. As a test, absolute density and rotational population profiles have been measured across five representative normal shock waves of N2 generated in a free jet, spanning the Mach number range 7.7shock waves shows a largely bimodal rotational distribution function with additional contribution of scattered molecules, in close analogy with the velocity distribution function known from helium shock waves [G. Pham-Van-Diep et al., Science 245, 624 (1989)]. Quantitative data on invariance trends of density profiles and properties of the wake beyond the shock waves are reported.

  13. Shock waves in the solar system.

    NASA Technical Reports Server (NTRS)

    Spreiter, J. R.

    1972-01-01

    Review of the role of gasdynamic processes involving shock waves in the transfer of solar material and energy to the earth and elsewhere in the solar system. The role of shock waves in maintaining the high temperature of the solar corona and in establishing the steady-state solar wind is discussed. An approximate hydromagnetic theory is developed to explain the flow of a supersonic solar wind past planets and the moon. Data concerning the passage of interplanetary shock waves and the ability of a solar flare to produce such a wave are reviewed, and some terrestrial consequences of solar activity are cited.

  14. Computing unsteady shock waves for aeroacoustic applications

    NASA Technical Reports Server (NTRS)

    Meadows, Kristine R.; Caughey, David A.; Casper, Jay

    1994-01-01

    The computation of unsteady shock waves, which contribute significantly to noise generation in supersonic jet flows, is investigated. The paper focuses on the difficulties of computing slowly moving shock waves. Numerical error is found to manifest itself principally as a spurious entropy wave. Calculations presented are performed using a third-order essentially nonoscillatory scheme. The effect of stencil biasing parameters and of two versions of numerical flux formulas on the magnitude of spurious entropy are investigated. The level of numerical error introduced in the calculation is quantified as a function of shock pressure ratio, shock speed, Courant number, and mesh density. The spurious entropy relative to the entropy jump across a static shock decreases with increasing shock strength and shock velocity relative to the grid, but is insensitive to Courant number. The structure of the spurious entropy wave is affected by the choice of flux formulas and algorithm biasing parameters. The effect of the spurious numerical waves on the calculation of sound amplification by a shock wave is investigated. For this class of problem, the acoustic pressure waves are relatively unaffected by the spurious numerical phenomena.

  15. Computing unsteady shock waves for aeroacoustic applications

    NASA Technical Reports Server (NTRS)

    Meadows,, Kristine r.; Caughey, David A.; Casper, Jay

    1994-01-01

    The computation of unsteady shock waves, which contribute significantly to noise generation in supersonic jet flows, is investigated. This paper focuses on the difficulties of computing slowly moving shock waves. Numerical error is found to manifest itself principally as a spurious entropy wave. Calculations presented are performed using a third order essentially nonoscillatory scheme. The effect of stencil biasing parameters and of two versions of numerical flux formulas on the magnitude of spurious entropy are investigated. The level of numerical error introduced in the calculation in quantified as a function of shock pressure ratio, shock speed, Courant number, and mesh density. The spurious entropy relative to the entropy jump across a static shock decreases with increasing shock strength and shock velocity relative to the grid, but is insensitive to Courant number. The structure of the spurious entropy wave is affected by the choice of flux formulas and algorithm biasing parameters. The effect of the spurious numerical waves on the calculation of sound amplification by a shock wave is investigated. For this class of problem, the acoustic pressure waves are relatively unaffected by the spurious numerical phenomena.

  16. Shock wave mitigation using Newtonian and non-Newtonian fluids

    NASA Astrophysics Data System (ADS)

    Tao, Xingtian; Colvert, Brendan; Eliasson, Veronica

    2014-11-01

    The effectiveness of a wall of liquid as a blast mitigation device is examined using a shock tube and a custom-designed and -built shock test chamber. High-speed schlieren photography and high-frequency pressure sensors allow measurement during the relevant shock interaction time periods of the liquid-gas interface. The characteristic quantities that reflect these effects include reflected-to-incident shock strength ratio, transmitted-to-incident shock strength ratio, transmitted and reflected impulse, and peak pressure reduction. In particular, the effects of viscous properties of the fluid are considered when using non-Newtonian dilatant and pseudoplastic fluids. Experiments have been performed with both Newtonian and non-Newtonian fluids. The impact of a shock waves on Non-newtonian fluids is compared to that of Newtonian fluids. Experiments show that non-Newtonian fluids have very strong reflection properties, acting like solid walls under the impact of a shock wave. Further work is to be performed to compare quantitatively the properties of Newtonian vs. non-Newtonian fluids.

  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 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.

  19. Wave reflection at a stent.

    PubMed

    Crespo, Antonio; García, Javier; Manuel, Fernando

    2013-01-01

    A simple analytical expression has been derived to calculate the characteristics of a wave that reflects at a stent implanted in a uniform vessel. The stent is characterized by its length and the wave velocity in the stented region. The reflected wave is proportional to the time derivative of the incident wave. The reflection coefficient is a small quantity of the order of the length of the stent divided by the wavelength of the unstented vessel. The results obtained coincide with those obtained numerically by Charonko et al. The main simplifications used are small amplitude of the waves so that equations can be linearized and that the length of the stent is small enough so that the values of the wave functions are nearly uniform along the stent. Both assumptions hold in typical situations. PMID:23516957

  20. Wave reflection at a stent.

    PubMed

    Crespo, Antonio; García, Javier; Manuel, Fernando

    2013-01-01

    A simple analytical expression has been derived to calculate the characteristics of a wave that reflects at a stent implanted in a uniform vessel. The stent is characterized by its length and the wave velocity in the stented region. The reflected wave is proportional to the time derivative of the incident wave. The reflection coefficient is a small quantity of the order of the length of the stent divided by the wavelength of the unstented vessel. The results obtained coincide with those obtained numerically by Charonko et al. The main simplifications used are small amplitude of the waves so that equations can be linearized and that the length of the stent is small enough so that the values of the wave functions are nearly uniform along the stent. Both assumptions hold in typical situations.

  1. Instability of spherically imploding shock waves

    SciTech Connect

    Chen, H.; Hilko, B.; Zhang, L.; Panarella, E.

    1995-12-31

    The importance of spherically imploding shock waves has increased recently due to their particular applications in inertial confinement fusion (ICF) and the Spherical Pinch (SP). In particular, the stability of spherically imploding shock waves plays a critical role in the ultimate success of ICF and SP. The instability of spherically imploding shock waves is now systematically investigated. The basic state is Guderley and Landau`s unsteady self-similar solution of the implosion of a spherical shock wave. The stability analysis is conducted by combining Chandresakhar`s approach to the stability of spherical flames together. The governing equations for disturbances are derived and they use the condition that perturbed gas flow is potential. The three dimensional perturbation velocity profile and a shock front perturbation are solved by using the kinematic and dynamic boundary conditions in the shock front. The time-dependent amplitudes of the perturbations are obtained by solving the system of ordinary differential equations. This enables them to study the time history of the spherically imploding shock wave subject to perturbations. The relative amplification and decay of the amplitudes of perturbations decides the stability/instability of the spherical imploding shock waves. Preliminary results are presented.

  2. Stability of imploding spherical shock waves

    NASA Astrophysics Data System (ADS)

    Chen, H. B.; Zhang, L.; Panarella, E.

    1995-12-01

    The stability of spherically imploding shock waves is systematically investigated in this letter. The basic state is Guderley and Landau's unsteady self-similar solution of the implosion of a spherical shock wave. The stability analysis is conducted by combining Chandrasekhar's approach to the stability of a viscous liquid drop with Zel'dovich's approach to the stability of spherical flames. The time-dependent amplitudes of the perturbations are obtained analytically by using perturbation method. The relative amplification and decay of the amplitudes of perturbations decides the stability/instability of the spherical imploding shock waves. It is found that the growth rate of perturbations is not in exponential form and near the collapse phase of the shocks, the spherically imploding shock waves are relatively stable.

  3. Stability of imploding spherical shock waves

    SciTech Connect

    Chen, H.B.; Zhang, L.; Panarella, E.

    1995-12-01

    The stability of spherically imploding shock waves is systematically investigated in this letter. The basic state is Guderley and Landau`s unsteady self-similar solution of the implosion of a spherical shock wave. The stability analysis is conducted by combining Chandrasekhar`s approach to the stability of a viscous liquid drop with Zel`dovich`s approach to the stability of spherical flames. The time-dependent amplitudes of the perturbations are obtained analytically by using perturbation method. The relative amplification and decay of the amplitudes of perturbations are obtained analytically by using perturbation method. The relative amplification and decay of the amplitudes of perturbations decides the stability/instability of the spherical imploding shock waves. It is found that the growth rate of perturbations is not in exponential form and near the collapse phase of the shocks, the spherically imploding shock waves are relatively stable. 14 refs., 1 fig.

  4. Application of shock waves in medicine.

    PubMed

    Thiel, M

    2001-06-01

    Extracorporeal-generated shock waves were introduced approximately 20 years ago to disintegrate kidney stones. This treatment method substantially changed the treatment of urolithiasis. Shock waves have become the treatment of choice for kidney and ureteral stones. Urology, however, is not the only medical field for the potential use of shock waves for problems. Shock waves subsequently have been used in orthopaedics and traumatology to treat various insertional tendinopathies (enthesiopathies) and delayed unions and nonunions of fracture. Shock wave application also has been used in the treatment of tendinopathies in veterinary conditions (race horses). The concept of orthopaedic disorders is that shock waves stimulate or reactivate healing processes in tendons, surrounding tissue and bones, probably through microdisruption of avascular or minimally vascular tissues to encourage revascularization, release of local growth factors, and the recruitment of appropriate stem cells conducive to more normal tissue healing. The current author will give an overview of history and basic research of the application of shock waves in medicine. PMID:11400881

  5. 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.

  6. Hybrid numerical model of shock waves in collisionless plasma

    NASA Astrophysics Data System (ADS)

    Vshivkova, L.; Dudnikova, G.; Vshivkov, K.

    2016-10-01

    We present a 2D hybrid numerical plasma model of generation and structure of collisionless shock waves in plasma and ion acceleration on their front considering physical processes in supernova remnant shock precursor. In modeling a shock wave is generated by sending a supersonic flow against a reflecting wall. The consequent interaction between incoming and reflected plasma flows lead to formation of waves, the structure of which depends on a flow velocity. The hybrid approach reduces the computational expenses relative to a fully kinetic one, and on the other hand, permits to model ions with a greater accuracy than the magnetohydrodynamics (MHD) allows. Also, another important advantage of the hybrid approach is the possibility to study the important instabilities on an ion time scale, neglecting the modes associated with electrons. In the current work a new computational scheme where stability condition allows carry out computations on more wide set of computational and physical parameters is presented.

  7. Rarefaction shock waves in shock-compressed diamond <110> crystal

    NASA Astrophysics Data System (ADS)

    Perriot, Romain; Lin, You; Zhakhovsky, Vasily; White, Carter; Oleynik, Ivan

    2013-03-01

    Piston-driven shock compression of diamond <110> crystal was simulated by molecular dynamics using the REBO potential. At piston velocities between 2 and 5 km/s and corresponding pressures 117 GPA < P < 278 GPa, diamond sample undergoes a polymorphic phase transition, characterized by the coexistence of two elastically compressed phases, low-pressure phase A and high-pressure phase B. This phase transition results in the splitting of the shock wave into two elastic shock waves, composed of pure phase A and a mixture of phases A and B. Upon removal of the piston, a release wave is observed at the rear of the sample, turning into a rarefaction shock wave where the material undergoes the reverse phase transition from coexisting phases to the original low-pressure phase. For strong plastic waves induced by larger piston velocities the release wave propagates as a rarefaction wave without any phase transition corresponding to the adiabatic expansion along the plastic branch of the Hugoniot.

  8. Guderley reflection for higher Mach numbers in a standard shock tube

    NASA Astrophysics Data System (ADS)

    Cachucho, A.; Skews, B. W.

    2012-03-01

    An experimental study shows that the Guderley reflection (GR) of shock waves can be produced in a standard shock tube. A new technique was utilised which comprises triple point of a developed weak Mach reflection undergoing a number of reflections off the ceiling and floor of the shock tube before arriving at the test section. Both simple perturbation sources and diverging ramps were used to generate a transverse wave in the tube which then becomes the weak reflected wave of the reflection pattern. Tests were conducted for three ramp angles (10°, 15°, and 20°) and two perturbation sources for a range of Mach numbers (1.10-1.40) and two shock tube expansion chamber lengths (2.0 and 4.0 m). It was found that the length of the Mach stem of the reflection pattern is the overall vertical distance traveled by the triple point. Images with equivalent Mach stem lengths in the order of 2.0 m were produced. All tests showed evidence of the fourth wave of the GR, namely the expansion wave behind the reflected shock wave. A shocklet terminating the expansion wave was also identified in a few cases mainly for incident wave Mach numbers of approximately 1.20.

  9. Shock waves in strongly coupled plasmas

    SciTech Connect

    Khlebnikov, Sergei; Kruczenski, Martin; Michalogiorgakis, Georgios

    2010-12-15

    Shock waves are supersonic disturbances propagating in a fluid and giving rise to dissipation and drag. Weak shocks, i.e., those of small amplitude, can be well described within the hydrodynamic approximation. On the other hand, strong shocks are discontinuous within hydrodynamics and therefore probe the microscopics of the theory. In this paper, we consider the case of the strongly coupled N=4 plasma whose microscopic description, applicable for scales smaller than the inverse temperature, is given in terms of gravity in an asymptotically AdS{sub 5} space. In the gravity approximation, weak and strong shocks should be described by smooth metrics with no discontinuities. For weak shocks, we find the dual metric in a derivative expansion, and for strong shocks we use linearized gravity to find the exponential tail that determines the width of the shock. In particular, we find that, when the velocity of the fluid relative to the shock approaches the speed of light v{yields}1 the penetration depth l scales as l{approx}(1-v{sup 2}){sup 1/4}. We compare the results with second-order hydrodynamics and the Israel-Stewart approximation. Although they all agree in the hydrodynamic regime of weak shocks, we show that there is not even qualitative agreement for strong shocks. For the gravity side, the existence of shock waves implies that there are disturbances of constant shape propagating on the horizon of the dual black holes.

  10. Ion-acoustic shocks with reflected ions: modelling and particle-in-cell simulations

    NASA Astrophysics Data System (ADS)

    Liseykina, T. V.; Dudnikova, G. I.; Vshivkov, V. A.; Malkov, M. A.

    2015-10-01

    > Non-relativistic collisionless shock waves are widespread in space and astrophysical plasmas and are known as efficient particle accelerators. However, our understanding of collisionless shocks, including their structure and the mechanisms whereby they accelerate particles, remains incomplete. We present here the results of numerical modelling of an ion-acoustic collisionless shock based on the one-dimensional kinetic approximation for both electrons and ions with a real mass ratio. Special emphasis is paid to the shock-reflected ions as the main driver of shock dissipation. The reflection efficiency, the velocity distribution of reflected particles and the shock electrostatic structure are studied in terms of the shock parameters. Applications to particle acceleration in geophysical and astrophysical shocks are discussed.

  11. Free boundary problems in shock reflection/diffraction and related transonic flow problems.

    PubMed

    Chen, Gui-Qiang; Feldman, Mikhail

    2015-09-13

    Shock waves are steep wavefronts that are fundamental in nature, especially in high-speed fluid flows. When a shock hits an obstacle, or a flying body meets a shock, shock reflection/diffraction phenomena occur. In this paper, we show how several long-standing shock reflection/diffraction problems can be formulated as free boundary problems, discuss some recent progress in developing mathematical ideas, approaches and techniques for solving these problems, and present some further open problems in this direction. In particular, these shock problems include von Neumann's problem for shock reflection-diffraction by two-dimensional wedges with concave corner, Lighthill's problem for shock diffraction by two-dimensional wedges with convex corner, and Prandtl-Meyer's problem for supersonic flow impinging onto solid wedges, which are also fundamental in the mathematical theory of multidimensional conservation laws. PMID:26261363

  12. Limiting Temperatures of Spherical Shock Wave Implosion.

    PubMed

    Liverts, Michael; Apazidis, Nicholas

    2016-01-01

    Spherical shock wave implosion in argon is studied both theoretically and experimentally. It is shown that as the strength of the converging shock increases the nonideal gas effects become dominant and govern the evolution of thermal and transport gas properties limiting the shock acceleration, lowering the gas adiabatic index and the achievable energy density at the focus. Accounting for multiple-level ionization, excitation, Coulomb interaction and radiation effects, the limiting equilibrium temperatures to be achieved during the shock implosion are estimated. Focal temperatures of the order of 30 000 K are measured in experiments where converging spherical shock waves are created using a conventional gas-dynamic shock tube facility. PMID:26799021

  13. Density wave theory. [interstellar gas dynamics and galactic shock waves

    NASA Technical Reports Server (NTRS)

    Roberts, W. W., Jr.

    1977-01-01

    The prospect that density waves and galactic shock waves are present on the large scale in disk shaped galaxies has received support in recent years from both theoretical and observational studies. Large-scale galactic shock waves in the interstellar gas are suggested to play an important governing role in star formation, molecule formation, and the degree of development of spiral structure. Through the dynamics of the interstellar gas and the galactic shock-wave phenomenon, a new insight into the physical basis underlying the morphological classification system of galaxies is suggested.

  14. Oblique shock reflection from an axis of symmetry: shock dynamics and relation to the Guderley singularity

    NASA Astrophysics Data System (ADS)

    Hornung, H. G.; Schwendeman, D. W.

    2001-07-01

    Oblique shock reflection from an axis of symmetry is studied using Whitham's theory of geometrical shock dynamics, and the results are compared with previous numerical simulations of the phenomenon by Hornung (2000). The shock shapes (for strong and weak shocks), and the location of the shock-shock (for strong shocks), are in good agreement with the numerical results, though the detail of the shock reflection structure is, of course, not resolved by shock dynamics. A guess at a mathematical form of the shock shape based on an analogy with the Guderley singularity in cylindrical shock implosion, in the form of a generalized hyperbola, fits the shock shape very well. The smooth variation of the exponent in this equation with initial shock angle from the Guderley value at zero to 0.5 at 90° supports the analogy. Finally, steady-flow shock reflection from a symmetry axis is related to the self-similar flow.

  15. 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

  16. The microphysics of collisionless shock waves

    NASA Astrophysics Data System (ADS)

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

    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.

  17. 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. PMID:27007555

  18. Dispersive shock waves with nonlocal nonlinearity.

    PubMed

    Barsi, Christopher; Wan, Wenjie; Sun, Can; Fleischer, Jason W

    2007-10-15

    We consider dispersive optical shock waves in nonlocal nonlinear media. Experiments are performed using spatial beams in a thermal liquid cell, and results agree with a hydrodynamic theory of propagation.

  19. Shock waves in a dilute granular gas

    NASA Astrophysics Data System (ADS)

    Reddy, M. H. Lakshminarayana; Ansumali, Santosh; Alam, Meheboob

    2014-12-01

    We study the evolution of shock waves in a dilute granular gas which is modelled using three variants of hydrodynamic equations: Euler, 10-moment and 14-moment models. The one-dimensional shock-wave problem is formulated and the resulting equations are solved numerically using a relaxation-type scheme. Focusing on the specific case of blast waves, the results on the density, the granular temperature, the skew temperature, the heat flux and the fourth moment are compared among three models. We find that the shock profiles are smoother for the 14-moment model compared to those predicted by the standard Euler equations. A shock-splitting phenomenon is observed in the skew granular temperature profiles for a blast wave.

  20. 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

  1. 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 PMID:27078450

  2. 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…

  3. Investigation of the hysteresis phenomena in steady shock reflection using kinetic and continuum methods

    NASA Astrophysics Data System (ADS)

    Ivanov, M.; Zeitoun, D.; Vuillon, J.; Gimelshein, S.; Markelov, G.

    1996-05-01

    The problem of transition of planar shock waves over straight wedges in steady flows from regular to Mach reflection and back was numerically studied by the DSMC method for solving the Boltzmann equation and finite difference method with FCT algorithm for solving the Euler equations. It is shown that the transition from regular to Mach reflection takes place in accordance with detachment criterion while the opposite transition occurs at smaller angles. The hysteresis effect was observed at increasing and decreasing shock wave angle.

  4. Finite Mach number spherical shock wave, application to shock ignition

    NASA Astrophysics Data System (ADS)

    Vallet, A.; Ribeyre, X.; Tikhonchuk, V.

    2013-08-01

    A converging and diverging spherical shock wave with a finite initial Mach number Ms0 is described by using a perturbative approach over a small parameter Ms-2. The zeroth order solution is the Guderley's self-similar solution. The first order correction to this solution accounts for the effects of the shock strength. Whereas it was constant in the Guderley's asymptotic solution, the amplification factor of the finite amplitude shock Λ(t)∝dUs/dRs now varies in time. The coefficients present in its series form are iteratively calculated so that the solution does not undergo any singular behavior apart from the position of the shock. The analytical form of the corrected solution in the vicinity of singular points provides a better physical understanding of the finite shock Mach number effects. The correction affects mainly the flow density and the pressure after the shock rebound. In application to the shock ignition scheme, it is shown that the ignition criterion is modified by more than 20% if the fuel pressure prior to the final shock is taken into account. A good agreement is obtained with hydrodynamic simulations using a Lagrangian code.

  5. Finite Mach number spherical shock wave, application to shock ignition

    SciTech Connect

    Vallet, A.; Ribeyre, X.; Tikhonchuk, V.

    2013-08-15

    A converging and diverging spherical shock wave with a finite initial Mach number M{sub s0} is described by using a perturbative approach over a small parameter M{sub s}{sup −2}. The zeroth order solution is the Guderley's self-similar solution. The first order correction to this solution accounts for the effects of the shock strength. Whereas it was constant in the Guderley's asymptotic solution, the amplification factor of the finite amplitude shock Λ(t)∝dU{sub s}/dR{sub s} now varies in time. The coefficients present in its series form are iteratively calculated so that the solution does not undergo any singular behavior apart from the position of the shock. The analytical form of the corrected solution in the vicinity of singular points provides a better physical understanding of the finite shock Mach number effects. The correction affects mainly the flow density and the pressure after the shock rebound. In application to the shock ignition scheme, it is shown that the ignition criterion is modified by more than 20% if the fuel pressure prior to the final shock is taken into account. A good agreement is obtained with hydrodynamic simulations using a Lagrangian code.

  6. Turbulence in argon shock waves

    NASA Technical Reports Server (NTRS)

    Johnson, J. A., III; Santiago, J. P.; I, L.

    1981-01-01

    Irregular density fluctuations with turbulent-like behaviors are found in ionizing shock fronts produced by an arc-driven shock tube. Electric probes are used as the primary diagnostic. Spectral analyses show statistical patterns which seem frozen-in and characterizable by a dominant mode and its harmonics.

  7. Whistler waves observed upstream from collisionless shocks

    NASA Technical Reports Server (NTRS)

    Fairfield, D. H.

    1973-01-01

    Waves in the frequency range 0.5 - 4 Hz were studied in the region upstream of the earth's bow shock using data from the fluxgate magnetic field experiment on IMP-6. Analysis of 150 examples of these waves during a three month interval indicates that amplitudes are generally less than 1 or 2 gammas and propagation directions generally make angles of between 20 and 40 degrees with the field direction. The waves as measured in the spacecraft frame of reference are either left or right hand polarized with respect to the average field direction. It is concluded that the observed waves are right handed waves in the plasma frame of reference with wavelengths of approximately 100 km propagating upstream in the whistler mode. Doppler shifting reduces the observed frequencies in the spacecraft frame and reverses the observed polarization for those waves propagating more directly upstream. Similar waves are seen ahead of most interplanetary shocks.

  8. Critical point anomalies include expansion shock waves

    SciTech Connect

    Nannan, N. R.; Guardone, A.; Colonna, P.

    2014-02-15

    From first-principle fluid dynamics, complemented by a rigorous state equation accounting for critical anomalies, we discovered that expansion shock waves may occur in the vicinity of the liquid-vapor critical point in the two-phase region. Due to universality of near-critical thermodynamics, the result is valid for any common pure fluid in which molecular interactions are only short-range, namely, for so-called 3-dimensional Ising-like systems, and under the assumption of thermodynamic equilibrium. In addition to rarefaction shock waves, diverse non-classical effects are admissible, including composite compressive shock-fan-shock waves, due to the change of sign of the fundamental derivative of gasdynamics.

  9. Shock Waves in Dispersive Eulerian Fluids

    NASA Astrophysics Data System (ADS)

    Hoefer, Mark

    2013-11-01

    Shock waves in dispersive media with negligible dissipation are studied in the context of the compressible Euler equations with weak dispersion. Example fluids of this type include superfluids, shallow water flows, and ion-acoustic plasma. A characterization of one-dimensional dispersive shock waves (DSWs) will be presented. DSWs are sharply distinct from classical, dissipatively regularized shock waves both in terms of physical significance and mathematical description. Drawing on terminology from classical gas dynamics, jump conditions (shock loci and speeds) and admissibility criteria for the long time evolution of step-like initial data will be presented utilizing a nonlinear wave averaging technique. While entropy conditions determine admissible, dissipatively regularized shock waves, conservative, dispersive systems are time reversible and can exhibit positive or negative dispersion. The universal structure of weak shocks will be shown to depend solely upon the dispersion sign and pressure law. Large amplitude DSWs can exhibit novel effects such as cavitation and ``implosion'' yielding internal, multi-phase dynamics. Support from NSF DMS-1008973.

  10. Numerical simulation of shock wave diffraction by TVD schemes

    NASA Technical Reports Server (NTRS)

    Young, Victor Y. C.; Yee, H. C.

    1987-01-01

    An upwind total variation diminishing (TVD) scheme and a predictor-corrector symmetric TVD scheme were used to numerically simulate the blast wave diffraction on a stationary object. The objective is to help design an optimum configuration so that lateral motion is minimized and at the same time vortex shedding and flow separation are reduced during a blast wave encounter. Results are presented for a generic configuration for both a coarse grid and a fine grid to illustrate the global and local diffraction flow fields. Numerical experiments for the shock wave reflection on a wedge are also included to validate the current approach. Numerical study indicated that these TVD schemes are more stable and produced higher shock resolution than classical shock capturing methods such as the explicit MacCormack scheme.

  11. Free boundary problems in shock reflection/diffraction and related transonic flow problems

    PubMed Central

    Chen, Gui-Qiang; Feldman, Mikhail

    2015-01-01

    Shock waves are steep wavefronts that are fundamental in nature, especially in high-speed fluid flows. When a shock hits an obstacle, or a flying body meets a shock, shock reflection/diffraction phenomena occur. In this paper, we show how several long-standing shock reflection/diffraction problems can be formulated as free boundary problems, discuss some recent progress in developing mathematical ideas, approaches and techniques for solving these problems, and present some further open problems in this direction. In particular, these shock problems include von Neumann's problem for shock reflection–diffraction by two-dimensional wedges with concave corner, Lighthill's problem for shock diffraction by two-dimensional wedges with convex corner, and Prandtl-Meyer's problem for supersonic flow impinging onto solid wedges, which are also fundamental in the mathematical theory of multidimensional conservation laws. PMID:26261363

  12. 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.

  13. Stishovite: Synthesis by shock wave

    USGS Publications Warehouse

    De Carli, P. S.; Milton, D.J.

    1965-01-01

    Small amounts of stishovite were separated from specimens of explosively shocked sandstones, novaculite, and single-crystal quartz. Estimated peak pressures for the syntheses ranged from 150 to 280 kilobars, and shock temperatures were from 150?? to 900??C. No coesite was detected in any sample. It is suggested that quartz can invert during shock to a short-range-order phase, with sixfold coordination. A small portion of this phase may develop the long-range order of stishovite, and, during the more protracted decrease of the pressure pulse through the stability field of coesite accompanying meteorite crater formation, a portion may invert to coesite.

  14. Transmission of light waves through normal shocks.

    PubMed

    Hariharan, S I; Johnson, D K

    1995-11-20

    We seek to characterize light waves transmitted through normal shock waves. The investigation is motivated by the need for a theory to support a shadowgraph experiment for flow in a convergent-divergent nozzle. In this experiment light beams are passed through the nozzle transverse to the direction of the flow in which a shock has formed in the vicinity of the throat. We present a formulation and an approximation that yield calculations of the intensity of transmitted waves. We also present experimental results to support the theory. The patterns predicted by the theory compare well with the patterns observed in experiments.

  15. 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.

  16. Oscillations of a standing shock wave generated by the Richtmyer-Meshkov instability

    NASA Astrophysics Data System (ADS)

    Mikaelian, Karnig O.

    2016-07-01

    In a typical Richtmyer-Meshkov experiment a fast moving flat shock strikes a stationary perturbed interface between fluids A and B creating a transmitted and a reflected shock, both of which are perturbed. We propose shock tube experiments in which the reflected shock is stationary in the laboratory. Such a standing perturbed shock undergoes well-known damped oscillations. We present the conditions required for producing such a standing shock wave, which greatly facilitates the measurement of the oscillations and their rate of damping. We define a critical density ratio Rcritical, in terms of the adiabatic indices of the two fluids, and a critical Mach number Mscritical of the incident shock wave, which produces a standing reflected wave. If the initial density ratio R of the two fluids is less than Rcritical then a standing shock wave is possible at Ms=Mscritical . Otherwise a standing shock is not possible and the reflected wave always moves in the direction opposite the incident shock. Examples are given for present-day operating shock tubes with sinusoidal or inclined interfaces. We consider the effect of viscosity, which affects the damping rate of the oscillations. We point out that nonlinear bubble and spike amplitudes depend relatively weakly on the viscosity of the fluids and that the interface area is a better diagnostic.

  17. Oscillations of a standing shock wave generated by the Richtmyer-Meshkov instability

    DOE PAGES

    Mikaelian, Karnig O.

    2016-07-13

    In a typical Richtmyer-Meshkov experiment a fast moving flat shock strikes a stationary perturbed interface between fluids A and B creating a transmitted and a reflected shock, both of which are perturbed. We propose shock tube experiments in which the reflected shock is stationary in the laboratory. Such a standing perturbed shock undergoes well-known damped oscillations. We present the conditions required for producing such a standing shock wave, which greatly facilitates the measurement of the oscillations and their rate of damping. We define a critical density ratio Rcritical, in terms of the adiabatic indices of the two fluids, and amore » critical Mach number Mcriticals of the incident shock wave, which produces a standing reflected wave. If the initial density ratio R of the two fluids is less than Rcritical then a standing shock wave is possible at Ms=Mcriticals. Otherwise a standing shock is not possible and the reflected wave always moves in the direction opposite the incident shock. Examples are given for present-day operating shock tubes with sinusoidal or inclined interfaces. We consider the effect of viscosity, which affects the damping rate of the oscillations. Furthermore, we point out that nonlinear bubble and spike amplitudes depend relatively weakly on the viscosity of the fluids and that the interface area is a better diagnostic.« less

  18. Turbulent water coupling in shock wave lithotripsy.

    PubMed

    Lautz, Jaclyn; Sankin, Georgy; Zhong, Pei

    2013-02-01

    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.

  19. Application of Underwater Shock Wave Focusing to the Development of Extracorporeal Shock Wave Lithotripsy

    NASA Astrophysics Data System (ADS)

    Takayama, Kazuyoshi

    1993-05-01

    This paper describes a summary of a research project for the development of extracorporeal shock wave lithotripsy (ESWL), which has been carried out, under close collaboration between the Shock Wave Research Center of Tohoku University and the School of Medicine, Tohoku University. The ESWL is a noninvasive clinical treatment of disintegrating human calculi and one of the most peaceful applications of shock waves. Underwater spherical shock waves were generated by explosion of microexplosives. Characteristics of the underwater shock waves and of ultrasound focusing were studied by means of holographic interferometric flow visualization and polyvinyliden-difluoride (PVDF) pressure transducers. These focused pressures, when applied to clinical treatments, could effectively and noninvasively disintegrate urinary tract stones or gallbladder stones. However, despite clincal success, tissue damage occurs during ESWL treatments, and the possible mechanism of tissue damage is briefly described.

  20. Shock wave interaction with interfaces between materials having different acoustic impedances

    NASA Astrophysics Data System (ADS)

    Hosseini, H.; Moosavi-Nejad, S.; Akiyama, H.; Menezes, V.

    2014-03-01

    We experimentally examined interaction of blast waves with water-air/air-water interfaces through high-speed-real-time visualization and measurement of pressure across the waves. The underwater shock wave, which was expected to reflect totally at the water-air interface, was observed transmitting a shock front to air. Transmission of a blast wave from air to water was also visualized and evaluated. Underwater shock waves are used in several medical/biological procedures, where such unforeseen transmissions can result in detriments. The details provide a guideline to evaluate blast wave transmissions, which can induce tissue and brain injuries. The results explain mechanisms behind blast-induced traumatic brain injury.

  1. Mitigation of shock waves in a cylindrical tunnel by foam

    NASA Astrophysics Data System (ADS)

    Fondaw, Grant W.

    1993-03-01

    The effectiveness of foam linings in mitigating shock waves in tunnels is investigated. A polyurethane foam liner of varying density, crush strength, and thickness was modeled inside a 1 meter radius tunnel and an explosion of 1.25 kg of plastic explosive was simulated. Using CTH, an Eulerian-Lagrangian hydrodynamics code from Sandia National Laboratories, the overpressures were computed and compared graphically to determine the effect of varying each foam parameter. The walls of the tunnel consisted of a perfectly reflecting boundary, and in some cases, a foam liner. Low density foam provided the most shock attenuation, with a 20 cm thick layer of 90% void 0.1265 g/cm(sup 3) foam reducing the shock overpressure by 70% at 50 meters. The effects of foam thickness on the shock pressure varied with the distance from the explosion. The thicker foams raised the initial pressure near the explosion due to constriction of the tunnel area. However, the thicker layers reduced the shock faster. Varying the crush strength of the foam from 1 atm to 3 atm overpressure did not affect its ability to mitigate shock propagation in the tunnel. The results strongly suggest that foam can mitigate shock waves significantly.

  2. 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.

  3. A numerical investigation of polygonal converging shock waves

    NASA Astrophysics Data System (ADS)

    Eliasson, Veronica; Henshaw, William D.

    2007-11-01

    Numerical simulations of cylindrically converging shock waves were performed. The converging shocks impinged upon a set of zero to sixteen regularly spaced cylindrical obstacles. For more than two obstacles, the resulting diffracted shock fronts formed polygonal-shaped patterns near the point of focus. For three obstacles, a triangular-shaped shock was observed during the last stages of the focusing process. The triangle was subjected to regular reflection, and thus the shape remained unchanged until it had focused. Guderley's self-similar solution for the radius, R, as a function of time, t, can be expressed as R=ɛ0( tc-t )^α. The self similar exponent, α, was close to the expected value of unity for the triangular case. For the square-shaped shock undergoing Mach reflection, the self-similar exponent was found to be α=0.844, which agrees well with Guderley's solution for cylindrical shocks (α=0.834). Also, the maximum pressure and temperature as a function of number of obstacles were studied. The highest maximum pressure and temperature occurred with no obstacles. This should be expected, since in all other cases, part of the flow is reflected by the obstacles and never reaches the focal point.

  4. 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.

  5. 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.

  6. 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.

  7. Comparative rates of exchange behind reflected shock waves. 2. /sup 15/No + C/sup 18/O vs. /sup 15/NO + N/sub 2/

    SciTech Connect

    Bopp, A.F.; Kern, R.D.; Niki, T.; Stack, G.M.

    1980-10-02

    The rates of isotopic exchange of nitric oxide with nitrogen and carbon monoxide were studied over the temperature range 2700-3800 K by analyzing the gas from the reflected shock zone at 20-..mu..s intervals with a time-of-flight mass spectrometer. Two mixtures containing 4% /sup 15/NO-4% N/sub 2/ in one and 4% /sup 15/NO-4% C/sup 18/O in the other were each diluted with a mixture of inert gases (Ne-Ar-Kr). The reacting gases were sampled dynamically in order to determine the time dependence of the products; i.e., m/e 29 and 30 for the first mixture and m/e 28 and 33 for the second mixture. The exchange of nitric oxide and carbon monoxide took place readily over the range investigated. The reaction profiles displayed nonlinear growth of the products with respect to reaction time. Computer simulation of the product profiles assuming an atomic mechanism revealed reasonable agreement with the experimental data. In contrast to /sup 15/NO + C/sup 18/O, the exchange of /sup 15/NO + N/sub 2/ did not occur to any measurable extent in accordance with the predictions of an atomic mechanism.

  8. PVDF Shock Compression Sensors in Shock Wave Physics

    NASA Astrophysics Data System (ADS)

    Bauer, F.

    2004-07-01

    Early works have shown that highly reproducible piezoelectric film PVDF (Poly(vinylidene fluoride)) can be reliably used in a wide range of precise stress and stress-rate measurements. The direct stress-derivative or stress-rate PVDF signals have nanosecond resolution and higher operating stress limits than any other technique. PVDF stress gauges have been used in many fields of shock wave physics. The present paper summarizes some of original applications of the PVDF gauges. Blast and shock in air measurements will be presented. Pressure responses of inert materials and polymer-materials will be recalled. Furthermore, example of pressure and particle velocity histories using PVDF and laser interferometry (VISAR) will be presented. Simultaneous measurements using VISAR and PVDF gauge will be discussed. The question of the validity of shock pressure profiles obtained with "in situ" PVDF gauges in one High Explosive in a detonation regime will be discussed.

  9. [Extracorporeal shock-wave lithotripsy for children].

    PubMed

    Wakabayashi, A; Matsuda, H; Uemura, T; Kohri, K; Kurita, T; Kanbara, N; Tamura, M

    1988-06-01

    We performed extracorporeal shock wave lithotripsy (ESWL) on a 5-year-old and 8-year-old. Ureteral calculi in both patients were disintegrated, and all fragments were passable spontaneously. The 5-year-old girl was the youngest of the cases of ESWL reported in Japan. As this patient was 107 cm in height, we put a styrofoam layer on the back of this patient. This protected her lung from the shock wave, and the height limit was released from the ESWL treatment. These cases and the peculiarities and devices for ESWL in the pediatric field are discussed. PMID:3223460

  10. ALEGRA Validation Studies for Regular, Mach, and Double Mach Shock Reflection in Gas Dynamics

    SciTech Connect

    CHEN, MARY I.; TRUCANO, TIMOTHY G.

    2002-09-01

    In this report we describe the performance of the ALEGRA shock wave physics code on a set of gas dynamic shock reflection problems that have associated experimental pressure data. These reflections cover three distinct regimes of oblique shock reflection in gas dynamics--regular, Mach, and double Mach reflection. For the selected data, the use of an ideal gas equation of state is appropriate, thus simplifying to a considerable degree the task of validating the shock wave computational capability of ALEGRA in the application regime of the experiments. We find good agreement of ALEGRA with reported experimental data for sufficient grid resolution. We discuss the experimental data, the nature and results of the corresponding ALEGRA calculations, and the implications of the presented experiment--calculation comparisons.

  11. Reflections of pressure waves at tunnel portals

    NASA Astrophysics Data System (ADS)

    Brown, J. M. B.; Vardy, A. E.

    1994-05-01

    Reflections of plane waves from the open ends (portals) of axisymmetric pipes and plane two-dimensional (2-D) channels are investigated analytically, numerically, and experimentally. An analytical approach developed by Rudinger for pressure decay at an axisymmetric, flanged portal is extended to longer times, and equivalent analyses are developed for reflections from unflanged portals - both axisymmetric and plane 2-D. Predictions for the latter case are compared with numerical results from a computer program based on a 2-D method of bicharacteristics. The theoretical results are compared with measurements from a low pressure shock tube, which was used to investigate alternative end configurations including scarfed portals with and without flange plates. These confirm that the rate of pressure decay is much slower in the plane 2-D case and that flange plates further reduce the rate of decay, albeit slightly. Scarfed portals are shown to cause more uniform decay rates than 90 deg portals.

  12. Reflection of cylindrical surface waves.

    PubMed

    Gordon, Reuven

    2009-10-12

    The reflection of the radially polarized surface wave on a metal wire at an abrupt end is derived. This theory allows for straightforward calculation of the reflection coefficient, including the phase and the amplitude, which will prove useful to the many applications in nanoplasmonics and terahertz spectroscopy. The theory shows excellent quantitative agreement with past comprehensive numerical simulations for small wires and for predicting the minima in reflection for larger wires. Using this theory, the wavelength dependent reflection is calculated for gold rods of diameter 10 nm, 26 nm and 85 nm, from which the Fabry-Perot resonance wavelengths are found. The Fabry-Perot resonances show good agreement with experimentally measured surface plasmon resonances in nanorods. This demonstrates the predictive ability of the theory for applications involving widely-used nanorods, optical antennas and plasmonic resonators. PMID:20372593

  13. 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.

  14. 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.

  15. Shock wave amplification by fabric materials

    NASA Astrophysics Data System (ADS)

    Thom, C. G.; Cronin, D. S.

    2009-04-01

    It has been shown that, when exposed to air shock waves, soft materials such as fabrics can lead to amplification of the peak pressure measured on a reflecting surface behind the fabric. This occurs for a wide range of fabric configurations, including those used in soft-ballistic protection. The goal of this study was to validate a numerical model to develop an improved understanding of this phenomenon and investigate different fabric parameters, including density, permeability and standoff, and their influence on blast amplification. The investigation of fabric parameters was carried out using numerical simulations in an explicit finite element code with coupled fluid-structure interaction. The benefit of this method was the ability to isolate individual parameters. The model predicted similar trends to existing experimental data, though the numerically predicted peak pressures were consistently higher than the experimental values. The parametric study showed that low permeability fabrics result in the highest pressure amplifications. At areal densities on the order 100 g/m2, typical of single layer fabrics, amplification also increased with areal density for low permeability materials.

  16. 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.

  17. Chromospheric heating by acoustic shock waves

    NASA Technical Reports Server (NTRS)

    Jordan, Stuart D.

    1993-01-01

    Work by Anderson & Athay (1989) suggests that the mechanical energy required to heat the quiet solar chromosphere might be due to the dissipation of weak acoustic shocks. The calculations reported here demonstrate that a simple picture of chromospheric shock heating by acoustic waves propagating upward through a model solar atmosphere, free of both magnetic fields and local inhomogeneities, cannot reproduce their chromospheric model. The primary reason is the tendency for vertically propagating acoustic waves in the range of allowed periods to dissipate too low in the atmosphere, providing insufficient residual energy for the middle chromosphere. The effect of diverging magnetic fields and the corresponding expanding acoustic wavefronts on the mechanical dissipation length is then discussed as a means of preserving a quasi-acoustic heating hypothesis. It is argued that this effect, in a canopy that overlies the low chromosphere, might preserve the acoustic shock hypothesis consistent with the chromospheric radiation losses computed by Anderson & Athay.

  18. International Shock-Wave Database: Current Status

    NASA Astrophysics Data System (ADS)

    Levashov, Pavel

    2013-06-01

    Shock-wave and related dynamic material response data serve for calibrating, validating, and improving material models over very broad regions of the pressure-temperature-density phase space. Since the middle of the 20th century vast amount of shock-wave experimental information has been obtained. To systemize it a number of compendiums of shock-wave data has been issued by LLNL, LANL (USA), CEA (France), IPCP and VNIIEF (Russia). In mid-90th the drawbacks of the paper handbooks became obvious, so the first version of the online shock-wave database appeared in 1997 (http://www.ficp.ac.ru/rusbank). It includes approximately 20000 experimental points on shock compression, adiabatic expansion, measurements of sound velocity behind the shock front and free-surface-velocity for more than 650 substances. This is still a useful tool for the shock-wave community, but it has a number of serious disadvantages which can't be easily eliminated: (i) very simple data format for points and references; (ii) minimalistic user interface for data addition; (iii) absence of history of changes; (iv) bad feedback from users. The new International Shock-Wave database (ISWdb) is intended to solve these and some other problems. The ISWdb project objectives are: (i) to develop a database on thermodynamic and mechanical properties of materials under conditions of shock-wave and other dynamic loadings, selected related quantities of interest, and the meta-data that describes the provenance of the measurements and material models; and (ii) to make this database available internationally through the Internet, in an interactive form. The development and operation of the ISWdb is guided by an advisory committee. The database will be installed on two mirrored web-servers, one in Russia and the other in USA (currently only one server is available). The database provides access to original experimental data on shock compression, non-shock dynamic loadings, isentropic expansion, measurements of sound

  19. Shock Wave Dynamics in Weakly Ionized Gases

    NASA Technical Reports Server (NTRS)

    Johnson, Joseph A., III

    1998-01-01

    We have begun a comprehensive series of analyses and experiments to study the basic problem of shock wave dynamics in ionized media. Our objective is to isolate the mechanisms that are responsible for the decrease in the shock amplitude and also to determine the relevant plasma parameters that will be required for a drag reduction scheme in an actual high altitude hypersonic flight. Specifically, we have initiated a program of analyses and measurements with the objective of (i) fully characterizing the propagation dynamics in plasmas formed in gases of aerodynamic interest, (ii) isolating the mechanisms responsible for the decreased shock strength and increased shock velocity, (iii) extrapolating the laboratory observations to the technology of supersonic flight.

  20. 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...

  1. 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...

  2. 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...

  3. The Interaction of Turbulence with Shock Waves

    SciTech Connect

    Zank, G. P.; Kryukov, I. A.; Pogorelov, N. V.; Shaikh, D.

    2010-03-25

    The heliosheath was expected to be turbulent, the result of upstream turbulence and disturbances (shock waves, pressure and density enhancements, structures, etc.) being transmitted across and interacting with the heliospheric termination shock (HTS). A turbulent heliosheath has indeed been observed downstream of the HTS, but the character of the turbulence is significantly different from that of the solar wind. Here, we discuss the transmission of waves and turbulence across the HTS, both analytically and numerically, in the large plasma beta approximation, and we investigate both small amplitude and large-amplitude cases. We find that the linear theory is a reasonable approximation for small amplitude waves incident on the shock. In the case of large amplitude entropy fluctuations incident on the shock, the downstream state is initially one of coherent wave forms, but this rapidly devolves to a highly disturbed state that evolves eventually to a state dominated by vortical structures. Of particular importance, we find that the HTS generates significant levels of downstream compressible turbulence, even in their absence upstream.

  4. 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.

  5. 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.

  6. Wave reflections from duct terminations.

    PubMed

    Selamet, A; Ji, Z L; Kach, R A

    2001-04-01

    The reflection coefficients and inertial end corrections of several duct terminations, including finite length duct extensions perpendicular to an infinite wall, as well as at a number of angles, curved interface surfaces, and annular cavities, are determined and analyzed in the absence of flow by employing the boundary element method. Predictions for the classical unflanged and flanged circular ducts show good agreement with analytical and computational results available in the literature. The predictions for curved interface surfaces (bellmouth or horn) are also consistent with the available experimental data. In view of its high reflection coefficient, the duct termination with an annular cavity may be suggested for the suppression of noise radiation in a specific frequency band or for an effective wave reflection from the termination. PMID:11325101

  7. Lithotripter shock wave interaction with a bubble near various biomaterials

    NASA Astrophysics Data System (ADS)

    Ohl, S. W.; Klaseboer, E.; Szeri, A. J.; Khoo, B. C.

    2016-10-01

    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 shock wave (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 shock wave 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 wave 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 shock wave 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 shock wave. The numerical model offers a computationally efficient way of understanding the complex phenomena involving the interplay of a bubble, a shock wave, and a nearby bio-material.

  8. Generation, saturation, and convection of electrostatic waves in Jupiter's shock foot

    NASA Technical Reports Server (NTRS)

    Moses, S. L.; Coroniti, F. V.; Kennel, C. F.; Scarf, F. L.

    1988-01-01

    In this paper, a model is developed for the analysis of the electrostatic waves produced in the shock foot at Jupiter. It is shown that an ion beam instability involving the ions reflected at the shock ramp and the incoming solar-wind electrons produces waves at the observed frequencies and that saturation via orbit diffusion limits the waves to amplitudes near to what is observed. Results from a two-dimensional model of the reflected beam in the foot indicate that the waves propagate against the solar wind away from the shock ramp and are amplified up to their saturation amplitudes. The saturation results, combined with the electron temperature profile due to wave-particle interactions predicted by quasi-linear theory, reproduce a wave amplitude profile for the shock foot that is in reasonable agreement with the observations.

  9. Application Of Holographic Interferometry To Shock Wave Research

    NASA Astrophysics Data System (ADS)

    Takayama, K.

    1983-10-01

    Paper reports a successful application of holographic interferometry to the shock wave research. Four topics are discussed; i) transonic flow over an aerofoil, ii) shock wave propagation and diffraction past a circular cross-sectional 90° bend and two-dimensional straight or curved wedges, iii) stability of converging cylindrical shock waves and iv) propagation and focusing of underwater shock waves. Experiments were conducted on shock tubes equipped with a double exposure holographic interferometer. In each case isopycnics around shock waves were determined and three-dimensional shock wave interactions were also observed. Results are not only bringing forth new interesting findings to the shock wave research but also showing a further potentiality of holographic interferometry to the high speed gasdynamic study.

  10. Chirped pulse reflectivity in laser driven shock experiments

    NASA Astrophysics Data System (ADS)

    Benuzzi, Alessandra; Koenig, Michel; Faral, Bernard; Batani, Dimitri; Scianitti, Francesca; di Santo, Domenico; Hall, Tom

    1998-11-01

    We performed an experiment based on using two pulses delivered by the 100 TW LULI laser. The first one is an uncompressed (FWHM =89 600 ps) chirped main pulse generating a shock wave in a CH-Al target coated into 2 mm fused quartz. The target rear side emissivity was recorded by a visible streak camera in order to check the shock uniformity. The second one is a partially compressed (FWHM =89 100 ps) chirped probe pulse which irradiates the rear face of the target (the quartz side). We measured on the same laser shot a)the chirped pulse reflectometry(1) which allowed us to obtain a very high temporal resolution, thus a good precision in the shock breakout time determination b) the reflected probe phase change as a function of time using the frequency domain interferometry technique(2). Such measurement allowed us to deduce the interface Al-quartz displacement velocity which yields information on preheating effects and on fluid velocity. [1] D. M. Gold, A. Sullivan, R. Sheperd, J. Dunn & R. Stewart, Proceedings of 26th Annual Anomalous Absorption Conference, Fairbanks, Alaska (1996). [2] J. P. Geindre, P. Audebert, A. Rousse, F. Falli=E8s, J. C. Gauthier, A. Mysyrowicz, A. D. Santos, G. Hammoniaux & A. Antonetti, Optics Lett. 19, 1997 (1994).

  11. Tailoring the Blast Exposure Conditions in the Shock Tube for Generating Pure, Primary Shock Waves: The End Plate Facilitates Elimination of Secondary Loading of the Specimen.

    PubMed

    Kuriakose, Matthew; Skotak, Maciej; Misistia, Anthony; Kahali, Sudeepto; Sundaramurthy, Aravind; Chandra, Namas

    2016-01-01

    The end plate mounted at the mouth of the shock tube is a versatile and effective implement to control and mitigate the end effects. We have performed a series of measurements of incident shock wave velocities and overpressures followed by quantification of impulse values (integral of pressure in time domain) for four different end plate configurations (0.625, 2, 4 inches, and an open end). Shock wave characteristics were monitored by high response rate pressure sensors allocated in six positions along the length of 6 meters long 229 mm square cross section shock tube. Tests were performed at three shock wave intensities, which was controlled by varying the Mylar membrane thickness (0.02, 0.04 and 0.06 inch). The end reflector plate installed at the exit of the shock tube allows precise control over the intensity of reflected waves penetrating into the shock tube. At the optimized distance of the tube to end plate gap the secondary waves were entirely eliminated from the test section, which was confirmed by pressure sensor at T4 location. This is pronounced finding for implementation of pure primary blast wave animal model. These data also suggest only deep in the shock tube experimental conditions allow exposure to a single shock wave free of artifacts. Our results provide detailed insight into spatiotemporal dynamics of shock waves with Friedlander waveform generated using helium as a driver gas and propagating in the air inside medium sized tube. Diffusion of driver gas (helium) inside the shock tube was responsible for velocity increase of reflected shock waves. Numerical simulations combined with experimental data suggest the shock wave attenuation mechanism is simply the expansion of the internal pressure. In the absence of any other postulated shock wave decay mechanisms, which were not implemented in the model the agreement between theory and experimental data is excellent. PMID:27603017

  12. Tailoring the Blast Exposure Conditions in the Shock Tube for Generating Pure, Primary Shock Waves: The End Plate Facilitates Elimination of Secondary Loading of the Specimen

    PubMed Central

    Misistia, Anthony; Kahali, Sudeepto; Sundaramurthy, Aravind; Chandra, Namas

    2016-01-01

    The end plate mounted at the mouth of the shock tube is a versatile and effective implement to control and mitigate the end effects. We have performed a series of measurements of incident shock wave velocities and overpressures followed by quantification of impulse values (integral of pressure in time domain) for four different end plate configurations (0.625, 2, 4 inches, and an open end). Shock wave characteristics were monitored by high response rate pressure sensors allocated in six positions along the length of 6 meters long 229 mm square cross section shock tube. Tests were performed at three shock wave intensities, which was controlled by varying the Mylar membrane thickness (0.02, 0.04 and 0.06 inch). The end reflector plate installed at the exit of the shock tube allows precise control over the intensity of reflected waves penetrating into the shock tube. At the optimized distance of the tube to end plate gap the secondary waves were entirely eliminated from the test section, which was confirmed by pressure sensor at T4 location. This is pronounced finding for implementation of pure primary blast wave animal model. These data also suggest only deep in the shock tube experimental conditions allow exposure to a single shock wave free of artifacts. Our results provide detailed insight into spatiotemporal dynamics of shock waves with Friedlander waveform generated using helium as a driver gas and propagating in the air inside medium sized tube. Diffusion of driver gas (helium) inside the shock tube was responsible for velocity increase of reflected shock waves. Numerical simulations combined with experimental data suggest the shock wave attenuation mechanism is simply the expansion of the internal pressure. In the absence of any other postulated shock wave decay mechanisms, which were not implemented in the model the agreement between theory and experimental data is excellent. PMID:27603017

  13. Tailoring the Blast Exposure Conditions in the Shock Tube for Generating Pure, Primary Shock Waves: The End Plate Facilitates Elimination of Secondary Loading of the Specimen.

    PubMed

    Kuriakose, Matthew; Skotak, Maciej; Misistia, Anthony; Kahali, Sudeepto; Sundaramurthy, Aravind; Chandra, Namas

    2016-01-01

    The end plate mounted at the mouth of the shock tube is a versatile and effective implement to control and mitigate the end effects. We have performed a series of measurements of incident shock wave velocities and overpressures followed by quantification of impulse values (integral of pressure in time domain) for four different end plate configurations (0.625, 2, 4 inches, and an open end). Shock wave characteristics were monitored by high response rate pressure sensors allocated in six positions along the length of 6 meters long 229 mm square cross section shock tube. Tests were performed at three shock wave intensities, which was controlled by varying the Mylar membrane thickness (0.02, 0.04 and 0.06 inch). The end reflector plate installed at the exit of the shock tube allows precise control over the intensity of reflected waves penetrating into the shock tube. At the optimized distance of the tube to end plate gap the secondary waves were entirely eliminated from the test section, which was confirmed by pressure sensor at T4 location. This is pronounced finding for implementation of pure primary blast wave animal model. These data also suggest only deep in the shock tube experimental conditions allow exposure to a single shock wave free of artifacts. Our results provide detailed insight into spatiotemporal dynamics of shock waves with Friedlander waveform generated using helium as a driver gas and propagating in the air inside medium sized tube. Diffusion of driver gas (helium) inside the shock tube was responsible for velocity increase of reflected shock waves. Numerical simulations combined with experimental data suggest the shock wave attenuation mechanism is simply the expansion of the internal pressure. In the absence of any other postulated shock wave decay mechanisms, which were not implemented in the model the agreement between theory and experimental data is excellent.

  14. Models and Observations of Shock Wave Propagation in Volcanic Settings

    NASA Astrophysics Data System (ADS)

    Anderson, J.; Johnson, J. B.; Ruiz, M. C.; Steele, A.

    2013-12-01

    High-amplitude air waves (shock waves) propagate nonlinearly; although this strongly affects recorded signals, it is not commonly modeled in studies of volcanic explosions. Failure to account for the shock wave component of air waves can lead to underestimation of source power and inaccurate source times. Additionally, propagation effects can significantly alter waveforms from the original source signals. In order to permit more accurate studies of shock wave sources, we examine modeling techniques and observations of shock waves. Shock wave signals begin with strong, abrupt compressions that, compared to typical sound waves, propagate and decay more quickly. Because of the high-amplitude discontinuities, numerical methods that are commonly used to study linear sound waves become unstable and inaccurate when applied to shock waves. We discuss the use of other techniques that are capable of modeling shock wave propagation. Equations relating wave speed to the difference of various physical quantities across the shock (such as pressure, density, and particle velocity) are useful for modeling these waves. Addressing the shock explicitly as such, in conjunction with use of traditional numerical methods for the remainder of the signal, permits modeling of full shock waveforms. Additionally, we present examples of recorded volcanic signals that propagate nonlinearly and demonstrate propagation effects on amplitude, waveform, and spectrum.

  15. Uniform shock waves in disordered granular matter

    NASA Astrophysics Data System (ADS)

    Gómez, Leopoldo R.; Turner, Ari M.; Vitelli, Vincenzo

    2012-10-01

    The confining pressure P is perhaps the most important parameter controlling the properties of granular matter. Strongly compressed granular media are, in many respects, simple solids in which elastic perturbations travel as ordinary phonons. However, the speed of sound in granular aggregates continuously decreases as the confining pressure decreases, completely vanishing at the jamming-unjamming transition. This anomalous behavior suggests that the transport of energy at low pressures should not be dominated by phonons. In this work we use simulations and theory to show how the response of granular systems becomes increasingly nonlinear as pressure decreases. In the low-pressure regime the elastic energy is found to be mainly transported through nonlinear waves and shocks. We numerically characterize the propagation speed, shape, and stability of these shocks and model the dependence of the shock speed on pressure and impact intensity by a simple analytical approach.

  16. Holographic flow visualization of time-varying shock waves

    NASA Technical Reports Server (NTRS)

    Decker, A. J.

    1981-01-01

    Rapid-double-exposure, diffuse-illumination holography is evaluated analytically and experimentally as a flow visualization method for time-varying shock waves. Conditions are determined that minimize the distance (localization error) between the surface or curve of interference-fringe localization and the shock surface. Treated specifically are the cases of shock waves in a transonic compressor rotor for which there is laser anemometer data for comparison and shock waves in a flutter cascade.

  17. Stability of spherical converging shock wave

    NASA Astrophysics Data System (ADS)

    Murakami, M.; Sanz, J.; Iwamoto, Y.

    2015-07-01

    Based on Guderley's self-similar solution, stability of spherical converging shock wave is studied. A rigorous linear perturbation theory is developed, in which the growth rate of perturbation is given as a function of the spherical harmonic number ℓ and the specific heats ratio γ. Numerical calculation reveals the existence of a γ-dependent cut-off mode number ℓc, such that all the eigenmode perturbations for ℓ > ℓc are smeared out as the shock wave converges at the center. The analysis is applied to partially spherical geometries to give significant implication for different ignition schemes of inertial confinement fusion. Two-dimensional hydrodynamic simulations are performed to verify the theory.

  18. Stability of spherical converging shock wave

    SciTech Connect

    Murakami, M.; Sanz, J.; Iwamoto, Y.

    2015-07-15

    Based on Guderley's self-similar solution, stability of spherical converging shock wave is studied. A rigorous linear perturbation theory is developed, in which the growth rate of perturbation is given as a function of the spherical harmonic number ℓ and the specific heats ratio γ. Numerical calculation reveals the existence of a γ-dependent cut-off mode number ℓ{sub c}, such that all the eigenmode perturbations for ℓ > ℓ{sub c} are smeared out as the shock wave converges at the center. The analysis is applied to partially spherical geometries to give significant implication for different ignition schemes of inertial confinement fusion. Two-dimensional hydrodynamic simulations are performed to verify the theory.

  19. Extra-corporeal shock wave lithotripsy.

    PubMed Central

    Pemberton, J.

    1987-01-01

    Extra-corporeal shock wave lithotripsy (ESWL) has proved to be a revolutionary advance in the treatment of renal stone disease. It, itself, is non-invasive but may necessitate or be used as an adjunct to more invasive auxiliary procedures. The basic principles of lithotripsy, the clinical experience thus far and probable future applications are discussed. Images Figure 2 Figure 4 Figure 5 Figure 7 Figure 8 PMID:3330235

  20. Ionospheric shock waves triggered by rockets

    NASA Astrophysics Data System (ADS)

    Lin, C. H.; Lin, J. T.; Chen, C. H.; Liu, J. Y.; Sun, Y. Y.; Kakinami, Y.; Matsumura, M.; Chen, W. H.; Liu, H.; Rau, R. J.

    2014-09-01

    This paper presents a two-dimensional structure of the shock wave signatures in ionospheric electron density resulting from a rocket transit using the rate of change of the total electron content (TEC) derived from ground-based GPS receivers around Japan and Taiwan for the first time. From the TEC maps constructed for the 2009 North Korea (NK) Taepodong-2 and 2013 South Korea (SK) Korea Space Launch Vehicle-II (KSLV-II) rocket launches, features of the V-shaped shock wave fronts in TEC perturbations are prominently seen. These fronts, with periods of 100-600 s, produced by the propulsive blasts of the rockets appear immediately and then propagate perpendicularly outward from the rocket trajectory with supersonic velocities between 800-1200 m s-1 for both events. Additionally, clear rocket exhaust depletions of TECs are seen along the trajectory and are deflected by the background thermospheric neutral wind. Twenty minutes after the rocket transits, delayed electron density perturbation waves propagating along the bow wave direction appear with phase velocities of 800-1200 m s-1. According to their propagation character, these delayed waves may be generated by rocket exhaust plumes at earlier rocket locations at lower altitudes.

  1. Experimental study of Richtmyer-Meshkov instability induced by cylindrical shock waves

    NASA Astrophysics Data System (ADS)

    Hosseini, S. H. R.; Takayama, K.

    2005-08-01

    The paper describes the results of holographic interferometric flow visualization of the Richtmyer-Meshkov instability induced by cylindrical shock waves propagating across cylindrical interfaces. Experiments were conducted in an annular coaxial vertical diaphragmless shock tube, which can produce converging cylindrical shock waves with minimum disturbances. The shock wave converged and interacted with a cylindrical soap bubble filled with He, Ne, air, Ar, Kr, Xe, or SF6. The soap bubble was placed coaxially in the test section. The effects of density variation on the Richtmyer-Meshkov instability for a wide range of Atwood numbers were determined. Pressure histories at different radii during the shock wave implosion and reflection from the center were measured. Double-exposure holographic interferometry was used and the motion of the converging shock wave and its interaction with the gaseous interface were visualized. The variation of the pressure at the center with interface Atwood number for constant incident shock Mach number was studied. It is found that the dominant mechanism limiting the maximum pressure at the center of convergence is related to the instability of the converging shock wave induced by its interaction with the interface. A short time after the impulsive acceleration, the interface started deforming, and the growth of these perturbations is described. The results show that after diverging shock wave interaction, the reshocked cylindrical interfaces have a higher growth rate of the turbulent mixing zone than that of the reshocked interface in a plane geometry reported by previous works.

  2. 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.

  3. Shock Wave - Boundary Layer Interaction in Reactive H2/O2 Mixture

    NASA Astrophysics Data System (ADS)

    Dziemińska, E.; Hayashi, A. K.

    Shock wave - boundary layer interaction (SWBLI) has been widely discussed over the decades. SWBLI is usually associated with high speed fights, airfoils etc. However, phenomena mentioned above are linked to non-reactive environment. As for reactive mixtures, SWBLI have been observed in reflected shocks studies and ram accelerators.

  4. Large-Amplitude Electrostatic Waves Observed at a Supercritical Interplanetary Shock

    NASA Technical Reports Server (NTRS)

    Wilson, L. B., III; Cattell, C. A.; Kellogg, P. J.; Goetz, K.; Kersten, K.; Kasper, J. C.; Szabo, A.; Wilber, M.

    2010-01-01

    We present the first observations at an interplanetary shock of large-amplitude (> 100 mV/m pk-pk) solitary waves and large-amplitude (approx.30 mV/m pk-pk) waves exhibiting characteristics consistent with electron Bernstein waves. The Bernstein-like waves show enhanced power at integer and half-integer harmonics of the cyclotron frequency with a broadened power spectrum at higher frequencies, consistent with the electron cyclotron drift instability. The Bernstein-like waves are obliquely polarized with respect to the magnetic field but parallel to the shock normal direction. Strong particle heating is observed in both the electrons and ions. The observed heating and waveforms are likely due to instabilities driven by the free energy provided by reflected ions at this supercritical interplanetary shock. These results offer new insights into collisionless shock dissipation and wave-particle interactions in the solar wind.

  5. Nonlinear interactions in superfluid dynamics: Nonstationary heat transfer due to second sound shock waves

    NASA Technical Reports Server (NTRS)

    Liepmann, H. W.; Torczynski, J. R.

    1983-01-01

    Second sound techniques were used to study superfluid helium. Second sound shock waves produced relative velocities in the bulk fluid. Maximum counterflow velocities produced in this way are found to follow the Langer-Fischer prediction for the fundamental critical velocity in its functional dependence on temperature and pressure. Comparison of successive shock and rotating experiments provides strong evidence that breakdown results in vorticity production in the flow behind the shock. Schlieren pictures have verified the planar nature of second sound shocks even after multiple reflections. The nonlinear theory of second sound was repeatedly verified in its prediction of double shocks and other nonlinear phenomena.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Convergence of shock waves between conical and parabolic boundaries

    NASA Astrophysics Data System (ADS)

    Yanuka, D.; Zinowits, H. E.; Antonov, O.; Efimov, S.; Virozub, A.; Krasik, Ya. E.

    2016-07-01

    Convergence of shock waves, generated by underwater electrical explosions of cylindrical wire arrays, between either parabolic or conical bounding walls is investigated. A high-current pulse with a peak of ˜550 kA and rise time of ˜300 ns was applied for the wire array explosion. Strong self-emission from an optical fiber placed at the origin of the implosion was used for estimating the time of flight of the shock wave. 2D hydrodynamic simulations coupled with the equations of state of water and copper showed that the pressure obtained in the vicinity of the implosion is ˜7 times higher in the case of parabolic walls. However, comparison with a spherical wire array explosion showed that the pressure in the implosion vicinity in that case is higher than the pressure in the current experiment with parabolic bounding walls because of strong shock wave reflections from the walls. It is shown that this drawback of the bounding walls can be significantly minimized by optimization of the wire array geometry.

  11. The Structure of Weak Shock Waves in Water

    NASA Astrophysics Data System (ADS)

    Baty, Roy; Tucker, Don; Hagelberg, Carl

    2010-11-01

    This talk presents solutions of the Navier-Stokes equations that model weak shock waves in water. One-dimensional jump functions are computed to describe the viscous microstructure of hydrodynamic shocks, which are approximately isentropic. The Tate and Grueneisen equations of state are applied separately with the conservation laws to derive the flow microstructure for shock compressions and pressures up to 1.3 and 20.0 kbars, respectively. The Navier-Stokes equations are integrated along characteristic lines to compute the shock wave thickness. On characteristic lines, the shock wave jump functions reduce to integral equations. The Tate and Grueneisen equations of state yield similar, strictly monotonically increasing, shock wave microstructures. Moreover, the non-dimensional shock wave thicknesses predicted by these equations of state as a function of compression are very similar.

  12. Nonequilibrium ionization phenomena behind shock waves

    SciTech Connect

    Panesi, Marco; Magin, Thierry; Huo, Winifred

    2011-05-20

    An accurate investigation of the behavior of electronically excited states of atoms and molecules in the post shock relaxation zone of a trajectory point of the FIRE II flight experiment is carried out by means of a one-dimensional flow solver coupled to a collisional-radiative model. In the rapidly ionizing regime behind a strong shock wave, the high lying bound electronic states of atoms are depleted. This leads the electronic energy level populations of atoms to depart from Boltzmann distributions which strongly affects the non-equilibrium ionization process as well as the radiative signature. The importance of correct modeling of the interaction of radiation and matter is discussed showing a strong influence on the physico-chemical properties of the gas. The paper clearly puts forward the shortcomings of the simplified approach often used in literature which strongly relies on the escape factors to characterize the optical thickness of the gas.

  13. 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.

  14. 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.

  15. Wave and particle evolution downstream of quasi-perpendicular shocks

    NASA Technical Reports Server (NTRS)

    Mckean, M. E.; Omidi, N.; Krauss-Varban, D.; Karimabadi, H.

    1995-01-01

    Distributions of ions heated in quasi-perpendicular bow shocks have large perpendicular temperature anisotropies that provide free energy for the growth of Alfven ion cyclotron (AIC) and mirror waves. These modes are often obsreved in the Earth's magnetosheath. Using two-dimensional hybrid simulations, we show that these waves are produced near the shock front and convected downstream rather than being produced locally downstream. The wave activity reduces the proton anisotropy to magnetosheath levels within a few tens of gyroradii of the shock but takes significantly longer to reduce the anisotropy of He(++) ions. The waves are primarily driven by proton anisotropy and the dynamics of the helium ions is controlled by the proton waves. Downstream of high Mach number shocks, mirror waves compete effectively with AIC waves. Downstream of low Mach number shocks, AIC waves dominate.

  16. Doppler effect for an optical discharge source of shock waves

    SciTech Connect

    Tishchenko, V N

    2005-11-30

    The Doppler effect for a moving pulsating optical discharge producing periodic shock waves is considered. The manifestations of the effect are limited by the wave merging mechanism. The validity conditions were found for the effect in the case of a pulsating source of shock waves. (interaction of laser radiation with matter. laser plasma)

  17. 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

  18. Electrostatic waves in the bow shock at Uranus

    NASA Technical Reports Server (NTRS)

    Moses, S. L.; Coroniti, F. V.; Kennel, C. F.; Bagenal, F.; Lepping, R. P.

    1989-01-01

    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 outer 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.

  19. 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.

  20. 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.

  1. 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.

  2. Large amplitude MHD waves upstream of the Jovian bow shock

    NASA Technical Reports Server (NTRS)

    Goldstein, M. L.; Smith, C. W.; Matthaeus, W. H.

    1983-01-01

    Observations of large amplitude magnetohydrodynamics (MHD) waves upstream of Jupiter's bow shock are analyzed. The waves are found to be right circularly polarized in the solar wind frame which suggests that they are propagating in the fast magnetosonic mode. A complete spectral and minimum variance eigenvalue analysis of the data was performed. The power spectrum of the magnetic fluctuations contains several peaks. The fluctuations at 2.3 mHz have a direction of minimum variance along the direction of the average magnetic field. The direction of minimum variance of these fluctuations lies at approximately 40 deg. to the magnetic field and is parallel to the radial direction. We argue that these fluctuations are waves excited by protons reflected off the Jovian bow shock. The inferred speed of the reflected protons is about two times the solar wind speed in the plasma rest frame. A linear instability analysis is presented which suggests an explanation for many of the observed features of the observations.

  3. Mitigating Shock Waves Using Solid Obstacles with Semi-Circular Grooves

    NASA Astrophysics Data System (ADS)

    Amen, Nicholas; Cajal, Arturo; Eliasson, Veronica

    2015-11-01

    An experimental investigation was performed to assess the effectiveness of multiple obstacles with semi-circular grooves placed along a logarithmic spiral curve as a method to attenuate a shock wave. Previous research has shown that the use of multiple obstacles arranged in a log spiral configuration can attenuate a shock wave by reducing the energy of the wave. In this study, four different obstacle cross-sections in the same log spiral configuration were considered. All spirals had square cross-sections with zero, one, two, or three semi-circular grooves in each face. They were placed inside a shock tube where the incident, reflected, and transmitted shocks were visualized with high-speed schlieren imaging and the pressure histories were recorded with four pressure transducers. Each case was studied varying shock Mach numbers between M =1.1 and M =1.5. The pressure traces were used to establish incident, reflected, and transmitted shock strength and wave speed. Results for the zero groove case were compared to that of the one, two, and three groove cross-sections which show that increasing the number of grooves has a profound effect on the generation of the reflected wave and impacts the transmitted wave via vortex generation behind the spiral.

  4. [Physical parameters of extracorporeal shock waves].

    PubMed

    Maier, M; Ueberle, F; Rupprecht, G

    1998-10-01

    Prerequisites for the successful investigation of the mechanism of action of ESWT (extracorporeal shockwave therapy) and the establishment of treatment standards, are the ability to measure, and a knowledge of, the physical parameters involved. The most accurate measurements are obtained with laser hydrophones. Various parameters (amplitude, rise time, pulse width, pressure pulse decay, rarification phase) of a typical shock wave can thus be determined. These can then be used to calculate energy flux density, focal extent, focal volume and as well as focal energy, effective energy in a defined area, and effective biological energy. These parameters can be utilized to work out a theoretical treatment protocol.

  5. Nonequilibrium processes in a shock wave profile

    NASA Astrophysics Data System (ADS)

    Bashlykov, A. M.; Velikodnyi, V. Iu.

    1989-03-01

    A modified Tamm-Mott-Smith approach is used to study the distribution of heat fluxes in a shock wave profile and their relationship with the distribution of partial temperature in gas mixtures. Results are presented on changes of partial and mean temperature, and heat fluxes in an He-Xe mixture at a Mach number of 4.4 and in an He-Ar mixture at a Mach number of 1.58. Conditions are established under which the heat flux of the heavy component of the mixture has the same sign as the gradient of its partial temperature.

  6. 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.

  7. Foreshock magnetic structure ahead of a laser-driven shock wave

    NASA Astrophysics Data System (ADS)

    Crowston, Robert; Doyle, H.; Gregori, G.; Meinecke, J.; Bell, A. R.; Kuramitsu, Y.; Takabe, H.; Morita, T.; Sano, T.; Moritaka, T.; Yamura, Y.; Ishikawa, T.; Yoneda, H.; Pelka, A.; Woolsey, Nigel

    2015-11-01

    The Earth's bow shock contains many wave species that propagate upstream from the shock, against the incoming flow. The mechanism by which these waves are produced remains an open problem. Here, we present an experiment for studying one proposed excitation mechanism. A shock is launched by laser irradiation of a carbon pin immersed in a nitrogen gas. A shock forms, propagates parallel to an externally imposed magnetic field and is diagnosed using interferometry, streaked optical emission imaging and a three axis induction coil. Imaging aids establishing the shock conditions and the induction coil data is used to infer the time evolution of magnetic fields. Analysis extracts the frequency, amplitude and polarisation of magnetic waves arriving ahead of the shock. The results are consistent with instabilities and magnetic waves driven by warm electrons generated at the shock mixing with cold electrons. These waves propagate along magnetic field lines, transport energy and matter ahead of the shock ultimately resulting in an extended foreshock consisting of shock-reflected ions and electrons.

  8. AN EXPERIMENTAL STUDY OF SHOCK WAVES RESULTING FROM THE IMPACT OF HIGH VELOCITY MISSILES ON ANIMAL TISSUES

    PubMed Central

    Harvey, E. Newton; McMillen, J. Howard

    1947-01-01

    The spark shadowgram method of studying shock waves is described. It has been used to investigate the properties of such waves produced by the impact of a high velocity missile on the surface of water. The method can be adapted for study of behavior of shock waves in tissue by placing the tissue on a water surface or immersing it in water. Spark shadowgrams then reveal waves passing from tissue to water or reflected from tissue surfaces. Reflection and transmission of shock waves from muscle, liver, stomach, and intestinal wall are compared with reflection from non-living surfaces such as gelatin gel, steel, plexiglas, cork, and air. Because of its heterogeneous structure, waves transmitted by tissue are dispersed and appear as a series of wavelets. When the accoustical impedance (density x wave velocity) of a medium is less than that in which the wave is moving, reflection will occur with inversion of the wave; i.e., a high pressure wave will become a low pressure wave. This inversion occurs at an air surface and is illustrated by shadowgrams of reflection from stomach wall, from a segment of colon filled with gas, and from air-filled rubber balloons. Bone (human skull and beef ribs) shows good reflection and some transmission of shock waves. When steel is directly hit by a missile, clearly visible elastic waves pass from metal to water, but a similar direct hit on bone does not result in elastic waves strong enough to be detected by a spark shadowgram. PMID:19871617

  9. 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.

  10. Shock wave processes in collisional gas particle mixtures

    NASA Astrophysics Data System (ADS)

    Khmel, T. A.; Fedorov, A. V.

    2016-06-01

    Structures and propagation of shock waves in high density particle suspensions in gas are investigated theoretically and numerically. A physical and mathematical model which takes into account integral collisions between the particles on the basis of molecular-kinetic approaches of theory of granular materials is applied. The possibility of different types of shock waves, including double front structures is revealed. The role of particle collisions in the dynamics of particle dense layer expansion under an influence of divergent shock wave and in processes of shock wave diffraction past a backward-facing step is analyzed.

  11. Magnetosonic shock wave in collisional pair-ion plasma

    NASA Astrophysics Data System (ADS)

    Adak, Ashish; Sikdar, Arnab; Ghosh, Samiran; Khan, Manoranjan

    2016-06-01

    Nonlinear propagation of magnetosonic shock wave has been studied in collisional magnetized pair-ion plasma. The masses of both ions are same but the temperatures are slightly different. Two fluid model has been taken to describe the model. Two different modes of the magnetosonic wave have been obtained. The dynamics of the nonlinear magnetosonic wave is governed by the Korteweg-de Vries Burgers' equation. It has been shown that the ion-ion collision is the source of dissipation that causes the Burgers' term which is responsible for the shock structures in equal mass pair-ion plasma. The numerical investigations reveal that the magnetosonic wave exhibits both oscillatory and monotonic shock structures depending on the strength of the dissipation. The nonlinear wave exhibited the oscillatory shock wave for strong magnetic field (weak dissipation) and monotonic shock wave for weak magnetic field (strong dissipation). The results have been discussed in the context of the fullerene pair-ion plasma experiments.

  12. Bragg Reflection of Ocean Waves from Sandbars

    NASA Astrophysics Data System (ADS)

    Elgar, S.; Raubenheimer, B.; Herbers, T. H.

    2002-12-01

    Resonant Bragg reflection of surface waves from a field of roughly shore-parallel sandbars was observed in Cape Cod Bay near Truro, MA during low energy wave conditions and during a storm. Although the Bragg resonance mechanism for wave reflection has been demonstrated convincingly in the laboratory, the corresponding impact of natural sandbars on ocean waves is not known. Multiple shore-parallel sandbars frequently are found in bays and gulfs, but observations of associated wave reflection have not been reported. Here, we present the first observations of resonant Bragg reflection of ocean surface waves by a natural field of sandbars. The waves were reflected both from the bars and from the steep beach shoreward of the bars, causing complicated interference patterns of seaward and shoreward propagating waves. The observed cross-shore variations in the onshore- and offshore-directed energy fluxes are consistent with theory (Yu and Mei JFM 2000) for resonant Bragg reflection, including a 20% decay of the incident wave energy flux that is an order of magnitude greater than expected for wave-orbital velocity induced bottom friction. When offshore wave heights were small (less than 0.25 m) there was no wave breaking across the sandbars, and the near-bottom velocities associated with the Bragg reflecting waves likely were too small to cause significant sediment transport. However, sediment mobilized during storms may be transported by velocity convergences and divergences associated with nodes and antinodes of the reflecting Bragg waves, possibly resulting in growth of the sandbars. Funding was provided by the Mellon Foundation, ONR, and NSF.

  13. Brane-induced-gravity shock waves.

    PubMed

    Kaloper, Nemanja

    2005-05-13

    We construct exact gravitational field solutions for a relativistic particle localized on a tensional brane in brane-induced gravity. They are a generalization of gravitational shock waves in 4D de Sitter space. We provide the metrics for both the normal branch and the self-inflating branch Dvali-Gabadadze-Porrati brane worlds, and compare them to the 4D Einstein gravity solution and to the case when gravity resides only in the 5D bulk, without any brane-localized curvature terms. At short distances the wave profile looks the same as in four dimensions. The corrections appear only far from the source, where they differ from the long distance corrections in 4D de Sitter space. We also discover a new nonperturbative channel for energy emission into the bulk from the self-inflating [corrected] branch, when gravity is modified at the de Sitter radius.

  14. Developments in strong shock wave position tracking

    NASA Astrophysics Data System (ADS)

    Rae, Philip; Glover, Brain; Perry, Lee; WX-6; WX-7 Team

    2011-06-01

    This poster will highlight several modified techniques to allow the position vs. time to be tracked in strong shock situations (such as detonation). Each is a modification or improvement of existing ideas either making use of advances in specialist materials availability or recent advances in electronics.) Shorting embedded mini-coaxial cable with a standing microwave pattern. This technique is a modified version of an old LANL method of shock position tracking making use of a traveling short imposed in an embedded coaxial cable. A high frequency standing wave (3-8GHz) is present in the cable and the moving short position can be tracked by monitoring the output voltage envelope as a function of time. A diode detector is used to allow the envelope voltage to be monitored on a regular low frequency digitizer significantly reducing the cost. The small and cheap high frequency voltage generators now available allow much greater spatial resolution than possible previously. 2) Very thin shorting resistance track gauges. Parallel tracks of constantan resistance material are etched on a thin dielectric substrate. The gauges are less than 0.2 mm thick. The ionized gas present in a detonation front sweeps up the tracks lowering the measured resistance. A potential divider circuit allows the shock position vs. time to be monitored on a regular digitizer after easy calibration. The novel feature is the thin section of the gauge producing minimal perturbation in the detonation front.

  15. 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.

  16. 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

  17. PARTICLE ENERGY SPECTRA AT TRAVELING INTERPLANETARY SHOCK WAVES

    SciTech Connect

    Reames, Donald V.

    2012-09-20

    We have searched for evidence of significant shock acceleration of He ions of {approx}1-10 MeV amu{sup -1} in situ at 258 interplanetary traveling shock waves observed by the Wind spacecraft. We find that the probability of observing significant acceleration, and the particle intensity observed, depends strongly upon the shock speed and less strongly upon the shock compression ratio. For most of the 39 fast shocks with significant acceleration, the observed spectral index agrees with either that calculated from the shock compression ratio or with the spectral index of the upstream background, when the latter spectrum is harder, as expected from diffusive shock theory. In many events the spectra are observed to roll downward at higher energies, as expected from Ellison-Ramaty and from Lee shock-acceleration theories. The dearth of acceleration at {approx}85% of the shocks is explained by (1) a low shock speed, (2) a low shock compression ratio, and (3) a low value of the shock-normal angle with the magnetic field, which may cause the energy spectra that roll downward at energies below our observational threshold. Quasi-parallel shock waves are rarely able to produce measurable acceleration at 1 AU. The dependence of intensity on shock speed, seen here at local shocks, mirrors the dependence found previously for the peak intensities in large solar energetic-particle events upon speeds of the associated coronal mass ejections which drive the shocks.

  18. 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. PMID:22559580

  19. 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.

  20. On imploding cylindrical and spherical shock waves in a perfect gas

    NASA Astrophysics Data System (ADS)

    Ponchaut, N. F.; Hornung, H. G.; Pullin, D. I.; Mouton, C. A.

    2006-08-01

    The problem of a cylindrically or spherically imploding and reflecting shock wave in a flow initially at rest is studied without the use of the strong-shock approximation. Dimensional arguments are first used to show that this flow admits a general solution where an infinitesimally weak shock from infinity strengthens as it converges towards the origin. For a perfect-gas equation of state, this solution depends only on the dimensionality of the flow and on the ratio of specific heats. The Guderley power-law result can then be interpreted as the leading-order, strong-shock approximation, valid near the origin at the implosion centre. We improve the Guderley solution by adding two further terms in the series expansion solution for both the incoming and the reflected shock waves. A series expansion, valid where the shock is still weak and very far from the origin, is also constructed. With an appropriate change of variables and using the exact shock-jump conditions, a numerical, characteristics-based solution is obtained describing the general shock motion from almost infinity to very close to the reflection point. Comparisons are made between the series expansions, the characteristics solution, and the results obtained using an Euler solver. These show that the addition of two terms to the Guderley solution significantly extends the range of validity of the strong-shock series expansion.

  1. Multi-reflective acoustic wave device

    DOEpatents

    Andle, Jeffrey C.

    2006-02-21

    An acoustic wave device, which utilizes multiple localized reflections of acoustic wave for achieving an infinite impulse response while maintaining high tolerance for dampening effects, is disclosed. The device utilized a plurality of electromechanically significant electrodes disposed on most of the active surface. A plurality of sensors utilizing the disclosed acoustic wave mode device are also described.

  2. 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.

  3. 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.

  4. A numerical scheme for ionizing shock waves

    SciTech Connect

    Aslan, Necdet . E-mail: naslan@yeditepe.edu.tr; Mond, Michael

    2005-12-10

    A two-dimensional (2D) visual computer code to solve the steady state (SS) or transient shock problems including partially ionizing plasma is presented. Since the flows considered are hypersonic and the resulting temperatures are high, the plasma is partially ionized. Hence the plasma constituents are electrons, ions and neutral atoms. It is assumed that all the above species are in thermal equilibrium, namely, that they all have the same temperature. The ionization degree is calculated from Saha equation as a function of electron density and pressure by means of a nonlinear Newton type root finding algorithms. The code utilizes a wave model and numerical fluctuation distribution (FD) scheme that runs on structured or unstructured triangular meshes. This scheme is based on evaluating the mesh averaged fluctuations arising from a number of waves and distributing them to the nodes of these meshes in an upwind manner. The physical properties (directions, strengths, etc.) of these wave patterns are obtained by a new wave model: ION-A developed from the eigen-system of the flux Jacobian matrices. Since the equation of state (EOS) which is used to close up the conservation laws includes electronic effects, it is a nonlinear function and it must be inverted by iterations to determine the ionization degree as a function of density and temperature. For the time advancement, the scheme utilizes a multi-stage Runge-Kutta (RK) algorithm with time steps carefully evaluated from the maximum possible propagation speed in the solution domain. The code runs interactively with the user and allows to create different meshes to use different initial and boundary conditions and to see changes of desired physical quantities in the form of color and vector graphics. The details of the visual properties of the code has been published before (see [N. Aslan, A visual fluctuation splitting scheme for magneto-hydrodynamics with a new sonic fix and Euler limit, J. Comput. Phys. 197 (2004) 1

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Dynamic reflectance of tin shocked from its beta to BCT phase

    NASA Astrophysics Data System (ADS)

    Stevens, Gerald; La Lone, Brandon; Veeser, Lynn; Turley, Dale

    2015-06-01

    Shock-induced phase transitions have historically been inferred by features in loading/unloading velocity wave profiles, which arise due to volume or sound speed differences between phases. In 2010, we used a flash-lamp illuminated multi-band reflectometer to demonstrate that iron, tin, cerium, and gallium have measureable reflectance changes at phase boundaries. We have improved upon our prior technique, utilizing an integrating sphere with an internal xenon flash lamp to illuminate a shocked metal beneath a LiF window. The new reflectance system is insensitive to motion, tilt, or curvature and measures the absolute (not relative) reflectance within five bands centered at 500, 700, 850, 1300, and 1550 nm. We have made dynamic reflectance measurements of tin samples shocked to pressures above and below the beta-bct phase transition using either high explosives or a gas gun. Below the transition, the visible reflectance decreases with pressure. At and above the transition, the visible reflectance increases to values higher than the ambient values. Reflectance can therefore be used to locate the beta-bct phase transition boundary for tin, independent of the velocity wave profile. This work was done by National Security Technologies, LLC, under Contract No. DE-AC52-06NA25946 with the U.S. Department of Energy, and supported by the Site-Directed Research and Development Program.

  12. On cylindrically converging shock waves shaped by obstacles

    SciTech Connect

    Eliasson, V; Henshaw, W D; Appelo, D

    2007-07-16

    Motivated by recent experiments, numerical simulations were performed of cylindrically converging shock waves. The converging shocks impinged upon a set of zero to sixteen regularly space obstacles. For more than two obstacles the resulting diffracted shock fronts formed polygonal shaped patterns near the point of focus. The maximum pressure and temperature as a function of number of obstacles were studied. The self-similar behavior of cylindrical, triangular and square-shaped shocks were also investigated.

  13. Optical beam distortions induced by a shock wave.

    PubMed

    Banakh, V A; Sukharev, A A; Falits, A V

    2015-03-10

    The mean intensity and the displacement from the initially given propagation direction of the optical beam passed through the shock wave have been calculated. It has been shown that the spatial inhomogeneity of the refractive index of air caused by the shock wave arising in supersonic flow flowing a conical body can cause the focusing of the beam and strong anisotropic distortions of the intensity distribution in its cross section. The angular displacement of the optical beam from the initially given propagation direction owing to the shock wave depends only on the height above the Earth's surface at which the shock wave is formed. As the height increases, the influence of the shock wave on the optical beam propagating through it decreases.

  14. Shock wave convergence in water with parabolic wall boundaries

    SciTech Connect

    Yanuka, D.; Shafer, D.; Krasik, Ya.

    2015-04-28

    The convergence of shock waves in water, where the cross section of the boundaries between which the shock wave propagates is either straight or parabolic, was studied. The shock wave was generated by underwater electrical explosions of planar Cu wire arrays using a high-current generator with a peak output current of ∼45 kA and rise time of ∼80 ns. The boundaries of the walls between which the shock wave propagates were symmetric along the z axis, which is defined by the direction of the exploding wires. It was shown that with walls having a parabolic cross section, the shock waves converge faster and the pressure in the vicinity of the line of convergence, calculated by two-dimensional hydrodynamic simulations coupled with the equations of state of water and copper, is also larger.

  15. 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.

  16. Shock wave relations in lunar ash flow

    NASA Technical Reports Server (NTRS)

    Pai, S. I.; Hsieh, T.

    1975-01-01

    A detailed analysis of steady normal shock waves in a layer of lunar ash by the theory of two phase flow of a mixture of a gas and small solid particles is presented. New terms of pressure gradient and virtual mass forces in the particle momentum equation and the particle kinetic energy and work done in the particle energy equation are included in the fundamental equations and their influences are investigated. The flow variables as functions of the free stream Mach number, initial particle volume fraction and the density ratio G are presented. The thickness of the relaxation zone is found to increase with decreasing initial particle volume fraction and almost independent of G for any given values of free stream Mach number. A new empirical relation of the drag coefficient for the spherical particles in the mixture is proposed to fit experimental data.

  17. Dispersive shock wave interactions and asymptotics.

    PubMed

    Ablowitz, Mark J; Baldwin, Douglas E

    2013-02-01

    Dispersive shock waves (DSWs) are physically important phenomena that occur in systems dominated by weak dispersion and weak nonlinearity. The Korteweg-de Vries (KdV) equation is the universal model for systems with weak dispersion and weak, quadratic nonlinearity. Here we show that the long-time-asymptotic solution of the KdV equation for general, steplike data is a single-phase DSW; this DSW is the "largest" possible DSW based on the boundary data. We find this asymptotic solution using the inverse scattering transform and matched-asymptotic expansions. So while multistep data evolve to have multiphase dynamics at intermediate times, these interacting DSWs eventually merge to form a single-phase DSW at large time. PMID:23496590

  18. Shock wave compacted, melt infiltrated ceramics

    SciTech Connect

    Stuivinga, M.; Carton, E. P.

    1998-07-10

    Using shock wave compaction followed by melt infiltration with aluminum, B{sub 4}C-Al and TiB{sub 2}-Al composites have been fabricated. The composites are fully dense and crack-free. They have a high (80-85 vol.%) ceramic content, which gives them good mechanical properties. Due to the infiltration with aluminum, they also have rather good conductive properties. This makes it possible to machine them using spark erosion, in order to obtain complex articles such as nozzles and dies. They are lightweight, an advantage for application in armor and fast turning spindles. In the present article, scanning electron micrographs of the fracture surfaces will be shown and some material properties will be presented.

  19. Impact-shocked zircons: Discovery of shock-induced textures reflecting increasing degrees of shock metamorphism

    NASA Technical Reports Server (NTRS)

    Bohor, B. F.; Betterton, W. J.; Krogh, T. E.

    1993-01-01

    Textural effects specifically characteristic of shock metamorphism in zircons from impact environments have not been reported previously. However, planar deformation features (PDF) due to shock metamorphism are well documented in quartz and other mineral grains from these same environments. An etching technique was developed that allows scanning electron microscope (SEM) visualization of PDF and other probable shock-induced textural features, such as granular (polycrystalline) texture, in zircons from a variety of impact shock environments. These textural features in shocked zircons from K/T boundary distal ejecta form a series related to increasing degrees of shock that should correlate with proportionate resetting of the U-Pb isotopic system.

  20. Impact-shocked zircons: discovery of shock-induced textures reflecting increasing degrees of shock metamorphism

    USGS Publications Warehouse

    Bohor, B.F.; Betterton, W.J.; Krogh, T.E.

    1993-01-01

    Textural effects specifically characteristic of shock metamorphism in zircons from impact environments have not been reported previously. However, planar deformation features (PDF) due to shock metamorphism are well documented in quartz and other mineral grains from these same environments. An etching technique was developed that allows SEM visualization of PDF and other probable shock-induced textural features, such as granular (polycrystalline) texture, in zircons from a variety of impact shock environments. These textural features in shocked zircons from K/T boundary distal ejecta form a series related to increasing degrees of shock that should correlate with proportionate resetting of the UPb isotopic system. ?? 1993.

  1. Laser-induced shock waves effects in materials

    SciTech Connect

    Dingus, R.S.; Shafer, B.P.

    1990-01-01

    A review of the effects of pressure pulses on materials is presented with an orientation toward laser-induced shock wave effects in biological tissue. The behavior is first discussed for small amplitudes, namely sound waves, since many important features in this region are also applicable at large amplitudes. The generation of pressure pulses by lasers is discussed along with amplitudes. The origin and characteristic properties of shock waves are discussed along with the different types of effects they can produce. The hydrodynamic code techniques required for shock wave calculations are discussed along with the necessary empirical data base and methods for generating that data base. 7 refs., 15 figs.

  2. A new shock wave assisted sandalwood oil extraction technique

    NASA Astrophysics Data System (ADS)

    Arunkumar, A. N.; Srinivasa, Y. B.; Ravikumar, G.; Shankaranarayana, K. H.; Rao, K. S.; Jagadeesh, G.

    A new shock wave assisted oil extraction technique from sandalwood has been developed in the Shock Waves Lab, IISc, Bangalore. The fragrant oil extracted from sandalwood finds variety of applications in medicine and perfumery industries. In the present method sandal wood specimens (2.5mm diameter and 25mm in length)are subjected to shock wave loading (over pressure 15 bar)in a constant area shock tube, before extracting the sandal oil using non-destructive oil extraction technique. The results from the study indicates that both the rate of extraction as well as the quantity of oil obtained from sandal wood samples exposed to shock waves are higher (15-40 percent) compared to non-destructive oil extraction technique. The compressive squeezing of the interior oil pockets in the sandalwood specimen due to shock wave loading appears to be the main reason for enhancement in the oil extraction rate. This is confirmed by the presence of warty structures in the cross-section and micro-fissures in the radial direction of the wood samples exposed to shock waves in the scanning electron microscopic investigation. In addition the gas chromatographic studies do not show any change in the q uality of sandal oil extracted from samples exposed to shock waves.

  3. 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

  4. Theoretical study of plasma effect on a conical shock wave

    SciTech Connect

    Kuo, S.P.; Kuo, Steven S.

    2006-03-15

    Experiments conducted previously in a Mach 2.5 wind tunnel showed that localized plasma generated by an on-board 60 Hz electric discharge in front of a 60 deg. cone-shaped model considerably increases the shock angle of the attached shock generated by the cone model. Based on the measured power and cycle energy of the electric discharge, the estimated peak and average temperature enhancements were too low to justify the heating effect as a possible cause of the observed shock wave modification. In this work, a theory also using a cone model as the shock wave generator is presented to explain the observed plasma effect on the shock wave. Through electron-neutral elastic collisions and ion-neutral charge transfer collisions, plasma generated in front of the baseline shock front can deflect the incoming flow before it reaches the cone model; such a flow deflection modifies the structure of the shock wave generated by the cone model from a conic shape to a slightly curved one. The shock remains to be attached to the tip of the cone; however, the shock front moves upstream to increase the shock angle, consistent with the experimental results.

  5. Interaction of Ion-Concentration Shock Waves in Microfluidics

    NASA Astrophysics Data System (ADS)

    Bahga, Supreet S.; Chambers, Robert D.; Santiago, Juan G.

    2011-11-01

    Electrophoresis based separation techniques, such as capillary electrophoresis and isotachophoresis (ITP), are routinely used in microfluidics to separate ionic species from complex mixtures. Nonlinearities in these electrophoretic processes can result in formation of shock and rarefaction waves. We here focus on shock waves which form in ITP between regions of high and low mobility ions. Depending on the charge of ions, these shocks can propagate either towards anode or cathode, and may interact with each other. We here demonstrate simultaneous anionic and cationic ITP process, in which shock waves approach each other and then interact. Using simulations and experimental visualizations, we show that the interaction of these shock waves can modify the electrophoretic conditions and result in formation of new shock and rarefaction waves. We show two applications where we use shock interaction to couple different electrophoretic processes: (i) where we first preconcentrate DNA fragments in anionic ITP and then use shock interaction to initiate DNA separation, and (ii) where we use shock interaction to elongate ITP zones for higher sensitivity.

  6. Shock waves in the large scale structure of the universe

    NASA Astrophysics Data System (ADS)

    Ryu, Dongsu

    Cosmological shock waves result from the supersonic flow motions induced by hierarchical formation of nonlinear structures in the universe. Like most astrophysical shocks, they are collisionless shocks which form in the tenuous intergalactic plasma via collective electromagnetic interactions between particles and electromagnetic fields. The gravitational energy released during the structure formation is transferred by these shocks to the intergalactic gas in several different forms. In addition to the gas entropy, cosmic rays are produced via diffusive shock acceleration, magnetic fields are generated via the Biermann battery mechanism and Weibel instability as well as the Bell-Lucek mechanism, and vorticity is generated at curved shocks. Here we review the properties, roles, and consequences of the shock waves in the context of the large scale structure of the universe.

  7. Shock Waves in the Large Scale Structure of the Universe

    NASA Astrophysics Data System (ADS)

    Ryu, Dongsu

    2008-04-01

    Cosmological shock waves result from the supersonic flow motions induced by hierarchical formation of nonlinear structures in the universe. Like most astrophysical shocks, they are collisionless shocks which form in the tenuous intergalactic plasma via collective electromagnetic interactions between particles and electromagnetic fields. The gravitational energy released during the structure formation is transferred by these shocks to the intergalactic gas in several different forms: in addition to the gas entropy, cosmic rays are produced via diffusive shock acceleration, magnetic fields are generated via the Biermann battery mechanism and Weibel instability, and vorticity is generated at curved shocks. Here I review the properties, roles, and consequences of the shock waves in the context of the large scale structure of the universe.

  8. Weak-wave analysis of shock interaction with a slipstream

    NASA Technical Reports Server (NTRS)

    Barger, Raymond L.

    1988-01-01

    A weak wave analysis of shock interaction with a slipstream is presented. The theory is compared to that for the acoustic case and to the exact nonlinear analysis. Sample calculations indicate that the weak wave theory yields a good approximation to the exact solution when the shock waves are sufficiently weak that the associated entropy increase is negligible. A qualitative discussion of the case of counterflowing streams is also included.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Fiber optic techniques for measuring various properties of shock waves

    NASA Astrophysics Data System (ADS)

    Prinse, Wim C.; van Esveld, Rene; Oostdam, Rene; van Rooijen, Murk; Bouma, Richard

    1999-06-01

    For the past years we have developed several optical techniques to measure properties of shock waves. The fiber optic probe (FOP) is developed to measure the shock-wave velocity and/or the detonation velocity inside an explosive. The space resolution can be as small as 0.5 mm. Single fibers are used as velocity pins, and as devices to measure the flatness of flyers. Arrays of fibers are used to measure the curvature of a shock or detonation front. Also a Fabry-Perot velocity Interferometer System is constructed to measure the velocity of the flyer of an electric gun and the particle velocity in a shock wave. It is possible to combine these two measurements to determine simultaneously the flyer velocity that induces a shock wave in sample and the particle velocity in a window material at the back in a single streak record.

  14. Characteristics of coronal shock waves and solar type 2 radio bursts

    NASA Technical Reports Server (NTRS)

    Mann, G.; Classen, H.-T.

    1995-01-01

    In the solar corona shock waves generated by flares and/or coronal mass ejections can be observed by radio astronomical methods in terms of solar type 2 radio bursts. In dynamic radio spectra they appear as emission stripes slowly drifting from high to low frequencies. A sample of 25 solar type 2 radio bursts observed in the range of 40 - 170 MHz with a time resolution of 0.1 s by the new radiospectrograph of the Astrophvsikalisches Institut Potsdam in Tremsdorf is statistically investigated concerning their spectral features, i.e, drift rate, instantaneous bandwidth, and fundamental harmonic ratio. In-situ plasma wave measurements at interplanetary shocks provide the assumption that type 2 radio radiation is emitted in the vicinity of the transition region of shock waves. Thus, the instantaneous bandwidth of a solar type 2 radio burst would reflect the density jump across the associated shock wave. Comparing the inspection of the Rankine-Hugoniot relations of shock waves under coronal circumstances with those obtained from the observational study, solar type 2 radio bursts should be regarded to be generated by weak supercritical, quasi-parallel, fast magnetosonic shock waves in the corona.

  15. The von Neumann paradox in weak shock reflection

    NASA Astrophysics Data System (ADS)

    Zakharian, A. R.; Brio, M.; Hunter, J. K.; Webb, G. M.

    2000-11-01

    We present a numerical solution of the Euler equations of gas dynamics for a weak-shock Mach reflection in a half-space. In our numerical solutions, the incident, reflected, and Mach shocks meet at a triple point, and there is a supersonic patch behind the triple point, as proposed by Guderley. A theoretical analysis supports the existence of an expansion fan at the triple point, in addition to the three shocks. This solution is in complete agreement with the numerical solution of the unsteady transonic small-disturbance equations obtained by Hunter & Brio (2000), which provides an asymptotic description of a weak-shock Mach reflection. The supersonic patch is extremely small, and this work is the first time it has been resolved in a numerical solution of the Euler equations. The numerical solution uses six levels of grid refinement around the triple point. A delicate combination of numerical techniques is required to minimize both the effects of numerical diffusion and the generation of numerical oscillations at grid interfaces and shocks.

  16. 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.

  17. What is a Shock Wave to an Explosive Molecule?

    SciTech Connect

    Tarver, C M

    2001-06-12

    An explosive molecule is a metastable chemical species that reacts exothermically given the correct stimulus. Impacting an explosive with a shock wave is a ''wake-up call'' or ''trigger'' which compresses and heats the molecule. The energy deposited by the shock wave must be distributed to the vibrational modes of the explosive molecule before chemical reaction can occur. If the shock pressure and temperature are high enough and last long enough, exothermic chemical decomposition can lead to the formation of a detonation wave. For gaseous, liquid, and perfect single crystal solid explosives, after an induction time, chemical reaction begins at or near the rear boundary of the charge. This induction time can be calculated by high pressure, high temperature transition state theory. A ''superdetonation'' wave travels through the preshocked explosive until it overtakes the initial shock wave and then slows to the steady state Chapman-Jouguet (C-J) velocity. In heterogeneous solid explosives, initiation of reaction occurs at ''hot spots'' created by shock compression. If there is a sufficient number of large and hot enough ''hot spots,'' these ignition sites grow creating a pressure pulse that overtakes the leading shock front causing detonation. Since the chemical energy is released well behind the leading shock front of a detonation wave, a mechanism is required for this energy to reinforce the leading shock front and maintain its overall constant velocity. This mechanism is the amplification of pressure wavelets in the reaction zone by the process of de-excitation of the initially highly vibrationally excited reaction product molecules. This process leads to the development of the three-dimensional structure of detonation waves observed for all explosives. In a detonation wave, the leading shock wave front becomes a ''burden'' for the explosive molecule to sustain by its chemical energy release.

  18. Shock Formation of Slow Magnetosonic Waves in Coronal Plumes

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    We investigate the height of shock formation in coroner 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/Ultraviolet Coronagraph Spectrometer (SOHO/UVCS). Our models show that shock formation occurs at low coronal heights, i.e., within 1.3 solar radius, depending on the model parameters. The shock formation is calculated using the well-established wave breaking condition 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 slow magnetosonic waves are most likely not a solely operating energy supply mechanism.

  19. 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.

  20. 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.

  1. High-frequency electrostatic waves near earth's bow shock

    NASA Technical Reports Server (NTRS)

    Onsager, T. G.; Holzworth, R. H.; Koons, H. C.; Bauer, O. H.; Gurnett, D. A.

    1989-01-01

    Electrostatic wave measurements from the Active Magnetospheric Particle Tracer Explorer Ion Release Module have been used to investigate the wave modes and their possible generation mechanisms in the earth's bow shock and magnetosheath. It is demonstrated that electrostatic waves are present in the bow shock and magnetosheath with frequencies above the maximum frequency for Doppler-shifted ion acoustic waves, yet below the plasma frequency. Waves in this frequency range are tentatively identified as electron beam mode waves. Data from 45 bow shock crossings are then used to investigate possible correlations between the electrostatic wave properties and the near-shock plasma parameters. The most significant relationships found are anticorrelations with Alfven Mach number and electron beta. Mechanisms which might produce electron beams in the shock and magnetosheath are discussed in terms of the correlation study results. These mechanisms include acceleration by the cross-shock electric field and by lower hybrid frequency waves. A magnetosheath 'time of flight' mechanism, in analogy to the electron foreshock region, is introduced as another possible beam generation mechanism.

  2. Shock waves in water at low energy pulsed electric discharges

    NASA Astrophysics Data System (ADS)

    Pinchuk, M. E.; Kolikov, V. A.; Rutberg, Ph G.; Leks, A. G.; Dolinovskaya, R. V.; Snetov, V. N.; Stogov, A. Yu

    2012-12-01

    Experimental results of shock wave formation and propagation in water at low energy pulsed electric discharges are presented. To study the hydrodynamic structure of the shock waves, the direct shadow optical diagnostic device with time resolution of 5 ns and spatial resolution of 0.1 mm was designed and developed. Synchronization of the diagnostic and electrodischarge units by the fast optocouplers was carried out. The dependences of shock wave velocities after breakdown of interelectrode gap for various energy inputs (at range of <=1 J) into discharge were obtained. Based on the experimental results the recommendations for the adjustment parameters of the power supply and load were suggested.

  3. Constant Density Approximations for the Flow Behind Axisymmetric Shock Waves

    NASA Technical Reports Server (NTRS)

    Munson, Albert G.

    1961-01-01

    The incompressible rotational flow equations are used to obtain solutions for the flow behind axisymmetric shock waves with conic longitudinal sections. The nonlinear part of the term due to rotation is retained in the analysis. Numerical results for standoff distance and stagnation point velocity gradient are presented for the case in which the shock wave is a paraboloid, a sphere, or an oblate or prolate ellipsoid. A similarity parameter is proposed which correlates approximately the flow behind geometrically similar shock waves at different free-stream conditions.

  4. 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.

  5. Electromagnetic shock wave in nonlinear vacuum: exact solution.

    PubMed

    Kovachev, Lubomir M; Georgieva, Daniela A; Kovachev, Kamen L

    2012-10-01

    An analytical approach to the theory of electromagnetic waves in nonlinear vacuum is developed. The evolution of the pulse is governed by a system of nonlinear wave vector equations. An exact solution with its own angular momentum in the form of a shock wave is obtained.

  6. Shock-wave behavior in explosive monocrystals

    SciTech Connect

    Dick, J.J.

    1994-09-09

    The shock response of explosive monocrystals is strongly anisotropic. Shock initiation sensitivity depends strongly on crystal orientation in PETN. This can be understood in terms of steric hindrance to shear during the shock-induced deformation of the molecular crystal. This initiation mechanism appears to be tribochemical rather than thermal.

  7. 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.

  8. Low Frequency Waves at and Upstream of Collisionless Shocks

    NASA Astrophysics Data System (ADS)

    Wilson, L. B.

    2016-02-01

    This chapter focuses on the range of low frequency electromagnetic modes observed at and upstream of collisionless shocks in the heliosphere. It discusses a specific class of whistler mode wave observed immediately upstream of collisionless shock ramps, called a whistler precursor. Though these modes have been (and are often) observed upstream of quasi-parallel shocks, the authors limit their discussion to those observed upstream of quasi-perpendicular shocks. The chapter discusses the various ion velocity distributions observed at and upstream of collisionless shocks. It also introduces some terminology and relevant instabilities for ion foreshock waves. The chapter discusses the most common ultra-low frequency (ULF) wave types, their properties, and their free energy sources. It discusses modes that are mostly Alfvénic (i.e., mostly transverse but can be compressive) in nature.

  9. Shock wave perturbation decay in granular materials

    SciTech Connect

    Vogler, Tracy J.

    2015-11-05

    A technique in which the evolution of a perturbation in a shock wave 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.

  10. Shock wave perturbation decay in granular materials

    DOE PAGES

    Vogler, Tracy J.

    2015-11-05

    A technique in which the evolution of a perturbation in a shock wave 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

  11. Observation of cavitation during shock wave lithotripsy

    NASA Astrophysics Data System (ADS)

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

    2005-04-01

    A system was built to detect cavitation in pig kidney during shock wave 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.

  12. Shock wave driven microparticles for pharmaceutical applications

    NASA Astrophysics Data System (ADS)

    Menezes, V.; Takayama, K.; Gojani, A.; Hosseini, S. H. R.

    2008-10-01

    Ablation created by a Q-switched Nd:Yttrium Aluminum Garnet (Nd:YAG) laser beam focusing on a thin aluminum foil surface spontaneously generates a shock wave 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.

  13. Dispersive shock waves and modulation theory

    NASA Astrophysics Data System (ADS)

    El, G. A.; Hoefer, M. A.

    2016-10-01

    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 shock wave 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.

  14. 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.

  15. Whistler wave bursts upstream of the Uranian bow shock

    NASA Technical Reports Server (NTRS)

    Smith, Charles W.; Goldstein, Melvyn L.; Wong, Hung K.

    1989-01-01

    Observations of magnetic field wave bursts upstream of the Uranian bow shock are reported which were recorded prior to the inbound shock crossing. Three wave types are identified. One exhibits a broad spectral enhancement from a few millihertz to about 50 mHz and is seen from 17 to 10 hr prior to the inbound shock crossing. It is argued that these waves are whistler waves that have propagated upstream from the shock. A second wave type has a spacecraft frame frequency between 20 and 40 mHz, is seen only within or immediately upstream of the shock pedestal, is right-hand polarized in the spacecraft frame, and has a typical burst duration of 90 s. The third wave type has a spacecraft frame frequency of about 0.15 Hz, is seen exclusively within the shock pedestal, is left-hand polarized in the spacecraft frame, and has a burst duration lasting up to 4 min. It is argued that the low-frequency bursts are whistler waves with phase speed comparable to, but in excess of, the solar wind speed.

  16. Shock wave synthesis of aluminium nitride with rocksalt structure

    NASA Astrophysics Data System (ADS)

    Keller, K.; Schlothauer, T.; Schwarz, M.; Heide, G.; Kroke, E.

    2012-03-01

    The high pressure phase of aluminium nitride with rocksalt structure (rs) is a ceramic with high potential and a challenging material to investigate. The rs-AlN was synthesised and recovered by shock wave experiments using the flyer-plate method with multiple reflections at peak pressures between 15 and 43 GPa. Successful syntheses were carried out using AlN nanopowder with ambient pressure wurtzite structure (w-AlN) as starting material. The high pressure modification could, however, not be obtained when starting from submicron w-AlN. The recovery of rs-AlN is sensitive to the synthesis conditions as these influence the reconversion of rs-AlN to w-AlN.

  17. Nonstandard jump functions for radially symmetric shock waves

    SciTech Connect

    Baty, Roy S.; Tucker, Don H.; Stanescu, Dan

    2008-10-01

    Nonstandard analysis is applied to derive generalized jump functions for radially symmetric, one-dimensional, magnetogasdynamic shock waves. It is assumed that the shock wave 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 shock wave. 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 shock waves coincide in a nonstandard sense for a specified density jump function

  18. Nonstandard jump functions for radically symmetric shock waves

    SciTech Connect

    Baty, Roy S; Tucker, Don H; Stanescu, Dan

    2008-01-01

    Nonstandard analysis is applied to derive generalized jump functions for radially symmetric, one-dimensional, magnetogasdynamic shock waves. It is assumed that the shock wave 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 shock wave. 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 shock waves coincide in a nonstandard sense for a specified density jump function.

  19. Density inhomogeneity driven electrostatic shock waves in planetary rings

    SciTech Connect

    Masood, W.; Siddiq, M.; Rizvi, H.; Haque, Q.; Hasnain, H.

    2011-05-15

    Dust inertia and background density driven dust drift shock waves are theoretically studied in a rotating planetary environment and are subsequently applied to the planetary rings where the collisional effects are pronounced. It has been found that the system under consideration admits significant shock formation if the collision frequency is of the order of or less than the rotational frequency of the Saturn's rings.

  20. Grain destruction in a supernova remnant shock wave

    SciTech Connect

    Raymond, John C.; Gaetz, Terrance J.; Ghavamian, Parviz; Williams, Brian J.; Blair, William P.; Borkowski, Kazimierz J.; Sankrit, Ravi

    2013-12-01

    Dust grains are sputtered away in the hot gas behind shock 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 shock wave in the northern Cygnus Loop. Overall, the intensity observed behind the shock 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 shocks and the sputtering rates used in models. However, there is a discrepancy in that the C IV intensity 10'' behind the shock is too high compared with the intensities at the shock and 25'' behind it. Variations in the density, hydrogen neutral fraction, and the dust properties over parsec scales in the pre-shock medium limit our ability to test dust destruction models in detail.

  1. Grain Destruction in a Supernova Remnant Shock Wave

    NASA Technical Reports Server (NTRS)

    Raymond, John C.; Ghavamian, Parviz; Williams, Brian J.; Blair, William P.; Borkowski, Kazimierz J.; Gaetz, Terrance J.; Sankrit, Ravi

    2014-01-01

    Dust grains are sputtered away in the hot gas behind shock 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 shock wave in the northern Cygnus Loop. Overall, the intensity observed behind the shock 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 shocks and the sputtering rates used in models. However, there is a discrepancy in that the CIV intensity 10'' behind the shock is too high compared to the intensities at the shock and 25'' behind it. Variations in the density, hydrogen neutral fraction and the dust properties over parsec scales in the pre- shock medium limit our ability to test dust destruction models in detail.

  2. Shock waves in luminous early-type stars

    SciTech Connect

    Castor, J.I.

    1986-07-01

    Shock waves that occur in stellar atmospheres have their origin in some hydrodynamic instability of the atmosphere itself or of the stellar interior. In luminous early-type stars these two possibilities are represented by shocks due to an unstable radiatively-accelerated wind, and to shocks generated by the non-radial pulsations known to be present in many or most OB stars. This review is concerned with the structure and development of the shocks in these two cases, and especially with the mass loss that may be due specifically to the shocks. Pulsation-produced shocks are found to be very unfavorable for causing mass loss, owing to the great radiation efficiency that allows them to remain isothermal. The situation regarding radiatively-driven shocks remains unclear, awaiting detailed hydrodynamics calculations. 20 refs., 2 figs.

  3. Simulation of shock wave boundary layer interaction in flat channel with jet injection

    NASA Astrophysics Data System (ADS)

    Shakhan, Nurtoleu; Beketaeva, Asel; Naimanova, Altynshash

    2016-08-01

    A multispecies supersonic gas flow in the flat channel with perpendicular jet injection is numerically simulated by using the Favre-averaged Navier-Stokes equations coupled with k - ω turbulence model. High order WENO scheme is applied to approximate convective terms. During the investigation of flow physics in detail, the three shock-wave structures are observed: in the region of the jet (barrel, bow, oblique and closing shocks), on the upper boundary layer (reflection, transmitted and reattachment shocks), and new structures behind the jet on the lower boundary layer, which are analogous to the structures on the upper boundary layer.

  4. A geometric singular perturbation approach for planar stationary shock waves

    NASA Astrophysics Data System (ADS)

    Wang, Zhuopu; Zhang, Jiazhong; Ren, Junheng; Aslam, Muhammad Nauman

    2015-08-01

    The non-linear non-equilibrium nature of shock waves 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 shock wave, where the flow relaxes from non-equilibrium to equilibrium. Recognizing the shock wave as a fast motion is found to be especially useful for shock wave detection when post-processing experimental measured or numerical calculated flow fields. Various existing shock detection methods can be derived from the proposed theory in a rigorous mathematical manner. The proposed theory provides a new shock detection method based on its non-linear non-equilibrium nature, and may also serve as the theoretical foundation for many popular shock wave detection techniques.

  5. Plasma mitigation of shock wave: experiments and theory

    NASA Astrophysics Data System (ADS)

    Kuo, Spencer P.

    2007-12-01

    Two types of plasma spikes, generated by on-board 60 Hz periodic and pulsed dc electric discharges in front of two slightly different wind tunnel models, were used to demonstrate the non-thermal plasma techniques for shock wave mitigation. The experiments were conducted in a Mach 2.5 wind tunnel. (1) In the periodic discharge case, the results show a transformation of the shock from a well-defined attached shock into a highly curved shock structure, which has increased shock angle and also appears in diffused form. As shown in a sequence with increasing discharge intensity, the shock in front of the model moves upstream to become detached with increasing standoff distance from the model and is eliminated near the peak of the discharge. The power measurements exclude the heating effect as a possible cause of the observed shock wave modification. A theory using a cone model as the shock wave generator is presented to explain the observed plasma effect on shock wave. The analysis shows that the plasma generated in front of the model can effectively deflect the incoming flow; such a flow deflection modifies the structure of the shock wave generated by the cone model, as shown by the numerical results, from a conic shape to a curved one. The shock front moves upstream with a larger shock angle, matching well with that observed in the experiment. (2) In the pulsed dc discharge case, hollow cone-shaped plasma that envelops the physical spike of a truncated cone model is produced in the discharge; consequently, the original bow shock is modified to a conical shock, equivalent to reinstating the model into a perfect cone and to increase the body aspect ratio by 70%. A significant wave drag reduction in each discharge is inferred from the pressure measurements; at the discharge maximum, the pressure on the frontal surface of the body decreases by more than 30%, the pressure on the cone surface increases by about 5%, whereas the pressure on the cylinder surface remains

  6. Ultrasonography and biliary extracorporeal shock-wave lithotripsy.

    PubMed

    Jakobeit, C; Greiner, L

    1993-05-01

    The results of shock-wave treatment of gallbladder stones depend to a very high degree on the quality and expertise of ultrasonography applied before, during, and after shock-wave disintegration of the stones. Ultrasonography is decisive in evaluating the inclusion criteria; it is the method of choice for directing the shockwave energy at the stones and monitoring the disintegration process. It is the only diagnostic modality to really demonstrate the gallbladder being free from stones.

  7. Tracking kidney stones with sound during shock wave lithotripsy

    NASA Astrophysics Data System (ADS)

    Kracht, Jonathan M.

    The prevalence of kidney stones has increased significantly over the past decades. One of the primary treatments for kidney stones is shock wave lithotripsy which focuses acoustic shock waves onto the stone in order to fragment it into pieces that are small enough to pass naturally. This typically requires a few thousand shock waves 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 shock waves were used. One factor that could be used to reduce the number of shock waves is accounting for the motion of the stone which causes a portion of the delivered shock waves 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 shock waves. 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 shock waves. The conclusion of this work is that tracking kidney stones with low frequency ultrasound should be effective clinically.

  8. In vivo transfection of melanoma cells by lithotripter shock waves.

    PubMed

    Bao, S; Thrall, B D; Gies, R A; Miller, D L

    1998-01-15

    The potential for gene transfection during shock wave tumor therapy was evaluated by searching for shock wave-induced DNA transfer in mouse tumor cells. B16 mouse melanoma cells were cultured by standard methods and implanted s.c. in female C57BL/6 mice 10-14 days before treatment. A luciferase reporter vector was used as the DNA plasmid for intratumoral injection at 0.2 mg/ml tumor. Air at 10% of tumor volume was injected after the DNA in some tumors to enhance acoustic cavitation activity. The shock wave generation system was similar to a Dornier HM-3 lithotripter with pressure amplitudes of 24.4 MPa peak positive and 5.2 MPa peak negative. Luciferase production in isolated tumor cells was measured with a luminometer 1 day after treatment to assess gene transfer and expression. Exposure to 800 shock waves, followed by immediate isolation and culture of tumor cells for 1 day, yielded 1.1 (0.43 SE) pg/10(6) cells for plasmid injection only and 7.5 (2.5 SE) pg/10(6) cells for plasmid plus air injection. Significantly increased luciferase production, relative to shams, occurred for 200-, 400-, 800-, and 1200-shock wave treatments with plasmid and air injection. Exposure with the isolation of tumor cells delayed for a day to allow gene expression within the growing tumors gave increased luciferase production for 100- and 400-shock wave exposures without and with air injection. Gene transfer therefore can be induced during lithotripter shock wave treatment in vivo, particularly with enhanced acoustic cavitation, which supports the concept that gene and shock wave therapy might be advantageously merged. PMID:9443395

  9. Interaction of turbulent plasma flow with a hypersonic shock wave

    SciTech Connect

    Belay, K.; Valentine, J.M.; Williams, R.L.; Johnson, J.A. III

    1997-02-01

    A transient increase is observed in both the spectral energy decay rate and the degree of chaotic complexity at the interface of a shock wave and a turbulent ionized gas. Even though the gas is apparently brought to rest by the shock wave, no evidence is found either of prompt relaminarization or of any systematic influence of end-wall material thermal conductivities on the turbulence parameters. {copyright} {ital 1997 American Institute of Physics.}

  10. Dust acoustic shock waves in two temperatures charged dusty grains

    SciTech Connect

    El-Shewy, E. K.; Abdelwahed, H. G.; Elmessary, M. A.

    2011-11-15

    The reductive perturbation method has been used to derive the Korteweg-de Vries-Burger equation and modified Korteweg-de Vries-Burger for dust acoustic shock waves 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 shock waves in the dusty plasma has been investigated.

  11. Shock wave interaction with an abrupt area change

    NASA Technical Reports Server (NTRS)

    Salas, Manuel D.

    1991-01-01

    The wave patterns that occur when a shock wave interacts with an abrupt area changed are analyzed in terms of the incident shock wave Mach number and area-jump ratio. The solutions predicted by a semi-similar models are in good agreement with those obtained numerically from the quasi-one-dimensional time-dependent Euler equations. The entropy production for the wave system is defined and the principle of minimum entropy production is used to resolve a nonuniqueness problem of the self-similar model.

  12. Particle Acceleration by Cme-driven Shock Waves

    NASA Technical Reports Server (NTRS)

    Reames, Donald V.

    1999-01-01

    In the largest solar energetic particle (SEP) events, acceleration occurs at shock waves driven out from the Sun by coronal mass ejections (CMEs). Peak particle intensities are a strong function of CME speed, although the intensities, spectra, and angular distributions of particles escaping the shock are highly modified by scattering on Alfven waves produced by the streaming particles themselves. Element abundances vary in complex ways because ions with different values of Q/A resonate with different parts of the wave spectrum, which varies with space and time. Just recently, we have begun to model these systematic variations theoretically and to explore other consequences of proton-generated waves.

  13. Attenuation of shock waves propagating through nano-structured porous materials

    NASA Astrophysics Data System (ADS)

    Al-Qananwah, Ahmad K.; Koplik, Joel; Andreopoulos, Yiannis

    2013-07-01

    Porous materials have long been known to be effective in energy absorption and shock wave attenuation. These properties make them attractive in blast mitigation strategies. Nano-structured materials have an even greater potential for blast mitigation because of their high surface-to-volume ratio, a geometric parameter which substantially attenuates shock wave propagation. A molecular dynamics approach was used to explore the effects of this remarkable property on the behavior of traveling shocks impacting on solid materials. The computational setup included a moving piston, a gas region and a target solid wall with and without a porous structure. The gas and porous solid were modeled by Lennard-Jones-like and effective atom potentials, respectively. The shock wave is resolved in space and time and its reflection from a solid wall is gradual, due to the wave's finite thickness, and entails a self-interaction as the reflected wave travels through the incoming incident wave. Cases investigated include a free standing porous structure, a porous structure attached to a wall and porous structures with graded porosity. The effects of pore shape and orientation have been also documented. The results indicate that placing a nano-porous material layer in front of the target wall reduced the stress magnitude and the energy deposited inside the solid by about 30 percent, while at the same time substantially decreasing the loading rate.

  14. Shock wave lithotripsy: advances in technology and technique

    PubMed Central

    Lingeman, James E.; McAteer, James A.; Gnessin, Ehud; Evan, Andrew P.

    2010-01-01

    Shock wave lithotripsy (SWL) is the only noninvasive method for stone removal. Once considered as a primary option for the treatment of virtually all stones, SWL is now recognized to have important limitations that restrict its use. In particular, the effectiveness of SWL is severely limited by stone burden, and treatment with shock waves carries the risk of acute injury with the potential for long-term adverse effects. Research aiming to characterize the renal response to shock waves and to determine the mechanisms of shock wave action in stone breakage and renal injury has begun to suggest new treatment strategies to improve success rates and safety. Urologists can achieve better outcomes by treating at slower shock wave rate using a step-wise protocol. The aim is to achieve stone comminution using as few shock waves and at as low a power level as possible. Important challenges remain, including the need to improve acoustic coupling, enhance stone targeting, better determine when stone breakage is complete, and minimize the occurrence of residual stone fragments. New technologies have begun to address many of these issues, and hold considerable promise for the future. PMID:19956196

  15. Energetic Particle Abundances as Probes of an Interplanetary Shock Wave

    NASA Technical Reports Server (NTRS)

    Reames, D. V.; Tylka, A. J.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    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 shock launched from W04 on April 9. Shock waves 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 shock waves, 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 wave spectrum near and behind the intermediate shock. A significant factor may be the residual proton-generated waves from the very hard proton spectrum accelerated by the early shock wave prior to the onset of the second event. Thus, ion abundances from the later event probe the residual wave spectrum at the earlier shock.

  16. Belt-snap and towel-snap shock waves

    NASA Astrophysics Data System (ADS)

    Settles, Gary; Hargather, Michael; Lawson, Michael; Bigger, Rory

    2007-11-01

    Traditional simple means of generating shock waves are examined by high-speed imaging. A leather belt is folded upon itself at mid-length and the ends are grasped firmly in each hand. When pushed together a loop forms, and when quickly pulled apart the loop closes rapidly, producing a sharp ``crack'' similar to the cracking of a whip (Shock Waves 8(1), 1998). The towel-snap mimics whip cracking by causing the towel end to rotate supersonically. We investigated these phenomena using a high-speed digital camera (10k and 30k frames/sec, 4 microsec exposure) and a sensitive schlieren optical system of 1m aperture. Results show that compression of the air between the two rapidly-approaching leather belt bands first causes a spherical shock wave to form near one hand. The compression then runs along the belt length toward the other hand at supersonic speed, producing an oblique shock wave that is responsible for the audible crack. In the towel-snap, shock waves are visible from tip motion in open air as well as from the compression due to snapping the towel against a surface. There are no known useful applications of these simple phenomena, but they do address how weak shock waves can be generated by muscle power alone. Several other related examples are also mentioned.

  17. 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).

  18. 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).

  19. Viscous solution of the triple-shock reflection problem

    NASA Astrophysics Data System (ADS)

    Lau-Chapdelaine, S. S.-M.; Radulescu, M. I.

    2016-09-01

    The reflection of a triple-shock configuration was studied numerically in two dimensions using the Navier-Stokes equations. The flow field was initialized using three shock theory, and the reflection of the triple point on a plane of symmetry was studied. The conditions simulated a stoichiometric methane-oxygen detonation cell at low pressure on time scales preceding ignition when the gas was assumed to be inert. Viscosity was found to play an important role on some shock reflection mechanisms believed to accelerate reaction rates in detonations when time scales are small. A small wall jet was present in the double Mach reflection and increased in size with Reynolds number, eventually forming a small vortex. Kelvin-Helmholtz instabilities were absent, and there was no Mach stem bifurcation at Reynolds numbers corresponding to when the Mach stem had travelled distances on the scale of the induction length. Kelvin-Helmholtz instabilities are found to not likely be a source of rapid reactions in detonations at time scales commensurate with the ignition delay behind the Mach stem.

  20. Viscous solution of the triple-shock reflection problem

    NASA Astrophysics Data System (ADS)

    Lau-Chapdelaine, S. S.-M.; Radulescu, M. I.

    2016-07-01

    The reflection of a triple-shock configuration was studied numerically in two dimensions using the Navier-Stokes equations. The flow field was initialized using three shock theory, and the reflection of the triple point on a plane of symmetry was studied. The conditions simulated a stoichiometric methane-oxygen detonation cell at low pressure on time scales preceding ignition when the gas was assumed to be inert. Viscosity was found to play an important role on some shock reflection mechanisms believed to accelerate reaction rates in detonations when time scales are small. A small wall jet was present in the double Mach reflection and increased in size with Reynolds number, eventually forming a small vortex. Kelvin-Helmholtz instabilities were absent, and there was no Mach stem bifurcation at Reynolds numbers corresponding to when the Mach stem had travelled distances on the scale of the induction length. Kelvin-Helmholtz instabilities are found to not likely be a source of rapid reactions in detonations at time scales commensurate with the ignition delay behind the Mach stem.

  1. Turbulent Magnetic Field Amplification behind Strong Shock Waves in GRB and SNR

    NASA Astrophysics Data System (ADS)

    Inoue, Tsuyoshi

    2012-09-01

    Using three-dimensional (special relativistic) magnetohydrodynamics simulations, the amplification of magnetic field behind strong shock wave is studied. In supernova remnants and gamma-ray bursts, strong shock waves propagate through an inhomogeneous density field. When the shock wave hit a density bump or density dent, the Richtmyer-Meshkov instability is induced that cause a deformation of the shock front. The deformed shock leaves vorticity behind the shock wave that amplifies the magnetic field due to the stretching of field lines.

  2. ULF waves upstream of the Venus bow shock - Properties of one-hertz waves

    NASA Technical Reports Server (NTRS)

    Orlowski, D. S.; Russell, C. T.

    1991-01-01

    Pioneer Venus Orbiter data are used here to study the properties of a class of ULF upstream waves with relatively high observed frequencies. These waves show significant similarity to 'one-Hz' waves identified at earth in the ISEE 1 and 2 observations and the whistler waves identified earlier by IMP 6 observations. The waves appear almost immediately after the spacecraft crosses the magnetic field tangent line to the bow shock surface into the region of connected field lines. The wave amplitude decreases with distance from the shock measured along the magnetic field line. Group velocities calculated using the cold plasma dispersion relation indicate that the waves have sufficient upstream velocities to propagate form the shock into the solar wind. The totality of observations seem best explained by a source of right-handed whistler mode waves at the bow shock.

  3. Shock-resolving direct numerical simulations of strong turbulence interacting with a normal shock wave

    NASA Astrophysics Data System (ADS)

    Chen, Chang-Hsin; Donzis, Diego

    2015-11-01

    In many natural and engineering systems, turbulence is found to interact with shock waves. Thus, canonical interactions between isotropic turbulence and a normal shock have been studied extensively, theoretically and numerically, though theories assume the shock to be a discontinuity and most simulations have used shock-capturing schemes which may miss details of the structure of the shock, especially for weak shocks in relatively strong turbulence. We present results on this regime from shock-resolving direct numerical simulations at a range of Reynolds and Mach numbers. Our focus is on the shock structure and the effect on turbulence downstream of the shock. We study the distribution of velocity gradients, in particular dilatation across the shock and compare with theory available. We characterize turbulent shock jumps which are found to depart from the laminar theory as they depend not only on the mean Mach number but also on the Reynolds and turbulent Mach number. Changes experienced by thermodynamic variables across the shock will also be discussed. The authors gratefully acknowledge the support of AFOSR.

  4. An analysis of combustion studies in shock expansion tunnels and reflected shock tunnels

    NASA Technical Reports Server (NTRS)

    Jachimowski, Casimir J.

    1992-01-01

    The effect of initial nonequilibrium dissociated air constituents on the combustion of hydrogen in high-speed flows for a simulated Mach 17 flight condition was investigated by analyzing the results of comparative combustion experiments performed in a reflected shock tunnel test gas and in a shock expansion tunnel test gas. The results were analyzed and interpreted with a one-dimensional quasi-three-stream combustor code that includes finite rate combustion chemistry. The results of this study indicate that the combustion process is kinetically controlled in the experiments in both tunnels and the presence of the nonequilibrium partially dissociated oxygen in the reflected shock tunnel enhances the combustion. Methods of compensating for the effect of dissociated oxygen are discussed.

  5. Effect of particle momentum transfer on an oblique-shock-wave/laminar-boundary-layer interaction

    NASA Astrophysics Data System (ADS)

    Teh, E.-J.; Johansen, C. T.

    2016-11-01

    Numerical simulations of solid particles seeded into a supersonic flow containing an oblique shock wave reflection were performed. The momentum transfer mechanism between solid and gas phases in the shock-wave/boundary-layer interaction was studied by varying the particle size and mass loading. It was discovered that solid particles were capable of significant modulation of the flow field, including suppression of flow separation. The particle size controlled the rate of momentum transfer while the particle mass loading controlled the magnitude of momentum transfer. The seeding of micro- and nano-sized particles upstream of a supersonic/hypersonic air-breathing propulsion system is proposed as a flow control concept.

  6. Fractionated Repetitive Extracorporeal Shock Wave Therapy: A New Standard in Shock Wave Therapy?

    PubMed Central

    Kisch, Tobias; Sorg, Heiko; Forstmeier, Vinzent; Mailaender, Peter; Kraemer, Robert

    2015-01-01

    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 shock wave 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 shock wave 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

  7. Numerical Simulation of Low-Density Shock-Wave Interactions

    NASA Technical Reports Server (NTRS)

    Glass, Christopher E.

    1999-01-01

    Computational Fluid Dynamics (CFD) numerical simulations of low-density shock-wave interactions for an incident shock impinging on a cylinder have been performed. Flow-field density gradient and surface pressure and heating define the type of interference pattern and corresponding perturbations. The maximum pressure and heat transfer level and location for various interaction types (i.e., shock-wave incidence with respect to the cylinder) are presented. A time-accurate solution of the Type IV interference is employed to demonstrate the establishment and the steadiness of the low-density flow interaction.

  8. 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.

  9. In the footsteps of Ernst Mach - A historical review of shock wave research at the Ernst-Mach-Institut

    NASA Astrophysics Data System (ADS)

    Reichenbach, H.

    The aim of this paper is to recall some of the historical work on shock waves and to give a brief survey of research activities at the Ernst-Mach-Institut (EMI). Some fundamental results of Ernst Mach (1838 - 1916) are demonstrated and historical remarks are given to the shock tube as an important tool in shock wave research. The activity at EMI in this field was initiated by Prof. H. Schardin (1902 - 1965) in 1955 and has since been continued. Propagation processes of shock and blast waves, blast loading phenomena, shock attenuation, shock reflection at various surfaces, development of new types of blast simulators, electromagnetically driven T-tubes, precursor and decursor phenomena are only a few examples of research topics at EMI that will be discussed.

  10. Numerical study of shock wave interaction in steady flows of a viscous heat-conducting gas with a low ratio of specific heats

    NASA Astrophysics Data System (ADS)

    Shoev, G. V.; Ivanov, M. S.

    2016-05-01

    Specific features of shock wave interaction in a viscous heat-conducting gas with a low ratio of specific heats are numerically studied. The case of the Mach reflection of shock waves with a negative angle of the reflected wave with respect to the free-stream velocity vector is considered, and the influence of viscosity on the flow structure is analyzed. Various issues of nonuniqueness of the shock wave configuration for different Reynolds numbers are discussed. Depending on the initial conditions and Reynolds numbers, two different shock wave configurations may exist: regular configuration interacting with an expansion fan and Mach configuration. In the dual solution domain, a possibility of the transition from regular to the Mach reflection of shock waves is considered.

  11. Development of an Explosively Driven Sustained Shock Generator for Shock Wave Studies

    NASA Astrophysics Data System (ADS)

    Taylor, P.; Cook, I. T.; Salisbury, D. A.

    2004-07-01

    Investigation of explosive initiation phenomena close to the initiation threshold with explosively driven shock waves is difficult due to the attenuative nature of the pressure input. The design and experimental testing of a sustained shock wave generator based on an explosive plane wave 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 wave 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 shock wave with a duration of over 4μs into the HMX based plastic explosive EDC37 was defined and tested. Experimental shock 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 shock is achieved, although the timing of subsequent shock waves is less well matched.

  12. Plasma wave turbulence associated with an interplanetary shock. [wave in solar wind upstream of magnetosphere

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.; Neubauer, F. M.; Schwenn, R.

    1979-01-01

    The present paper deals with interplanetary shocks, detected and analyzed to date, from the Helios 1 and 2 spacecraft in eccentric solar orbits. The plasma wave turbulence associated with the shock observed on March 30, 1976 is studied in detail. This event is of particular interest because it represents a clearly defined burst of turbulence against a quiet solar wind background both upstream and downstream of the shock. The shock itself is an oblique shock with upstream parameters characterized by a low Mach number, a low beta, and an abnormally large electron to ion temperature ratio. The types of plasma wave detected are discussed.

  13. Growth and decay of weak shock waves in magnetogasdynamics

    NASA Astrophysics Data System (ADS)

    Singh, L. P.; Singh, D. B.; Ram, S. D.

    2015-12-01

    The purpose of the present study is to investigate the problem of the propagation of weak shock waves 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 shock wave and the first-order discontinuity induced behind it, are derived that admit a solution that agrees with the classical decay laws for a weak shock. An analytic expression for the determination of the shock formation distance is obtained. How the magnetic field strength, whether axial or azimuthal, influences the shock formation is also assessed.

  14. Head-on collision of shock wave induced vortices with solid and perforated walls

    NASA Astrophysics Data System (ADS)

    Kontis, K.; An, R.; Zare-Behtash, H.; Kounadis, D.

    2008-01-01

    An experimental study has been conducted to examine the interaction of shock wave induced vortices with a flat plate and a perforated plate. The experiments were carried out using a 30mm internal diameter shock-tube at Mach numbers 1.31, 1.49, and 1.61 under critical driver conditions. Air was used both in the driver and driven sections. High-speed schlieren photography was employed to study the flow development and the resulting interactions with the plates. Wall pressure measurements on both plates were also carried out in order to study the flow interactions quantitatively. The experimental results indicated that a region of strong flow development is generated near the wall surface, due to the flow interactions of reflected waves and oncoming induced vortices. This flow behavior causes the generation of multiple pressure fluctuations on the wall. In the case of the perforated plate, a weaker initial reflected wave is produced, which is followed by compression waves, due to the internal reflections within the plate. The transmitted wave is reduced in strength, compared to the initial incident shock wave.

  15. Reflected-wave maser. [low noise amplifier

    NASA Technical Reports Server (NTRS)

    Clauss, R. C. (Inventor)

    1976-01-01

    A number of traveling-wave, slow-wave maser structures, containing active maser material but absent the typical ferrite isolators, are immersed in a nonuniform magnetic field. The microwave signal to be amplified is inserted at a circulator which directs the signal to a slow-wave structure. The signal travels through the slow-wave structure, being amplified according to the distance traveled. The end of the slow-wave structure farthest from the circulator is arranged to be a point of maximum reflection of the signal traveling through the slow-wave structure. As a consequence, the signal to be amplified traverses the slow-wave structure again, in the opposite direction (towards the circulator) experiencing amplification equivalent to that achieved by a conventional traveling-wave maser having twice the length. The circulator directs the amplified signal to following like stages of amplification. Isolators are used in between stages to prevent signals from traveling in the wrong direction, between the stages. Reduced signal loss is experienced at each stage. The high gain produced by each slow-wave structure is reduced to a moderate value by use of a nonuniform magnetic field which also broadens the line width of the maser material. The resulting bandwidth can be exceptionally wide. Cascaded stages provide high gain, exceptionally wide bandwith and very low noise temperature.

  16. Schlieren imaging of shock waves radiated by a trumpet

    NASA Astrophysics Data System (ADS)

    Rendon, Pablo L.; Velasco-Segura, Roberto; Echeverria, Carlos; Porta, David; Vazquez, Teo; Perez-Lopez, Antonio; Stern, Catalina

    2014-11-01

    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 shock waves inside the instrument resonator, and the radiated shocks are then visualised using Schlieren imaging. Through these images we are able to study the geometry of the shock waves 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 shock waves separate from the instrument. We acknowledge financial support from PAPIIT IN109214 and PAPIIT IN117712.

  17. Development of a Novel Shock Wave Catheter Ablation System

    NASA Astrophysics Data System (ADS)

    Yamamoto, H.; Hasebe, Yuhi; Kondo, Masateru; Fukuda, Koji; Takayama, Kazuyoshi; Shimokawa, Hiroaki

    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 shock waves, extracorporeal shock wave lithotripter (ESWL) has been established [1]. It was demonstrated that the underwater shock 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 shock waves that can treat myocardium at arbitrary depth without causing heat.

  18. Attenuation of shock waves in copper and stainless steel

    SciTech Connect

    Harvey, W.B.

    1986-06-01

    By using shock pins, data were gathered on the trajectories of shock waves in stainless steel (SS-304L) and oxygen-free-high-conductivity copper (OFHC-Cu). Shock 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 shock pressures generated in the steel experiments were approximately 109, 130, and 147 GPa and in the copper experiments, the peak shock pressures were approximately 111, 132, and 143 GPa. In each experiment, an attenuation of the shock wave by a following release wave was clearly observed. An extensive effort using two characteristic codes (described in this work) to theoretically calculate the attenuation of the shock waves was made. The efficacy of several different constitutive equations to successfully model the experiments was studied by comparing the calculated shock 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 shock waves 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.

  19. The anatomy of floating shock fitting. [shock waves computation for flow field

    NASA Technical Reports Server (NTRS)

    Salas, M. D.

    1975-01-01

    The floating shock 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 shock waves and contact surfaces. A new procedure, based on the coalescence of characteristics, is developed to detect the formation of shock waves. Results are presented to validate and demonstrate the versatility of the technique.

  20. Dispersive nature of high mach number collisionless plasma shocks: Poynting flux of oblique whistler waves.

    PubMed

    Sundkvist, David; Krasnoselskikh, V; Bale, S D; Schwartz, S J; Soucek, J; Mozer, F

    2012-01-13

    Whistler wave trains are observed in the foot region of high Mach number quasiperpendicular shocks. The waves are oblique with respect to the ambient magnetic field as well as the shock normal. The Poynting flux of the waves is directed upstream in the shock normal frame starting from the ramp of the shock. This suggests that the waves are an integral part of the shock structure with the dispersive shock as the source of the waves. These observations lead to the conclusion that the shock ramp structure of supercritical high Mach number shocks is formed as a balance of dispersion and nonlinearity.

  1. Propagation of acoustic shock waves between parallel rigid boundaries and into shadow zones

    SciTech Connect

    Desjouy, C. Ollivier, S.; Dragna, D.; Blanc-Benon, P.; Marsden, O.

    2015-10-28

    The study of acoustic shock propagation in complex environments is of great interest for urban acoustics, but also for source localization, an underlying problematic in military applications. To give a better understanding of the phenomenon taking place during the propagation of acoustic shocks, laboratory-scale experiments and numerical simulations were performed to study the propagation of weak shock waves between parallel rigid boundaries, and into shadow zones created by corners. In particular, this work focuses on the study of the local interactions taking place between incident, reflected, and diffracted waves according to the geometry in both regular or irregular – also called Von Neumann – regimes of reflection. In this latter case, an irregular reflection can lead to the formation of a Mach stem that can modify the spatial distribution of the acoustic pressure. Short duration acoustic shock waves were produced by a 20 kilovolts electric spark source and a schlieren optical method was used to visualize the incident shockfront and the reflection/diffraction patterns. Experimental results are compared to numerical simulations based on the high-order finite difference solution of the two dimensional Navier-Stokes equations.

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

    PubMed

    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 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 ultrafast Ti:sapphire laser to generate high-intensity broadband light at nanosecond time scales. This diagnostic was demonstrated over the wavelength range 450-1150 nm with up to 16 time displaced spectra during a single shock experiment. Simultaneous off-normal incidence velocity interferometry (velocity interferometer system for any reflector) characterized the sample under laser-compression and also provided an independent reflectivity measurement at 532 nm wavelength. The shock-driven semiconductor-to-metallic transition in germanium was documented by the way of reflectivity measurements with 0.5 ns time resolution and a wavelength resolution of 10 nm.

  3. 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 .

  4. Shock-wave studies of anomalous compressibility of glassy carbon

    NASA Astrophysics Data System (ADS)

    Molodets, A. M.; Golyshev, A. A.; Savinykh, A. S.; Kim, V. V.

    2016-02-01

    The physico-mechanical properties of amorphous glassy carbon are investigated under shock compression up to 10 GPa. Experiments are carried out on the continuous recording of the mass velocity of compression pulses propagating in glassy carbon samples with initial densities of 1.502(5) g/cm3 and 1.55(2) g/cm3. It is shown that, in both cases, a compression wave in glassy carbon contains a leading precursor with amplitude of 0.135(5) GPa. It is established that, in the range of pressures up to 2 GPa, a shock discontinuity in glassy carbon is transformed into a broadened compression wave, and shock waves are formed in the release wave, which generally means the anomalous compressibility of the material in both the compression and release waves. It is shown that, at pressure higher than 3 GPa, anomalous behavior turns into normal behavior, accompanied by the formation of a shock compression wave. In the investigated area of pressure, possible structural changes in glassy carbon under shock compression have a reversible character. A physico-mechanical model of glassy carbon is proposed that involves the equation of state and a constitutive relation for Poisson's ratio and allows the numerical simulation of physico-mechanical and thermophysical properties of glassy carbon of different densities in the region of its anomalous compressibility.

  5. Dynamics of shock waves in a superfluid unitary Fermi gas

    NASA Astrophysics Data System (ADS)

    Wen, Wen; Shui, Tiankun; Shan, Yafei; Zhu, Changping

    2015-09-01

    We study the formation and dynamics of shock waves initiated by a repulsive potential in a superfluid unitary Fermi gas by using the order-parameter equation. In the theoretical framework, the regularization process of shock waves mediated by the quantum pressure term is purely dispersive. Our results show good agreement with the experiment of Joseph et al (2011 Phys. Rev. Lett. 106 150401). We reveal that the boxlike-shaped density peak observed in the experiment consists of many vortex rings due to the transverse instability of the dispersive shock wave. In addition, we study the transition from a sound wave to subsonic shock waves as the strength of the repulsive potential increases and show a strong qualitative change in the propagation speed of the wavefronts. For a relatively small strength of the repulsive potential, the propagation speed decreases below the sound speed with the increase of the strength as a scaling behavior. For a large strength where the shock waves are formed by colliding two spatially separated clouds, the speed is still smaller than the sound speed, but remains almost unchanged as the strength increases, which can be interpreted as the same expansion speed of the proliferation of the vortex rings originated from the transverse instability.

  6. Converging shock wave focusing and interaction with a target

    NASA Astrophysics Data System (ADS)

    Nitishinskiy, M.; Efimov, S.; Antonov, O.; Yanuka, D.; Gurovich, V. Tz.; Bernshtam, V.; Fisher, V.; Krasik, Ya. E.

    2016-04-01

    Converging shock waves in liquids can be used efficiently in the research of the extreme state of matter and in various applications. In this paper, the recent results related to the interaction of a shock wave with plasma preliminarily formed in the vicinity of the shock wave convergence are presented. The shock wave is produced by the underwater electrical explosion of a spherical wire array. The plasma is generated prior to the shock wave's arrival by a low-pressure gas discharge inside a quartz capillary placed at the equatorial plane of the array. Analysis of the Stark broadening of Hα and Hβ spectral lines and line-to-continuum ratio, combined with the ratio of the relative intensities of carbon C III/C II and silicon Si III/Si II lines, were used to determine the plasma density and temperature evolution. It was found that during the first ˜200 ns with respect to the beginning of the plasma compression by the shock wave and when the spectral lines are resolved, the plasma density increases from 2 × 1017 cm-3 to 5 × 1017 cm-3, while the temperature remains at the same value of 3-4 eV. Further, following the model of an adiabatically imploding capillary, the plasma density increases >1019 cm-3, leading to the continuum spectra obtained experimentally, and the plasma temperature >30 eV at radii of compression of ≤20 μm. The data obtained indicate that the shock wave generated by the underwater electrical explosion of a spherical wire array retains its uniformity during the main part of its convergence.

  7. 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 <span class="hlt">reflecting</span> 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://www.osti.gov/scitech/biblio/1033823','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1033823"><span id="translatedtitle">Setting Time Measurement Using Ultrasonic <span class="hlt">Wave</span> <span class="hlt">Reflection</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chung, Chul-Woo; Suraneni, Prannoy; Popovics, John S.; Struble, Leslie J.</p> <p>2012-01-09</p> <p>Ultrasonic shear <span class="hlt">wave</span> <span class="hlt">reflection</span> was used to investigate setting times of cement pastes by measuring the <span class="hlt">reflection</span> coefficient at the interface between hydrating cement pastes of varying water-to-cement ratio and an ultrasonic buffer material. Several different buffer materials were employed, and the choice of buffer was seen to strongly affect measurement sensitivity; high impact polystyrene showed the highest sensitivity to setting processes because it had the lowest acoustic impedance value. The results show that ultrasonic shear-<span class="hlt">wave</span> <span class="hlt">reflection</span> can be used successfully to monitor early setting processes of cement paste with good sensitivity when such a very low impedance buffer is employed. Criteria are proposed to define set times, and the resulting initial and final set times agreed broadly with those determined using the standard penetration resistance test.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013MNRAS.428.1643P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013MNRAS.428.1643P"><span id="translatedtitle">Cosmological <span class="hlt">shock</span> <span class="hlt">waves</span>: clues to the formation history of haloes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Planelles, Susana; Quilis, Vicent</p> <p>2013-01-01</p> <p><span class="hlt">Shock</span> <span class="hlt">waves</span> developed during the formation and evolution of cosmic structures are key features encoding crucial information on the hierarchical formation of the Universe. We present the analysis of an Eulerian adaptive mesh refinement hydrodynamical and N-body simulation in a Λ cold dark matter cosmology especially focused on the study of cosmological <span class="hlt">shock</span> <span class="hlt">waves</span>. The combination of a <span class="hlt">shock</span>-capturing algorithm together with the use of a halo finder allows us to study the morphological structures of the <span class="hlt">shock</span> patterns, the statistical properties of <span class="hlt">shocked</span> cells and the correlations between the cosmological <span class="hlt">shock</span> <span class="hlt">waves</span> appearing at different scales and the properties of the haloes harbouring them. According to their localization with respect to the population of haloes in the simulation, <span class="hlt">shocks</span> can be split into two broad classes: internal weak <span class="hlt">shocks</span> related with evolutionary events within haloes and external strong <span class="hlt">shocks</span> associated with large-scale events. The <span class="hlt">shocks</span>' segregation according to their characteristic sizes is also visible in the <span class="hlt">shock</span> distribution function. This function contains information on the abundances and strength of the different <span class="hlt">shocks</span>, and it can be fitted by a double power law with a break in the slope around a Mach number of 20. We introduce a generalized scaling relation that correlates the average Mach numbers within the virial radius of haloes and their virial masses. In this plane, Mach number-virial mass, two well-differentiated regimes appear. Haloes occupy different areas of such plane according to their early evolutionary histories: those haloes with a relatively quiet evolution have an almost constant Mach number independently of their masses, whereas haloes undergoing significant merger events very early in their evolution show a linear dependence on their masses. At high redshift, the distribution of haloes in this plane forms an L-like pattern that evolves with time, bending the vertical branch towards the horizontal one. We</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/2016PhFl...28e6102S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhFl...28e6102S"><span id="translatedtitle">Plane <span class="hlt">shock</span> <span class="hlt">wave</span> interaction with a cylindrical water column</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sembian, S.; Liverts, M.; Tillmark, N.; Apazidis, N.</p> <p>2016-05-01</p> <p>A complex system of <span class="hlt">waves</span> propagating inside a water column due to the impact of plane <span class="hlt">shock</span> <span class="hlt">wave</span> is investigated both experimentally and numerically. Flow features, such as, focusing of expansion <span class="hlt">waves</span> generating large negative pressure, nucleation of cavitation bubbles, and a re-circulation zone are observed and discussed qualitatively and quantitatively. Experiments are conducted on a 22 mm diametrical water column hit by <span class="hlt">shock</span> <span class="hlt">waves</span> with Mach numbers 1.75 and 2.4 in a newly constructed exploding wire facility. A new technique to create a properly shaped, repeatable, large diameter water column with straight walls is presented. Qualitative features of the flow are captured using the shadowgraph technique. With the aid of numerical simulations the <span class="hlt">wave</span> motions inside the column are analyzed; the spatial location of the expansion <span class="hlt">wave</span> focusing point and the corresponding negative peak pressures is estimated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6824056','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6824056"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">waves</span> as turbulent mix amplifiers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Buckingham, A.C.</p> <p>1988-06-09</p> <p>In our initial studies of the shockwave-turbulence interaction process we emphasized the apparent enhancement a pre-existing turbulent field induced by <span class="hlt">shock</span> passage. The present investigations are concerned with the possibly significant changes induced in <span class="hlt">shock</span>-front structure during interactions with turbulence. The <span class="hlt">shock</span> front may be diffracted; its initially planar surface may deform into a wrinkled or corrugated pattern; or it may break up into a succession of wavelets. A crucial question is whether or not the shockwave remains a sharp discontinuity albeit randomly wrinkled or corrugated by interaction with random perturbations in density, velocity, and/or pressure associated with the downstream turbulence. An additional question concerns the time of influence exerted by the shockwave in redistribution of turbulence. At some point, the apparent enhancement ceases and the turbulence decays to pre-existing levels. Geometrical distortions at the front alter the mean flow strain pattern influencing the persistence of duration of this <span class="hlt">shock</span> interaction/turbulent enhancement process after passage of the <span class="hlt">shock</span> front well downstream of the interaction region. Examination and description of the influence of these alterations to shockwave structure during <span class="hlt">shock</span>-turbulence interaction are the basic themes of this work. 6 refs., 4 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011APS..SHK.F1097L&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011APS..SHK.F1097L&link_type=ABSTRACT"><span id="translatedtitle">International <span class="hlt">Shock-Wave</span> Database: Systematization of Experimental Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Levashov, Pavel R.; Khishchenko, Konstantin V.; Lomonosov, Igor V.; Minakov, Dmitry V.; Zakharenkov, Alexey S.</p> <p>2011-06-01</p> <p>In this work, we announce the creation of the International <span class="hlt">Shock-Wave</span> Database (ISWDB). <span class="hlt">Shock-wave</span> and related dynamic material response data serve for calibrating, validating, and improving material models over very broad regions of the pressure-temperature-density phase space. Our objectives are (i) to develop a database on thermodynamic and mechanical properties of materials under conditions of <span class="hlt">shock</span> <span class="hlt">wave</span> and other dynamic loadings, selected related quantities of interest, and the meta-data that describes the provenance of the measurements and material models, and (ii) to make this database available internationally thru the Internet, in an interactive form. The development and operation of the ISWDB will be guided by input from a steering committee. The database will be installed on two mirrored web-servers, one in Russia and the other in USA. The database will provide access to original experimental data on <span class="hlt">shock</span> compression, non-<span class="hlt">shock</span> dynamic loadings, isentropic expansion, measurements of sound speed in the Hugoniot state, and time-dependent free-surface or window-interface velocity profiles. We believe that the ISWDB will be a useful tool for the <span class="hlt">shock-wave</span> community.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6053909','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6053909"><span id="translatedtitle">Isotope systematics and <span class="hlt">shock-wave</span> metamorphism: I. U-Pb in zircon, titanite, and monazite, <span class="hlt">shocked</span> experimentally up to 59 GPa</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Deutsch, A. ); Schaerer, U. )</p> <p>1990-12-01</p> <p>This study reports the first U-Pb isotope analyses on experimentally <span class="hlt">shocked</span> zircon, titanite, and monazite extracted from Proterozoic granitoid rocks. In all three types of minerals, <span class="hlt">shock-waves</span> produce drastic changes in the crystal lattices, causing strong lowering of birefringence, turbidization, and decolorization of the individual grains. Moreover, X-ray patterns indicate transition of the crystals into polycrystalline aggregates of <10{sup {minus}5} mm block-size. Precisely dated grains with concordant or nearly concordant ages were embedded in KBr and <span class="hlt">shocked</span> at 35, 47.5, and 59 GPa. U-Pb isotope analyses on these grains show that <span class="hlt">shock</span> metamorphism does not fractionate Pb isotopes within the analytical precision of {plus minus}0.1%. As far as chemical fractionation is concerned, there is no difference in degree of concordancy between <span class="hlt">shocked</span> and unshocked monazite, and small degrees (<2%) of relative U/Pb fractionation in <span class="hlt">shocked</span> zircon and titanite are due to time-integrated Pb-loss and not to the <span class="hlt">shock</span> experiment. In consequence, the data document that <span class="hlt">shock-wave</span> metamorphism alone does not measurably effect the U-Pb chronometer, questioning the view that lower intercept ages of discordant U-Pb data <span class="hlt">reflect</span> <span class="hlt">shock</span>-induced re-equilibration of the chronometer in moderately to highly <span class="hlt">shocked</span>, rapidly cooling rocks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1087699','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1087699"><span id="translatedtitle">Flash Lamp Integrating Sphere Technique for Measuring the Dynamic <span class="hlt">Reflectance</span> of <span class="hlt">Shocked</span> Materials</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Stevens, Gerald; La Lone, Brandon; Veeser, Lynn; Hixson, Rob; Holtkamp, David</p> <p>2013-07-08</p> <p>Accurate <span class="hlt">reflectance</span> (R) measurements of metals undergoing <span class="hlt">shock</span> <span class="hlt">wave</span> compression can benefit high pressure research in several ways. For example, pressure dependent <span class="hlt">reflectance</span> measurements can be used to deduce electronic band structure, and discrete changes with pressure or temperature may indicate the occurrence of a phase boundary. Additionally, knowledge of the wavelength dependent emissivity (1 -R, for opaque samples) of the metal surface is essential for accurate pyrometric temperature measurement because the radiance is a function of both the temperature and emissivity. We have developed a method for measuring dynamic <span class="hlt">reflectance</span> in the visible and near IR spectral regions with nanosecond response time and less than 1.5% uncertainty. The method utilizes an integrating sphere fitted with a xenon flash-lamp illumination source. Because of the integrating sphere, the measurements are insensitive to changes in surface curvature or tilt. The in-situ high brightness of the flash-lamp exceeds the sample’s thermal radiance and also enables the use of solid state detectors for recording the <span class="hlt">reflectance</span> signals with minimal noise. Using the method, we have examined the dynamic <span class="hlt">reflectance</span> of gallium and tin subjected to <span class="hlt">shock</span> compression from high explosives. The results suggest significant <span class="hlt">reflectance</span> changes across phase boundaries for both metals. We have also used the method to determine the spectral emissivity of <span class="hlt">shock</span> compressed tin at the interface between tin and a LiF window. The results were used to perform emissivity corrections to previous pyrometry data and obtain <span class="hlt">shock</span> temperatures of the tin/LiF interface with uncertainties of less than 2%.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=208737','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=208737"><span id="translatedtitle"><span class="hlt">Shock-wave</span> cosmology inside a black hole</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Smoller, Joel; Temple, Blake</p> <p>2003-01-01</p> <p>We construct a class of global exact solutions of the Einstein equations that extend the Oppeheimer–Snyder model to the case of nonzero pressure, inside the black hole, by incorporating a <span class="hlt">shock</span> <span class="hlt">wave</span> at the leading edge of the expansion of the galaxies, arbitrarily far beyond the Hubble length in the Friedmann–Robertson–Walker (FRW) spacetime. Here the expanding FRW universe emerges be-hind a subluminous blast <span class="hlt">wave</span> that explodes outward from the FRW center at the instant of the big bang. The total mass behind the <span class="hlt">shock</span> decreases as the <span class="hlt">shock</span> <span class="hlt">wave</span> expands, and the entropy condition implies that the <span class="hlt">shock</span> <span class="hlt">wave</span> must weaken to the point where it settles down to an Oppenheimer–Snyder interface, (bounding a finite total mass), that eventually emerges from the white hole event horizon of an ambient Schwarzschild spacetime. The entropy condition breaks the time symmetry of the Einstein equations, selecting the explosion over the implosion. These <span class="hlt">shock-wave</span> solutions indicate a cosmological model in which the big bang arises from a localized explosion occurring inside the black hole of an asymptotically flat Schwarzschild spacetime. PMID:12972640</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19860026497&hterms=Sound+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3D%2528Sound%2Bwaves%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19860026497&hterms=Sound+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3D%2528Sound%2Bwaves%2529"><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/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/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/2015JPhCS.653a2045P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JPhCS.653a2045P"><span id="translatedtitle">Numerical investigations of <span class="hlt">shock</span> <span class="hlt">wave</span> propagation in polymethylmethacrylate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Popova, T. V.; Mayer, A. E.; Khishchenko, K. V.</p> <p>2015-11-01</p> <p>Using the Maxwell model of viscoelastic medium, we numerically investigate the influence of the viscoelastic properties of polymethylmethacrylate on the variation of the <span class="hlt">shock</span> <span class="hlt">wave</span> amplitude with depth. Parameters of the Maxwell model are chosen by comparison with experimental data on the high-speed impact of plates in order to fit the modeling results with the experimentally measured profiles of the free-surface velocity. A caloric equation of state is used to calculate the pressure from density and internal energy. It is shown that at the limit of weak <span class="hlt">shock</span> <span class="hlt">waves</span>, the accounting of the viscoelastic properties allows one to achieve a better agreement between calculated and experimental data for the magnitude of the <span class="hlt">shock</span> <span class="hlt">wave</span> velocity in comparison with the case of hydrodynamic calculations. Using the viscoelastic and hydrodynamic approaches, we investigated the dynamics of <span class="hlt">shock</span> <span class="hlt">waves</span> in polymethylmethacrylate initiated by micro-, nano- and picosecond pulses of pressure on the sample surface. The calculation results show that the changes in the <span class="hlt">shock</span> <span class="hlt">wave</span> amplitude with depth are approximately identical in the hydrodynamic and viscoelastic cases.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003ASAJ..114.2453S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003ASAJ..114.2453S"><span id="translatedtitle">Regulatory standards and calibration procedures for <span class="hlt">shock</span> <span class="hlt">wave</span> devices</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schafer, Mark E.</p> <p>2003-10-01</p> <p>In order to bring any <span class="hlt">shock</span> <span class="hlt">wave</span> device into commercial use, i.e., clinical practice, it must receive regulatory approval from either the U.S Food and Drug Administration (FDA) or the appropriate national agency. A key part of this process involves the complete temporal and spatial description of the <span class="hlt">shock</span> <span class="hlt">wave</span> field. This device characterization presents a number of formidable measurement challenges, principally due to the destructive effects of <span class="hlt">shock</span> <span class="hlt">waves</span> on the measurement sensor, and <span class="hlt">shock</span> <span class="hlt">wave</span> variability (especially for electrohydraulic systems). This presentation reviews the measurement and regulatory approaches used for characterizing <span class="hlt">shock</span> <span class="hlt">wave</span> devices, including FDA and international measurement standards. The current approach is a compromise between the desire for a complete characterization of all possible parameters, and the realities of making the measurements. The complete measurement process will be described, including equipment, procedures and pitfalls. Polyvinylidene Fluoride (PVDF) membrane hydrophones have been the key enabling technology, providing sufficient temporal bandwidth and minimal effective sensor area, all at reasonable cost. Other types of sensors, both good and bad, have been used for these measurements. The talk will also present case studies of measurements of several lithotripters measured over the last 15 years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25655309','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25655309"><span id="translatedtitle">Radial extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> treatment harms developing chicken embryos.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kiessling, Maren C; Milz, Stefan; Frank, Hans-Georg; Korbel, Rüdiger; Schmitz, Christoph</p> <p>2015-02-06</p> <p>Radial extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> treatment (rESWT) has became one of the best investigated treatment modalities for cellulite, including the abdomen as a treatment site. Notably, pregnancy is considered a contraindication for rESWT, and concerns have been raised about possible harm to the embryo when a woman treated with rESWT for cellulite is not aware of her pregnancy. Here we tested the hypothesis that rESWT may cause serious physical harm to embryos. To this end, chicken embryos were exposed in ovo to various doses of radial <span class="hlt">shock</span> <span class="hlt">waves</span> on either day 3 or day 4 of development, resembling the developmental stage of four- to six-week-old human embryos. We found a dose-dependent increase in the number of embryos that died after radial <span class="hlt">shock</span> <span class="hlt">wave</span> exposure on either day 3 or day 4 of development. Among the embryos that survived the <span class="hlt">shock</span> <span class="hlt">wave</span> exposure a few showed severe congenital defects such as missing eyes. Evidently, our data cannot directly be used to draw conclusions about potential harm to the embryo of a pregnant woman treated for cellulite with rESWT. However, to avoid any risks we strongly recommend applying radial <span class="hlt">shock</span> <span class="hlt">waves</span> in the treatment of cellulite only if a pregnancy is ruled out.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4319177','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4319177"><span id="translatedtitle">Radial extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> treatment harms developing chicken embryos</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kiessling, Maren C.; Milz, Stefan; Frank, Hans-Georg; Korbel, Rüdiger; Schmitz, Christoph</p> <p>2015-01-01</p> <p>Radial extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> treatment (rESWT) has became one of the best investigated treatment modalities for cellulite, including the abdomen as a treatment site. Notably, pregnancy is considered a contraindication for rESWT, and concerns have been raised about possible harm to the embryo when a woman treated with rESWT for cellulite is not aware of her pregnancy. Here we tested the hypothesis that rESWT may cause serious physical harm to embryos. To this end, chicken embryos were exposed in ovo to various doses of radial <span class="hlt">shock</span> <span class="hlt">waves</span> on either day 3 or day 4 of development, resembling the developmental stage of four- to six-week-old human embryos. We found a dose-dependent increase in the number of embryos that died after radial <span class="hlt">shock</span> <span class="hlt">wave</span> exposure on either day 3 or day 4 of development. Among the embryos that survived the <span class="hlt">shock</span> <span class="hlt">wave</span> exposure a few showed severe congenital defects such as missing eyes. Evidently, our data cannot directly be used to draw conclusions about potential harm to the embryo of a pregnant woman treated for cellulite with rESWT. However, to avoid any risks we strongly recommend applying radial <span class="hlt">shock</span> <span class="hlt">waves</span> in the treatment of cellulite only if a pregnancy is ruled out. PMID:25655309</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007ShWav..16..455A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007ShWav..16..455A"><span id="translatedtitle">Moving <span class="hlt">shocks</span> through metallic grids: their interaction and potential for blast <span class="hlt">wave</span> mitigation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Andreopoulos, Y.; Xanthos, S.; Subramaniam, K.</p> <p>2007-07-01</p> <p>Numerical simulations and laboratory measurements have been used to illuminate the interaction of a moving <span class="hlt">shock</span> <span class="hlt">wave</span> impacting on metallic grids at various <span class="hlt">shock</span> strengths and grid solidities. The experimental work was carried out in a large scale <span class="hlt">shock</span> tube facility while computational work simulated the flow field with a time-dependent inviscid and a time-dependent viscous model. The pressure drop measured across the grids is a result of two phenomena which are associated with the impact of the <span class="hlt">shock</span> on the metallic grids. First are the <span class="hlt">reflection</span> and refraction of the incoming <span class="hlt">shock</span> on the grid itself. This appears to be the main inviscid mechanism associated with the reduction of the strength of the transmitted <span class="hlt">shock</span>. Second, viscous phenomena are present during the <span class="hlt">reflection</span> and refraction of the <span class="hlt">wave</span> as well as during the passage of the induced flow of the air through the grid. The experimental data of pressure drop across the grid obtained in the present investigation are compared with those obtained from computations. The numerical results slightly overpredict the experimental data of relative pressure drop which increases substantially with grid solidity at fixed flow Mach numbers. The processes of <span class="hlt">shock</span> <span class="hlt">reflection</span> and refraction are continuous and they can be extended in duration by using thicker grids that will result in lower compression rates of the structural loading and increase the viscous losses associated with these phenomena which will further attenuate the impacting <span class="hlt">shock</span>. Preliminary theoretical analysis suggests that the use of a graded porosity/solidity material will result in higher pressure drop than a constant porosity/solidity material and thus provide effective blast mitigation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25615159','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25615159"><span id="translatedtitle">Asymptotic dynamics of <span class="hlt">reflecting</span> spiral <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>Langham, Jacob; Biktasheva, Irina; Barkley, Dwight</p> <p>2014-12-01</p> <p>Resonantly forced spiral <span class="hlt">waves</span> in excitable media drift in straight-line paths, their rotation centers behaving as pointlike objects moving along trajectories with a constant velocity. Interaction with medium boundaries alters this velocity and may often result in a <span class="hlt">reflection</span> of the drift trajectory. Such <span class="hlt">reflections</span> have diverse characteristics and are known to be highly nonspecular in general. In this context we apply the theory of response functions, which via numerically computable integrals, reduces the reaction-diffusion equations governing the whole excitable medium to the dynamics of just the rotation center and rotation phase of a spiral <span class="hlt">wave</span>. Spiral <span class="hlt">reflection</span> trajectories are computed by this method for both small- and large-core spiral <span class="hlt">waves</span> in the Barkley model. Such calculations provide insight into the process of <span class="hlt">reflection</span> as well as explanations for differences in trajectories across parameters, including the effects of incidence angle and forcing amplitude. Qualitative aspects of these results are preserved far beyond the asymptotic limit of weak boundary effects and slow resonant drift. PMID:25615159</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ShWav..24....3S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ShWav..24....3S"><span id="translatedtitle">Experimental study on a heavy-gas cylinder accelerated by cylindrical converging <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>Si, T.; Zhai, Z.; Luo, X.; Yang, J.</p> <p>2014-01-01</p> <p>The Richtmyer-Meshkov instability behavior of a heavy-gas cylinder accelerated by a cylindrical converging <span class="hlt">shock</span> <span class="hlt">wave</span> is studied experimentally. A curved wall profile is well-designed based on the <span class="hlt">shock</span> dynamics theory [Phys. Fluids, 22: 041701 (2010)] with an incident planar <span class="hlt">shock</span> Mach number of 1.2 and a converging angle of in a mm square cross-section <span class="hlt">shock</span> tube. The cylinder mixed with the glycol droplets flows vertically through the test section and is illuminated horizontally by a laser sheet. The images obtained only one per run by an ICCD (intensified charge coupled device) combined with a pulsed Nd:YAG laser are first presented and the complete evolution process of the cylinder is then captured in a single test shot by a high-speed video camera combined with a high-power continuous laser. In this way, both the developments of the first counter-rotating vortex pair and the second counter-rotating vortex pair with an opposite rotating direction from the first one are observed. The experimental results indicate that the phenomena induced by the converging <span class="hlt">shock</span> <span class="hlt">wave</span> and the <span class="hlt">reflected</span> <span class="hlt">shock</span> formed from the center of convergence are distinct from those found in the planar <span class="hlt">shock</span> case.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012ShWav..22..253S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012ShWav..22..253S"><span id="translatedtitle">Analysis of <span class="hlt">reflected</span> blast <span class="hlt">wave</span> pressure profiles in a confined room</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sauvan, P. E.; Sochet, I.; Trélat, S.</p> <p>2012-05-01</p> <p>To understand the blast effects of confined explosions, it is necessary to study the characteristic parameters of the blast <span class="hlt">wave</span> in terms of overpressure, impulse and arrival time. In a previous study, experiments were performed using two different scales of a pyrotechnic workshop. The main purpose of these experiments was to compare the TNT equivalent for solid and gaseous explosives in terms of mass to define a TNT equivalent in a <span class="hlt">reflection</span> field and to validate the similitude between real and small scales. To study the interactions and propagations of the <span class="hlt">reflected</span> <span class="hlt">shock</span> <span class="hlt">waves</span>, the present study was conducted by progressively building a confined volume around the charge. In this way, the influence of each wall and the origins of the <span class="hlt">reflected</span> <span class="hlt">shock</span> <span class="hlt">waves</span> can be determined. The purpose of this paper is to report the blast <span class="hlt">wave</span> interactions that resulted from the detonation of a stoichiometric propane-oxygen mixture in a confined room.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6525673','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6525673"><span id="translatedtitle">Plane <span class="hlt">shock</span> <span class="hlt">wave</span> studies of Westerly granite and Nugget sandstone</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Larson, D.B.; Anderson, G.D.</p> <p>1980-12-01</p> <p>Plane <span class="hlt">shock</span> <span class="hlt">wave</span> experiments were performed by using a light-gas gun on dry and water-saturated Westerly granite and dry Nugget sandstone. Changes in the slopes of the <span class="hlt">shock</span> velocity versus particle velocity curves at 2 to 3 GPa and 1 to 2 GPa for dry granite and for dry sandstone, respectively, are attributed to the onset of pore collapse. However, there is little apparent loss of shear strength in either dry rock over the stress range of the experiments (i.e., 9.3 GPa in Westerly granite and 9.2 GPa in Nugget sandstone). Agreement between the <span class="hlt">shock</span> <span class="hlt">wave</span> data and quasistatic, uniaxial strain data for the dry rock implies the absence of rate-dependence in uniaxial strain. The <span class="hlt">shock</span> data on saturated granite agree well with those for dry granite, thus suggesting there was no loss in shear strength as a result of pore pressure buildup.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19750033814&hterms=blast+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dblast%2Bwaves','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19750033814&hterms=blast+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dblast%2Bwaves"><span id="translatedtitle">Hypersonic flows generated by parabolic and paraboloidal <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>Schwartz, L. W.</p> <p>1974-01-01</p> <p>A computer algorithm has been developed to determine the blunt-body flowfields supporting symmetric parabolic and paraboloidal <span class="hlt">shock</span> <span class="hlt">waves</span> at infinite free-stream Mach number. Solutions are expressed in an analytic form as high-order power series, in the coordinate normal to the <span class="hlt">shock</span>, whose coefficients can be determined exactly. Analytic continuation is provided by the use of Pade approximations. Test cases provide solutions of very high accuracy. In the axisymmetric case for gamma equals 715 the solution has been found far downstream, where it agrees with the modified blast-<span class="hlt">wave</span> results. For plane flow, on the other hand, a limit line appears within the <span class="hlt">shock</span> layer, a short distance past the sonic line, suggesting the presence of an imbedded <span class="hlt">shock</span>. Local solutions in the downstream limit are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvD..94b5004L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvD..94b5004L"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">waves</span>, rarefaction <span class="hlt">waves</span>, and nonequilibrium steady states in quantum critical systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lucas, Andrew; Schalm, Koenraad; Doyon, Benjamin; Bhaseen, M. J.</p> <p>2016-07-01</p> <p>We reexamine the emergence of a universal nonequilibrium steady state following a local quench between quantum critical heat baths in spatial dimensions greater than one. We show that energy transport proceeds by the formation of an instantaneous <span class="hlt">shock</span> <span class="hlt">wave</span> and a broadening rarefaction <span class="hlt">wave</span> on either side of the interface, and not by two <span class="hlt">shock</span> <span class="hlt">waves</span> as previously proposed. For small temperature differences the universal steady state energy currents of the two-<span class="hlt">shock</span> and rarefaction-<span class="hlt">shock</span> solutions coincide. Over a broad range of parameters, the difference in the energy flow across the interface between these two solutions is at the level of 2%. The properties of the energy flow remain fully universal and independent of the microscopic theory. We briefly discuss the width of the <span class="hlt">shock</span> <span class="hlt">wave</span> in a viscous fluid, the effects of momentum relaxation, and the generalization to charged fluids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17837616','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17837616"><span id="translatedtitle">Nonequilibrium molecular motion in a hypersonic <span class="hlt">shock</span> <span class="hlt">wave</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pham-Van-Diep, G; Erwin, D; Muntz, E P</p> <p>1989-08-11</p> <p>Molecular velocities have been measured inside a hypersonic, normal <span class="hlt">shock</span> <span class="hlt">wave</span>, where the gas experiences rapid changes in its macroscopic properties. As first hypothesized by Mott-Smith, but never directly observed, the molecular velocity distribution exhibits a qualitatively bimodal character that is derived from the distribution functions on either side of the <span class="hlt">shock</span>. Quantitatively correct forms of the molecular velocity distribution function in highly nonequilibrium flows can be calculated, by means of the Direct Simulation Monte Carlo technique.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820008935','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820008935"><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://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dittmar, J. H.; Rice, E. J.</p> <p>1981-01-01</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://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://www.osti.gov/scitech/biblio/22043508','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22043508"><span id="translatedtitle">Multiple spherically converging <span class="hlt">shock</span> <span class="hlt">waves</span> in liquid deuterium</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Boehly, T. R.; Goncharov, V. N.; Seka, W.; Hu, S. X.; Marozas, J. A.; Meyerhofer, D. D.; Celliers, P. M.; Hicks, D. G.; Barrios, M. A.; Fratanduono, D.; Collins, G. W.</p> <p>2011-09-15</p> <p>To achieve ignition, inertial confinement fusion target designs use a sequence of <span class="hlt">shocks</span> to compress the target before it implodes. To minimize the entropy acquired by the fuel, the strength and timing of these <span class="hlt">shocks</span> will be precisely set during a series of tuning experiments that adjust the laser pulse to achieve optimal conditions. We report measurements of the velocity and timing of multiple, converging <span class="hlt">shock</span> <span class="hlt">waves</span> inside spherical targets filled with liquid (cryogenic) deuterium. These experiments produced the highest reported <span class="hlt">shock</span> velocity observed in liquid deuterium (U{sub s} = 135 km/s at {approx}25 Mb) and observed an increase in <span class="hlt">shock</span> velocity due to spherical convergence. These direct-drive experiments are best simulated when hydrodynamic codes use a nonlocal model for the transport of absorbed laser energy from the coronal plasma to the ablation surface.</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('http://ntrs.nasa.gov/search.jsp?R=19830033736&hterms=Exodus&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DExodus','NASA-TRS'); return false;" href="http://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/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('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('http://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="http://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('http://www.osti.gov/scitech/biblio/20662072','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20662072"><span id="translatedtitle">A physical mechanism of nonthermal plasma effect on <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>Kuo, S.P.; Kuo, Steven S.</p> <p>2005-01-01</p> <p>An electric discharge is applied to generate a plasma spike in front of a wedge. Use of this plasma spike to modify the <span class="hlt">shock</span> <span class="hlt">wave</span> structure in a supersonic flow over the wedge is then studied. It is shown that the plasma spike can effectively deflect the incoming flow before the flow reaches the wedge; consequently, the <span class="hlt">shock</span> structure in the interaction region is modified from an oblique to a curved shape. Moreover, the <span class="hlt">shock</span> becomes detached as the strength of the plasma spike exceeds a critical level.</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://ntrs.nasa.gov/search.jsp?R=20000086187&hterms=treated+water&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dtreated%2Bwater','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20000086187&hterms=treated+water&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dtreated%2Bwater"><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://www.osti.gov/scitech/biblio/22036754','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22036754"><span id="translatedtitle">Stability of <span class="hlt">shock</span> <span class="hlt">waves</span> in high temperature plasmas</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Das, Madhusmita; Bhattacharya, Chandrani; Menon, S. V. G.</p> <p>2011-10-15</p> <p>The Dyakov-Kontorovich criteria for spontaneous emission of acoustic <span class="hlt">waves</span> behind <span class="hlt">shock</span> 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 <span class="hlt">shock</span> 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 <span class="hlt">shock</span> front. While the <span class="hlt">shock</span> 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 <span class="hlt">shock</span> 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 <span class="hlt">shock</span> front, thereby giving rise to spontaneously emitted <span class="hlt">waves</span>, which decay the <span class="hlt">shock</span> front.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20821262','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20821262"><span id="translatedtitle">Potential of <span class="hlt">shock</span> <span class="hlt">waves</span> to remove calculus and biofilm.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Müller, Philipp; Guggenheim, Bernhard; Attin, Thomas; Marlinghaus, Ernst; Schmidlin, Patrick R</p> <p>2011-12-01</p> <p>Effective calculus and biofilm removal is essential to treat periodontitis. Sonic and ultrasonic technologies are used in several scaler applications. This was the first feasibility study to assess the potential of a <span class="hlt">shock</span> <span class="hlt">wave</span> device to remove calculus and biofilms and to kill bacteria. Ten extracted teeth with visible subgingival calculus were treated with either <span class="hlt">shock</span> <span class="hlt">waves</span> for 1 min at an energy output of 0.4 mJ/mm(2) at 3 Hz or a magnetostrictive ultrasonic scaler at medium power setting for 1 min, which served as a control. Calculus was determined before and after treatment planimetrically using a custom-made software using a grey scale threshold. In a second experiment, multispecies biofilms were formed on saliva-preconditioned bovine enamel discs during 64.5 h. They were subsequently treated with <span class="hlt">shock</span> <span class="hlt">waves</span> or the ultrasonic scaler (N = 6/group) using identical settings. Biofilm detachment and bactericidal effects were then assessed. Limited efficiency of the <span class="hlt">shock</span> <span class="hlt">wave</span> therapy in terms of calculus removal was observed: only 5% of the calculus was removed as compared to 100% when ultrasound was used (P ≤ 0.0001). However, <span class="hlt">shock</span> <span class="hlt">waves</span> were able to significantly reduce adherent bacteria by three orders of magnitude (P ≤ 0.0001). The extent of biofilm removal by the ultrasonic device was statistically similar. Only limited bactericidal effects were observed using both methods. Within the limitations of this preliminary study, the <span class="hlt">shock</span> <span class="hlt">wave</span> device was not able to reliably remove calculus but had the potential to remove biofilms by three log steps. To increase the efficacy, technical improvements are still required. This novel noninvasive intervention, however, merits further investigation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://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="http://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://ntrs.nasa.gov/search.jsp?R=19950046290&hterms=whistler&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dwhistler','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950046290&hterms=whistler&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dwhistler"><span id="translatedtitle">An analysis of whistler <span class="hlt">waves</span> at interplanetary <span class="hlt">shocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lengyel-Frey, D.; Farrell, W. M.; Stone, R. G.; Balogh, A.; Forsyth, R.</p> <p>1994-01-01</p> <p>We present an analysis of whistler <span class="hlt">wave</span> magnetic and electric field amplitude ratios from which we compute <span class="hlt">wave</span> propagation angles and energies of electrons in resonance with the <span class="hlt">waves</span>. To do this analysis, we compute the theoretical dependence of ratios of <span class="hlt">wave</span> components on the whistler <span class="hlt">wave</span> propagation angle Theta for various combinations of orthogonal <span class="hlt">wave</span> components. Ratios of <span class="hlt">wave</span> components that would be observed by a spinning spacecraft are determined, and the effects of arbitrary inclinations of the spacecraft to the ambient magnetic field and to the whistler <span class="hlt">wave</span> vector are studied. This analysis clearly demonstrates that B/E, the ratio of magnetic to electric field amplitudes, cannot be assumed to be the <span class="hlt">wave</span> index of refraction, contrary to assumptions of some earlier studies. Therefore previous interpretations of whistler <span class="hlt">wave</span> observations based on this assumption must be reinvestigated. B/E ratios derived using three orthogonal <span class="hlt">wave</span> components can be used to unambiguously determine Theta. Using spin plane observations alone, a significant uncertainty occurs in the determination of Theta. Nevertheless, for whistler <span class="hlt">waves</span> observed downstream of several interplanetary <span class="hlt">shocks</span> by the Ulysses plasma <span class="hlt">wave</span> experiment we find that Theta is highly oblique. We suggest that the analysis of <span class="hlt">wave</span> amplitude ratios used in conjunction with traditional stability analyses provide a promising tool for determining which particle distributions and resonances are likely to be dominant contributors to <span class="hlt">wave</span> growth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720020644','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720020644"><span id="translatedtitle">The interaction of moderately strong <span class="hlt">shock</span> <span class="hlt">waves</span> with thick perforated walls of low porosity</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Grant, D. J.</p> <p>1972-01-01</p> <p>A theoretical prediction is given of the flow through thick perforated walls of low porosity resulting from the impingement of a moderately strong traveling <span class="hlt">shock</span> <span class="hlt">wave</span>. The model was a flat plate positioned normal to the direction of the flow. Holes bored in the plate parallel to the direction of the flow provided nominal hole length-to-diameter ratios of 10:1 and an axial porosity of 25 percent of the flow channel cross section. The flow field behind the <span class="hlt">reflected</span> <span class="hlt">shock</span> <span class="hlt">wave</span> was assumed to behave as a reservoir producing a quasi-steady duct flow through the model. Rayleigh and Fanno duct flow theoretical computations for each of three possible auxiliary <span class="hlt">wave</span> patterns that can be associated with the transmitted <span class="hlt">shock</span> (to satisfy contact surface compatibility) were used to provide bounding solutions as an alternative to the more complex influence coefficients method. Qualitative and quantitative behavior was verified in a 1.5- by 2.0-in. helium <span class="hlt">shock</span> tube. High speed Schlieren photography, piezoelectric pressure-time histories, and electronic-counter <span class="hlt">wave</span> speed measurements were used to assess the extent of correlation with the theoretical flow models. Reduced data indicated the adequacy of the bounding theory approach to predict <span class="hlt">wave</span> phenomena and quantitative response.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990PhLA..151...12H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990PhLA..151...12H"><span id="translatedtitle">Tachyonic torsion <span class="hlt">shock</span> <span class="hlt">waves</span> in Poincaré gauge theory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hecht, R. D.; Lemke, J.; Wallner, R. P.</p> <p>1990-11-01</p> <p>The requirement that the Poincaré gauge theory of gravitation has a correct Newtonian limit leads to tachyonic torsion <span class="hlt">shock</span> <span class="hlt">waves</span>. We show that the problems are due to those parts of the Levi-Civita connection which are vertical to the hypersurface in which the <span class="hlt">shock</span> <span class="hlt">waves</span> propagate. We argue that, as a consequence of certain symmetries of a (3 + 1)-decomposition of spacetime, the non-dynamical parts are Lagrange multipliers. We point out that this interpretation is not compatible with the minimal coupling procedure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770003415','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770003415"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">wave</span>-turbulent boundary layer interactions in transonic flow</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Adamson, T. C., Jr.; Messiter, A. F.</p> <p>1976-01-01</p> <p>The method of matched asymptotic expansions is used in analyzing the structure of the interaction region formed when a <span class="hlt">shock</span> <span class="hlt">wave</span> impinges on a turbulent flat plate boundary layer in transonic flow. Solutions in outer regions, governed by inviscid flow equations, lead to relations for the wall pressure distribution. Solutions in the inner regions, governed by equations in which Reynolds and/or viscous stresses are included, lead to a relation for the wall shear stress. Solutions for the wall pressure distribution are reviewed for both oblique and normal incoming <span class="hlt">shock</span> <span class="hlt">waves</span>. Solutions for the wall shear stress are discussed.</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('http://adsabs.harvard.edu/abs/1990AIPC..208..137T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990AIPC..208..137T"><span id="translatedtitle">Underwater <span class="hlt">shock</span> <span class="hlt">wave</span> focusing in an ellipsoidal cavity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Takayama, K.; Saito, K.; Obara, T.; Kameshima, N.</p> <p>1990-07-01</p> <p>A primary study was made experimentally and numerically of spherical underwater <span class="hlt">shock</span> <span class="hlt">wave</span> focusing and high pressure generation in an ellipsoidal cavity. Spherical <span class="hlt">shock</span> <span class="hlt">waves</span> were produced by microexplosion of silver azide or PETN of 10 to 100 mg. The ellipsoidal cavity has major and minor axes of 700 and 500 mm, respectively. The focused pressure was measured along the major axis by PVDF pressure gauges. By exploding a 100 mg PETN pellet the peak pressure at 8 kbar was obtained near the second focal point. The TVD finite difference numerical simulation was also conducted. Good agreement was obtained between the experiment and simulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001ICRC...10.4234U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001ICRC...10.4234U"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">wave</span> fractionated noble gases in the early solar system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ustinova, G. K.</p> <p>2001-08-01</p> <p>Many processes in the active star-forming regions are accompanied by strong <span class="hlt">shock</span> <span class="hlt">waves</span>, in acceleration by which the nuclear-active particles form the power-law energy spectrum of high rigidity: F(> E0) ˜ Eγ , with the spectral index γ ≤ 1.5-2. It must affect the production rates of spallogenic components of the isotopes, whose excitation functions depend on the shape of the energy spectrum of radiation. Thus, the isotopic signatures formed in the conditions of the strong <span class="hlt">shock</span> <span class="hlt">wave</span> propagation must be different from those formed in the calm environment. The early solar system incorporated all the presumed processes of the starforming stage, so that its matter had to conserve such isotopic anomalies. In previous works [1] the <span class="hlt">shock</span> <span class="hlt">wave</span> effects in generation of extinct radionu-clides and light elements Li, Be and B were considered. In the report some results for their evidence in the noble gas signatures are presented. Modelling the Kr isotope generation in spallation of Rb, Sr, Y and Zr with the nuclear-active particles, the energy spectrum of which was variable in the range of γ= 1.1-6.0, shows the different pace of growth of abundances of the dif-ferent Kr isotopes with decreasing . It leads to the quite diverse behaviour of the various Kr isotope ratios: the 78,80 Kr/83 Kr ratios increase, and the 82,84,86 Kr/83 Kr ratios decrease for the smaller γ. According to such criteria, for instance, the isotopically heavier SEP-Kr in the lunar ilmenites was pro-duced with the accelerated particles of the more rigid energy spectrum (γ ˜ 2) in comparison with the SW-Kr. Another important feature of the <span class="hlt">shock</span> <span class="hlt">wave</span> acceleration of particles is the enrichment of their specrtum with heavier ions in proportion to A/Z. Clearly, the <span class="hlt">shock</span> <span class="hlt">wave</span> fractionation of the noble gases, favouring the heavier isotopes, had to be inevitable. Such a fractionation depends on timing episodes of <span class="hlt">shock</span> <span class="hlt">wave</span> acceleration: after the n-th act of the ion acceleration their fractionation is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19870025302&hterms=heterogeneous+mixture&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dheterogeneous%2Bmixture','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19870025302&hterms=heterogeneous+mixture&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dheterogeneous%2Bmixture"><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://www.osti.gov/scitech/biblio/20875777','SCIGOV-STC'); return false;" href="http://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://adsabs.harvard.edu/abs/2009ShWav..19..453D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009ShWav..19..453D"><span id="translatedtitle">Some physical aspects of <span class="hlt">shock</span> <span class="hlt">wave</span>/boundary layer interactions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Délery, Jean; Dussauge, Jean-Paul</p> <p>2009-12-01</p> <p>When the flow past a vehicle flying at high velocity becomes supersonic, <span class="hlt">shock</span> <span class="hlt">waves</span> form, caused either by a change in the slope of a surface, a downstream obstacle or a back pressure constraining the flow to become subsonic. In modern aerodynamics, one can cite a large number of circumstances where <span class="hlt">shock</span> <span class="hlt">waves</span> are present. The encounter of a <span class="hlt">shock</span> <span class="hlt">wave</span> with a boundary layer results in complex phenomena because of the rapid retardation of the boundary layer flow and the propagation of the <span class="hlt">shock</span> in a multilayered structure. The consequence of <span class="hlt">shock</span> <span class="hlt">wave</span>/boundary layer interaction (SWBLI) are multiple and often critical for the vehicle or machine performance. The <span class="hlt">shock</span> submits the boundary layer to an adverse pressure gradient which may strongly distort its velocity profile. At the same time, in turbulent flows, turbulence production is enhanced which amplifies the viscous dissipation leading to aggravated performance losses. In addition, <span class="hlt">shock</span>-induced separation most often results in large unsteadiness which can damage the vehicle structure or, at least, severely limit its performance. The article first presents basic and well-established results on the physics of SWBLI corresponding to a description in terms of an average two-dimensional steady flow. Such a description allows apprehending the essential properties of SWBLIs and drawing the main features of the overall flow structure associated with SWBLI. Then, some emphasis is placed on unsteadiness in SWBLI which constitutes a salient feature of this phenomenon. In spite of their importance, fluctuations in SWBLI have been considered since a relatively recent date although they represent a domain which deserves a special attention because of its importance for a clear physical understanding of interactions and of its practical consequences as in aeroelasticity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19830056012&hterms=Revolution&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DRevolution','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19830056012&hterms=Revolution&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DRevolution"><span id="translatedtitle">An experimental and numerical investigation of the impingement of an oblique <span class="hlt">shock</span> <span class="hlt">wave</span> on a body of revolution</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Brosh, A.; Kussoy, M. I.; Hung, C. M.</p> <p>1983-01-01</p> <p>Attention is given to the experimental study and numerical simulation of the impingement of oblique <span class="hlt">shock</span> <span class="hlt">wave</span> on a cylinder, in order both to document the complex three-dimensional <span class="hlt">shock</span> <span class="hlt">wave</span> and boundary layer interaction occurring in practical problems (such as stores carriage interference in a supersonic tactical aircraft) and to conduct a critical comparison of experimental measurements and numerical computations for such complex flows. A thin layer approximation of the Navier-Stokes equations was solved by means of a mixed explicit-implicit scheme. Experimental measurements reveal a highly complex flow field with two distinct adjacent separation zones, regions of high cross flow, and multiply <span class="hlt">reflected</span> <span class="hlt">shocks</span> and expansion fans.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19960021262&hterms=solar+wave&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dsolar%2Bwave','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19960021262&hterms=solar+wave&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dsolar%2Bwave"><span id="translatedtitle">Electron acceleration to high energies at quasi-parallel <span class="hlt">shock</span> <span class="hlt">waves</span> in the solar corona</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mann, G.; Classen, H.-T.</p> <p>1995-01-01</p> <p>In the solar corona <span class="hlt">shock</span> <span class="hlt">waves</span> are generated by flares and/or coronal mass ejections. They manifest themselves in solar type 2 radio bursts appearing as emission stripes with a slow drift from high to low frequencies in dynamic radio spectra. Their nonthermal radio emission indicates that electrons are accelerated to suprathermal and/or relativistic velocities at these <span class="hlt">shocks</span>. As well known by extraterrestrial in-situ measurements supercritical, quasi-parallel, collisionless <span class="hlt">shocks</span> are accompanied by so-called SLAMS (short large amplitude magnetic field structures). These SLAMS can act as strong magnetic mirrors, at which charged particles can be <span class="hlt">reflected</span> and accelerated. Thus, thermal electrons gain energy due to multiple <span class="hlt">reflections</span> between two SLAMS and reach suprathermal and relativistic velocities. This mechanism of accelerating electrons is discussed for circumstances in the solar corona and may be responsible for the so-called 'herringbones' observed in solar type 2 radio bursts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840008422','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/2014JPhCS.500r2026L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JPhCS.500r2026L"><span id="translatedtitle">The bactericidal effect 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>Leighs, J. A.; Appleby-Thomas, G. J.; Wood, D. C.; Goff, M. J.; Hameed, A.; Hazell, P. J.</p> <p>2014-05-01</p> <p>There are a variety of theories relating to the origins of life on our home planet, some of which discuss the possibility that life may have been spread via inter-planetary bodies. There have been a number of investigations into the ability of life to withstand the likely conditions generated by asteroid impact (both contained in the impactor and buried beneath the planet surface). Previously published data regarding the ability of bacteria to survive such applied shockwaves has produced conflicting conclusions. The work presented here used an established and published technique in combination with a single stage gas gun, to <span class="hlt">shock</span> and subsequently recover Escherichia coli populations suspended in a phosphate buffered saline solution. Peak pressure across the sample region was calculated via numerical modelling. Survival data against peak sample pressure for recovered samples is presented alongside control tests. SEM micrographs of <span class="hlt">shocked</span> samples are presented alongside control sets to highlight key differences between cells in each case.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016LPICo1921.6335H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016LPICo1921.6335H"><span id="translatedtitle">Tracing <span class="hlt">Shock</span> <span class="hlt">Wave</span> Attenuation in Porous, Particulate Targets: Insights from Impact Experiments and Numerical Modeling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hamann, C.; Zhu, M.-H.; Wünnemann, K.; Hecht, L.; Stöffler, D.</p> <p>2016-08-01</p> <p>We directly compare <span class="hlt">shock</span> zoning (representing <span class="hlt">shock</span> pressures from ~59 to ~5 GPa) preserved in layered melt particles recovered from impact experiments with quartz sand targets with numerical models of crater formation and <span class="hlt">shock</span> <span class="hlt">wave</span> attenuation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920071742&hterms=DeVries&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DDeVries','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920071742&hterms=DeVries&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DDeVries"><span id="translatedtitle"><span class="hlt">Wave</span> diffraction in weak cosmic-ray-modified <span class="hlt">shocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Webb, G. M.; Zank, G. P.</p> <p>1992-01-01</p> <p>Weakly multidirectional, long-wavelength cosmic-ray-modified <span class="hlt">shocks</span> are studied via multiple scale perturbation techniques. The effects of diffraction are discussed in terms of Green's function solutions of the linearized 1 + 3D Burgers and 1 + 3D KdVB equations, and also in terms of solutions with singular Dirac delta initial distributions. The solutions show a monotonic decrease of the <span class="hlt">wave</span>-front curvature with increasing time owing to the effects of <span class="hlt">wave</span> diffraction. The shape of the <span class="hlt">wave</span> surface is discussed in terms of solutions S to the <span class="hlt">wave</span> eikonal equation corresponding to singular initial conditions. For the fast magnetosonic <span class="hlt">wave</span> propagating in the positive x-direction, the <span class="hlt">wave</span> phase surface S = 0 has elliptic cross sections with the planes x = constant and has a convex paraboloidal shape. Plane-<span class="hlt">wave</span> solutions of the 1 + 3D KdVB equation are discussed.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22252089','SCIGOV-STC'); return false;" href="http://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/1997APS..DPPgTP215B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997APS..DPPgTP215B"><span id="translatedtitle">Possible Implications of Anomalous <span class="hlt">Shock</span> <span class="hlt">Wave</span> Behavior for Laser Fusion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bates, Jason W.; Montgomery, David C.</p> <p>1997-11-01</p> <p>In ``normal'' materials, <span class="hlt">shocks</span> are compressive because of the inequality (partial^2p / partial V^2)_s> 0, which is, however, not dictated by thermodynamics.(e.g.), Ya. B. Zel'dovich and Yu. P. Raizer, ``Physics of <span class="hlt">Shock</span> <span class="hlt">Waves</span> and High-Temperature Hydrodynamic Phenomena,'' (N.Y., Academic Press, 1967), Vol I, pp. 67-69; Vol II, pp. 750-762. In ``anomalous'' materials, the inequality may go the other way, and exotic phenomena result: rarefactive <span class="hlt">shocks</span>, spreading compressive pulses, and <span class="hlt">shock</span> <span class="hlt">wave</span> ``splitting'' or instability.^2,(N. M. Kuznetsov, Sov. Phys. JETP 61), 275 (1985). Materials tend to behave ``anomalously'' in the vicinities of phase transitions. <span class="hlt">Shock</span>-imploded DT fusion fuels will experience a variety of phase transitions, including melting, vaporization, molecular dissociation, and ionization. Imperfectly explored gas-dynamic problems may require attention to each case. For example, in the <span class="hlt">shock</span> Hugoniot measurements of Da Silva et al. [Phys. Rev. Lett. 78, 483 (1997)], the high-pressure part of Fig. 4b suggests the possibility of ``anomalous'' behavior.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/15014330','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/15014330"><span id="translatedtitle">SIMULATION OF <span class="hlt">SHOCK</span> <span class="hlt">WAVE</span> PROPAGATION AND DAMAGE IN GEOLOGIC MATERIALS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lomov, I; Vorobiev, O; Antoun, T H</p> <p>2004-09-17</p> <p>A new thermodynamically consistent material model for large deformation has been developed. It describes quasistatic loading of limestone as well as high-rate phenomena. This constitutive model has been implemented into an Eulerian <span class="hlt">shock</span> <span class="hlt">wave</span> code with adaptive mesh refinement. This approach was successfully used to reproduce static triaxial compression tests and to simulate experiments of blast loading and damage of limestone. Results compare favorably with experimentally available <span class="hlt">wave</span> profiles from spherically-symmetric explosion in rock samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhFl...27f6101V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhFl...27f6101V"><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://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vignati, F.; Guardone, A.</p> <p>2015-06-01</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 LE/rLE ref are 1, 2, and 2.5, where rLE ref = 7 is the dimensionless reference distance from the origin. Considered impinging <span class="hlt">shock</span> Mach numbers Ms 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 LE = 7 , M 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 <span class="hlt">reflection</span> 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 <span class="hlt">reflection</span>, 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 2 rLE ref . In terms of compression 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 collaborators.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22403239','SCIGOV-STC'); return false;" href="http://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 <span class="hlt">reflection</span> 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 <span class="hlt">reflection</span>, 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 compression 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('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('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>2015-10-01</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://www.ncbi.nlm.nih.gov/pubmed/24607758','PUBMED'); return false;" href="http://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. PMID:24607758</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013APS..SHK.D1002S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013APS..SHK.D1002S"><span id="translatedtitle">Measurement of Strength at High Pressures Using Oblique <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>Stolyar, Victoria; Ravichandran, Guruswami; Alexander, Scott</p> <p>2013-06-01</p> <p>At high pressures and high strain rates, the measurement of strength is important to many implications including planetary impact and inertial confinement fusion. Understanding how strength depends on pressure allows for the characterization of materials and validation of constitutive models. Slotted barrel guns have traditionally been used in experiments, such as the pressure-shear plate impact technique, to generate longitudinal and shear <span class="hlt">waves</span> through an oblique impact. A new methodology for measuring material strength using normal impact (1-2 km/s) is described. In this configuration, a composite target is designed with an angled material of interest embedded into a driver material. This driver material is used to generate an oblique <span class="hlt">shock</span> <span class="hlt">wave</span> that is followed by a shear <span class="hlt">wave</span>, due to the angled nature of the target material. Using <span class="hlt">shock</span> polar analysis, the rear surface of the target is designed to be parallel to the transmitted <span class="hlt">shock</span> <span class="hlt">wave</span> in order to mitigate <span class="hlt">wave</span> interactions at the rear surface. A window is used on the rear surface of the target to measure the in-situ particle velocities at the target-window interface. Using three VISAR measurements, the tangential and longitudinal particle velocities at the rear surface of the target are found from which the shear stress (strength) is inferred as a function of pressure. Results are presented for 6061-T6 Aluminum as well as Tantalum. Hydrocode simulations are used to predict the experimental results as well as characterize the <span class="hlt">wave</span> interactions in the oblique wedge experiments.</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.osti.gov/scitech/biblio/21576765','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21576765"><span id="translatedtitle">ELECTRON INJECTION BY WHISTLER <span class="hlt">WAVES</span> IN NON-RELATIVISTIC <span class="hlt">SHOCKS</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Riquelme, Mario A.; Spitkovsky, Anatoly E-mail: anatoly@astro.princeton.edu</p> <p>2011-05-20</p> <p>Electron acceleration to non-thermal, ultra-relativistic energies ({approx}10-100 TeV) is revealed by radio and X-ray observations of <span class="hlt">shocks</span> in young supernova remnants (SNRs). The diffusive <span class="hlt">shock</span> acceleration (DSA) mechanism is usually invoked to explain this acceleration, but the way in which electrons are initially energized or 'injected' into this acceleration process starting from thermal energies is an unresolved problem. In this paper we study the initial acceleration of electrons in non-relativistic <span class="hlt">shocks</span> from first principles, using two- and three-dimensional particle-in-cell (PIC) plasma simulations. We systematically explore the space of <span class="hlt">shock</span> parameters (the Alfvenic Mach number, M{sub A} , the <span class="hlt">shock</span> velocity, v{sub sh}, the angle between the upstream magnetic field and the <span class="hlt">shock</span> normal, {theta}{sub Bn}, and the ion to electron mass ratio, m{sub i} /m{sub e} ). We find that significant non-thermal acceleration occurs due to the growth of oblique whistler <span class="hlt">waves</span> in the foot of quasi-perpendicular <span class="hlt">shocks</span>. This acceleration strongly depends on using fairly large numerical mass ratios, m{sub i} /m{sub e} , which may explain why it had not been observed in previous PIC simulations of this problem. The obtained electron energy distributions show power-law tails with spectral indices up to {alpha} {approx} 3-4. The maximum energies of the accelerated particles are consistent with the electron Larmor radii being comparable to that of the ions, indicating potential injection into the subsequent DSA process. This injection mechanism, however, requires the <span class="hlt">shock</span> <span class="hlt">waves</span> to have fairly low Alfenic Mach numbers, M{sub A} {approx}< 20, which is consistent with the theoretical conditions for the growth of whistler <span class="hlt">waves</span> in the <span class="hlt">shock</span> foot (M{sub A} {approx}< (m{sub i} /m{sub e}){sup 1/2}). Thus, if the whistler mechanism is the only robust electron injection process at work in SNR <span class="hlt">shocks</span>, then SNRs that display non-thermal emission must have significantly amplified</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21100299','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21100299"><span id="translatedtitle">Discontinuity breakdown on <span class="hlt">shock</span> <span class="hlt">wave</span> interaction with nanosecond discharge</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Znamenskaya, I. A.; Koroteev, D. A.; Lutsky, A. E.</p> <p>2008-05-15</p> <p>Discontinuity breakdown conditions were experimentally realized by instant energy input in front of a plane <span class="hlt">shock</span> <span class="hlt">wave</span>. A <span class="hlt">shock</span> tube and a special type of transversal nanosecond electric discharge with plasma electrodes were used for this research. A two-dimensional (2D) numerical simulation under experimental conditions has been undertaken. The pressure, density, temperature, and velocity fields have been examined. A comparison of numerical data and shadow images of a 2D flow after <span class="hlt">shock</span> <span class="hlt">wave</span> interaction with the discharge area was conducted. The geometry of the disturbed flowfield was found to be in good correspondence with one from numerical calculations. The results of the investigation also showed that, by using the described experimental setup, it is possible to achieve a special type of Richtmyer-Meshkov instability without applying an additional curved diaphragm.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007APS..SHK.G4005H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007APS..SHK.G4005H"><span id="translatedtitle">Solitary and <span class="hlt">shock</span> <span class="hlt">waves</span> in discrete double power law materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Herbold, Eric; Nesterenko, Vitali</p> <p>2007-06-01</p> <p>A novel strongly nonlinear metamaterial is composed using a periodic arrangement of toroidal rings between plates. The toroids are considered massless strongly nonlinear springs where the force versus displacement relationship is described by two additive power-law relationships. In these systems the nonlinearity is due to the dramatic change of the contact plane, which starts as an arbitrarily thin circle then increases in thickness with increasing compression. Solitary and <span class="hlt">shock</span> <span class="hlt">waves</span> are examined numerically and experimentally using three different types of polymer or rubber o-rings allowing mitigation of higher amplitude <span class="hlt">shock</span> impulses in comparison with granular systems. In these systems a train of pulses can consist of two separate groups related to two strongly nonlinear regimes with different values of exponents, depending on the amplitude. In experiments two types of <span class="hlt">shock</span> <span class="hlt">waves</span> (monotonic or oscillatory) were observed depending on the type of o-rings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22130476','SCIGOV-STC'); return false;" href="http://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://www.ncbi.nlm.nih.gov/pubmed/21918295','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/21918295"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">wave</span>-bubble interaction near soft and rigid boundaries during lithotripsy: numerical analysis by the improved ghost fluid method.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kobayashi, Kazumichi; Kodama, Tetsuya; Takahira, Hiroyuki</p> <p>2011-10-01</p> <p>In the case of extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy (ESWL), a <span class="hlt">shock</span> <span class="hlt">wave</span>-bubble interaction inevitably occurs near the focusing point of stones, resulting in stone fragmentation and subsequent tissue damage. Because <span class="hlt">shock</span> <span class="hlt">wave</span>-bubble interactions are high-speed phenomena occurring in tissue consisting of various media with different acoustic impedance values, numerical analysis is an effective method for elucidating the mechanism of these interactions. However, the mechanism has not been examined in detail because, at present, numerical simulations capable of incorporating the acoustic impedance of various tissues do not exist. Here, we show that the improved ghost fluid method (IGFM) can treat <span class="hlt">shock</span> <span class="hlt">wave</span>-bubble interactions in various media. Nonspherical bubble collapse near a rigid or soft tissue boundary (stone, liver, gelatin and fat) was analyzed. The <span class="hlt">reflection</span> <span class="hlt">wave</span> of an incident <span class="hlt">shock</span> <span class="hlt">wave</span> at a tissue boundary was the primary cause for the acceleration or deceleration of bubble collapse. The impulse that was obtained from the temporal evolution of pressure created by the bubble collapse increased the downward velocity of the boundary and caused subsequent boundary deformation. Results of this study showed that the IGFM is a useful method for analyzing the <span class="hlt">shock</span> <span class="hlt">wave</span>-bubble interaction near various tissues with different acoustic impedance. PMID:21918295</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21918295','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21918295"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">wave</span>-bubble interaction near soft and rigid boundaries during lithotripsy: numerical analysis by the improved ghost fluid method.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kobayashi, Kazumichi; Kodama, Tetsuya; Takahira, Hiroyuki</p> <p>2011-10-01</p> <p>In the case of extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy (ESWL), a <span class="hlt">shock</span> <span class="hlt">wave</span>-bubble interaction inevitably occurs near the focusing point of stones, resulting in stone fragmentation and subsequent tissue damage. Because <span class="hlt">shock</span> <span class="hlt">wave</span>-bubble interactions are high-speed phenomena occurring in tissue consisting of various media with different acoustic impedance values, numerical analysis is an effective method for elucidating the mechanism of these interactions. However, the mechanism has not been examined in detail because, at present, numerical simulations capable of incorporating the acoustic impedance of various tissues do not exist. Here, we show that the improved ghost fluid method (IGFM) can treat <span class="hlt">shock</span> <span class="hlt">wave</span>-bubble interactions in various media. Nonspherical bubble collapse near a rigid or soft tissue boundary (stone, liver, gelatin and fat) was analyzed. The <span class="hlt">reflection</span> <span class="hlt">wave</span> of an incident <span class="hlt">shock</span> <span class="hlt">wave</span> at a tissue boundary was the primary cause for the acceleration or deceleration of bubble collapse. The impulse that was obtained from the temporal evolution of pressure created by the bubble collapse increased the downward velocity of the boundary and caused subsequent boundary deformation. Results of this study showed that the IGFM is a useful method for analyzing the <span class="hlt">shock</span> <span class="hlt">wave</span>-bubble interaction near various tissues with different acoustic impedance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910067030&hterms=white+dwarf&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dwhite%2Bdwarf','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910067030&hterms=white+dwarf&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dwhite%2Bdwarf"><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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22408340','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22408340"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">wave</span> acceleration of protons in inhomogeneous plasma interacting with ultrashort intense laser pulses</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lecz, Zs.; Andreev, A.</p> <p>2015-04-15</p> <p>The acceleration of protons, triggered by solitary <span class="hlt">waves</span> in expanded solid targets is investigated using particle-in-cell simulations. The near-critical density plasma is irradiated by ultrashort high power laser pulses, which generate the solitary <span class="hlt">wave</span>. The transformation of this soliton into a <span class="hlt">shock</span> <span class="hlt">wave</span> during propagation in plasma with exponentially decreasing density profile is described analytically, which allows to obtain a scaling law for the proton energy. The high quality proton bunch with small energy spread is produced by <span class="hlt">reflection</span> from the <span class="hlt">shock</span>-front. According to the 2D simulations, the mechanism is stable only if the laser pulse duration is shorter than the characteristic development time of the parasitic Weibel instability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910067367&hterms=whistler&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dwhistler','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910067367&hterms=whistler&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dwhistler"><span id="translatedtitle">Whistler <span class="hlt">waves</span> associated with the Uranian bow <span class="hlt">shock</span> - Outbound observations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smith, Charles W.; Wong, Hung K.; Goldstein, Melvyn L.</p> <p>1991-01-01</p> <p>High-resolution magnetic field measurements from the first outbound crossing of the Uranian bowshock by the Voyager 2 spacecraft between January 27 and 30, 1986, are examined. Evidence is found of enhanced whistler <span class="hlt">wave</span> activity in the vicinity of three <span class="hlt">shock</span> crossings but little or no evidence of such activity elsewhere. Two <span class="hlt">wave</span> events display two separate and simultaneous <span class="hlt">wave</span> enhancements each. From an investigation of these events using high-resolution field data, it is concluded that they are analogous to those whistler <span class="hlt">waves</span> upstream of the earth's bow <span class="hlt">shock</span> that are driven by beams of electrons. An instability analysis is presented to show that a single electron beam with reasonable parameters can penetrate both of the upstream and downstream of a <span class="hlt">shock</span> crossing. This event displays only one relatively broad spectral enhancement in the same frequency regime and is left-hand polarized in the spacecraft frame. It is argued that this event is the result of a gyrating proton distribution associated with the oblique <span class="hlt">shock</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9282172','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9282172"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">wave</span> permeabilization as a new gene transfer method.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lauer, U; Bürgelt, E; Squire, Z; Messmer, K; Hofschneider, P H; Gregor, M; Delius, M</p> <p>1997-07-01</p> <p>Uptake of naked functional DNA into mammalian cells can be achieved by a number of physical methods. However, for most of these techniques possibilities for therapeutic in vivo applications--especially to solid organs--are often limited. In this report, we describe <span class="hlt">shock</span> <span class="hlt">wave</span> permeabilization as a new physical gene transfer method, which can be easily applied, provides great flexibility in the size and sequence of the DNA molecules to be delivered, and which should exhibit an advantageous security profile in vivo. Upon exposure to lithotripter-generated <span class="hlt">shock</span> <span class="hlt">waves</span> eukaryotic cells display a temporary increase in membrane permeability. This effect was shown to be caused by cavitation resulting in the transient generation of cell pores which allows the direct transfer of naked plasmid DNA. Shockwave transfection of a variety of cell lines was demonstrated. Since <span class="hlt">shock</span> <span class="hlt">waves</span> can be well focused within particular body regions, future applications of extracorporally generated <span class="hlt">shock</span> <span class="hlt">waves</span> to tissues simultaneously perfused with DNA solutions might open up the possibility of achieving a regionally enhanced in vivo gene transfer.</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/2007AIPC..955..231H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AIPC..955..231H"><span id="translatedtitle">Solitary and <span class="hlt">Shock</span> <span class="hlt">Waves</span> in Strongly Nonlinear Metamaterials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Herbold, E. B.; Nesterenko, V. F.</p> <p>2007-12-01</p> <p>Strongly nonlinear laminar metamaterials can be assembled using rigid metal plates interacting through light deformable strongly nonlinear elements placed between them. They may consist of single toroidal polymer o-rings, combinations of o-rings with different stiffness or combinations of hardening and softening nonlinear elements including gaps between them. Solitary <span class="hlt">waves</span> and <span class="hlt">shocks</span> are investigated in these metamaterials numerically and experimentally.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3844425','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3844425"><span id="translatedtitle">Treatment of chronic plantar fasciopathy with extracorporeal <span class="hlt">shock</span> <span class="hlt">waves</span> (review)</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2013-01-01</p> <p>There is an increasing interest by doctors and patients in extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> therapy (ESWT) for chronic plantar fasciopathy (PF), particularly in second generation radial extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> therapy (RSWT). The present review aims at serving this interest by providing a comprehensive overview on physical and medical definitions of <span class="hlt">shock</span> <span class="hlt">waves</span> and a detailed assessment of the quality and significance of the randomized clinical trials published on ESWT and RSWT as it is used to treat chronic PF. Both ESWT and RSWT are safe, effective, and technically easy treatments for chronic PF. The main advantages of RSWT over ESWT are the lack of need for any anesthesia during the treatment and the demonstrated long-term treatment success (demonstrated at both 6 and 12 months after the first treatment using RSWT, compared to follow-up intervals of no more than 12 weeks after the first treatment using ESWT). In recent years, a greater understanding of the clinical outcomes in ESWT and RSWT for chronic PF has arisen in relationship not only in the design of studies, but also in procedure, energy level, and <span class="hlt">shock</span> <span class="hlt">wave</span> propagation. Either procedure should be considered for patients 18 years of age or older with chronic PF prior to surgical intervention. PMID:24004715</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920045571&hterms=VTE&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DVTE','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920045571&hterms=VTE&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DVTE"><span id="translatedtitle">Internal structure of <span class="hlt">shock</span> <span class="hlt">waves</span> in disparate mass mixtures</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chung, Chan-Hong; De Witt, Kenneth J.; Jeng, Duen-Ren; Penko, Paul F.</p> <p>1992-01-01</p> <p>The detailed flow structure of a normal <span class="hlt">shock</span> <span class="hlt">wave</span> for a gas mixture is investigated using the direct-simulation Monte Carlo method. A variable diameter hard-sphere (VDHS) model is employed to investigate the effect of different viscosity temperature exponents (VTE) for each species in a gas mixture. Special attention is paid to the irregular behavior in the density profiles which was previously observed in a helium-xenon experiment. It is shown that the VTE can have substantial effects in the prediction of the structure of <span class="hlt">shock</span> <span class="hlt">waves</span>. The variable hard-sphere model of Bird shows good agreement, but with some limitations, with the experimental data if a common VTE is chosen properly for each case. The VDHS model shows better agreement with the experimental data without adjusting the VTE. The irregular behavior of the light-gas component in <span class="hlt">shock</span> <span class="hlt">waves</span> of disparate mass mixtures is observed not only in the density profile, but also in the parallel temperature profile. The strength of the <span class="hlt">shock</span> <span class="hlt">wave</span>, the type of molecular interactions, and the mole fraction of heavy species have substantial effects on the existence and structure of the irregularities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5648716','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5648716"><span id="translatedtitle">Internal structure of <span class="hlt">shock</span> <span class="hlt">waves</span> in disparate mass mixtures</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chung, Chan-Hong; De witt, K.J.; Jeng, Duen-Ren; Penko, P.F. Toledo, University, OH )</p> <p>1992-01-01</p> <p>The detailed flow structure of a normal <span class="hlt">shock</span> <span class="hlt">wave</span> for a gas mixture is investigated using the direct-simulation Monte Carlo method. A variable diameter hard-sphere (VDHS) model is employed to investigate the effect of different viscosity temperature exponents (VTE) for each species in a gas mixture. Special attention is paid to the irregular behavior in the density profiles which was previously observed in a helium-xenon experiment. It is shown that the VTE can have substantial effects in the prediction of the structure of <span class="hlt">shock</span> <span class="hlt">waves</span>. The variable hard-sphere model of Bird shows good agreement, but with some limitations, with the experimental data if a common VTE is chosen properly for each case. The VDHS model shows better agreement with the experimental data without adjusting the VTE. The irregular behavior of the light-gas component in <span class="hlt">shock</span> <span class="hlt">waves</span> of disparate mass mixtures is observed not only in the density profile, but also in the parallel temperature profile. The strength of the <span class="hlt">shock</span> <span class="hlt">wave</span>, the type of molecular interactions, and the mole fraction of heavy species have substantial effects on the existence and structure of the irregularities. 14 refs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040046928','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040046928"><span id="translatedtitle">Survey of Temperature Measurement Techniques For Studying Underwater <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>Danehy, Paul M.; Alderfer, David W.</p> <p>2004-01-01</p> <p>Several optical methods for measuring temperature near underwater <span class="hlt">shock</span> <span class="hlt">waves</span> are reviewed and compared. The relative merits of the different techniques are compared, considering accuracy, precision, ease of use, applicable temperature range, maturity, spatial resolution, and whether or not special additives are required.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title21-vol8/pdf/CFR-2014-title21-vol8-sec876-5990.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title21-vol8/pdf/CFR-2014-title21-vol8-sec876-5990.pdf"><span id="translatedtitle">21 CFR 876.5990 - Extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripter.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-04-01</p> <p>... Section 876.5990 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... focuses ultrasonic <span class="hlt">shock</span> <span class="hlt">waves</span> into the body to noninvasively fragment urinary calculi within the kidney..., control console, imaging/localization system, and patient table. Prior to treatment, the urinary stone...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title21-vol8/pdf/CFR-2011-title21-vol8-sec876-5990.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title21-vol8/pdf/CFR-2011-title21-vol8-sec876-5990.pdf"><span id="translatedtitle">21 CFR 876.5990 - Extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripter.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-04-01</p> <p>... Section 876.5990 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... focuses ultrasonic <span class="hlt">shock</span> <span class="hlt">waves</span> into the body to noninvasively fragment urinary calculi within the kidney..., control console, imaging/localization system, and patient table. Prior to treatment, the urinary stone...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6679548','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6679548"><span id="translatedtitle">Dynamic Theory: some <span class="hlt">shock</span> <span class="hlt">wave</span> and energy implications</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Williams, P.E.</p> <p>1981-02-01</p> <p>The Dynamic Theory, a unifying five-dimensional theory of space, time, and matter, is examined. The theory predicts an observed discrepancy between <span class="hlt">shock</span> <span class="hlt">wave</span> viscosity measurements at low and high pressures in aluminum, a limiting mass-to-energy conversion rate consistent with the available data, and reduced pressures in electromagneticaly contained controlled-fusion plasmas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21503631','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21503631"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">waves</span> and Birkhoff's theorem in Lovelock gravity</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gravanis, E.</p> <p>2010-11-15</p> <p>Spherically symmetric <span class="hlt">shock</span> <span class="hlt">waves</span> are shown to exist in Lovelock gravity. They amount to a change of branch of the spherically symmetric solutions across a null hypersurface. The implications of their existence for the status of Birkhoff's theorem in the theory is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150003513','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150003513"><span id="translatedtitle">Destruction of Interstellar Dust in Evolving Supernova Remnant <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>Slavin, Jonathan D.; Dwek, Eli; Jones, Anthony P.</p> <p>2015-01-01</p> <p>Supernova generated <span class="hlt">shock</span> <span class="hlt">waves</span> are responsible for most of the destruction of dust grains in the interstellar medium (ISM). Calculations of the dust destruction timescale have so far been carried out using plane parallel steady <span class="hlt">shocks</span>, however that approximation breaks down when the destruction timescale becomes longer than that for the evolution of the supernova remnant (SNR) <span class="hlt">shock</span>. In this paper we present new calculations of grain destruction in evolving, radiative SNRs. To facilitate comparison with the previous study by Jones et al. (1996), we adopt the same dust properties as in that paper. We find that the efficiencies of grain destruction are most divergent from those for a steady <span class="hlt">shock</span> when the thermal history of a <span class="hlt">shocked</span> gas parcel in the SNR differs significantly from that behind a steady <span class="hlt">shock</span>. This occurs in <span class="hlt">shocks</span> with velocities 200 km s(exp -1) for which the remnant is just beginning to go radiative. Assuming SNRs evolve in a warm phase dominated ISM, we find dust destruction timescales are increased by a factor of approximately 2 compared to those of Jones et al. (1996), who assumed a hot gas dominated ISM. Recent estimates of supernova rates and ISM mass lead to another factor of approximately 3 increase in the destruction timescales, resulting in a silicate grain destruction timescale of approximately 2-3 Gyr. These increases, while not able resolve the problem of the discrepant timescales for silicate grain destruction and creation, are an important step towards understanding the origin, and evolution of dust in the ISM.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840009453','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840009453"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">wave</span> properties of anorthosite and gabbro</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Boslough, M. B.; Ahrens, T. J.</p> <p>1984-01-01</p> <p>Hugoniot data on San Gabriel anorthosite and San Marcos gabbro to 11 GPA are presented. Release paths in the stress-density plane and sound velocities are reported as determined from particl velocity data. Electrical interference effects precluded the determination of accurate release paths for the gabbro. Because of the loss of shear strength in the <span class="hlt">shocked</span> state, the plastic behavior exhibited by anorthosite indicates that calculations of energy partitioning due to impact onto planetary surfaces based on elastic-plastic models may underestimate the amount of internal energy deposited in the impacted surface material.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016CoPhC.207..186Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016CoPhC.207..186Q"><span id="translatedtitle">Parallel implementation of geometrical <span class="hlt">shock</span> dynamics for two dimensional converging <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; Liu, Kuang; Eliasson, Veronica</p> <p>2016-10-01</p> <p>Geometrical <span class="hlt">shock</span> dynamics (GSD) theory is an appealing method to predict the <span class="hlt">shock</span> motion in the sense that it is more computationally efficient than solving the traditional Euler equations, especially for converging <span class="hlt">shock</span> <span class="hlt">waves</span>. However, to solve and optimize large scale configurations, the main bottleneck is the computational cost. Among the existing numerical GSD schemes, there is only one that has been implemented on parallel computers, with the purpose to analyze detonation <span class="hlt">waves</span>. To extend the computational advantage of the GSD theory to more general applications such as converging <span class="hlt">shock</span> <span class="hlt">waves</span>, a numerical implementation using a spatial decomposition method has been coupled with a front tracking approach on parallel computers. In addition, an efficient tridiagonal system solver for massively parallel computers has been applied to resolve the most expensive function in this implementation, resulting in an efficiency of 0.93 while using 32 HPCC cores. Moreover, symmetric boundary conditions have been developed to further reduce the computational cost, achieving a speedup of 19.26 for a 12-sided polygonal converging <span class="hlt">shock</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012AIPC.1474...19C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012AIPC.1474...19C&link_type=ABSTRACT"><span id="translatedtitle">Sources and propagation of atmospherical 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>Coulouvrat, François</p> <p>2012-09-01</p> <p> within <span class="hlt">shocks</span>, is controlled by humidity, cloudiness or surface properties. Variability is large at all scales, and depends simultaneously on climate, daily meteorology, and local turbulent state, especially near the ground in the planetary boundary layer. Numerous features of outdoor propagation remain to be explored in the nonlinear case, such as complex 3D atmospheric description (role of turbulence, partial <span class="hlt">reflections</span>, gravity <span class="hlt">waves</span>) or topography.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhyD..333..310X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhyD..333..310X"><span id="translatedtitle">Incoherent <span class="hlt">shock</span> <span class="hlt">waves</span> in long-range optical turbulence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xu, G.; Garnier, J.; Faccio, D.; Trillo, S.; Picozzi, A.</p> <p>2016-10-01</p> <p>Considering the nonlinear Schrödinger (NLS) equation as a representative model, we report a unified presentation of different forms of incoherent <span class="hlt">shock</span> <span class="hlt">waves</span> that emerge in the long-range interaction regime of a turbulent optical <span class="hlt">wave</span> system. These incoherent singularities can develop either in the temporal domain through a highly noninstantaneous nonlinear response, or in the spatial domain through a highly nonlocal nonlinearity. In the temporal domain, genuine dispersive <span class="hlt">shock</span> <span class="hlt">waves</span> (DSW) develop in the spectral dynamics of the random <span class="hlt">waves</span>, despite the fact that the causality condition inherent to the response function breaks the Hamiltonian structure of the NLS equation. Such spectral incoherent DSWs are described in detail by a family of singular integro-differential kinetic equations, e.g. Benjamin-Ono equation, which are derived from a nonequilibrium kinetic formulation based on the weak Langmuir turbulence equation. In the spatial domain, the system is shown to exhibit a large scale global collective behavior, so that it is the fluctuating field as a whole that develops a singularity, which is inherently an incoherent object made of random <span class="hlt">waves</span>. Despite the Hamiltonian structure of the NLS equation, the regularization of such a collective incoherent <span class="hlt">shock</span> does not require the formation of a DSW - the regularization is shown to occur by means of a different process of coherence degradation at the <span class="hlt">shock</span> point. We show that the collective incoherent <span class="hlt">shock</span> is responsible for an original mechanism of spontaneous nucleation of a phase-space hole in the spectrogram dynamics. The robustness of such a phase-space hole is interpreted in the light of incoherent dark soliton states, whose different exact solutions are derived in the framework of the long-range Vlasov formalism.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22486428','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22486428"><span id="translatedtitle">Ion acoustic <span class="hlt">shock</span> <span class="hlt">wave</span> in collisional equal mass plasma</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Adak, Ashish; Ghosh, Samiran; Chakrabarti, Nikhil</p> <p>2015-10-15</p> <p>The effect of ion-ion collision on the dynamics of nonlinear ion acoustic <span class="hlt">wave</span> in an unmagnetized pair-ion plasma has been investigated. The two-fluid model has been used to describe the dynamics of both positive and negative ions with equal masses. It is well known that in the dynamics of the weakly nonlinear <span class="hlt">wave</span>, the viscosity mediates <span class="hlt">wave</span> dissipation in presence of weak nonlinearity and dispersion. This dissipation is responsible for the <span class="hlt">shock</span> structures in pair-ion plasma. Here, it has been shown that the ion-ion collision in presence of collective phenomena mediated by the plasma current is the source of dissipation that causes the Burgers' term which is responsible for the <span class="hlt">shock</span> structures in equal mass pair-ion plasma. The dynamics of the weakly nonlinear <span class="hlt">wave</span> is governed by the Korteweg-de Vries Burgers equation. The analytical and numerical investigations revealed that the ion acoustic <span class="hlt">wave</span> exhibits both oscillatory and monotonic <span class="hlt">shock</span> structures depending on the frequency of ion-ion collision parameter. The results have been discussed in the context of the fullerene pair-ion plasma experiments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015PhPl...22j2307A&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015PhPl...22j2307A&link_type=ABSTRACT"><span id="translatedtitle">Ion acoustic <span class="hlt">shock</span> <span class="hlt">wave</span> in collisional equal mass plasma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Adak, Ashish; Ghosh, Samiran; Chakrabarti, Nikhil</p> <p>2015-10-01</p> <p>The effect of ion-ion collision on the dynamics of nonlinear ion acoustic <span class="hlt">wave</span> in an unmagnetized pair-ion plasma has been investigated. The two-fluid model has been used to describe the dynamics of both positive and negative ions with equal masses. It is well known that in the dynamics of the weakly nonlinear <span class="hlt">wave</span>, the viscosity mediates <span class="hlt">wave</span> dissipation in presence of weak nonlinearity and dispersion. This dissipation is responsible for the <span class="hlt">shock</span> structures in pair-ion plasma. Here, it has been shown that the ion-ion collision in presence of collective phenomena mediated by the plasma current is the source of dissipation that causes the Burgers' term which is responsible for the <span class="hlt">shock</span> structures in equal mass pair-ion plasma. The dynamics of the weakly nonlinear <span class="hlt">wave</span> is governed by the Korteweg-de Vries Burgers equation. The analytical and numerical investigations revealed that the ion acoustic <span class="hlt">wave</span> exhibits both oscillatory and monotonic <span class="hlt">shock</span> structures depending on the frequency of ion-ion collision parameter. The results have been discussed in the context of the fullerene pair-ion plasma experiments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18..200S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18..200S"><span id="translatedtitle">The Saturnian Environment as a Unique Laboratory for Collisionless <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>Sulaiman, Ali; Masters, Adam; Dougherty, Michele; Burgess, David; Fujimoto, Masaki; Hospodarsky, George</p> <p>2016-04-01</p> <p>Collisionless <span class="hlt">shock</span> <span class="hlt">waves</span> are ubiquitous in the universe and fundamental to understanding the nature of collisionless plasmas. The interplay between particles (ions and electrons) and fields (electromagnetic) introduces a variety of both physical and geometrical parameters such as Mach numbers (e.g. MA, Mf), β, and θBn. These vary drastically from terrestrial to astrophysical regimes resulting in radically different characteristics of <span class="hlt">shocks</span>. This poses two complexities. Firstly, separating the influences of these parameters on physical mechanisms such as energy dissipation. Secondly, correlating observations of <span class="hlt">shock</span> <span class="hlt">waves</span> over a wide range of each parameter, enough to span across different regimes. Investigating the latter has been restricted since the majority of studies on <span class="hlt">shocks</span> at exotic regimes (such as supernova remnants) have been achieved either remotely or via simulations, but rarely by means of in-situ observations. It is not clear what happens in the higher MA regime. Here we show the parameter space of MA for all bow <span class="hlt">shock</span> crossings from 2004-2012 as measured by the Cassini spacecraft. We found that the Saturnian bow <span class="hlt">shock</span> exhibits characteristics akin to both terrestrial and astrophysical regimes (MA of order 100), which is principally controlled by the upstream magnetic field strength. Moreover, we estimated the θbn of each crossing and were able to further constrain the sample into categories of similar features. Our results demonstrate how MA plays a central role in controlling the onset of physical mechanisms in collisionless <span class="hlt">shocks</span>, particularly reformation. While ongoing studies have investigated this process extensively both theoretically and via simulations, their observations remain few and far between. We show conclusive evidence for cyclic reformation controlled by specular ion <span class="hlt">reflection</span> occurring at the predicted timescale of ˜0.3 τc, where τc is the ion gyroperiod. In addition, we experimentally underpin the relationship between</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980039333','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980039333"><span id="translatedtitle">Studies of <span class="hlt">Shock</span> <span class="hlt">Wave</span> Interactions with Homogeneous and Isotropic Turbulence</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Briassulis, G.; Agui, J.; Watkins, C. B.; Andreopoulos, Y.</p> <p>1998-01-01</p> <p>A nearly homogeneous nearly isotropic compressible turbulent flow interacting with a normal <span class="hlt">shock</span> <span class="hlt">wave</span> has been studied experimentally in a large <span class="hlt">shock</span> 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 <span class="hlt">shock</span> <span class="hlt">wave</span> in all investigated cases with flow Mach numbers ranging from 0.3 to 0.7 and <span class="hlt">shock</span> 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 <span class="hlt">shock</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840010505','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840010505"><span id="translatedtitle">An experimental investigation of the impingement of a planar <span class="hlt">shock</span> <span class="hlt">wave</span> on an axisymmetric body at Mach 3</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Brosh, A.; Kussoy, M. I.</p> <p>1983-01-01</p> <p>An experimental study of the flow caused by a planar <span class="hlt">shock</span> <span class="hlt">wave</span> impinging obliquely on a cylinder is presented. The complex three dimensional <span class="hlt">shock</span> <span class="hlt">wave</span> and boundary layer interaction occurring in practical problems, such as the <span class="hlt">shock</span> <span class="hlt">wave</span> impingement from the shuttle nose on an external fuel tank, and store carriage interference on a supersonic tactical aircraft were investigated. A data base for numerical computations of complex flows was also investigated. The experimental techniques included pressure measurements and oil flow patterns on the surface of the cylinder, and shadowgraphs and total and static pressure surveys on the leeward and windward planes of symmetry. The complete data is presented in tabular form. The results reveal a highly complex flow field with two separation zones, regions of high crossflow, and multiple <span class="hlt">reflected</span> <span class="hlt">shocks</span> and expansion fans.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007APS..SHK.A1001T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007APS..SHK.A1001T"><span id="translatedtitle">Applications of <span class="hlt">Shock</span> <span class="hlt">Wave</span> Research to Developments of Therapeutic Devices.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Takayama, Kazuyoshi</p> <p>2007-06-01</p> <p>Underwater <span class="hlt">shock</span> <span class="hlt">wave</span> research applied to medicine started in 1980 by exploding micro lead azide pellets in water. Collaboration with urologists in the School of Medicine, Tohoku University at the same time was directed to disintegration of kidney stones by controlling <span class="hlt">shock</span> <span class="hlt">waves</span>. We initially proposed a miniature truncated ellipsoidal cavity for generating high-pressures enough to disintegrate the stone but gave up the idea, when encountering the Dornie Systems' invention of an extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripter (ESWL). Then we confirmed its effectiveness by using 10 mg silver azide pellets and constructed our own lithotripter, which was officially approved for a clinical use in 1987. Tissue damage during ESWL was attributable to bubble collapse and we convinced it could be done in a controlled fashion. In 1996, we used 160 mJ pulsed Ho:YAG laser beam focusing inside a catheter for <span class="hlt">shock</span> generation and applied it to the revascularization of cerebral embolism, which is recently expanded to the treatment of pulmonary infarction. Micro water jets discharged in air were so effective to dissect soft tissues preserving small blood vessels. Animal experiments are successfully performed with high frequency water jets driven by an actuator-assisted micro-pump. A metal foil is deformed at high speed by a Q-switched Nd:YAG laser beam loading. We used this technique to project micro-particles or dry drugs attached on its reverse side and extended it to a laser ablation assisted dry drug delivery or DNA introductory system.</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/2012PhDT........12A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012PhDT........12A"><span id="translatedtitle">Molecular Dynamics of <span class="hlt">Shock</span> <span class="hlt">Wave</span> Interaction with Nanoscale Structured Materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Al-Qananwah, Ahmad K.</p> <p></p> <p>Typical theoretical treatments of <span class="hlt">shock</span> <span class="hlt">wave</span> interactions are based on a continuum approach, which cannot resolve the spatial variations in solids with nano-scale porous structure. Nano-structured materials have the potential to attenuate the strength of traveling <span class="hlt">shock</span> <span class="hlt">waves</span> because of their high surface-to-volume ratio. To investigate such interactions we have developed a molecular dynamics simulation model, based on Short Range Attractive interactions. A piston, modeled as a uni-directional repulsive force field translating at a prescribed velocity, impinges on a region of gas which is compressed to form a <span class="hlt">shock</span>, which in turn is driven against an atomistic solid wall. Periodic boundary conditions are used in the directions orthogonal to the piston motion, and we have considered solids based on either embedded atom potentials (target structure) or tethered potential (rigid piston, holding wall). Velocity, temperature and stress fields are computed locally in both gas and solid regions, and displacements within the solid are interpreted in terms of its elastic constants. In this work we present results of the elastic behavior of solid structures subjected to <span class="hlt">shock</span> <span class="hlt">wave</span> impact and analysis of energy transport and absorption in porous materials. The results indicated that the presence of nano-porous material layers in front of a target wall reduced the stress magnitude detected inside and the energy deposited there by about 30 percent while, at the same time, its loading rate was decreased substantially.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006PhDT........59Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006PhDT........59Z"><span id="translatedtitle">Terahertz <span class="hlt">wave</span> <span class="hlt">reflective</span> sensing and imaging</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhong, Hua</p> <p></p> <p>Sensing and imaging technologies using terahertz (THz) radiation have found diverse applications as they approach maturity. Since the burgeoning of this technique in the 1990's, many THz sensing and imaging investigations have been designed and conducted in transmission geometry, which provides sufficient phase and amplitude contrast for the study of the spectral properties of targets in the THz domain. Driven by rising expectations that THz technology will be a potential candidate in the next generation of security screening, remote sensing, biomedical imaging and non-destructive testing (NDT), most THz sensing and imaging modalities are being extended to <span class="hlt">reflection</span> geometry, which offers unique and adaptive solutions, and multi-dimensional information in many real scenarios. This thesis takes an application-focused approach to the advancement of THz <span class="hlt">wave</span> <span class="hlt">reflective</span> sensing and imaging systems: The absorption signature of the explosive material hexahydro-1,3,5-trinitro-1,3,5triazine (RDX) is measured at 30 m---the longest standoff distance so far attained by THz time-domain spectroscopy (THz-TDS). The standoff distance sensing ability of THz-TDS is investigated along with discussions specifying the influences of a variety of factors such as propagation distance, water vapor absorption and collection efficiency. Highly directional THz radiation from four-<span class="hlt">wave</span> mixing in laser-induced air plasmas is first observed and measured, which provides a potential solution for the atmospheric absorption effect in standoff THz sensing. The simulations of the beam profiles also illuminate the underlying physics behind the interaction of the optical beam with the plasma. THz <span class="hlt">wave</span> <span class="hlt">reflective</span> spectroscopic focal-plane imaging is realized the first time. Absorption features of some explosives and related compounds (ERCs) and biochemical materials are identified by using adaptive feature extraction method. Good classification results using multiple pattern recognition methods are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1989STIN...9011970H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1989STIN...9011970H"><span id="translatedtitle">Simulation of glancing <span class="hlt">shock</span> <span class="hlt">wave</span> and 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>Hung, Ching-Mao</p> <p>1989-09-01</p> <p><span class="hlt">Shock</span> <span class="hlt">waves</span> generated by sharp fins, glancing across a laminar boundary layer growing over a flat plate, are simulated numerically. Several basic issues concerning the resultant three-dimensional flow separation are studied. Using the same number of grid points, different grid spacings are employed to investigate the effects of grid resolution on the origin of the line of separation. Various <span class="hlt">shock</span> strengths (generated by different fin angles) are used to study the so-called separated and unseparated boundary layer and to establish the existence or absence of the secondary separation. The usual interpretations of the flow field from previous studies and new interpretations arising from the present simulation are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhRvL.112n4504H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhRvL.112n4504H"><span id="translatedtitle"><span class="hlt">Shock-Wave</span> Compression and Joule-Thomson Expansion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hoover, Wm. G.; Hoover, Carol G.; Travis, Karl P.</p> <p>2014-04-01</p> <p>Structurally stable atomistic one-dimensional <span class="hlt">shock</span> <span class="hlt">waves</span> have long been simulated by injecting fresh cool particles and extracting old hot particles at opposite ends of a simulation box. The resulting <span class="hlt">shock</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900002654','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900002654"><span id="translatedtitle">Simulation of glancing <span class="hlt">shock</span> <span class="hlt">wave</span> and boundary layer interaction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hung, Ching-Mao</p> <p>1989-01-01</p> <p><span class="hlt">Shock</span> <span class="hlt">waves</span> generated by sharp fins, glancing across a laminar boundary layer growing over a flat plate, are simulated numerically. Several basic issues concerning the resultant three-dimensional flow separation are studied. Using the same number of grid points, different grid spacings are employed to investigate the effects of grid resolution on the origin of the line of separation. Various <span class="hlt">shock</span> strengths (generated by different fin angles) are used to study the so-called separated and unseparated boundary layer and to establish the existence or absence of the secondary separation. The usual interpretations of the flow field from previous studies and new interpretations arising from the present simulation are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19720052777&hterms=organic+synthesis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dorganic%2Bsynthesis','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19720052777&hterms=organic+synthesis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dorganic%2Bsynthesis"><span id="translatedtitle">'Thunder' - <span class="hlt">Shock</span> <span class="hlt">waves</span> in pre-biological organic synthesis.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bar-Nun, A.; Tauber, M. E.</p> <p>1972-01-01</p> <p>Theoretical study of the gasdynamics and chemistry of lightning-produced <span class="hlt">shock</span> <span class="hlt">waves</span> in a postulated primordial reducing atmosphere. It is shown that the conditions are similar to those encountered in a previously performed <span class="hlt">shock</span>-tube experiment which resulted in 36% of the ammonia in the original mixture being converted into amino acids. The calculations give the (very large) energy rate of about 0.4 cal/sq cm/yr available for amino acid production, supporting previous hypotheses that 'thunder' could have been responsible for efficient large-scale production of organic molecules serving as precursors of life.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14611406','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14611406"><span id="translatedtitle">Observation of <span class="hlt">shock</span> transverse <span class="hlt">waves</span> in elastic media.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Catheline, S; Gennisson, J-L; Tanter, M; Fink, M</p> <p>2003-10-17</p> <p>We report the first experimental observation of a <span class="hlt">shock</span> transverse <span class="hlt">wave</span> propagating in an elastic medium. This observation was possible because the propagation medium, a soft solid, allows one to reach a very high Mach number. In this extreme configuration, the <span class="hlt">shock</span> formation is observed over a distance of less than a few wavelengths, thanks to a prototype of an ultrafast scanner (that acquires 5000 frames per second). A comparison of these new experimental data with theoretical predictions, based on a modified Burger's equation, shows good agreement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6558616','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6558616"><span id="translatedtitle">Fiber-coupled optical pyrometer for <span class="hlt">shock-wave</span> studies</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Holmes, N.C. )</p> <p>1995-03-01</p> <p>We have developed a new optical pyrometer with unique advantages for <span class="hlt">shock-wave</span> studies and for measurements of systems that are moving with respect to the detection system. Our pyrometer is fully fiber optic coupled. This completely eliminates any time-dependent imaging or aperture effects common to imaging pyrometers, and is simple to align and calibrate. The sensitivity is also higher than typical imaging systems used for <span class="hlt">shock</span> experiments. The design is excellent for observations of time-varying phenomena. Detection is done with fast photomultiplier tubes with roughly 1 ns response. In addition, one may also include a streaked spectroscopic system, making this system ideal for fast spectroscopic studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4549845','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4549845"><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="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ohl, Siew-Wan; Klaseboer, Evert; Khoo, Boo Cheong</p> <p>2015-01-01</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> wave–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> wave–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. PMID:26442143</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1983PhFl...26.1234N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1983PhFl...26.1234N"><span id="translatedtitle">Analysis of self-similar problems of imploding <span class="hlt">shock</span> <span class="hlt">waves</span> by the method of characteristics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nakamura, Y.</p> <p>1983-05-01</p> <p>The asymptotic self-similar form of cylindrically or spherically imploding <span class="hlt">shock</span> <span class="hlt">waves</span> is extracted by numerically solving non-self-similar problems. The <span class="hlt">shock</span> <span class="hlt">wave</span> is generated by a contracting piston with finite initial velocity. For the initial <span class="hlt">shock</span> motion, a perturbation method is used to determine the starting condition for the numerical calculation. Propagation of the <span class="hlt">shock</span> <span class="hlt">wave</span> and flow field properties are obtained and the transition of the non-self-similar motion of the <span class="hlt">shock</span> <span class="hlt">wave</span> into the self-similar one is presented. Good agreement between self-similar exponents determined from the variation of the <span class="hlt">shock</span> strength and those calculated by Guderley is obtained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005ASAJ..117.2384H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005ASAJ..117.2384H"><span id="translatedtitle">Study of a tissue protecting system for clinical applications of underwater <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>Hosseini, S. H. R.; Takayama, Kazuyoshi</p> <p>2005-04-01</p> <p>Applications of underwater <span class="hlt">shock</span> <span class="hlt">waves</span> have been extended to various clinical therapies during the past two decades. Besides the successful contribution of extracorporeal <span class="hlt">shock</span> <span class="hlt">waves</span>, tissue damage especially to the vasculature has been reported. These side effects are believed to be due to the <span class="hlt">shock</span> <span class="hlt">wave</span>-tissue interaction and cavitation. In the present research in order to minimize <span class="hlt">shock</span> <span class="hlt">wave</span> induced damage a <span class="hlt">shock</span> <span class="hlt">wave</span> attenuating system was designed and studied. The attenuating system consisted of thin gas packed layers immersed in water, which could attenuate more than 90% of <span class="hlt">shock</span> <span class="hlt">waves</span> overpressure. Silver azide micro-pellets (10 mg) were ignited by irradiation of a pulsed Nd:YAG laser to generate <span class="hlt">shock</span> <span class="hlt">waves</span>. Pressure histories were measured with fiber optic probe and PVDF needle hydrophones. The strength of incident <span class="hlt">shock</span> <span class="hlt">waves</span> was changed by adjusting the distance between the pellets and the layers. The whole sequences of the <span class="hlt">shock</span> <span class="hlt">wave</span> attenuation due to the interaction of <span class="hlt">shock</span> <span class="hlt">waves</span> with the dissipating layers were quantitatively visualized by double exposure holographic interferometry and time resolved high speed photography. The attenuated <span class="hlt">shock</span> had overpressure less than threshold damage of brain tissue evaluated from histological examination of the rat brain treated by <span class="hlt">shock</span> <span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21538207','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21538207"><span id="translatedtitle">Enhancement of airborne <span class="hlt">shock</span> <span class="hlt">wave</span> by laser-induced breakdown of liquid column in laser <span class="hlt">shock</span> cleaning</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jang, Deoksuk; Kim, Dongsik; Park, Jin-Goo</p> <p>2011-04-01</p> <p>In laser <span class="hlt">shock</span> cleaning (LSC), the <span class="hlt">shock</span> <span class="hlt">wave</span> is generated by laser-induced breakdown of the ambient gas. The <span class="hlt">shock</span> <span class="hlt">wave</span> intensity has thus been a factor limiting the performance of the LSC process. In this work, a novel method of amplifying a laser-induced plasma-generated <span class="hlt">shock</span> <span class="hlt">wave</span> by the breakdown of a liquid column is proposed and analyzed. When the laser beam is focused on a microscale liquid column, a <span class="hlt">shock</span> <span class="hlt">wave</span> having a significantly amplified intensity compared to that generated by air breakdown alone can be generated in air. Therefore, substantially amplified cleaning force can be obtained. The dynamics of a <span class="hlt">shock</span> <span class="hlt">wave</span> induced by a Q-switched Nd:YAG laser was analyzed by laser flash shadowgraphy. The peak pressure of the laser-induced <span class="hlt">shock</span> <span class="hlt">wave</span> was approximately two times greater than that of air breakdown at the same laser fluence. The proposed method of <span class="hlt">shock</span> <span class="hlt">wave</span> generation is expected to be useful in various applications of laser <span class="hlt">shock</span> processing, including surface cleaning.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19800008577','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19800008577"><span id="translatedtitle">Second sound <span class="hlt">shock</span> <span class="hlt">waves</span> and critical velocities in liquid helium 2. Ph.D. Thesis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Turner, T. N.</p> <p>1979-01-01</p> <p>Large amplitude second-sound <span class="hlt">shock</span> <span class="hlt">waves</span> were generated and the experimental results compared to the theory of nonlinear second-sound. The structure and thickness of second-sound <span class="hlt">shock</span> fronts are calculated and compared to experimental data. Theoretically it is shown that at T = 1.88 K, where the nonlinear <span class="hlt">wave</span> steepening vanishes, the thickness of a very weak <span class="hlt">shock</span> must diverge. In a region near this temperature, a finite-amplitude <span class="hlt">shock</span> pulse evolves into an unusual double-<span class="hlt">shock</span> configuration consisting of a front steepened, temperature raising <span class="hlt">shock</span> followed by a temperature lowering <span class="hlt">shock</span>. Double-<span class="hlt">shocks</span> are experimentally verified. It is experimentally shown that very large second-sound <span class="hlt">shock</span> <span class="hlt">waves</span> initiate a breakdown in the superfluidity of helium 2, which is dramatically displayed as a limit to the maximum attainable <span class="hlt">shock</span> strength. The value of the maximum <span class="hlt">shock</span>-induced relative velocity represents a significant lower bound to the intrinsic critical velocity of helium 2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20060047586','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20060047586"><span id="translatedtitle">The Curious Events Leading to the Theory of <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>Salas, Manuel D.</p> <p>2006-01-01</p> <p>We review the history of the development of the modern theory of <span class="hlt">shock</span> <span class="hlt">waves</span>. Several attempts at an early-theory quickly collapsed for lack of foundations in mathematics and thermodynamics. It is not until the works of Rankine and later Hugoniot that a full theory is established. Rankine is the first to show that within the <span class="hlt">shock</span> a non-adiabatic process must occur. Hugoniot showed that in the absence of viscosity and heat conduction conservation of energy implies conservation of entropy in smooth regions and a jump in entropy across a <span class="hlt">shock</span>. Even after the theory is fully developed, old notions continue to pervade the literature well into the early part of the 20th Century.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhDT.........1J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhDT.........1J"><span id="translatedtitle">The effect of <span class="hlt">shock</span> <span class="hlt">wave</span> impingement on thin, woven glass fiber reinforced, polymer composite plates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jahnke, Douglas M.</p> <p></p> <p> deformation of the test specimen. The technique has been validated by comparing the results obtained in a static experiment with the results measured by laser displacement sensors. Additional validation of dynamically obtained strain measurements was carried out by using a 13 mm (1/2") thick in-house fabricated composite specimen with embedded strain gauges and piezoelectric sensors. Surface mounted sensors due to the large inertia forces experienced by a test specimen tend to detach from it almost immediately after the <span class="hlt">shock</span> impact, so very little useful data could be collected. The present work has created a strong foundation in testing methodology and baseline results in studying the effects of <span class="hlt">shock</span> <span class="hlt">wave</span> impingement on FRP composites. It was found that the maximum deformation of the plate occurs immediate after the <span class="hlt">shock</span> impact and much before the whole loading cycle is completed. The results of permanent deformation have been normalized by using the impulse of the loading force. Additional work has been focused on the energy exchange between the incoming <span class="hlt">shock</span> <span class="hlt">wave</span> and the specimen. Understanding how much energy is associated with the <span class="hlt">shock</span> <span class="hlt">reflection</span>, transmission, absorption, or passed through is critical to designing protective systems using FRP composites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010ChPhB..19e0515G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010ChPhB..19e0515G"><span id="translatedtitle"><span class="hlt">Reflection</span> and refraction of <span class="hlt">waves</span> in oscillatory media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gu, Guo-Feng; Lü, Yao-Ping; Tang, Guo-Ning</p> <p>2010-05-01</p> <p>This paper uses the two-dimensional Brusselator model to study <span class="hlt">reflection</span> and refraction of chemical <span class="hlt">waves</span>. It presents some boundary conditions of chemical <span class="hlt">waves</span>, with which occurence of observed phenomena at interface as refraction and <span class="hlt">reflection</span> of chemical <span class="hlt">waves</span> can be interpreted. Moreover, the angle of <span class="hlt">reflection</span> may be calculated by using the boundary conditions. It finds that <span class="hlt">reflection</span> and refraction of chemical <span class="hlt">waves</span> can occur simultaneously even if plane <span class="hlt">wave</span> goes from a medium with higher speed to a medium with lower speed, provided the incident angle is larger than the critical angle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21455272','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21455272"><span id="translatedtitle">From weak discontinuities to nondissipative <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>Garifullin, R. N. Suleimanov, B. I.</p> <p>2010-01-15</p> <p>An analysis is presented of the effect of weak dispersion on transitions from weak to strong discontinuities in inviscid fluid dynamics. In the neighborhoods of transition points, this effect is described by simultaneous solutions to the Korteweg-de Vries equation u{sub t}'+ uu{sub x}' + u{sub xxx}' = 0 and fifth-order nonautonomous ordinary differential equations. As x{sup 2} + t{sup 2} {yields}{infinity}, the asymptotic behavior of these simultaneous solutions in the zone of undamped oscillations is given by quasi-simple <span class="hlt">wave</span> solutions to Whitham equations of the form r{sub i}(t, x) = tl{sub i} x/t{sup 2}.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JETP..122.1111A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JETP..122.1111A"><span id="translatedtitle">Time fractional effect on ion acoustic <span class="hlt">shock</span> <span class="hlt">waves</span> in ion-pair plasma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Abdelwahed, H. G.; El-Shewy, E. K.; Mahmoud, A. A.</p> <p>2016-06-01</p> <p>The nonlinear properties of ion acoustic <span class="hlt">shock</span> <span class="hlt">waves</span> are studied. The Burgers equation is derived and converted into the time fractional Burgers equation by Agrawal's method. Using the Adomian decomposition method, <span class="hlt">shock</span> <span class="hlt">wave</span> solutions of the time fractional Burgers equation are constructed. The effect of the time fractional parameter on the <span class="hlt">shock</span> <span class="hlt">wave</span> properties in ion-pair plasma is investigated. The results obtained may be important in investigating the broadband electrostatic <span class="hlt">shock</span> noise in D- and F-regions of Earth's ionosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993SPIE.1801.1029T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993SPIE.1801.1029T"><span id="translatedtitle">Application of holographic interferometric studies of underwater <span class="hlt">shock-wave</span> focusing to medicine</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Takayama, Kazuyoshi; Nagoya, H.; Obara, Tetsuro; Kuwahara, M.</p> <p>1993-01-01</p> <p>Holographic interferometric flow visualization was successfully applied to underwater <span class="hlt">shock</span> <span class="hlt">wave</span> focusing and its application to extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy (ESWL). Real time diffuse holograms revealed the <span class="hlt">shock</span> <span class="hlt">wave</span> focusing process in an ellipsoidal reflector made from PMMA and double exposure holographic interferometry also clarified quantitatively the <span class="hlt">shock</span> focusing process. Disintegration of urinary tract stones and gallbladder stones was observed by high speed photogrammetry. Tissue damage associated with the ESWL treatment is discussed in some detail.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1982JFM...120..451V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1982JFM...120..451V"><span id="translatedtitle">The converging <span class="hlt">shock</span> <span class="hlt">wave</span> from a spherical or cylindrical piston</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>van Dyke, M.; Guttmann, A. J.</p> <p>1982-07-01</p> <p>A spherical or cylindrical cavity containing quiescent gas begins to contract at high constant radial speed, driving an axisymmetric <span class="hlt">shock</span> <span class="hlt">wave</span> inward to collapse at the center. We analyze the flow field by expanding the solution in powers of time, and calculate 40 terms by delegating the arithmetic to a computer. Analysis of the series for the radius of the <span class="hlt">shock</span> <span class="hlt">wave</span> confirms Guderley's local self-similar solution for the focusing, including recent refined values for his similarity exponent, and yields higher terms in his local expansion. In the range of adiabatic exponent where the Guderley solution has been shown not to be unique we find, in accord with a conjecture of Gel'fand, that the smallest admissible similarity exponent is realized.</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.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4095641','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4095641"><span id="translatedtitle">Extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> therapy in periodontics: A new paradigm</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Venkatesh Prabhuji, Munivenkatappa Lakshmaiah; Khaleelahmed, Shaeesta; Vasudevalu, Sujatha; Vinodhini, K.</p> <p>2014-01-01</p> <p>The quest for exploring new frontiers in the field of medical science for efficient and improved treatment modalities has always been on a rise. Extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> therapy (ESWT) has been enormously used in medical practice, principally, for the management of urolithiasis, cholelithiasis and also in various orthopedic and musculoskeletal disorders. The efficacy of ESWT in the stimulation of osteoblasts, fibroblasts, induction of neovascularization and increased expression of bone morphogenic proteins has been well documented in the literature. However, dentistry is no exception to this trend. The present article enlightens the various applications of ESWT in the field of dentistry and explores its prospective applications in the field of periodontics, and the possibility of incorporating the beneficial properties of <span class="hlt">shock</span> <span class="hlt">waves</span> in improving the treatment outcome. PMID:25024562</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/108177','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/108177"><span id="translatedtitle">Sonoluminescence, <span class="hlt">shock</span> <span class="hlt">waves</span>, and micro-thermonuclear fusion</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Moss, W.C.; Clarke, D.B.; White, J.W.; Young, D.A.</p> <p>1995-08-01</p> <p>We have performed numerical hydrodynamic simulations of the growth and collapse of a sonoluminescing bubble in a liquid. Our calculations show that spherically converging <span class="hlt">shock</span> <span class="hlt">waves</span> are generated during the collapse of the bubble. The combination of the <span class="hlt">shock</span> <span class="hlt">waves</span> and a realistic equation of state for the gas in the bubble provides an explanation for the measured picosecond optical pulse widths and indicates that the temperatures near the center of the bubble may exceed 3O eV. This leads naturally to speculation about obtaining micro-thermonuclear fusion in a bubble filled with deuterium (D{sub 2}) gas. Consequently, we performed numerical simulations of the collapse of a D{sub 2} bubble in D{sub 2}0. A pressure spike added to the periodic driving amplitude creates temperatures that may be sufficient to generate a very small, but measurable number of thermonuclear D-D fusion reactions in the bubble.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1044133','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1044133"><span id="translatedtitle">Simulation and Analysis of Converging <span class="hlt">Shock</span> <span class="hlt">Wave</span> Test Problems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ramsey, Scott D.; Shashkov, Mikhail J.</p> <p>2012-06-21</p> <p>Results and analysis pertaining to the simulation of the Guderley converging <span class="hlt">shock</span> <span class="hlt">wave</span> test problem (and associated code verification hydrodynamics test problems involving converging <span class="hlt">shock</span> <span class="hlt">waves</span>) in the LANL ASC radiation-hydrodynamics code xRAGE are presented. One-dimensional (1D) spherical and two-dimensional (2D) axi-symmetric geometric setups are utilized and evaluated in this study, as is an instantiation of the xRAGE adaptive mesh refinement capability. For the 2D simulations, a 'Surrogate Guderley' test problem is developed and used to obviate subtleties inherent to the true Guderley solution's initialization on a square grid, while still maintaining a high degree of fidelity to the original problem, and minimally straining the general credibility of associated analysis and conclusions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25024562','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25024562"><span id="translatedtitle">Extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> therapy in periodontics: A new paradigm.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Venkatesh Prabhuji, Munivenkatappa Lakshmaiah; Khaleelahmed, Shaeesta; Vasudevalu, Sujatha; Vinodhini, K</p> <p>2014-05-01</p> <p>The quest for exploring new frontiers in the field of medical science for efficient and improved treatment modalities has always been on a rise. Extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> therapy (ESWT) has been enormously used in medical practice, principally, for the management of urolithiasis, cholelithiasis and also in various orthopedic and musculoskeletal disorders. The efficacy of ESWT in the stimulation of osteoblasts, fibroblasts, induction of neovascularization and increased expression of bone morphogenic proteins has been well documented in the literature. However, dentistry is no exception to this trend. The present article enlightens the various applications of ESWT in the field of dentistry and explores its prospective applications in the field of periodontics, and the possibility of incorporating the beneficial properties of <span class="hlt">shock</span> <span class="hlt">waves</span> in improving the treatment outcome.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22410459','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22410459"><span id="translatedtitle">Investigation of <span class="hlt">shock-shock</span> interaction and Mach <span class="hlt">reflection</span> in laterally colliding laser-blow-off plasmas</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kumar, Bhupesh; Singh, R. K.; Sengupta, Sudip; Kaw, P. K.; Kumar, Ajai</p> <p>2015-06-15</p> <p>Interactions of two Li plasma plumes and <span class="hlt">shock</span> <span class="hlt">waves</span> are investigated at various pressures (∼10{sup −5} to 3 mbar) in the argon gas ambient. Fast imaging and optical emission spectroscopy are used to study the plume dynamics and characteristic emission of plasmas. The plasma plumes are created in laser-blow-off geometry. The expansion of plasma plumes in the ambient gas leads to the formation of an interaction zone. The formation of interaction zone is dependent on the ambient pressure and below a certain pressure, no significant change is observed in the shape and size of the interaction plasma. In the higher pressure, formation of interaction zone and its shape are dependent on ambient pressure. Dynamics of seed plasmas and interaction zone are also affected by the <span class="hlt">shock-shock</span> interactions. The <span class="hlt">shock-shock</span> interaction depends on the angle of incidence (α) between two <span class="hlt">shock</span> <span class="hlt">waves</span> at the initial time of interaction but as the plumes expand, the <span class="hlt">shock-shock</span> interaction does not follow α dependence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22043623','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22043623"><span id="translatedtitle">Tracking <span class="hlt">shocked</span> dust: State estimation for a complex plasma during a <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>Oxtoby, Neil P.; Ralph, Jason F.; Durniak, Celine; Samsonov, Dmitry</p> <p>2012-01-15</p> <p>We consider a two-dimensional complex (dusty) plasma crystal excited by an electrostatically-induced <span class="hlt">shock</span> <span class="hlt">wave</span>. Dust particle kinematics in such a system are usually determined using particle tracking velocimetry. In this work we present a particle tracking algorithm which determines the dust particle kinematics with significantly higher accuracy than particle tracking velocimetry. The algorithm uses multiple extended Kalman filters to estimate the particle states and an interacting multiple model to assign probabilities to the different filters. This enables the determination of relevant physical properties of the dust, such as kinetic energy and kinetic temperature, with high precision. We use a Hugoniot <span class="hlt">shock</span>-jump relation to calculate a pressure-volume diagram from the <span class="hlt">shocked</span> dust kinematics. Calculation of the full pressure-volume diagram was possible with our tracking algorithm, but not with particle tracking velocimetry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..SHK.O1005S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..SHK.O1005S"><span id="translatedtitle"><span class="hlt">Shock</span>-driven chemistry and reactive <span class="hlt">wave</span> dynamics in benzene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sheffield, Stephen; Dattelbaum, Dana; Coe, Joshua; Los Alamos National Laboratory Team</p> <p>2015-06-01</p> <p>Benzene is a stable organic chemistry molecule because of its electronic structure - aromatic stability is derived from its delocalized, π-bonded, 6-membered planar ring structure. Benzene principal <span class="hlt">shock</span> Hugoniot states have been reported previously by several groups, at both high and low pressures. Cusps (or discontinuities) in the <span class="hlt">shock</span> Hugoniot provide evidence that chemical reactions take place under shockwave compression of benzene at input pressure conditions above 12 GPa. In other <span class="hlt">shock</span>-driven experiments, spectral changes have been observed near this cusp condition, indicating that the cusp is associated with <span class="hlt">shock</span>-driven chemical reaction(s). In this work, a series of gas-gun-driven plate impact experiments were performed to measure and quantify the details associated with <span class="hlt">shock</span>-driven reactive flow in benzene. Using embedded electromagnetic gauges (with up to 10 Lagrangian gauge positions in-material in a single experiment) multiple, evolving <span class="hlt">wave</span> structures have been measured in benzene when the inputs were above 12 GPa, with the details changing as the input pressure was increased. Detailed insights into the volume changes associated with the chemical reaction(s), reaction rates, and estimates of the bulk moduli of reaction intermediates and products were obtained. Using this new experimental data (along with the older experimental data from others), the benzene reactant and product Hugoniot loci have been modeled by thermodynamically complete equations of state.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DPPUP2052J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DPPUP2052J"><span id="translatedtitle">Flow induced dust acoustic <span class="hlt">shock</span> <span class="hlt">waves</span> in a complex plasma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jaiswal, Surabhi; Bandyopadhyay, Pintu; Sen, Abhijit</p> <p>2015-11-01</p> <p>We report on experimental observations of particle flow induced large amplitude <span class="hlt">shock</span> <span class="hlt">waves</span> in a dusty plasma. These dust acoustic <span class="hlt">shocks</span> (DAS) are observed for strongly supersonic flows and have been studied in a U-shaped Dusty Plasma Experimental (DPEx) device for charged kaolin dust in a background of Argon plasma. The strong flow of the dust fluid is induced by adjusting the pumping speed and neutral gas flow into the device. An isolated copper wire mounted on the cathode acts as a potential barrier to the flow of dust particles. A sudden change of the dust density near the potential hill is used to trigger the onset of high velocity dust acoustic <span class="hlt">shocks</span>. The dynamics of the <span class="hlt">shocks</span> are captured by fast video pictures of the structures that are illuminated by a laser sheet beam. The physical characteristics of the <span class="hlt">shock</span> are delineated from a parametric scan of their dynamical properties over a range of plasma parameters and flow speeds. Details of these observations and a physical explanation based on model calculations will be presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920069674&hterms=downstream&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Ddownstream','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920069674&hterms=downstream&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Ddownstream"><span id="translatedtitle">A simulation study of multiple ion <span class="hlt">wave</span> generation downstream of low Mach number quasiperpendicular <span class="hlt">shocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Motschmann, Uwe; Raeder, Joachim</p> <p>1992-01-01</p> <p>The behavior of minor ions just downstream of a low Mach number quasi-perpendicular <span class="hlt">shock</span> is investigated both theoretically and by computer simulations. Because all ions see the same cross <span class="hlt">shock</span> electric field their deceleration depends on their charge to mass ratio, yielding different downstream velocities. It is shown that these differences in velocity can lead to coherent <span class="hlt">wave</span> structures in the downstream region of quasi-perpendicular <span class="hlt">shocks</span> with a narrow transition layer. These <span class="hlt">waves</span> are shown to be multi ion hybrid <span class="hlt">waves</span> in contrast to mirror <span class="hlt">waves</span> and ion cyclotron <span class="hlt">waves</span>. Under favorable conditions these <span class="hlt">waves</span> should be observable both at interplanetary <span class="hlt">shocks</span> and at planetary bowshocks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23927195','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23927195"><span id="translatedtitle">A heuristic model of stone comminution in <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Smith, Nathan B; Zhong, Pei</p> <p>2013-08-01</p> <p>A heuristic model is presented to describe the overall progression of stone comminution in <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy (SWL), accounting for the effects of <span class="hlt">shock</span> <span class="hlt">wave</span> dose and the average peak pressure, P+(avg), incident on the stone during the treatment. The model is developed through adaptation of the Weibull theory for brittle fracture, incorporating threshold values in dose and P+(avg) that are required to initiate fragmentation. The model is validated against experimental data of stone comminution from two stone types (hard and soft BegoStone) obtained at various positions in lithotripter fields produced by two <span class="hlt">shock</span> <span class="hlt">wave</span> sources of different beam width and pulse profile both in water and in 1,3-butanediol (which suppresses cavitation). Subsequently, the model is used to assess the performance of a newly developed acoustic lens for electromagnetic lithotripters in comparison with its original counterpart both under static and simulated respiratory motion. The results have demonstrated the predictive value of this heuristic model in elucidating the physical basis for improved performance of the new lens. The model also provides a rationale for the selection of SWL treatment protocols to achieve effective stone comminution without elevating the risk of tissue injury.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AIPC.1481...76D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AIPC.1481...76D"><span id="translatedtitle">Optically triggered solid state driver for <span class="hlt">shock</span> <span class="hlt">wave</span> therapy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Duryea, Alexander P.; Roberts, William W.; Cain, Charles A.; Hall, Timothy L.</p> <p>2012-10-01</p> <p><span class="hlt">Shock</span> <span class="hlt">wave</span> lithotripsy (SWL) represents one of several first-line therapies for the treatment of stones located in the kidneys and ureters. Additional applications for <span class="hlt">shock</span> <span class="hlt">wave</span> therapy are also under exploration, including non-urinary calculi, orthopedics, and neovascularization. Except for the elimination of a large water bath in which the treatment is performed, current procedures remain largely unchanged, with one of the original commercial devices (the Dornier HM3) still considered a gold standard for comparison. To accelerate research in this area, Coleman, et al. published an experimental electrohydraulic <span class="hlt">shock</span> <span class="hlt">wave</span> generator capable of simulating the acoustic field generated by the HM3. We propose a further update of this system, replacing the triggered spark gap with an optically triggered solid state switch. The new system has better reliability, a wider operating range, and reduced timing jitter allowing synchronization with additional acoustic sources under exploration for improving efficacy and reducing injury. Originally designed for exciting electrohydraulic spark electrodes, the system can also be adapted for driving piezoelectric and electromagnetic sources.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhPl...23e2706V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhPl...23e2706V"><span id="translatedtitle">Stability of stagnation via an expanding accretion <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>Velikovich, A. L.; Murakami, M.; Taylor, B. D.; Giuliani, J. L.; Zalesak, S. T.; Iwamoto, Y.</p> <p>2016-05-01</p> <p>Stagnation of a cold plasma streaming to the center or axis of symmetry via an expanding accretion <span class="hlt">shock</span> <span class="hlt">wave</span> is ubiquitous in inertial confinement fusion (ICF) and high-energy-density plasma physics, the examples ranging from plasma flows in x-ray-generating Z pinches [Maron et al., Phys. Rev. Lett. 111, 035001 (2013)] to the experiments in support of the recently suggested concept of impact ignition in ICF [Azechi et al., Phys. Rev. Lett. 102, 235002 (2009); Murakami et al., Nucl. Fusion 54, 054007 (2014)]. Some experimental evidence indicates that stagnation via an expanding <span class="hlt">shock</span> <span class="hlt">wave</span> is stable, but its stability has never been studied theoretically. We present such analysis for the stagnation that does not involve a rarefaction <span class="hlt">wave</span> behind the expanding <span class="hlt">shock</span> front and is described by the classic ideal-gas Noh solution in spherical and cylindrical geometry. In either case, the stagnated flow has been demonstrated to be stable, initial perturbations exhibiting a power-law, oscillatory or monotonic, decay with time for all the eigenmodes. This conclusion has been supported by our simulations done both on a Cartesian grid and on a curvilinear grid in spherical coordinates. Dispersion equation determining the eigenvalues of the problem and explicit formulas for the eigenfunction profiles corresponding to these eigenvalues are presented, making it possible to use the theory for hydrocode verification in two and three dimensions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JEPT...89.1047F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JEPT...89.1047F"><span id="translatedtitle">How the Term "<span class="hlt">Shock</span> <span class="hlt">Waves</span>" Came Into Being</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fomin, N. A.</p> <p>2016-07-01</p> <p>The present paper considers the history of works on <span class="hlt">shock</span> <span class="hlt">waves</span> beginning from S. D. Poisson's publication in 1808. It expounds on the establishment of the Polytechnic School in Paris and its fellows and teachers — Gaspard Monge, Lazare Carnot, Joseph Louis Gay-Lussac, Simeon Denis Poisson, Henri Navier, Augustin Louis Cauchy, Joseph Liouville, Ademar de Saint-Venant, Henri Regnault, Pierre Dulong, Emile Jouguet, Pierre Duhem, and others. It also describes the participation in the development of the <span class="hlt">shock</span> <span class="hlt">wave</span> theory of young scientists from the universities of Cambridge, among which were George Airy, James Challis, Samuel Earnshaw, George Stokes, Lord Rayleigh, Lord Kelvin, and James Maxwell, as well as of scientists from the Göttingen University, Germany — Bernhard Riemann and Ernst Heinrich Weber. The pioneer works on <span class="hlt">shock</span> <span class="hlt">waves</span> of the Scottish engineer William Renkin, the French artillerist Pierre-Henri Hugoniot, German scientists August Toepler and Ernst Mach, and a Hungarian scientist Gyözö Zemplén are also considered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3122580','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3122580"><span id="translatedtitle">Needleless Vaccine Delivery Using Micro-<span class="hlt">Shock</span> <span class="hlt">Waves</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>Jagadeesh, Gopalan; Prakash, G. Divya; Rakesh, S. G.; Allam, Uday Sankar; Krishna, M. Gopala; Eswarappa, Sandeepa M.; Chakravortty, Dipshikha</p> <p>2011-01-01</p> <p><span class="hlt">Shock</span> <span class="hlt">waves</span> are one of the most efficient mechanisms of energy dissipation observed in nature. In this study, utilizing the instantaneous mechanical impulse generated behind a micro-<span class="hlt">shock</span> <span class="hlt">wave</span> during a controlled explosion, a novel nonintrusive needleless vaccine delivery system has been developed. It is well-known that antigens in the epidermis are efficiently presented by resident Langerhans cells, eliciting the requisite immune response, making them a good target for vaccine delivery. Unfortunately, needle-free devices for epidermal delivery have inherent problems from the perspective of the safety and comfort of the patient. The penetration depth of less than 100 μm in the skin can elicit higher immune response without any pain. Here we show the efficient utilization of our needleless device (that uses micro-<span class="hlt">shock</span> <span class="hlt">waves</span>) for vaccination. The production of liquid jet was confirmed by high-speed microscopy, and the penetration in acrylamide gel and mouse skin was observed by confocal microscopy. Salmonella enterica serovar Typhimurium vaccine strain pmrG-HM-D (DV-STM-07) was delivered using our device in the murine salmonellosis model, and the effectiveness of the delivery system for vaccination was compared with other routes of vaccination. Vaccination using our device elicits better protection and an IgG response even at a lower vaccine dose (10-fold less) compared to other routes of vaccination. We anticipate that our novel method can be utilized for effective, cheap, and safe vaccination in the near future. PMID:21307276</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3745501','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3745501"><span id="translatedtitle">A heuristic model of stone comminution in <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Smith, Nathan B.; Zhong, Pei</p> <p>2013-01-01</p> <p>A heuristic model is presented to describe the overall progression of stone comminution in <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy (SWL), accounting for the effects of <span class="hlt">shock</span> <span class="hlt">wave</span> dose and the average peak pressure, P+(avg), incident on the stone during the treatment. The model is developed through adaptation of the Weibull theory for brittle fracture, incorporating threshold values in dose and P+(avg) that are required to initiate fragmentation. The model is validated against experimental data of stone comminution from two stone types (hard and soft BegoStone) obtained at various positions in lithotripter fields produced by two <span class="hlt">shock</span> <span class="hlt">wave</span> sources of different beam width and pulse profile both in water and in 1,3-butanediol (which suppresses cavitation). Subsequently, the model is used to assess the performance of a newly developed acoustic lens for electromagnetic lithotripters in comparison with its original counterpart both under static and simulated respiratory motion. The results have demonstrated the predictive value of this heuristic model in elucidating the physical basis for improved performance of the new lens. The model also provides a rationale for the selection of SWL treatment protocols to achieve effective stone comminution without elevating the risk of tissue injury. PMID:23927195</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/pages/biblio/1295510-negative-pressures-spallation-water-drops-subjected-nanosecond-shock-waves','SCIGOV-DOEP'); return false;" href="http://www.osti.gov/pages/biblio/1295510-negative-pressures-spallation-water-drops-subjected-nanosecond-shock-waves"><span id="translatedtitle">Negative pressures and spallation in water drops subjected to nanosecond <span class="hlt">shock</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Stan, Claudiu A.; Willmott, Philip R.; Stone, Howard A.; Koglin, Jason E.; Liang, Mengning; Aquila, Andrew L.; Robinson, Joseph S.; Gumerlock, Karl L.; Blaj, Gabriel; Sierra, Raymond G.; et al</p> <p>2016-05-16</p> <p>Most experimental studies of cavitation in liquid water at negative pressures reported cavitation at tensions significantly smaller than those expected for homogeneous nucleation, suggesting that achievable tensions are limited by heterogeneous cavitation. We generated tension pulses with nanosecond rise times in water by <span class="hlt">reflecting</span> cylindrical <span class="hlt">shock</span> <span class="hlt">waves</span>, produced by X-ray laser pulses, at the internal surface of drops of water. Depending on the X-ray pulse energy, a range of cavitation phenomena occurred, including the rupture and detachment, or spallation, of thin liquid layers at the surface of the drop. When spallation occurred, we evaluated that negative pressures below –100 MPamore » were reached in the drops. As a result, we model the negative pressures from <span class="hlt">shock</span> <span class="hlt">reflection</span> experiments using a nucleation-and-growth model that explains how rapid decompression could outrun heterogeneous cavitation in water, and enable the study of stretched water close to homogeneous cavitation pressures.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27182751','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27182751"><span id="translatedtitle">Negative Pressures and Spallation in Water Drops Subjected to Nanosecond <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>Stan, Claudiu A; Willmott, Philip R; Stone, Howard A; Koglin, Jason E; Liang, Mengning; Aquila, Andrew L; Robinson, Joseph S; Gumerlock, Karl L; Blaj, Gabriel; Sierra, Raymond G; Boutet, Sébastien; Guillet, Serge A H; Curtis, Robin H; Vetter, Sharon L; Loos, Henrik; Turner, James L; Decker, Franz-Josef</p> <p>2016-06-01</p> <p>Most experimental studies of cavitation in liquid water at negative pressures reported cavitation at tensions significantly smaller than those expected for homogeneous nucleation, suggesting that achievable tensions are limited by heterogeneous cavitation. We generated tension pulses with nanosecond rise times in water by <span class="hlt">reflecting</span> cylindrical <span class="hlt">shock</span> <span class="hlt">waves</span>, produced by X-ray laser pulses, at the internal surface of drops of water. Depending on the X-ray pulse energy, a range of cavitation phenomena occurred, including the rupture and detachment, or spallation, of thin liquid layers at the surface of the drop. When spallation occurred, we evaluated that negative pressures below -100 MPa were reached in the drops. We model the negative pressures from <span class="hlt">shock</span> <span class="hlt">reflection</span> experiments using a nucleation-and-growth model that explains how rapid decompression could outrun heterogeneous cavitation in water, and enable the study of stretched water close to homogeneous cavitation pressures. PMID:27182751</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27182751','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27182751"><span id="translatedtitle">Negative Pressures and Spallation in Water Drops Subjected to Nanosecond <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>Stan, Claudiu A; Willmott, Philip R; Stone, Howard A; Koglin, Jason E; Liang, Mengning; Aquila, Andrew L; Robinson, Joseph S; Gumerlock, Karl L; Blaj, Gabriel; Sierra, Raymond G; Boutet, Sébastien; Guillet, Serge A H; Curtis, Robin H; Vetter, Sharon L; Loos, Henrik; Turner, James L; Decker, Franz-Josef</p> <p>2016-06-01</p> <p>Most experimental studies of cavitation in liquid water at negative pressures reported cavitation at tensions significantly smaller than those expected for homogeneous nucleation, suggesting that achievable tensions are limited by heterogeneous cavitation. We generated tension pulses with nanosecond rise times in water by <span class="hlt">reflecting</span> cylindrical <span class="hlt">shock</span> <span class="hlt">waves</span>, produced by X-ray laser pulses, at the internal surface of drops of water. Depending on the X-ray pulse energy, a range of cavitation phenomena occurred, including the rupture and detachment, or spallation, of thin liquid layers at the surface of the drop. When spallation occurred, we evaluated that negative pressures below -100 MPa were reached in the drops. We model the negative pressures from <span class="hlt">shock</span> <span class="hlt">reflection</span> experiments using a nucleation-and-growth model that explains how rapid decompression could outrun heterogeneous cavitation in water, and enable the study of stretched water close to homogeneous cavitation pressures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JAP...105e4902I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JAP...105e4902I"><span id="translatedtitle">Terahertz <span class="hlt">reflection</span> response measurement using a phonon polariton <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>Inoue, Hayato; Katayama, Kenji; Shen, Qing; Toyoda, Taro; Nelson, Keith A.</p> <p>2009-03-01</p> <p>We developed a new technique for the measurement of terahertz <span class="hlt">reflection</span> responses utilizing a propagating phonon polariton <span class="hlt">wave</span>. Frequency tunable phonon polariton <span class="hlt">waves</span> were generated by the recently developed continuously variable spatial frequency transient grating method [K. Katayama, H. Inoue, H. Sugiya, Q. Shen, T. Taro, and K. A. Nelson, Appl. Phys. Lett. 92, 031906 (2008)]. The phonon polariton <span class="hlt">wave</span> traveled in a ferroelectric crystal in an in-plane direction with an inclined angle of 26°, and the <span class="hlt">wave</span> <span class="hlt">reflected</span> at the crystal edge where a sample was positioned. The <span class="hlt">reflected</span> polariton <span class="hlt">wave</span> was detected by the same method as that used for the generation of the polariton <span class="hlt">waves</span>. By comparing the <span class="hlt">reflection</span> intensities in the presence and absence of the sample, <span class="hlt">reflectivity</span> of the polariton <span class="hlt">wave</span> was calculated, and the refractive index and absorption in the terahertz region were obtained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1810690M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1810690M"><span id="translatedtitle">Unstable whistlers and Bernstein <span class="hlt">waves</span> within the front of supercritical perpendicular <span class="hlt">shocks</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Muschietti, Laurent; Lembege, Bertrand</p> <p>2016-04-01</p> <p>In supercritical <span class="hlt">shocks</span> a significant fraction of ions is <span class="hlt">reflected</span> at the steep <span class="hlt">shock</span> ramp and carries a considerable amount of energy. The existence of <span class="hlt">reflected</span> ions enables streaming instabilities to develop which are excited by the relative drifts between the populations of incoming ions, <span class="hlt">reflected</span> ions, and electrons. The processes are fundamental to the transformation of directed kinetic energy into thermal energy, a tenet of <span class="hlt">shock</span> physics. We model the particle distributions as a broad electron population and two ion populations, namely a core and a beam (representing the <span class="hlt">reflected</span> ions) in order to investigate the kinetic instabilities possible under various <span class="hlt">wave</span> propagation angles. Recently, assuming the ion beam is directed along the <span class="hlt">shock</span> normal at 90° to the magnetic field Bo, we analyzed the linear dispersion properties by computing the full electromagnetic dielectric tensor [Muschietti and Lembege, AGU Fall meeting 2015]. Three types of <span class="hlt">waves</span> were shown to be unstable: (1) Oblique whistlers with wavelengths about the ion inertia length which propagate toward upstream at angles about 50° to the magnetic field. Frequencies are a few times the lower-hybrid. The <span class="hlt">waves</span> share many similarities to the obliquely propagating whistlers measured in detail by Polar [Hull et al., JGR 117, 2012]. (2) Quasi-perpendicular whistlers with wavelength covering a fraction of the electron inertia length which propagate toward downstream at angles larger than 80° to Bo. Frequencies are close to the lower-hybrid. (3) Bernstein <span class="hlt">waves</span> with wavelengths close to the electron gyroradius which propagate toward upstream at angles within 5° of perpendicular to the magnetic field. Frequencies are close to the electron cyclotron. The <span class="hlt">waves</span> have similarities to those reported by Wind and Stereo [Breneman et al., JGR 118, 2013; Wilson et al., JGR 115, 2010]. We will present electromagnetic 1D3V PIC simulations with predetermined propagation angles which illustrate the three types</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016cosp...41E.385C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016cosp...41E.385C"><span id="translatedtitle">Analysis of Metric Type II Burst and EUV <span class="hlt">Waves</span> Generated by <span class="hlt">Shock</span> <span class="hlt">Wave</span> Driven by Cme</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cunha-Silva, Rafael; Fernandes, Francisco; Selhorst, Caius</p> <p>2016-07-01</p> <p>The relationship between solar type II radio bursts produced by plasma oscillations and coronal <span class="hlt">shocks</span> is well shown since the 1960s. However, the details of the association between the drivers of the <span class="hlt">shocks</span> and the metric type II bursts remains a controversial issue. The flares and the coronal mass ejections (CMEs) are the potential drivers of these <span class="hlt">shocks</span>. In this work, we present the analysis of a metric type II burst observed on May 17, 2013, by spectrometers from e-CALLISTO network and EUV images from the Extreme Ultraviolet Imager (EUVI), aboard the STEREO. The event was associated with an M3.2 X-ray flare and a halo CME. The EUV images show the EUV <span class="hlt">wave</span> was produced by the expansion of the CME. The heights of the EUV <span class="hlt">wave</span> fronts and the magnetic field intensity determined in the regions of the <span class="hlt">shock</span> are consistent with those the heights of radio source obtained with the three-fold Newkirk density model, which suggests an oblique propagation of the <span class="hlt">shock</span>. The finding of an accelerating <span class="hlt">shock</span> with speed of 530-640 km/s and of 870-1220 km/s for the first and the second stages of the type II emission, respectively, is consistent with both the average speed of the associated EUV <span class="hlt">wave</span> front, of 626 km/s, during the initial expansion of the CME, and with the linear speed of the CME, of 1345 km/s. These results will be presented and discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013lpia.book...49E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013lpia.book...49E"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">Waves</span> and Equations of State Related to Laser Plasma Interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Eliezer, Shalom</p> <p></p> <p>Equations of state (EOS) of are fundamental to numerous fields of science, such as astrophysics, geophysics, plasma physics, inertial confinement physics and more. Laser induced <span class="hlt">shock</span> <span class="hlt">waves</span> techniques enable the study of equations of states and related properties, expanding the thermodynamic range reached by conventional gas gun <span class="hlt">shock</span> <span class="hlt">waves</span> and static loading experiments. Two basic techniques are used in laser-induced <span class="hlt">shock</span> <span class="hlt">wave</span> research, direct drive and indirect drive. In direct drive, one or more beams irradiate the target. In the indirect drive, thermal x-rays generated in laser heated cavities create the <span class="hlt">shock</span> <span class="hlt">wave</span>. Most of the laser induced <span class="hlt">shock</span> <span class="hlt">waves</span> experiments in the last decade used the impedance matching. Both direct and indirect drive can be used to accelerate a small foil-flyer and collide it with the studied sample, creating a <span class="hlt">shock</span> in the sample, similar to gas-gun accelerated plates experiments. These lectures describe the physics of laser induced <span class="hlt">shock</span> <span class="hlt">waves</span> and rarefaction <span class="hlt">waves</span>. The different formulae of the ideal gas EOS are used in connection with <span class="hlt">shock</span> <span class="hlt">waves</span> and rarefaction <span class="hlt">waves</span>. The critical problems in laser induced <span class="hlt">shock</span> <span class="hlt">waves</span> are pointed out and the <span class="hlt">shock</span> <span class="hlt">wave</span> stability is explained. A general description of the various thermodynamic EOS is given. In particular the Gruneisen EOS is derived fromEinstein and Debye models of the solid state of matter. Furthermore, the very useful phenomenological EOS, namely the linear relation between the <span class="hlt">shock</span> <span class="hlt">wave</span> velocity and the particle flow velocity, is analysed. This EOS is used to explain the ≈ 1 Gbar pressures in laser plasma induced <span class="hlt">shock</span> <span class="hlt">waves</span>. Last but not least, the <span class="hlt">shock</span> <span class="hlt">wave</span> jump conditions are derived in the presence of a magnetic field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19880003924','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19880003924"><span id="translatedtitle">Interferometric data for a <span class="hlt">shock-wave</span>/boundary-layer interaction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dunagan, Stephen E.; Brown, James L.; Miles, John B.</p> <p>1986-01-01</p> <p>An experimental study of the axisymmetric <span class="hlt">shock-wave</span> / 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 <span class="hlt">shock</span> <span class="hlt">wave</span> 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 <span class="hlt">shock-wave</span> / 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 <span class="hlt">shock</span> unsteadiness. Comparisons with Navier-Stokes computations using a two-equation turbulence model are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930049652&hterms=terrestre&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dterrestre','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930049652&hterms=terrestre&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dterrestre"><span id="translatedtitle">Plasma <span class="hlt">wave</span> phenomena at interplanetary <span class="hlt">shocks</span> observed by the Ulysses URAP experiment. [Unified Radio and Plasma <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>Lengyel-Frey, D.; Macdowall, R. J.; Stone, R. G.; Hoang, S.; Pantellini, F.; Harvey, C.; Mangeney, A.; Kellogg, P.; Thiessen, J.; Canu, P.</p> <p>1992-01-01</p> <p>We present Ulysses URAP observations of plasma <span class="hlt">waves</span> at seven interplanetary <span class="hlt">shocks</span> detected between approximately 1 and 3 AU. The URAP data allows ready correlation of <span class="hlt">wave</span> phenomena from .1 Hz to 1 MHz. <span class="hlt">Wave</span> phenomena observed in the <span class="hlt">shock</span> vicinity include abrupt changes in the quasi-thermal noise continuum, Langmuir <span class="hlt">wave</span> activity, ion acoustic noise, whistler <span class="hlt">waves</span> and low frequency electrostatic <span class="hlt">waves</span>. We focus on the forward/reverse <span class="hlt">shock</span> pair of May 27, 1991 to demonstrate the characteristics of the URAP data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950024161','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950024161"><span id="translatedtitle">On <span class="hlt">reflection</span> of Alfven <span class="hlt">waves</span> in the solar wind</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Krogulec, M.; Musielak, Z. E.; Suess, S. T.; Moore, R. L.; Nerney, S. F.</p> <p>1993-01-01</p> <p>We have revisited the problem of propagation of toroidal and linear Alfven <span class="hlt">waves</span> formulated by Heinemann and Olbert (1980) to compare WKB and non-WKB <span class="hlt">waves</span> and their effects on the solar wind. They considered two solar wind models and showed that <span class="hlt">reflection</span> is important for Alfven <span class="hlt">waves</span> with periods of the order of one day and longer, and that non-WKB Alfven <span class="hlt">waves</span> are no more effective in accelerating the solar wind than WKB <span class="hlt">waves</span>. There are several recently published papers which seem to indicate that Alfven <span class="hlt">waves</span> with periods of the order of several minutes should be treated as non-WKB <span class="hlt">waves</span> and that these non-WKB <span class="hlt">waves</span> exert a stronger acceleration force than WKB <span class="hlt">waves</span>. The purpose of this paper is to study the origin of these discrepancies by performing parametric studies of the behavior of the <span class="hlt">waves</span> under a variety of different conditions. In addition, we want to investigate two problems that have not been addressed by Heinemann and Olbert, namely, calculate the efficiency of Alfven <span class="hlt">wave</span> <span class="hlt">reflection</span> by using the <span class="hlt">reflection</span> coefficient and identify the region of strongest <span class="hlt">wave</span> <span class="hlt">reflection</span> in different wind models. To achieve these goals, we investigated the influence of temperature, electron density distribution, wind velocity and magnetic field strength on the <span class="hlt">waves</span>. The obtained results clearly demonstrate that Alfven <span class="hlt">wave</span> <span class="hlt">reflection</span> is strongly model dependent and that the strongest <span class="hlt">reflection</span> can be expected in models with the base temperatures higher than 10(exp 6) K and with the base densities lower than 7 x 10(exp 7) cm(exp -3). In these models as well as in the models with lower temperatures and higher densities, Alfven <span class="hlt">waves</span> with periods as short as several minutes have negligible <span class="hlt">reflection</span> so that they can be treated as WKB <span class="hlt">waves</span>; however, for Alfven <span class="hlt">waves</span> with periods of the order of one hour or longer <span class="hlt">reflection</span> is significant, requiring a non-WKB treatment. We also show that non-WKB, linear Alfven <span class="hlt">waves</span> are always less effective in accelerating the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950048201&hterms=solar+wave&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dsolar%2Bwave','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950048201&hterms=solar+wave&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dsolar%2Bwave"><span id="translatedtitle"><span class="hlt">Reflection</span> of Alfven <span class="hlt">waves</span> in the solar wind</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Krogulec, M.; Musielak, Z. E.; Suess, S. T.; Nerney, S. F.; Moore, R. L.</p> <p>1994-01-01</p> <p>We have revisited the problem of propagation of toroidal and linear Alfven <span class="hlt">waves</span> formulated by Heinemann and Olbert (1980) to compare Wentzel-Kramers-Brillouin (WKB) and non-WKB <span class="hlt">waves</span> and their effects on the solar wind. They considered two solar wind models and showed that <span class="hlt">reflection</span> is important for Alfven <span class="hlt">waves</span> with periods of the order of one day and longer and that non-WKB Alfven <span class="hlt">waves</span> are no more effective in accelerating the solar wind than in WKB <span class="hlt">waves</span>. There are several recently published papers that seem to indicate that Alfven <span class="hlt">waves</span> with periods of the order of several minutes should be treated as non-WKB <span class="hlt">waves</span> and that these non-WKB <span class="hlt">waves</span> exert a stronger acceleration force than WKB <span class="hlt">waves</span>. The purposse of this paper is to study the origin of these discrepancies by performing parametric studies of the behavior of the <span class="hlt">waves</span> under a variety of different conditions. In addition, we want to investigate two problems that have not been addressed by Heinimann and Olbert, namely, calculate the efficieny of Alfven <span class="hlt">wave</span> <span class="hlt">reflection</span> by using the <span class="hlt">reflection</span> coefficient and identfy the region of strongest <span class="hlt">wave</span> <span class="hlt">reflection</span> in different wind models. To achieve these goals, we investigate the influence of temperature, electron desity distribution, wind velocity, and magnetic field strength on te <span class="hlt">waves</span>. The obtained results clearly demonstrate that Alfven <span class="hlt">wave</span> <span class="hlt">reflection</span> is strongly model dependent and that the strongest <span class="hlt">reflection</span> can be expected in models with the base temperatures higher than 10(exp 6) K and with the base densities lower than 7 x 10(exp 7)/cu cm. In these models as well as in the models with lower temperatures and higher densities Alfven <span class="hlt">waves</span> with periods as short as several minutes have negligible <span class="hlt">reflection</span> so that they can be treated as WKB <span class="hlt">waves</span>; however, for Alfven <span class="hlt">waves</span> with periods of the order of one hour or longer <span class="hlt">reflection</span> is significant, requiring a non-WKB treatment. We also show that non-WKB, linear Alfven <span class="hlt">waves</span> are always less effective</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6138630','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6138630"><span id="translatedtitle">Relativistic <span class="hlt">shock</span> <span class="hlt">waves</span> and the excitation of plerions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Arons, J. ); Gallant, Y.A. . Dept. of Physics); Hoshino, Masahiro; Max, C.E. . Inst. of Geophysics and Planetary Physics); Langdon, A.B. )</p> <p>1991-01-07</p> <p>The <span class="hlt">shock</span> termination of a relativistic magnetohydrodynamic wind from a pulsar is the most interesting and viable model for the excitation of the synchrotron sources observed in plerionic supernova remnants. We have studied the structure of relativistic magnetosonic <span class="hlt">shock</span> <span class="hlt">waves</span> in plasmas composed purely of electrons and positrons, as well as those whose composition includes heavy ions as a minority constituent by number. We find that relativistic <span class="hlt">shocks</span> in symmetric pair plasmas create fully thermalized distributions of particles and fields downstream. Therefore, such <span class="hlt">shocks</span> are not good candidates for the mechanism which converts rotational energy lost from a pulsar into the nonthermal synchrotron emission observed in plerions. However, when the upstream wind contains heavy ions which are minority constituent by number density, but carry the bulk of the energy density, much of the energy of the <span class="hlt">shock</span> goes into a downstream, nonthermal power law distribution of positrons with energy distribution N(E)dE {proportional to}E{sup {minus}s}. In a specific model presented in some detail, s = 3. These characteristics are close to those assumed for the pairs in macroscopic MHD wind models of plerion excitation. The essential mechanism is collective synchrotron emission of left-handed extraordinary modes by the ions in the <span class="hlt">shock</span> front at high harmonics of the ion cyclotron frequency, with the downstream positrons preferentially absorbing almost all of this radiation, mostly at their fundamental (relativistic) cyclotron frequencies. Possible applications to models of plerions and to constraints on theories of energy loss from pulsars are briefly outlines. 27 refs., 5 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22264720','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22264720"><span id="translatedtitle">Effects of tandem <span class="hlt">shock</span> <span class="hlt">waves</span> combined with photosan and cytostatics on the growth of tumours.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Beneš, J; Poučková, P; Zeman, J; Zadinová, M; Sunka, P; Lukeš, P; Kolářová, H</p> <p>2011-01-01</p> <p><span class="hlt">Shock</span> <span class="hlt">waves</span>, pressure <span class="hlt">waves</span> manifested as a sharp increase in positive pressure followed by a decrease and the negative part of the <span class="hlt">wave</span>, are not only used to treat concrements in medicine. Recently, research has been focused on the possibility of their use for damaging the tumour tissue. In contrast to concrements, which are different from the surrounding tissue by their acoustic impedance, the tumour tissue has the same acoustic impedance as the surrounding soft tissue. Therefore, we have developed a new source of <span class="hlt">shock</span> <span class="hlt">waves</span>, which is based on the principle of multichannel discharge. This new source generates two successive <span class="hlt">shock</span> <span class="hlt">waves</span> (tandem <span class="hlt">shock</span> <span class="hlt">waves</span>). The first <span class="hlt">shock</span> creates acoustic non-homogeneity and cavitations in the tissue, and the second <span class="hlt">shock</span> is damped in it. In this work we demonstrated the effect of tandem <span class="hlt">shock</span> <span class="hlt">waves</span> on the muscle tissue in depth. The damage is shown on the images from the magnetic resonance imaging and histological sections. In the further part of the experiment, we investigated the in vivo effects of tandem <span class="hlt">shock</span> <span class="hlt">waves</span> in combination with Photosan and cisplatin on the tumour tissue. The application of tandem <span class="hlt">shock</span> <span class="hlt">waves</span> resulted in the inhibition of tumour growth, compared with controls, in both parts of the experiment. The largest inhibition effect was observed in the groups of tandem <span class="hlt">shock</span> <span class="hlt">waves</span> combined with Photosan and in the second part with cisplatin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..MAR.M1283T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..MAR.M1283T"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">wave</span> irradiations avoiding fluid flow evoke intracellular Ca2+ signaling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Takahashi, Toru; Tsukamoto, Akira; Tada, Shigeru</p> <p></p> <p><span class="hlt">Shock</span> <span class="hlt">wave</span> irradiation accelerates therapeutic effects including angiogenesis. One mechanism underlying those effects is cellular responses evoked by <span class="hlt">shock</span> <span class="hlt">wave</span> irradiation. Fluid flow is one of major physical phenomena induced by <span class="hlt">shock</span> <span class="hlt">wave</span> irradiation. Cellular responses evoked by fluid flow are similar to those evoked by <span class="hlt">shock</span> <span class="hlt">wave</span> irradiation. Thus, fluid flow could be responsible for cellular responses evoked by <span class="hlt">shock</span> <span class="hlt">wave</span> irradiation. However, it is obscure whether fluid flow is required for the cellular responses evoked by <span class="hlt">shock</span> <span class="hlt">wave</span> irradiation. In this study, intracellular Ca2 + signaling was observed in cells seeded in down-sized chambers. In the down-sized chambers, fluid flow was supposed to be suppressed because size of chambers (6 mm in diameter, 1 mm in thickness) was analogous to size of <span class="hlt">shock</span> <span class="hlt">wave</span> focus region (3mm in diameter). Dynamics of polystyrene microbeads suspended in the chambers were visualized with a CCD camera and analyzed with a particle image velocimetry (PIV) method to quantify fluid flow in the chamber. As a result, <span class="hlt">shock</span> <span class="hlt">wave</span> irradiation evoked intracellular Ca2 + signaling. However, fluid flow was not observed in the chamber due to <span class="hlt">shock</span> <span class="hlt">wave</span> irradiation. Thus, it was suggested that physical mechanics, not fluid flow, are further required for evoking intracellular Ca2 + signaling following to <span class="hlt">shock</span> <span class="hlt">wave</span> irradiation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMNG23A1369S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMNG23A1369S"><span id="translatedtitle">Experimental particle acceleration by water evaporation induced by <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>Scolamacchia, T.; Alatorre Ibarguengoitia, M.; Scheu, B.; Dingwell, D. B.; Cimarelli, C.</p> <p>2010-12-01</p> <p><span class="hlt">Shock</span> <span class="hlt">waves</span> are commonly generated during volcanic eruptions. They induce sudden changes in pressure and temperature causing phase changes. Nevertheless, their effects on flowfield properties are not well understood. Here we investigate the role of gas expansion generated by <span class="hlt">shock</span> <span class="hlt">wave</span> propagation in the acceleration of ash particles. We used a <span class="hlt">shock</span> tube facility consisting of a high-pressure (HP) steel autoclave (450 mm long, 28 mm in internal diameter), pressurized with Ar gas, and a low-pressure tank at atmospheric conditions (LP). A copper diaphragm separated the HP autoclave from a 180 mm tube (PVC or acrylic glass) at ambient P, with the same internal diameter of the HP reservoir. Around the tube, a 30 cm-high acrylic glass cylinder, with the same section of the LP tank (40 cm), allowed the observation of the processes occurring downstream from the nozzle throat, and was large enough to act as an unconfined volume in which the initial diffracting <span class="hlt">shock</span> and gas jet expand. All experiments were performed at Pres/Pamb ratios of 150:1. Two ambient conditions were used: dry air and air saturated with steam. Carbon fibers and glass spheres in a size range between 150 and 210 μm, were placed on a metal wire at the exit of the PVC tube. The sudden decompression of the Ar gas, due to the failure of the diaphragm, generated an initial air <span class="hlt">shock</span> <span class="hlt">wave</span>. A high-speed camera recorded the processes between the first 100 μsec and several ms after the diaphragm failure at frame rates ranging between 30,000 and 50,000 fps. In the experiments with ambient air saturated with steam, the high-speed camera allowed to visualize the condensation front associated with the initial air <span class="hlt">shock</span>; a maximum velocity of 788 m/s was recorded, which decreases to 524 m/s at distance of 0.5 ±0.2 cm, 1.1 ms after the diaphragm rupture. The condensation front preceded the Ar jet front exhausting from the reservoir, by 0.2-0.5 ms. In all experiments particles velocities following the initial</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AdSpR..56.2804C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AdSpR..56.2804C&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">wave</span> driven by CME evidenced by metric type II burst and EUV <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>Cunha-Silva, R. D.; Fernandes, F. C. R.; Selhorst, C. L.</p> <p>2015-12-01</p> <p>Solar type II radio bursts are produced by plasma oscillations in the solar corona as a result of <span class="hlt">shock</span> <span class="hlt">waves</span>. The relationship between type II bursts and coronal <span class="hlt">shocks</span> is well evidenced by observations since the 1960s. However, the drivers of the <span class="hlt">shocks</span> associated with type II events at metric wavelengths remain as a controversial issue among solar physicists. The flares and the coronal mass ejections (CMEs) are considered as potential drivers of these <span class="hlt">shocks</span>. In this article, we present an analysis of a metric type II burst observed on May 17, 2013, using data provided by spectrometers from e-CALLISTO (extended-Compound Astronomical Low-cost Low-frequency Instrument for Spectroscopy and Transportable Observatories) and EUV images from the Extreme Ultraviolet Imager (EUVI), aboard the Solar Terrestrial Relations Observatory (STEREO). The event was associated with an M3.2 SXR flare and a halo CME. The EUV <span class="hlt">wave</span> produced by the expansion of the CME was clear from the EUV images. The heights of the EUV <span class="hlt">wave</span> fronts proved to be consistent with the heights of the radio source obtained with the 2-4 × Newkirk density model, which provided a clue to an oblique propagation of the type-II-emitting <span class="hlt">shock</span> segment. The results for the magnetic field in the regions of the <span class="hlt">shock</span> also revealed to be consistent with the heights of the radio source obtained using the 2-4 × Newkirk density model. Exponential fit on the intensity maxima of the harmonic emission provided a <span class="hlt">shock</span> speed of ∼580-990 km s-1, consistent with the average speed of the associated EUV <span class="hlt">wave</span> front of 626 km s-1.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15759678','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15759678"><span id="translatedtitle">Nonlinear focusing of acoustic <span class="hlt">shock</span> <span class="hlt">waves</span> at a caustic cusp.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Marchiano, Régis; Coulouvrat, François; Thomas, Jean-Louis</p> <p>2005-02-01</p> <p>The present study investigates the focusing of acoustical weak <span class="hlt">shock</span> <span class="hlt">waves</span> incoming on a cusped caustic. The theoretical model is based on the Khokhlov-Zabolotskaya equation and its specific boundary conditions. Based on the so-called Guiraud's similitude law for a step <span class="hlt">shock</span>, a new explanation about the wavefront unfolding due to nonlinear self-refraction is proposed. This effect is shown to be associated not only to nonlinearities, as expected by previous authors, but also to the nonlocal geometry of the wavefront. Numerical simulations confirm the sensitivity of the process to wavefront geometry. Theoretical modeling and numerical simulations are substantiated by an original experiment. This one is carried out in two steps. First, the canonical Pearcey function is synthesized in linear regime by the inverse filter technique. In the second step, the same wavefront is emitted but with a high amplitude to generate <span class="hlt">shock</span> <span class="hlt">waves</span> during the propagation. The experimental results are compared with remarkable agreement to the numerical ones. Finally, applications to sonic boom are briefly discussed. PMID:15759678</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014APS..DPPUP8071B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APS..DPPUP8071B"><span id="translatedtitle">The corrugation instability of a piston-driven <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>Bates, Jason</p> <p>2014-10-01</p> <p>We investigate the dynamics of a <span class="hlt">shock</span> <span class="hlt">wave</span> that is driven into an inviscid fluid by the steady motion of a two-dimensional planar piston with small corrugations on its surface. This problem was first considered by Freeman [Proc. Royal Soc. A. 228, 341 (1955)], who showed that piston-driven <span class="hlt">shocks</span> are unconditionally stable when the medium through which they propagate is an ideal gas. Here, we generalize his work to account for a fluid with an arbitrary equation of state. We find that <span class="hlt">shocks</span> are stable when - 1 < h <hc , where h is the D'yakov parameter and hc is a critical value less than unity. For values of h within this range, linear perturbations imparted to the front at time t = 0 attenuate asymptotically as t - 3 / 2 or t - 1 / 2. Outside of this range, they grow--at first quadratically and later linearly--with time. Such instabilities are associated with non-equilibrium fluid states and imply a non-unique solution to the hydrodynamic equations. These results may have important implications for driven <span class="hlt">shocks</span> in laser-fusion and astrophysical environments. As a benchmark of this analysis, we compare our solution with one derived independently by Zaidel' [J. Appl. Math. Mech. 24, 316 (1960)] for stable h-values and find excellent agreement. This work was supported by DOE/NNSA.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760017041','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760017041"><span id="translatedtitle">Three dimensional aspects of interplanetary <span class="hlt">shock</span> <span class="hlt">waves</span>. [and the solar wind</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Siscoe, G. L.</p> <p>1976-01-01</p> <p>Most of the interplanetary <span class="hlt">shock</span> <span class="hlt">waves</span> observed with 1 AU of the sun originate from some short lived solar event, such as a solar flare, and then propagate out as a more-or-less spherical <span class="hlt">shock</span> <span class="hlt">wave</span> until they leave the solar system. Beyond 1 AU another class of interplanetary <span class="hlt">shock</span> <span class="hlt">wave</span> becomes common--the corotating <span class="hlt">shock</span> pair formed by the interaction of long lived solar wind streams. The three dimensional geometry of these two classes of interplanetary <span class="hlt">shocks</span> is discussed. Also discussed are how these geometries can be statistically studied with an out-of-the-ecliptic mission. Diagrams of <span class="hlt">shock</span> <span class="hlt">wave</span> propagation are shown. Also given are numerical examples of <span class="hlt">shock</span> <span class="hlt">wave</span> propagation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994AIPC..309.1651F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994AIPC..309.1651F"><span id="translatedtitle">Six-mm, plane-<span class="hlt">wave</span> <span class="hlt">shock</span> driver</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Frank, Alan M.; Chau, Henry H.</p> <p>1994-07-01</p> <p>A 6-mm-diameter, plane-<span class="hlt">wave</span> <span class="hlt">shock</span> generation system has been developed and characterized as a laboratory bench driver for small scale experiments. The driver is based on an exploding-foil-driven slapper used either directly or to initiate an HE pellet. The slapper is driven by a low-inductance fireset with burst currents on the order of 30 kA and burst times of about 250 ns, with time-to-burst jitter under 10 ns. Both the slapper impact and the detonation breakout of the pellet have been measured to be flat to within 10 ns over a 6-mm diameter. Fabry-Perot velocimetry of impacts with LiF crystals were used to characterize <span class="hlt">shock</span> pressures and durations. Attenuator plates and flyers driven by the HE were also measured, which provided a variety of available pulse shapes and data for modeling efforts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10170262','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10170262"><span id="translatedtitle">Six-mm, plane-<span class="hlt">wave</span> <span class="hlt">shock</span> driver</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Frank, A.M.; Chau, H.H.</p> <p>1993-06-14</p> <p>A 6-mm-diameter, plane-<span class="hlt">wave</span> <span class="hlt">shock</span> generation system has been developed and characterized as a laboratory bench driver for small scale experiments. The driver is based on an exploding-foil-driven slapper used either directly or to initiate an HE pellet. The slapper is driven by a low-inductance fireset with burst currents on the order of 30 kA and burst times of about 250ns, with a time-to-burst jitter under 10ns. Both the slapper impact and the detonation breakout of the pellet have been measured to be flat to within 10ns over a 6-mm diameter. Fabry-Perot velocimetry of impacts with LiF crystals were used to characterize <span class="hlt">shock</span> pressures and durations. Attenuator plates and flyers driven by the HE were also measured, which provided a variety of available pulse shapes and data for modeling efforts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7013880','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7013880"><span id="translatedtitle">Six-mm, plane-<span class="hlt">wave</span> <span class="hlt">shock</span> driver</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Frank, A.M.; Chau, H.H. )</p> <p>1994-07-10</p> <p>A 6-mm-diameter, plane-<span class="hlt">wave</span> <span class="hlt">shock</span> generation system has been developed and characterized as a laboratory bench driver for small scale experiments. The driver is based on an exploding-foil-driven slapper used either directly or to initiate an HE pellet. The slapper is driven by a low-inductance fireset with burst currents on the order of 30 kA and burst times of about 250 ns, with time-to-burst jitter under 10 ns. Both the slapper impact and the detonation breakout of the pellet have been measured to be flat to within 10 ns over a 6-mm diameter. Fabry-Perot velocimetry of impacts with LiF crystals were used to characterize <span class="hlt">shock</span> pressures and durations. Attenuator plates and flyers driven by the HE were also measured, which provided a variety of available pulse shapes and data for modeling efforts. [copyright]American Institute of Physics</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhPl...23h2702L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhPl...23h2702L"><span id="translatedtitle">The preplasma effect on the properties of the <span class="hlt">shock</span> <span class="hlt">wave</span> driven by a fast electron beam</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Llor Aisa, E.; Ribeyre, X.; Gus'kov, S. Yu.; Tikhonchuk, V. T.</p> <p>2016-08-01</p> <p>Strong <span class="hlt">shock</span> <span class="hlt">wave</span> generation by a mono-energetic fast electron beam in a plasma with an increasing density profile is studied theoretically. The proposed analytical model describes the <span class="hlt">shock</span> <span class="hlt">wave</span> characteristics for a homogeneous plasma preceded by a low density precursor. The <span class="hlt">shock</span> pressure and the time of <span class="hlt">shock</span> formation depend on the ratio of the electron stopping length to the preplasma areal density and on the initial energy of injected electrons. The conclusions of theoretical model are confirmed in numerical simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013SoSyR..47..520G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013SoSyR..47..520G"><span id="translatedtitle">On the boundary conditions on a <span class="hlt">shock</span> <span class="hlt">wave</span> for hypersonic flow around a descent vehicle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Golomazov, M. M.; Ivankov, A. A.</p> <p>2013-12-01</p> <p>Stationary hypersonic flow around a descent vehicle is examined by considering equilibrium and nonequilibrium reactions. We study how physical-chemical processes and <span class="hlt">shock</span> <span class="hlt">wave</span> conditions for gas species influence the <span class="hlt">shock</span>-layer structure. It is shown that conservation conditions of species on the <span class="hlt">shock</span> <span class="hlt">wave</span> cause high-temperature and concentration gradients in the <span class="hlt">shock</span> layer when we calculate spacecraft deceleration trajectory in the atmosphere at 75 km altitude.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004APS..APRR14010F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004APS..APRR14010F"><span id="translatedtitle">Nonideal Plasma Under Exreme Conditions Generated by Intense <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>Fortov, Vladimir</p> <p>2004-05-01</p> <p>Physical properties of hot dense matter at megabar pressures are the physical basis for astrophysics, planetary physics, energetics, ICF target design, beam-matter interaction, and for many other applications. The new experimental results of pressure ionization investigation of the hot dense matter generated by multiple <span class="hlt">shock</span> compression of metals, H2, He, noble gases, S, I, fullerene C60, and H2O in the megabar pressure range are presented. High energy plasma states were generated by single and multiple <span class="hlt">shock</span> compression and adiabatic expansion of initially warm and cryogenic solid, liquid, porous and low-density foams (aerogels) samples. These data in combination with exploding wire conductivity measurements demonstrate an ionization rate increase up to ten orders of magnitude as a result of compression of dense matter. Multiple <span class="hlt">shock</span> compression of H2, Ar, He, Kr, Ne, Xe, and fullerene C60 in initially gaseous and cryogenic liquid state allows to measure the electrical conductivity, equation of state, and laser beam <span class="hlt">reflectivity</span>. Thermal and pressure ionization of strongly coupled states of matter is the most prominent effects under the experimental conditions. It was shown that plasma compression strongly deforms the ionization potentials, emission spectra and scattering cross-sections of the neutrals and ions in the strongly coupled matter. Comparison of the data obtained with theoretical models (percolation, Mott transition, Zeeman and Lorenz approach etc.) is presented. In contrast to the plasma compression experiments the multiple <span class="hlt">shock</span> compression of solid Li, Na, and Ca shows dielectrization of these elements.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ShWav.tmp...72E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ShWav.tmp...72E"><span id="translatedtitle"><span class="hlt">Shock-wave</span> dynamics during oil-filled transformer explosions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Efremov, V. P.; Ivanov, M. F.; Kiverin, A. D.; Utkin, A. V.</p> <p>2016-08-01</p> <p>This paper presents a numerical and experimental study of the <span class="hlt">shock-wave</span> 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 <span class="hlt">shock</span> <span class="hlt">waves</span> 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 <span class="hlt">waves</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24483561','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24483561"><span id="translatedtitle">Solid-particle jet formation under <span class="hlt">shock-wave</span> acceleration.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rodriguez, V; Saurel, R; Jourdan, G; Houas, L</p> <p>2013-12-01</p> <p>When solid particles are impulsively dispersed by a <span class="hlt">shock</span> <span class="hlt">wave</span>, they develop a spatial distribution which takes the form of particle jets whose selection mechanism is still unidentified. The aim of the present experimental work is to study particle dispersal with fingering effects in an original quasi-two-dimensional experiment facility in order to accurately extract information. <span class="hlt">Shock</span> and blast <span class="hlt">waves</span> are generated in the carrier gas at the center of a granular medium ring initially confined inside a Hele-Shaw cell and impulsively accelerated. With the present experimental setup, the particle jet formation is clearly observed. From fast flow visualizations, we notice, in all instances, that the jets are initially generated inside the particle ring and thereafter expelled outward. This point has not been observed in three-dimensional experiments. We highlight that the number of jets is unsteady and decreases with time. For a fixed configuration, considering the very early times following the initial acceleration, the jet size selection is independent of the particle diameter. Moreover, the influence of the initial overpressure and the material density on the particle jet formation have been studied. It is shown that the <span class="hlt">wave</span> number of particle jets increases with the overpressure and with the decrease of the material density. The normalized number of jets as a function of the initial ring acceleration shows a power law valid for all studied configurations involving various initial pressure ratios, particle sizes, and particle materials. PMID:24483561</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012PhRvS..15b0401W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012PhRvS..15b0401W"><span id="translatedtitle"><span class="hlt">Shock-wave</span>-based density down ramp for electron injection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Chunmei; Li, Ji; Sun, Jun; Luo, Xisheng</p> <p>2012-02-01</p> <p>We demonstrate a sharp density transition for electron injection in laser wakefield acceleration through numerical study. This density transition is generated by a detached <span class="hlt">shock</span> <span class="hlt">wave</span> induced by a cylinder inserted into a supersonic helium gas flow. In a Mach 1.5 flow, the scale length of the density transition Lgrad can approximately equal to plasma wavelength λp at the <span class="hlt">shock</span> front, and can be further reduced with an increase of the flow Mach number. A density down ramp with Lgrad≥λp can reduce the phase velocity of the wakefield and lower the energy threshold for the electrons to be trapped. Moreover, the quality of the accelerated beam may be greatly improved by precisely controlling of Lgrad to be one λp. For an even sharper density down ramp with Lgrad≪λp, the oscillating electrons in the plasma <span class="hlt">wave</span> will up shift their phase when crossing the ramp, therefore a fraction of the electrons are injected into the accelerating field. For this injection mechanism, there is no threshold requirement for the pump laser intensity to reach <span class="hlt">wave</span> breaking, which is a big advantage as compared with other injection mechanisms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24483561','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24483561"><span id="translatedtitle">Solid-particle jet formation under <span class="hlt">shock-wave</span> acceleration.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rodriguez, V; Saurel, R; Jourdan, G; Houas, L</p> <p>2013-12-01</p> <p>When solid particles are impulsively dispersed by a <span class="hlt">shock</span> <span class="hlt">wave</span>, they develop a spatial distribution which takes the form of particle jets whose selection mechanism is still unidentified. The aim of the present experimental work is to study particle dispersal with fingering effects in an original quasi-two-dimensional experiment facility in order to accurately extract information. <span class="hlt">Shock</span> and blast <span class="hlt">waves</span> are generated in the carrier gas at the center of a granular medium ring initially confined inside a Hele-Shaw cell and impulsively accelerated. With the present experimental setup, the particle jet formation is clearly observed. From fast flow visualizations, we notice, in all instances, that the jets are initially generated inside the particle ring and thereafter expelled outward. This point has not been observed in three-dimensional experiments. We highlight that the number of jets is unsteady and decreases with time. For a fixed configuration, considering the very early times following the initial acceleration, the jet size selection is independent of the particle diameter. Moreover, the influence of the initial overpressure and the material density on the particle jet formation have been studied. It is shown that the <span class="hlt">wave</span> number of particle jets increases with the overpressure and with the decrease of the material density. The normalized number of jets as a function of the initial ring acceleration shows a power law valid for all studied configurations involving various initial pressure ratios, particle sizes, and particle materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9366384','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9366384"><span id="translatedtitle">Controlled, forced collapse of cavitation bubbles for improved stone fragmentation during <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhong, P; Cocks, F H; Cioanta, I; Preminger, G M</p> <p>1997-12-01</p> <p>The feasibility of using controlled, forced collapse of cavitation bubbles for improved stone fragmentation during <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy was demonstrated using microsecond tandem shockwave pulses. High-speed photography revealed that a secondary <span class="hlt">shock</span> <span class="hlt">wave</span>, released in less than 500 microseconds (microsec.) following a lithotripter-generated <span class="hlt">shock</span> <span class="hlt">wave</span>, can be used to control and force the collapse of cavitation bubbles toward target concretions. This timely enforced shockwave-bubble interaction was found to greatly enhance the cavitational activity near the stone surface, with a resultant up to 43% increment in stone fragmentation. Since most of the cavitation energy is directed and concentrated toward the target stones and fewer <span class="hlt">shock</span> <span class="hlt">waves</span> are needed for successful stone comminution, tissue injury associated with this new lithotripsy procedure may also be reduced. This novel concept of <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy may be used to improve the treatment efficiency and safety of existing clinical lithotripters, as well as in the design of new <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19870030585&hterms=WAVE+DENSITY+SPECTRA&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DWAVE%2BDENSITY%2BSPECTRA','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19870030585&hterms=WAVE+DENSITY+SPECTRA&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DWAVE%2BDENSITY%2BSPECTRA"><span id="translatedtitle">Plasma <span class="hlt">waves</span> in the <span class="hlt">shock</span> interaction regions at Comet Giacobini-Zinner</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kennel, C. F.; Coroniti, F. V.; Scarf, F. L.; Tsurutani, B. T.; Smith, E. J., Jr.</p> <p>1986-01-01</p> <p>The nature of the comet-solar wind interaction is studied by analyzing the detailed evolution of the plasma <span class="hlt">wave</span> spectra of Comet Giacobini-Zinner across the interaction region. Electron heat fluxes and associated electron plasma <span class="hlt">waves</span>, steepened low-frequency <span class="hlt">wave</span> packets, and density fluctuations observed upstream of Giacobini-Zinner <span class="hlt">shocks</span> are also found upstream of quasi-parallel bow <span class="hlt">shocks</span>. Downstream, the pulsations in the cometary magnetic field magnitude, in addition to the large density spikes, are usually also found downstream of quasi-parallel bow <span class="hlt">shocks</span>. Other similarities to interplanetary <span class="hlt">shocks</span> and terrestrial bow <span class="hlt">shocks</span> are described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/2403909','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/2403909"><span id="translatedtitle">[Extracorporeal <span class="hlt">shock-wave</span> lithotripsy of a salivary stone].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Iro, H; Schneider, T; Nitsche, N; Waitz, G; Marienhagen, J; Ell, C</p> <p>1990-01-01</p> <p>Ultrasonography revealed a 12 mm concrement in the left parotid duct of a 67-year-old man with an acute exacerbation of a left-sided purulent parotitis. After the acute phase had subsided under antibiotic therapy it was not possible to remove the stone either by bougie or cutting into the duct close to the papilla. Piezoelectric shockwave lithotripsy with a total of 1000 <span class="hlt">shock-waves</span> fragmented the stone, and sonography 48 hours and four weeks later demonstrated that the parotid gland was free of stone.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19860045471&hterms=informatique&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dinformatique','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19860045471&hterms=informatique&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dinformatique"><span id="translatedtitle">The behaviour of turbulence anisotropy through <span class="hlt">shock</span> <span class="hlt">waves</span> and expansions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Minh, H. H.; Kollmann, W.; Vandromme, D.</p> <p>1985-01-01</p> <p>A second order closure has been implemented in an implicit Navier-Stokes solver to study the behavior of the Reynolds stresses under the influence of severe pressure gradients. In the boundary layer zone, the strongly sheared character of the mean flow dominates the turbulence generation mechanisms. However, the pressure gradients play also a very important role for these processes, but at different locations within the boundary layer. This aspect may be emphasized by the analysis of turbulence anisotropy through <span class="hlt">shock</span> <span class="hlt">waves</span> and expansions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21550289','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21550289"><span id="translatedtitle">Observation of <span class="hlt">Shock</span> <span class="hlt">Waves</span> in a Strongly Interacting Fermi Gas</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Joseph, J. A.; Thomas, J. E.; Kulkarni, M.; Abanov, A. G.</p> <p>2011-04-15</p> <p>We study collisions between two strongly interacting atomic Fermi gas clouds. We observe exotic nonlinear hydrodynamic behavior, distinguished by the formation of a very sharp and stable density peak as the clouds collide and subsequent evolution into a boxlike shape. We model the nonlinear dynamics of these collisions by using quasi-1D hydrodynamic equations. Our simulations of the time-dependent density profiles agree very well with the data and provide clear evidence of <span class="hlt">shock</span> <span class="hlt">wave</span> formation in this universal quantum hydrodynamic system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930040866&hterms=crossing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcrossing','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930040866&hterms=crossing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcrossing"><span id="translatedtitle">Hypersonic crossing <span class="hlt">shock-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>Kussoy, M. I.; Horstman, K. C.; Horstman, C. C.</p> <p>1993-01-01</p> <p>Experimental data for two three-dimensional intersecting <span class="hlt">shock-wave</span>/turbulent boundary-layer interaction flows at Mach 8.3 are presented. The test bodies, composed of two sharp fins fastened to a flat plate test bed, were designed to generate flows with varying degrees of pressure gradient, boundary-layer separation, and turning angle. The data include surface pressure and heat transfer distributions as well as mean flow field surveys both in the undisturbed and interaction regimes. The data are presented in a convenient form to be used to validate existing or future computational models of these hypersonic flows.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21568532','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21568532"><span id="translatedtitle">Observation of <span class="hlt">shock</span> <span class="hlt">waves</span> in a strongly interacting Fermi gas.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Joseph, J A; Thomas, J E; Kulkarni, M; Abanov, A G</p> <p>2011-04-15</p> <p>We study collisions between two strongly interacting atomic Fermi gas clouds. We observe exotic nonlinear hydrodynamic behavior, distinguished by the formation of a very sharp and stable density peak as the clouds collide and subsequent evolution into a boxlike shape. We model the nonlinear dynamics of these collisions by using quasi-1D hydrodynamic equations. Our simulations of the time-dependent density profiles agree very well with the data and provide clear evidence of <span class="hlt">shock</span> <span class="hlt">wave</span> formation in this universal quantum hydrodynamic system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21476310','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21476310"><span id="translatedtitle">Refractive phenomena in the <span class="hlt">shock</span> <span class="hlt">wave</span> dispersion with variable gradients</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Markhotok, A.; Popovic, S.</p> <p>2010-06-15</p> <p>In this article the refraction effects in the weak <span class="hlt">shock</span> <span class="hlt">wave</span> (SW) dispersion on an interface with a temperature variation between two mediums are described. In the case of a finite-gradient boundary, the effect of the SW dispersion is remarkably stronger than in the case of a step change in parameters. In the former case the vertical component of velocity for the transmitted SW (the refraction effect) must be taken into account. Results of comparative calculations based on the two-dimensional model corrected for the refraction effect show significant differences in the shapes of the dispersed SW fronts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/8073928','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/8073928"><span id="translatedtitle">[Extracorporeal <span class="hlt">shock-wave</span> lithotripsy in horseshoe kidney].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Blasco Casares, F J; Ibarz Servio, L; Ramón Dalmau, M; Ruiz Marcellán, F J</p> <p>1994-05-01</p> <p>Presentation of our experience in the use of extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy (ESWL) for the treatment of lithiasis that occurred in 34 renal units from 28 patients with horseshoe kidneys. All patients but one were placed in supine decubitus with the calculus positioned in F2. A total of 47 sessions were performed for 34 treatments apart from 3 ureteroscopies for ureteral voiding. The results of the follow-up is absence of lithiasis in 13 renal units, debris of less than 3 mm in six, non-removable debris in 13 cases and relapse in two.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AIPC..829..440C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AIPC..829..440C"><span id="translatedtitle">Acoustic and Cavitation Fields of <span class="hlt">Shock</span> <span class="hlt">Wave</span> Therapy Devices</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chitnis, Parag V.; Cleveland, Robin O.</p> <p>2006-05-01</p> <p>Extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> therapy (ESWT) is considered a viable treatment modality for orthopedic ailments. Despite increasing clinical use, the mechanisms by which ESWT devices generate a therapeutic effect are not yet understood. The mechanistic differences in various devices and their efficacies might be dependent on their acoustic and cavitation outputs. We report acoustic and cavitation measurements of a number of different <span class="hlt">shock</span> <span class="hlt">wave</span> therapy devices. Two devices were electrohydraulic: one had a large reflector (HMT Ossatron) and the other was a hand-held source (HMT Evotron); the other device was a pneumatically driven device (EMS Swiss DolorClast Vet). Acoustic measurements were made using a fiber-optic probe hydrophone and a PVDF hydrophone. A dual passive cavitation detection system was used to monitor cavitation activity. Qualitative differences between these devices were also highlighted using a high-speed camera. We found that the Ossatron generated focused <span class="hlt">shock</span> <span class="hlt">waves</span> with a peak positive pressure around 40 MPa. The Evotron produced peak positive pressure around 20 MPa, however, its acoustic output appeared to be independent of the power setting of the device. The peak positive pressure from the DolorClast was about 5 MPa without a clear <span class="hlt">shock</span> front. The DolorClast did not generate a focused acoustic field. Shadowgraph images show that the <span class="hlt">wave</span> propagating from the DolorClast is planar and not focused in the vicinity of the hand-piece. All three devices produced measurable cavitation with a characteristic time (cavitation inception to bubble collapse) that varied between 95 and 209 μs for the Ossatron, between 59 and 283 μs for the Evotron, and between 195 and 431 μs for the DolorClast. The high-speed camera images show that the cavitation activity for the DolorClast is primarily restricted to the contact surface of the hand-piece. These data indicate that the devices studied here vary in acoustic and cavitation output, which may imply that the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JPhCS.208a2040G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JPhCS.208a2040G"><span id="translatedtitle">Ion acoustic <span class="hlt">shock</span> <span class="hlt">waves</span> in weakly relativistic multicomponent quantum plasma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gill, T. S.; Bains, A. S.; Bedi, C.</p> <p>2010-02-01</p> <p>Ion acoustic <span class="hlt">Shock</span> <span class="hlt">waves</span> (IASWs) are studied in an collisionless unmagnetized relativistic quantum electron-positron-ion(e-p-i) plasma employing the quantum hydro -dynamic(QHD) model. Korteweg-deVries- Burger equation(KdVB) is derived using small amplitude perturbation expansion method to study the nonlinear propagation of the quantum IASWs. It is found that the coefficients of the KdVB equation are significantely modified by the positron density p, relativistic factor(Ur), temperatures σ, kinematic viscosity η and quantum factor(H).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1013920','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1013920"><span id="translatedtitle">Flocculation and Sedimentation in Suspensions Using Ultrasonic <span class="hlt">Wave</span> <span class="hlt">Reflection</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chung, Chul-Woo; Popovics, John S.; Struble, Leslie J.</p> <p>2011-05-05</p> <p>This work was undertaken to help understand and interpret the ultrasonic <span class="hlt">wave</span> <span class="hlt">reflection</span> (UWR) response of portland cement paste as it transforms from a fluid-like suspension to a solid in the first hours after mixing. A high impact polystyrene buffer (delay line) was used to measure small changes in the P-<span class="hlt">wave</span> and S-<span class="hlt">wave</span> <span class="hlt">reflection</span> coefficients. Two materials were studied: a non-hydrating colloidal alumina suspension whose microstructure was manipulated between dispersed and flocculated states by adjusting the pH, and a coarse silica suspension that readily sedimented. The S-<span class="hlt">wave</span> <span class="hlt">reflection</span> coefficient clearly distinguished between dispersed and flocculated states. Sedimentation of particles in dispersed suspensions was distinguished using the P-<span class="hlt">wave</span> <span class="hlt">reflection</span> coefficient. Based on these findings, the observed P- and S-<span class="hlt">wave</span> responses from hydrating portland cement paste are interpreted in terms of flocculation and sedimentation processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.T13G2704J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.T13G2704J"><span id="translatedtitle"><span class="hlt">Shock</span> and Rarefaction <span class="hlt">Waves</span> in a Heterogeneous Mantle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jordan, J.; Hesse, M. A.</p> <p>2012-12-01</p> <p> has a zero eigenvalue, corresponding to a <span class="hlt">wave</span> speed of zero, which preserves a residual imprint of the initial condition. Freezing fronts textemdash those that result in a negative change in porositytextemdash feature fast path <span class="hlt">waves</span> that travel as <span class="hlt">shocks</span>, whereas the fast path <span class="hlt">waves</span> of melting fronts travel as spreading, rarefaction <span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70022542','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70022542"><span id="translatedtitle">SH-<span class="hlt">wave</span> refraction/<span class="hlt">reflection</span> and site characterization</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Wang, Z.; Street, R.L.; Woolery, E.W.; Madin, I.P.</p> <p>2000-01-01</p> <p>Traditionally, nonintrusive techniques used to characterize soils have been based on P-<span class="hlt">wave</span> refraction/<span class="hlt">reflection</span> methods. However, near-surface unconsolidated soils are oftentimes water-saturated, and when groundwater is present at a site, the velocity of the P-<span class="hlt">waves</span> is more related to the compressibility of the pore water than to the matrix of the unconsolidated soils. Conversely, SH-<span class="hlt">waves</span> are directly relatable to the soil matrix. This makes SH-<span class="hlt">wave</span> refraction/<span class="hlt">reflection</span> methods effective in site characterizations where groundwater is present. SH-<span class="hlt">wave</span> methods have been used extensively in site characterization and subsurface imaging for earthquake hazard assessments in the central United States and western Oregon. Comparison of SH-<span class="hlt">wave</span> investigations with geotechnical investigations shows that SH-<span class="hlt">wave</span> refraction/<span class="hlt">reflection</span> techniques are viable and cost-effective for engineering site characterization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22492655','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22492655"><span id="translatedtitle">Nonlinear <span class="hlt">reflection</span> of a spherically divergent N-<span class="hlt">wave</span> from a plane surface: Optical interferometry measurements in air</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Karzova, M.; Yuldashev, P.; Khokhlova, V.; Ollivier, S.; Blanc-Benon, Ph.</p> <p>2015-10-28</p> <p>Mach stem is a well-known structure typically observed in the process of strong (acoustic Mach numbers greater than 0.4) step-<span class="hlt">shock</span> <span class="hlt">waves</span> <span class="hlt">reflection</span> from a rigid boundary. However, this phenomenon has been much less studied for weak <span class="hlt">shocks</span> in nonlinear acoustic fields where Mach numbers are in the range from 0.001 to 0.01 and pressure waveforms have more complicated waveforms than step <span class="hlt">shocks</span>. The goal of this work was to demonstrate experimentally how nonlinear <span class="hlt">reflection</span> occurs in air for very weak spherically divergent acoustic spark-generated pulses resembling an N-<span class="hlt">wave</span>. Measurements of <span class="hlt">reflection</span> patterns were performed using a Mach-Zehnder interferometer. A thin laser beam with sub-millimeter cross-section was used to obtain the time resolution of 0.4 µs, which is 6 times higher than the time resolution of the condenser microphones. Pressure waveforms were reconstructed using the inverse Abel transform applied to the phase of the signal measured by the interferometer. The Mach stem formation was observed experimentally as a result of collision of the incident and <span class="hlt">reflected</span> <span class="hlt">shock</span> pulses. It was shown that irregular <span class="hlt">reflection</span> of the pulse occurred in a dynamic way and the length of the Mach stem increased linearly while the pulse propagated along the surface. Since the front <span class="hlt">shock</span> of the spark-generated pulse was steeper than the rear <span class="hlt">shock</span>, irregular type of <span class="hlt">reflection</span> was observed only for the front <span class="hlt">shock</span> of the pulse while the rear <span class="hlt">shock</span> <span class="hlt">reflection</span> occurred in a regular regime.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ShWav..26....1L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ShWav..26....1L"><span id="translatedtitle">Tandem <span class="hlt">shock</span> <span class="hlt">waves</span> in medicine and biology: a review of potential applications and successes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lukes, P.; Fernández, F.; Gutiérrez-Aceves, J.; Fernández, E.; Alvarez, U. M.; Sunka, P.; Loske, A. M.</p> <p>2016-01-01</p> <p><span class="hlt">Shock</span> <span class="hlt">waves</span> have been established as a safe and effective treatment for a wide range of diseases. Research groups worldwide are working on improving <span class="hlt">shock</span> <span class="hlt">wave</span> technology and developing new applications of <span class="hlt">shock</span> <span class="hlt">waves</span> to medicine and biology. The passage of a <span class="hlt">shock</span> <span class="hlt">wave</span> through soft tissue, fluids, and suspensions containing cells may result in acoustic cavitation i.e., the expansion and violent collapse of microbubbles, which generates secondary <span class="hlt">shock</span> <span class="hlt">waves</span> and the emission of microjets of fluid. Cavitation has been recognized as a significant phenomenon that produces both desirable and undesirable biomedical effects. Several studies have shown that cavitation can be controlled by emitting two <span class="hlt">shock</span> <span class="hlt">waves</span> that can be delayed by tenths or hundreds of microseconds. These dual-pulse pressure pulses, which are known as tandem <span class="hlt">shock</span> <span class="hlt">waves</span>, have been shown to enhance in vitro and in vivo urinary stone fragmentation, cause significant cytotoxic effects in tumor cells, delay tumor growth, enhance the bactericidal effect of <span class="hlt">shock</span> <span class="hlt">waves</span> and significantly increase the efficiency of genetic transformations in bacteria and fungi. This article provides an overview of the basic physical principles, methodologies, achievements and potential uses of tandem <span class="hlt">shock</span> <span class="hlt">waves</span> to improve biomedical applications.</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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