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Sample records for reflected shock waves

  1. Reflection of curved shock waves

    NASA Astrophysics Data System (ADS)

    Mölder, S.

    2017-03-01

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

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

    NASA Technical Reports Server (NTRS)

    Brillouin, J.

    1957-01-01

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

  3. 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.

  4. A new configuration of irregular reflection of shock waves

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    A new configuration of shock waves has been found in the reflection of shock waves in a stationary supersonic gas flow in addition to the wellknown regular and Mach reflections. This new three-shock configuration occurs with a negative angle of reflection and Mach numbers greater than 3 and an adiabatic index smaller than 1.4. It has been shown that this new configuration is unstable and leads to a radical change of the total flow pattern. The emergence of this new kind of instability can negatively affect operation of aircraft and rocket engines due to the failure of the flow to be as conventionally predicted.

  5. Simulations for detonation initiation behind reflected shock waves

    NASA Astrophysics Data System (ADS)

    Takano, Yasunari

    Numerical simulations are carried out for detonation initiation behind reflected shock waves in a shock tube. The two-dimensional thin-layer Navier-Stokes equations with chemical effects are numerically solved by use of a combined method consisting of the Flux-Corrected Transport scheme, the Crank-Nicolson scheme, and a chemical calculation step. Effects of chemical reactions occurring in a shock-heated hydrogen, oxygen, and argon mixture are estimated by using a simplified reaction model: two progress parameters are introduced to take account of induction reactions as well as exothermic reactions. Simulations are carried out referring to several experiments: generation of multidimensional and unstable reaction shock waves; strong and mild ignitions; and reacting shock waves in hydrogen and oxygen diluted in argon mixture.

  6. Shock wave reflection over convex and concave wedge

    NASA Astrophysics Data System (ADS)

    Kitade, M.; Kosugi, T.; Yada, K.; Takayama, Kazuyoshi

    2001-04-01

    It is well known that the transition criterion nearly agrees with the detachment criterion in the case of strong shocks, two-dimensional, and pseudosteady flow. However, when the shock wave diffracts over a wedge whose angle is below the detachment criterion, that is, in the domain of Mach reflection, precursory regular reflection (PRR) appears near the leading edge and as the shock wave propagates, the PRR is swept away by the overtaking corner signal (cs) that forces the transition to Mach reflection. It is clear that viscosity and thermal conductivity influences transition and the triple point trajectory. On the other hand, the reflection over concave and convex wedges is truly unsteady flow, and the effect of viscosity and thermal conductivity on transition and triple point trajectory has not been reported. This paper describes that influence of viscosity over convex and concave corners investigated both experiments and numerical simulations.

  7. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  9. Steady shock wave reflections in nonequilibrium flows: thermodynamic stability and regular- to Mach-reflection transitions.

    NASA Astrophysics Data System (ADS)

    Grasso, Francesco; Paoli, Roberto

    1999-11-01

    Shock wave reflections in steady flows have been widely studied in the last decades for their importance in many aerospace applications, such as supersonic intakes and wind tunnel technologies. One of the yet unresolved problems is the understanding of the physical mechanism responsible for the transition between regular and Mach reflections and the hysteresis phenomenon (i.e. the attainement of different shock configurations for the same incident shock angle) as well as the stability of shock wave configurations. In the present paper we study the influence of thermochemical relaxation phenomena on shock reflections by means of a two-temperature model for the thermal nonequilibrium and the reduced Park's model for finite rate chemistry. Stable shock wave configurations are characterized by invoking Prigogine minimum entropy production principle. For that purpose we formulate the entropy budget for nonequilibrium flows and identify the different contributions to the evolution of entropy due to translational and vibrational heat conduction and species diffusion, as well as dissociation reactions and translational vibrational energy exchanges. A study of shock reflection transition is carried out at two Mach numbers (M=7.5 and M=9.8) both for air and nitrogen. In order to identify the controlling mechanisms that affect the transition and the hysteresis we also carry out simulations assuming an ideal gas behaviour.

  10. Reflection of a converging cylindrical shock wave segment by a straight wedge

    NASA Astrophysics Data System (ADS)

    Gray, B.; Skews, B.

    2017-01-01

    As a converging cylindrical shock wave propagates over a wedge, the shock wave accelerates and the angle between the shock wave and the wedge decreases. This causes the conditions at the reflection point to move from what would be the irregular reflection domain for a straight shock wave into the regular reflection domain. This paper covers a largely qualitative study of the reflection of converging shock wave segments with Mach numbers between 1.2 and 2.1 by wedges inclined at angles between 15° and 60° from experimental and numerical results. The sonic condition conventionally used for predicting the type of reflection of straight shock waves was found to also be suitable for predicting the initial reflection of a curved shock wave. Initially regular reflections persisted until the shock was completely reflected by the wedge, whereas the triple point of initially irregular reflections was observed to return to the wedge surface, forming transitioned regular reflection. After the incident shock wave was completely reflected by the wedge, a shock wave focusing mechanism was observed to amplify the pressure on the surface of the wedge by a factor of up to 100 for low wedge angles.

  11. Geometry of the transition criterion of shock wave reflection over a wedge

    NASA Astrophysics Data System (ADS)

    Cui, T.; Jiao, X.; Yu, D.

    2015-01-01

    The hysteresis phenomena of shock wave reflection observed during recent numerical and experimental investigations are analyzed in this paper using dynamical system theory. It is found through the analysis that the geometry of the transition criterion of shock wave reflection over a wedge has the shape of a butterfly. Knowledge of the geometry can provide important information on the hysteresis behavior of shock wave reflection. The geometry of the transition criterion can be used not only for the explanation of already known hysteresis behavior of shock wave reflection, but also for the prediction of novel hysteresis phenomena.

  12. 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.

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

    PubMed

    Davie, C J; Evans, R G

    2013-05-03

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

  14. 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.

  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. Experimental study of shock-wave reflection from a thermally accommodating wall.

    NASA Technical Reports Server (NTRS)

    Hanson, R. K.

    1973-01-01

    Shock-tube experiments have been conducted to study the nonequilibrium gas-surface interaction which occurs when a thick shock wave in argon reflects from a coplanar, heat-conducting wall. Fast-response instrumentation was used to monitor variations in temperature and normal stress on the surface of the shock-tube end wall during and immediately following reflection of the incident shock wave. The laboratory observations are compared with computer predictions obtained by Deiwert using the direct-simulation Monte Carlo method, and excellent agreement is obtained when a suitable average thermal accommodation coefficient is chosen for the wall surface.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Effect of Pressure Gradients on the Initiation of PBX-9502 via Irregular (Mach) Reflection of Low Pressure Curved Shock Waves

    SciTech Connect

    Hull, Lawrence Mark; Miller, Phillip Isaac; Moro, Erik Allan

    2016-11-28

    In the instance of multiple fragment impact on cased explosive, isolated curved shocks are generated in the explosive. These curved shocks propagate and may interact and form irregular or Mach reflections along the interaction loci, thereby producing a single shock that may be sufficient to initiate PBX-9501. However, the incident shocks are divergent and their intensity generally decreases as they expand, and the regions behind the Mach stem interaction loci are generally unsupported and allow release waves to rapidly affect the flow. The effects of release waves and divergent shocks may be considered theoretically through a “Shock Change Equation”.

  2. 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.

  3. 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

  4. Ion reflection by shock waves and pulse generation by cross-field ion beams

    NASA Astrophysics Data System (ADS)

    Ohsawa, Yukiharu

    2017-02-01

    Comparisons are made of two different particle simulations: one for the study of plasma-based accelerators (Gueroult & Fisch, Phys. Plasmas, vol. 23, 2016, 032113) and the other for the study of shock formation in the interstellar medium (Yamauchi & Ohsawa, Phys. Plasmas, vol. 14, 2007, 053110). In the former, shock waves used for plasma density control create ion beams by reflection. In the latter, a fast and dense beam of exploding ions penetrates a surrounding plasma. In both simulations, magnetic bumps are generated from the motion of ion beams perpendicular to a magnetic field. Despite the apparent differences of their purposes, configurations and spatial scales, the two simulations show strong similarities in the generation processes and effects of the bumps, suggesting that these are not rare plasma phenomena. The bump created by the exploding ions develops into backward and forward magnetosonic pulses.

  5. 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.

  6. 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.

  7. Kinetic and modeling studies on ETBE pyrolysis behind reflected shock waves

    NASA Astrophysics Data System (ADS)

    Yasunaga, Kenji; Kuraguchi, Yuma; Hidaka, Yoshiaki; Takahashi, Osamu; Yamada, Hiroshi; Koike, Tohru

    2008-01-01

    The high temperature pyrolysis of ethyl tert-butyl ether (ETBE) was studied behind reflected shock waves coupled with the single-pulse method and UV (195 nm) absorption spectroscopy in the temperature range 1000-1500 K at total pressures ranging between 1.0 and 9.0 atm. The energies of ETBE and transition states for the reactions ETBE = iso-C 4H 8 + C 2H 5OH (1) and ETBE = C 2H 4 + tert-C 4H 9OH (2) were calculated at the MP4/cc-pVTZ//MP2/cc-pVTZ level of theory. A 170-reaction mechanism was constructed to explain the product distribution. From the UV absorption experiment, the rate coefficient k1 = 1.7 × 10 14exp(-254.0 kJ mol -1/RT) s -1 was found to reach its high-pressure limit.

  8. 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.

  9. Temperature measurements behind reflected shock waves in air. [radiometric measurement of gas temperature in self-absorbing gas flow

    NASA Technical Reports Server (NTRS)

    Bader, J. B.; Nerem, R. M.; Dann, J. B.; Culp, M. A.

    1972-01-01

    A radiometric method for the measurement of gas temperature in self-absorbing gases has been applied in the study of shock tube generated flows. This method involves making two absolute intensity measurements at identical wavelengths, but for two different pathlengths in the same gas sample. Experimental results are presented for reflected shock waves in air at conditions corresponding to incident shock velocities from 7 to 10 km/s and an initial driven tube pressure of 1 torr. These results indicate that, with this technique, temperature measurements with an accuracy of + or - 5 percent can be carried out. The results also suggest certain facility related problems.

  10. Comparison between holographic interferometry and high-speed videography techniques in the study of the reflection of plane shock waves

    NASA Astrophysics Data System (ADS)

    Barbosa, Filipe J.; Skews, Beric W.

    1997-05-01

    Double exposure holographic interferometry and high speed laser shadowgraph photography and videography are used to investigate the mutual reflection of two plane shock waves. Normally research on the transition from regular to Mach reflection is undertaken by allowing a plane shock wave to impinge on a wedge. However due to the boundary layer growth on the wedge, regular reflection persists at wedge angles higher than that allowed for by inviscid shock wave theory. Several bifurcated shock tubes have been constructed, wherein an initially planar shock wave is split symmetrically into two and then recombined at the trailing edge of a wedge. The plane of symmetry acts as an ideal rigid wall eliminating thermal and viscous boundary layer effects. The flow visualization system used needs to provide high resolution information on the shockwave, slipstream, triple point and vortex positions and angles. Initially shadowgraph and schlieren methods, with a Xenon light source, were used. These results, while proving useful, are not of a sufficient resolution to measure the Mach stem and slipstream lengths accurately enough in order to determine the transition point between regular and Mach reflection. To obtain the required image resolution a 2 joule double pulse ruby laser, with a 30 ns pulse duration, was used to make holographic interferograms. The combined advantages of holographic interferometry and the 30 ns pulse laser allows one to obtain much sharper definition, and more qualitative as well as quantitative information on the flow field. The disadvantages of this system are: the long time taken to develop holograms, the difficulty of aligning the pulse laser and the fact that only one image per test is obtained. Direct contact shadowgraphs were also obtained using the pulse ruby laser to help determine triple point trajectory angles. In order to provide further information a one million frames per second CCD camera, which can take up to 10 superimposed images, was

  11. Flow behind concave shock waves

    NASA Astrophysics Data System (ADS)

    Mölder, S.

    2017-03-01

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

  12. 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.

  13. Modeling of reflection of detonation and shock waves from a rigid wall in mixtures of a reactive gas and chemically inert particles

    NASA Astrophysics Data System (ADS)

    Fedorov, A. V.; Fomin, P. A.; Tropin, D. A.; Chen, J.-R.

    2012-05-01

    An algorithm of approximate calculation of the reflection of detonation waves in mixtures of a reactive gas and chemically inert microparticles has been proposed. Consideration has been given to the case where the gas behind the wave front is in chemical equilibrium (D → D reflection). It has been shown that the presence of the condensed phase can substantially decrease the parameters of the reflected wave (its velocity, pressure, and temperature). Within the framework of a one-dimensional nonstationary approach and with allowance for the detailed kinetics of chemical reactions, the evolution of the shock wave in a stoichiometric hydrogen-oxygen mixture with sand particles in its reflection from a rigid wall has been calculated. The limiting particle concentration below which the reflected wave is of the detonation type and above which it is of the shock type has been found.

  14. The kinetic characteristic features of the low temperature hydrogen oxidation during the induction period behind reflected shock waves

    NASA Astrophysics Data System (ADS)

    Agafonov, G. L.; Garmash, A. A.; Medvedev, S. P.; Seletkova, A. V.; Smirnov, V. N.; Shumova, V. V.; Tereza, A. M.; Vlasov, P. A.

    2016-11-01

    The experiments on the ignition of H2-O2 mixtures behind reflected shock waves were carried out. In these experiments the chemiluminescence of electronically excited OH* radicals (λ = 308 nm) at the early stage of the ignition induction period is studied over the temperature range of 800 < T < 1050 K at a pressure of 0.1 MPa. The OH* emission signal is measured for a time less than 1 ms, when the influence of physicochemical factors capable to influencing the homogeneous autoignition process such as flow turbulence in a boundary layer, various heterogeneous processes, and residual active particles is negligibly small. Significant difference between the ignition delay times derived from the pressure rise and sharp increase of the emission of electronically excited OH* radicals was experimentally observed. The experiments showed that the onset of OH* emission is always ahead of the time of pressure rise. Any regular dependence between the onset of OH* emission and the initial temperature behind the reflected shock wave T50 is not observed. This is indicative of a stochastic character of this process or hotspot ignition of the reactive mixture.

  15. When shock waves collide

    SciTech Connect

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

    2016-06-01

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

  16. When shock waves collide

    DOE PAGES

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

    2016-06-01

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

  17. 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.

  18. 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.

  19. 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.

  20. Ion reflection and dissipation at quasi-parallel collisionless shocks

    NASA Astrophysics Data System (ADS)

    Scholer, Manfred; Terasawa, Toshio

    1990-02-01

    Large scale one-dimensional hybrid simulations have been performed of a quasi-parallel high Mach number collisionless shock. It is found that backstreaming reflected ions, i.e., upstream ions with velocities exceeding the shock ram velocity, originate from the outer part of the velocity space of the incident distribution. The backstreaming ions produce very low-frequency magnetosonic waves which propagate upstream with about 1.3 Alfven speed. As the wave crests convect toward the shock, they steepen up the shock reforms itself. During shock reformation a large part of the incident ions are reflected. This, in turn, slows the incident ions down. The slowed down incident particle distribution and the reflected particle distribution merge and constitute the new thermalized downstream distribution. In the interval of a relatively stationary shock low-frequency whistler waves stand at the shock front. During these time intervals, the whistler waves are probably responsible for dissipation by nonadiabatic compression of the incident ions.

  1. 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.

  2. 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.

  3. 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.

  4. SPHERICAL SHOCK WAVES IN SOLIDS

    DTIC Science & Technology

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

  5. 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.

  6. 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.

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

    NASA Astrophysics Data System (ADS)

    Kim, Yong W.

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

  8. Ignition of mixtures of SiH sub 4, CH sub 4, O sub 2, and Ar or N sub 2 behind reflected shock waves

    NASA Technical Reports Server (NTRS)

    Mclain, A. G.; Jachimowski, C. J.; Rogers, R. C.

    1985-01-01

    Ignition delay times in mixtures of methane, silane, and oxygen diluted with argon and nitrogen were measured behind reflected shock waves generated in the chemical kinetic shock tube at Langley Research Center. The delay times were inferred from the rapid increase in pressure that occurs at ignition, and the ignition of methane was verified from the emission of infrared radiation from carbon dioxide. Pressures of 1.25 atm and temperatures from 1100 K to 1300 K were generated behind the reflected shocks; these levels are representative of those occurring within a supersonic Ramjet combustor. Expressions for the ignition delay time as a function of temperature were obtained from least squares curve fits to the data for overall equivalence ratios of 0.7 and 1.0. The ignition delay times with argon as the diluent were longer than those with nitrogen as the diluent. The infrared wavelength observations at 4.38 microns for carbon dioxide indicated that silane and methane ignited simultaneously (i.e., within the time resolution of the measurement). A combined chemical kinetic mechanism for mixtures of silane, methane, oxygen, and argon or nitrogen was assembled from one mechanism that accurately predicted the ignition of methane and a second mechanism that accurately predicted silane hydrogen ignition. Comparisons between this combined mechanism and experiment indicated that additional reactions, possibly between silyl and methyl fragments, are needed to develop a good silane methane mechanism.

  9. Shock waves show icebreaking promise

    SciTech Connect

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

    1985-11-01

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

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

    NASA Astrophysics Data System (ADS)

    Grogan, Kevin; Ihme, Matthias

    2015-11-01

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

  11. Shock waves in polycrystalline iron.

    PubMed

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

    2007-03-30

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

  12. 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

  13. Shock wave-droplet interaction

    NASA Astrophysics Data System (ADS)

    Habibi Khoshmehr, Hamed; Krechetnikov, Rouslan

    2016-11-01

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

  14. Experimental study of the emission of electronically excited CH*, C*2, OH*, and CO*2 during ignition of hydrocarbons behind reflected shock waves

    NASA Astrophysics Data System (ADS)

    Tereza, A. M.; Demidenko, T. S.; Garmash, A. A.; Smirnov, V. N.; Shumova, V. V.; Vlasov, P. A.

    2016-11-01

    The autoignition of simple hydrocarbons, such as ethane, ethylene, and acetylene, in mixtures with oxygen diluted with Ar behind reflected shock waves in a temperature range of 1150-1800 K and a pressure of ∼ 0.1 MPa is studied using the chemiluminescence from electronically excited CH* (λ = 430 nm), C2* (λ = 516.5 nm), OH* (λ = 308 nm), and CO2* (λ = 363 nm). Our experimental results are in good agreement with the published data obtained under similar conditions. Numerical simulations within the framework of a well-tested kinetic mechanism closely reproduce the measured values of the ignition delay times and time profiles of the emission signals. A comparison of the experimental and calculated shapes of the emission signals made it possible to identify key reactions responsible for the chemiluminescence of the indicated emitters.

  15. Burst of reflected electrons in nonstationary quasi-perpendicular shocks

    NASA Astrophysics Data System (ADS)

    Matsukiyo, S.; Scholer, M.

    2013-05-01

    One-dimensional full particle-in-cell simulations are performed to investigate energetic electron bursts produced at a nonstationary quasi-perpendicular shock. Some of the incoming electrons are intermittently energized and reflected by interacting with nonstationary electromagnetic fields in the shock front. The reflected electrons form an upstream non-thermal population. The reflection process is strongly affected by the non-coplanar magnetic field which is temporarily rather strong in the transition region of a highly nonstationary shock. Oblique whistler waves in the shock transition region generated due to dispersion effect or due to modified two-stream instability may pitch angle scatter the electrons and thus blur the loss-cone feature of the reflected electrons. Some electrons are trapped by the waves while staying in the transition region and energized through the shock drift acceleration mechanism. They are suddenly released toward upstream when the magnetic overshoot begins to collapse in a reformation cycle resulting in the clumps of the reflected electrons in a phase space. It is also discussed how upstream physical quantities associated with the reflected electrons can give information about the shock front nonstationarity as well as about local small scale wave activities in the transition region.

  16. Propagation of shock waves through clouds

    NASA Astrophysics Data System (ADS)

    Zhou, Xin Xin

    1990-10-01

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

  17. 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.

  18. 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.

  19. History of shock wave lithotripsy

    NASA Astrophysics Data System (ADS)

    Delius, Michael

    2000-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

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

  1. 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.

  2. Rayleigh-Taylor Shock Waves

    SciTech Connect

    Olson, B J; Cook, A W

    2007-08-30

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

  3. Spatiotemporal dynamics of underwater conical shock wave focusing

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

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

  4. Diagnostic of shock wave processes

    NASA Astrophysics Data System (ADS)

    Urtiew, P. A.

    1992-05-01

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

  5. 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.

  6. Numerical Study of Shock Wave Attenuation Using Logarithmic Spiral Liquid Sheet

    NASA Astrophysics Data System (ADS)

    Wan, Qian; Deiterding, Ralf; Eliasson, Veronica

    2016-11-01

    Research of shock wave attenuation has drawn much attention due to its military and civilian applications. One method to attenuate shock waves is to use water to block the shock wave propagation path and allow the shock wave to lose energy by breaking up the water sheet. We propose a way by holding a water sheet in logarithmic spiral shape, which has the ability of focusing the incident shock wave to its focal region. In addition, the shock wave will break up the bulk water and thus lose energy. The process of shock wave reflecting off and transmitting through the water sheet is numerically modeled using Euler equations and stiffened gas equation of state. In this study, the shock focusing ability of a logarithmic spiral water sheet is compared for various logarithmic spiral sheets. Further, the attenuation effect is quantified by the measurement of pressure impulse and peak pressure behind the transmitted and reflected shock waves.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

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

    NASA Technical Reports Server (NTRS)

    Bird, G. A.

    1991-01-01

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

  12. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  14. 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.

  15. Cavitation in shock wave lithotripsy

    NASA Astrophysics Data System (ADS)

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

    2003-10-01

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

  16. Shock Wave Technology and Application: An Update☆

    PubMed Central

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

    2012-01-01

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

  17. Reflectance Changes during Shock-induced Phase Transformations in Metals

    SciTech Connect

    Stevens, G. D.; Turley, W. D.; Veeser, L. R.; Jensen, B. J.; Rigg, P. A.

    2010-06-01

    In performing shock wave experiments to study the characteristics of metals at high pressures, wave profiles (i.e., velocity measurements of the surface of the sample) are an established and useful way to study phase transformations. For example, a sudden change in the velocity or its slope can occur when the phase transformation induces a large volume change leading to a change in particle velocity. Allowing the shock to release into a transparent window that is in contact with the sample surface allows the study of conditions away from the shock Hugoniot. However, in cases where the wave profile is not definitive an additional phase-transformation diagnostic would be useful. Changes in the electronic structure of the atoms in the crystal offer opportunities to develop new phase-change diagnostics. We have studied optical reflectance changes for several phase transformations to see whether reflectance changes might be a generally applicable phase-transformation diagnostic. Shocks were produced by direct contact with explosives or with impacts from guns. Optical wavelengths for the reflectance measurements ranged from 355 to 700 nm. We studied samples of tin, iron, gallium, and cerium as each passed through a phase transformation during shock loading and, if observable, a reversion upon unloading. For solid-solid phase changes in tin and iron we saw small changes in the surface scattering characteristics, perhaps from voids or rough areas frozen into the surface of the sample as it transformed to a new crystal structure. For melt in gallium and cerium we saw changes in the wavelength dependence of the reflectance, and we surmise that these changes may result from changes in the crystal electronic structure. It appears that reflectance measurements can be a significant part of a larger suite of diagnostics to search for difficult-to-detect phase transformations.

  18. 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].

  19. Shock wave interactions with liquid sheets

    NASA Astrophysics Data System (ADS)

    Jeon, H.; Eliasson, V.

    2017-04-01

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

  20. 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.

  1. Shock tubes and waves; Proceedings of the Sixteenth International Symposium, Rheinisch-Westfaelische Technische Hochschule, Aachen, Federal Republic of Germany, July 26-31, 1987

    NASA Astrophysics Data System (ADS)

    Groenig, Hans

    Topics discussed in this volume include shock wave structure, propagation, and interaction; shocks in condensed matter, dusty gases, and multiphase media; chemical processes and related combustion and detonation phenomena; shock wave reflection, diffraction, and focusing; computational fluid dynamic code development and shock wave application; blast and detonation waves; advanced shock tube technology and measuring technique; and shock wave applications. Papers are presented on dust explosions, the dynamics of shock waves in certain dense gases, studies of condensation kinetics behind incident shock waves, the autoignition mechanism of n-butane behind a reflected shock wave, and a numerical simulation of the focusing process of reflected shock waves. Attention is also given to the equilibrium shock tube flow of real gases, blast waves generated by planar detonations, modern diagnostic methods for high-speed flows, and interaction between induced waves and electric discharge in a very high repetition rate excimer laser.

  2. Ion Dynamics at Shocks: Ion Reflection and Beam Formation at Quasi-perpendicular Shocks

    SciTech Connect

    Kucharek, Harald; Moebius, Eberhard

    2005-08-01

    The physics of collisionless shocks is controlled by the ion dynamics. The generation of gyrating ions by reflection as well as the formation of field-aligned ion beams are essential parts of this dynamic. On the one hand reflection is most likely the first interaction of ions with the shock before they undergo the downstream thermalization process. On the other hand field-aligned ion beams, predominately found at the quasi-perpendicular bow shock, propagate into the distant foreshock region and may create wave activity. We revisit ion reflection, the source and basic production mechanism of field-aligned ion beams, by using multi-spacecraft measurements and contrast these observations with existing theories. Finally, we propose an alternative production mechanism.

  3. Formation of triple shock configurations with negative reflection angle in steady flows

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    Triple configurations of shock waves with negative reflection angles are considered. These configurations have been observed in quasi-steady cases of shock wave reflection from a planar wedge in real gases, while in steady cases three-shock configurations are only known to occur with positive reflection angles. Boundaries for the appearance of a three-shock configuration with a negative reflection angle in steady cases are analytically determined as dependent on the initial Mach number of the flow, angle of incidence, and adiabatic index. The formation of a three-shock configuration with a negative reflection angle in a steady flow must lead to a change in the character of the wave pattern, and under certain conditions it can lead to instability.

  4. 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.

  5. 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

  6. 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.

  7. Optical carrier wave shocking: detection and dispersion.

    PubMed

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

    2007-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2006-05-01

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

  9. Shock wave equation of state of muscovite

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  10. 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.

  11. Shock wave structure in a lattice gas

    NASA Astrophysics Data System (ADS)

    Broadwell, James E.; Han, Donghee

    2007-05-01

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

  12. Optimization on the focusing of multiple shock waves

    NASA Astrophysics Data System (ADS)

    Qiu, Shi; Eliasson, Veronica

    2016-11-01

    Focusing of multiple shock waves can lead to extreme thermodynamic conditions, which are desired for applications like shock wave lithotripsy and inertial confinement fusion. To study shock focusing effects, multiple energy sources have been placed in a circular pattern around an intended target, while the distance between each source and the target is fixed. All the sources are set to release the same amount of energy at the same time in order to create multiple identical shock waves. The object is to optimize the thermodynamic conditions at the target by rearranging the initial placement of each source. However, dealing with this optimization problem can be challenging due to the high computational cost introduced by solving the Euler equations. To avoid this issue, both numerical and analytical methods have been applied to handle shock focusing more efficiently. A numerical method, an approximate theory named Geometrical Shock Dynamics (GSD), has been utilized to describe the motion of shock. Using an analytical method, a transition curve between regular and irregular reflection has been employed to predict shock interactions. Results show that computational cost can be reduced dramatically by combining GSD and a transition curve. In addition, optimization results based on varying initial setups is discussed.

  13. 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.

  14. 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

  15. 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

  16. 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…

  17. 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.

  18. Nonlinear Fresnel diffraction of weak shock waves.

    PubMed

    Coulouvrat, François; Marchiano, Régis

    2003-10-01

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

  19. Ion-acoustic shocks with self-regulated ion reflection and acceleration

    NASA Astrophysics Data System (ADS)

    Malkov, M. A.; Sagdeev, R. Z.; Dudnikova, G. I.; Liseykina, T. V.; Diamond, P. H.; Papadopoulos, K.; Liu, C.-S.; Su, J. J.

    2016-04-01

    An analytic solution describing an ion-acoustic collisionless shock, self-consistently with the evolution of shock-reflected ions, is obtained. The solution extends the classic soliton solution beyond a critical Mach number, where the soliton ceases to exist because of the upstream ion reflection. The reflection transforms the soliton into a shock with a trailing wave and a foot populated by the reflected ions. The solution relates parameters of the entire shock structure, such as the maximum and minimum of the potential in the trailing wave, the height of the foot, as well as the shock Mach number, to the number of reflected ions. This relation is resolvable for any given distribution of the upstream ions. In this paper, we have resolved it for a simple "box" distribution. Two separate models of electron interaction with the shock are considered. The first model corresponds to the standard Boltzmannian electron distribution in which case the critical shock Mach number only insignificantly increases from M ≈1.6 (no ion reflection) to M ≈1.8 (substantial reflection). The second model corresponds to adiabatically trapped electrons. They produce a stronger increase, from M ≈3.1 to M ≈4.5 . The shock foot that is supported by the reflected ions also accelerates them somewhat further. A self-similar foot expansion into the upstream medium is described analytically.

  20. 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

  1. 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.

  2. 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.

  3. 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

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

    SciTech Connect

    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 a 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.

  5. Plasma shock waves excited by THz radiation

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  6. 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.

  7. Weak-shock theory for spherical shock waves

    SciTech Connect

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

    1982-03-01

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

  8. 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.

  9. Turbulent water coupling in shock wave lithotripsy.

    PubMed

    Lautz, Jaclyn; Sankin, Georgy; Zhong, Pei

    2013-02-07

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

  10. Shock waves: The Maxwell-Cattaneo case

    NASA Astrophysics Data System (ADS)

    Uribe, F. J.

    2016-03-01

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

  11. Nonplanar Shock Waves in Dusty Plasmas

    SciTech Connect

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

    2011-11-29

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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Transmitted, reflected, quasi-reflected, and multiply reflected ions in low-Mach number shocks

    NASA Astrophysics Data System (ADS)

    Gedalin, M.

    2016-11-01

    The dependence of ion dynamics on the cross-shock potential and upstream βi in low-Mach number marginally critical shocks is studied using advanced test particle analysis,. The directly transmitted ions provide the main contribution to the downstream ion pressure. The fraction of reflected ions increases with the increase of the cross-shock potential and βi. This fraction is small and their contribution to the downstream ion pressure is negligible in marginally critical shocks. A population of quasi-reflected ions is identified. These ions make a loop inside the ramp and do not appear upstream. They acquire energies comparable to the energies of the true reflected ions, are observed as a halo in the downstream ion distribution, and contribute significantly to the downstream pressure. Thus, the transmitted and quasi-reflected ions shape the downstream magnetic profile. At higher cross-shock potentials and βi the reflected ions cause formation of a magnetic dip just ahead of the ramp. A small fraction of ions are multiply reflected at the shock front. All these ions escape into the upstream region and all escaping ions are mutliply reflected.

  17. Mechanochemistry for shock wave energy dissipation

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

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

  18. Shock Waves and the Origin of Life

    DTIC Science & Technology

    1977-01-01

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

  19. Analytic description of the domain of existence of triple configurations with a negative slope of reflected shock

    NASA Astrophysics Data System (ADS)

    Sil'nikov, M. V.; Chernyshov, M. V.; Gvozdeva, L. G.

    2016-11-01

    We consider triple configurations of compression shocks in supersonic flows of an inviscid perfect gas. The boundaries of the domain of existence of shock-wave structures of a new type (triple configurations with a negative slope of the reflected shock or negative triple configurations) on a set of flow parameters have been theoretically investigated.

  20. 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.

  1. 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.

  2. 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...

  3. 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...

  4. 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...

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

  6. 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.

  7. Passive control of unsteady condensation shock wave

    NASA Astrophysics Data System (ADS)

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

    2000-12-01

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

  8. Shock wave absorber having a deformable liner

    DOEpatents

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

    1983-08-26

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

  9. The Collisions of Chondrules Behind Shock Waves

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  10. Uncovering the Secret of Shock Wave Lithotripsy

    NASA Astrophysics Data System (ADS)

    Zhong, P.

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

  11. Density Shock Waves in Confined Microswimmers

    NASA Astrophysics Data System (ADS)

    Tsang, Alan Cheng Hou; Kanso, Eva

    2016-01-01

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

  12. 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.

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

    PubMed

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

    2016-10-07

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2005-12-01

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

  15. 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.

  16. 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.

  17. 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

  18. Molecular beam brightening by shock-wave suppression

    PubMed Central

    Segev, Yair; Bibelnik, Natan; Akerman, Nitzan; Shagam, Yuval; Luski, Alon; Karpov, Michael; Narevicius, Julia; Narevicius, Edvardas

    2017-01-01

    Supersonic beams are a prevalent source of cold molecules used in the study of chemical reactions, atom interferometry, gas-surface interactions, precision spectroscopy, molecular cooling, and more. The triumph of this method emanates from the high densities produced in relation to other methods; however, beam density remains fundamentally limited by interference with shock waves reflected from collimating surfaces. We show experimentally that this shock interaction can be reduced or even eliminated by cryocooling the interacting surface. An increase of nearly an order of magnitude in beam density was measured at the lowest surface temperature, with no further fundamental limitation reached. Visualization of the shock waves by plasma discharge and reproduction with direct simulation Monte Carlo calculations both indicate that the suppression of the shock structure is partially caused by lowering the momentum flux of reflected particles and significantly enhanced by the adsorption of particles to the surface. We observe that the scaling of beam density with source pressure is recovered, paving the way to order-of-magnitude brighter, cold molecular beams. PMID:28345047

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

    NASA Astrophysics Data System (ADS)

    Krimmel, Jeff; Colonius, Tim

    2007-11-01

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

  20. Modelling of ion-acoustic shocks with reflected ions

    NASA Astrophysics Data System (ADS)

    Hanusch, Adrian; Liseykina, Tatyana

    2016-10-01

    In the studies of electrostatic shocks a distinction is made between electrons, that freely pass the shock structure and those that get trapped into the shock potential. If the width of the trapping region in velocity space is bigger than the change of the electron velocity by collisions over the evolution time of the trapping potential, the captured electrons are better described by the adiabatic trapping model. In the opposite case electrons remain Maxwellian. Which model is suitable in the real situation depends on how the shock is generated: adiabatic trapping is used for the shock generated in the piston tube, while Boltzmannian - in the shock tube. Recently the self-regulated ion reflection and acceleration in ion-acoustic shocks for both electron models was studied analytically. Here we present the numerical study of electrostatic shocks generated by reflection of a high-speed plasma off a conducting wall and by the decay of plasma density discontinuity. Different assumptions for the electron distribution are compared to the fully kinetic simulations. Special attention is given to the shock reflected ions. The finite ion temperature effect on the shock electrostatic structure and ion reflection efficiency is analyzed. The work was supported by DFG Grant Number 278305671 ``Plasma hybrid modelling of supernova remnants shock precursors''.

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

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

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

  2. Fluid dynamics of the shock wave reactor

    NASA Astrophysics Data System (ADS)

    Masse, Robert Kenneth

    2000-10-01

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

  3. Resonant wavepackets and shock waves in an atomtronic SQUID

    NASA Astrophysics Data System (ADS)

    Wang, Yi-Hsieh; Kumar, A.; Jendrzejewski, F.; Wilson, Ryan M.; Edwards, Mark; Eckel, S.; Campbell, G. K.; Clark, Charles W.

    2015-12-01

    The fundamental dynamics of ultracold atomtronic devices are reflected in their phonon modes of excitation. We probe such a spectrum by applying a harmonically driven potential barrier to a 23Na Bose-Einstein condensate in a ring-shaped trap. This perturbation excites phonon wavepackets. When excited resonantly, these wavepackets display a regular periodic structure. The resonant frequencies depend upon the particular configuration of the barrier, but are commensurate with the orbital frequency of a Bogoliubov sound wave traveling around the ring. Energy transfer to the condensate over many cycles of the periodic wavepacket motion causes enhanced atom loss from the trap at resonant frequencies. Solutions of the time-dependent Gross-Pitaevskii equation exhibit quantitative agreement with the experimental data. We also observe the generation of supersonic shock waves under conditions of strong excitation, and collisions of two shock wavepackets.

  4. Resonant wavepackets and shock waves in an atomtronic SQUID

    NASA Astrophysics Data System (ADS)

    Wang, Yi-Hsieh; Kumar, A.; Jendrzejewski, F.; Wilson, Ryan M.; Edwards, Mark; Eckel, S.; Campbell, G. K.; Clark, Charles W.

    The fundamental dynamics of ultracold atomtronic devices are reflected in their phonon modes of excitation. We probe such a spectrum by applying a harmonically driven potential barrier to a 23Na Bose-Einstein condensate in a ring-shaped trap. This perturbation excites phonon wavepackets. When excited resonantly, these wavepackets display a regular periodic structure. The resonant frequencies depend upon the particular configuration of the barrier, but are commensurate with the orbital frequency of a Bogoliubov sound wave traveling around the ring. Energy transfer to the condensate over many cycles of the periodic wavepacket motion causes enhanced atom loss from the trap at resonant frequencies. Solutions of the time-dependent Gross-Pitaevskii equation exhibit quantitative agreement with the experimental data. We also observe the generation of supersonic shock waves under conditions of strong excitation, and collisions of two shock wavepackets. Work supported by the U. S. Army Research Office Atomtronics MURI program.

  5. Modeling shock waves in orthotropic elastic materials

    NASA Astrophysics Data System (ADS)

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

    2008-08-01

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

  6. Material Point Methods for Shock Waves

    NASA Astrophysics Data System (ADS)

    Zhang, Duan; Dhakal, Tilak

    2016-11-01

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

  7. 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.

  8. Innovations in shock wave lithotripsy technology

    NASA Astrophysics Data System (ADS)

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

    2003-10-01

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

  9. 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.

  10. Shock-wave processing of C60 in hydrogen

    NASA Astrophysics Data System (ADS)

    Biennier, L.; Jayaram, V.; Suas-David, N.; Georges, R.; Singh, M. Kiran; Arunan, E.; Kassi, S.; Dartois, E.; Reddy, K. P. J.

    2017-02-01

    Context. Interstellar carbonaceous particles and molecules are subject to intense shocks in astrophysical environments. Shocks induce a rapid raise in temperature and density which strongly affects the chemical and physical properties of both the gas and solid phases of the interstellar matter. Aims: The shock-induced thermal processing of C60 particles in hydrogen has been investigated in the laboratory under controlled conditions up to 3900 K with the help of a material shock-tube. Methods: The solid residues generated by the exposure of a C60/H2 mixture to a millisecond shock wave were collected and analyzed using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman micro-spectroscopy, and infrared micro-spectroscopy. The gaseous products were analyzed by Gas Chromatography and Cavity Ring Down Spectroscopy. Results: Volatile end-products appear above reflected shock gas temperatures of 2540 K and reveal the substantial presence of small molecules with one or two C atoms. These observations confirm the role played by the C2 radical as a major product of C60 fragmentation and less expectedly highlight the existence of a single C atom loss channel. Molecules with more than two carbon atoms are not observed in the post-shock gas. The analysis of the solid component shows that C60 particles are rapidly converted into amorphous carbon with a number of aliphatic bridges. Conclusions: The absence of aromatic CH stretches on the IR spectra indicates that H atoms do not link directly to aromatic cycles. The fast thermal processing of C60 in H2 over the 800-3400 K temperature range leads to amorphous carbon. The analysis hints at a collapse of the cage with the formation of a few aliphatic connections. A low amount of hydrogen is incorporated into the carbon material. This work extends the range of applications of shock tubes to studies of astrophysical interest.

  11. 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.

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

    NASA Astrophysics Data System (ADS)

    Stevens, Gerald D.; Lone, Brandon M. La; Turley, W. Dale; Veeser, Lynn R.

    2017-01-01

    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 multiband 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 reflectance within five bands centered at 500, 700, 850, 1064, 1300, and 1550 nm. We have made dynamic reflectance measurements of tin samples shocked to pressures above and below the β-BCT phase transition using a light 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 β-BCT phase transition boundary for tin, independent of the velocity wave profile. Using the reflectance data, we also present experimental estimates of the phase fraction as a function of shock stress.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Reflection of underwater sound from surface waves.

    PubMed

    Tindle, Chris T; Deane, Grant B; Preisig, James C

    2009-01-01

    A tank experiment has been conducted to measure reflection of underwater sound from surface waves. Reflection from a wave crest leads to focusing and caustics and results in rapid variation in the received waveform as the surface wave moves. Theoretical results from wavefront modeling show that interference of three surface reflected eigenrays for each wave crest produces complicated interference waveforms. There is good agreement between theory and experiment even on the shadow side of caustics where there are two surface reflected arrivals but only one eigenray.

  19. Particle Acceleration in SN1006 Shock Waves

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  20. 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.

  1. 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.

  2. Nonplanar electrostatic shock waves in dense plasmas

    SciTech Connect

    Masood, W.; Rizvi, H.

    2010-02-15

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

  3. 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.

  4. Shock Reflection in a Binary Mixture of Noble Gases

    NASA Astrophysics Data System (ADS)

    Whitlock, S. T.; Baganoff, D.

    1996-11-01

    The standard implementation of Bird's Direct Simulation Monte Carlo (DSMC) method for the simulation of multiple-specie flows uses single-specie transport data as input to an ad hoc combining formula to define parameters used in binary collisions between non-like species. To ascertain the suitability of this approach, we focus on the details of translational nonequilibrium in the flow of a binary mixture of noble gases. Existing experimental results for the one-dimensional reflection of a shock wave in a mixture of helium (He) and xenon (Xe) yield a standard of comparison. The molecular weight and diameter of He:Xe are sufficiently disparate so that the relevant time scales of the reflection process are distinct. Simulations are performed on the Intel Paragon using an adaptation of the DSMC method suitable for the parallel computing environment. Using the best characterizations of noble gas intermolecular potentials that have been published to date, we are able to produce simulations of the reflection process which compare favorably with experiment over a range of Xe concentrations. Investigations of various combining rules to arrive at non-like specie collision parameters indicate that any reasonable combining rule works provided that the single-specie data is physically realistic.

  5. Tension of Liquids by Shock Waves

    NASA Astrophysics Data System (ADS)

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

    2004-07-01

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

  6. 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.

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

    SciTech Connect

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

    2004-09-03

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

  8. 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.

  9. 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

  10. Nonlinear waves and shocks in a rigid acoustical guide.

    PubMed

    Fernando, Rasika; Druon, Yann; Coulouvrat, François; Marchiano, Régis

    2011-02-01

    A model is developed for the propagation of finite amplitude acoustical waves and weak shocks in a straight duct of arbitrary cross section. It generalizes the linear modal solution, assuming mode amplitudes slowly vary along the guide axis under the influence of nonlinearities. Using orthogonality properties, the model finally reduces to a set of ordinary differential equations for each mode at each of the harmonics of the input frequency. The theory is then applied to a two-dimensional waveguide. Dispersion relations indicate that there can be two types of nonlinear interactions either called "resonant" or "non-resonant." Resonant interactions occur dominantly for modes propagating at a rather large angle with respect to the axis and involve mostly modes propagating with the same phase velocity. In this case, guided propagation is similar to nonlinear plane wave propagation, with the progressive steepening up to shock formation of the two waves that constitute the mode and reflect onto the guide walls. Non-resonant interactions can be observed as the input modes propagate at a small angle, in which case, nonlinear interactions involve many adjacent modes having close phase velocities. Grazing propagation can also lead to more complex phenomena such as wavefront curvature and irregular reflection.

  11. 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.

  12. Shock waves and nucleosynthesis in type II supernovae

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  13. 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

  14. 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.

  15. 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.

  16. Expansion shock waves in regularized shallow-water theory

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  17. Cluster II Constraints on Electron Acceleration and Langmuir Waves at Earth's Bow Shock

    NASA Astrophysics Data System (ADS)

    Cairns, I. H.; Krasnoselskikh, V. V.; Lobzin, V. V.; Lucek, E.; Lefebvre, B.

    2005-12-01

    Electron acceleration, Langmuir waves and radio emissions at multiples of the plasma frequency are associated with numerous shocks in the heliosphere, including Earth's bow shock and the shocks producing coronal and interplanetary type II radio bursts. Here Cluster data from the Whisper, FGM, and PEACE instruments are used to study electron acceleration at Earth's bow shock and by SLAMS, as well as the production of electron beams and Langmuir waves in Earth's foreshock. The results found include: (1) The most intense Langmuir waves are found where Cluster is magnetically connected to almost perpendicular regions of the shock with |θbn| > 70°. (2) The wave characteristics and analytic theory strongly imply that the `standard'' foreshock model is relevant: these electrons are produced by the magnetic mirror reflection/shock-drift acceleration (SDA) at the shock, the beams are produced by time-of-flight effects, and the waves are driven by beams with speeds greater than the electron thermal speed. (3) Weak bursts of broadband waves are found where |θbn| <70° and cutoff effects are unimportant. This is consistent with another electron acceleration or beam formation process being active. (4) Isolated SLAMS, even in periods between two SLAMS, produce only very weak, irregular bursts of Langmuir waves, implying that they are ineffective in accelerating electrons and/or forming beam distributions. This argues against SLAMS playing a role in type II bursts.

  18. Cylindrically converging shock and detonation waves

    NASA Astrophysics Data System (ADS)

    Matsuo, H.

    1983-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

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

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Smart structures for shock wave attenuation using ER inserts

    NASA Astrophysics Data System (ADS)

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

    2001-08-01

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

  6. Waves in low-beta plasmas - Slow shocks

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  7. Shock waves in a long-period optical fiber

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

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

  8. 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.

  9. a Study of One-Dimensional Nonlinear Hydromagnetic Waves and Collisionless Shocks.

    NASA Astrophysics Data System (ADS)

    Lyu, Ling-Hsiao

    A variety of nonlinear hydromagnetic waves have been observed in the collisionless solar wind plasma. A comprehensive theoretical study of nonlinear hydromagnetic waves, including rotational discontinuities and collisionless shocks, is carried out in this thesis by means of both analytical solutions and numerical simulations. Nonlinear hydromagnetic waves are governed by the interplay of the dispersion process, the collisionless dissipation process and the nonlinear steepening process. The purpose of this thesis is to understand the nonlinear behavior of hydromagnetic waves in terms of these fundamental processes. It is shown that the rotational discontinuity structures observed in the solar wind and at the magnetopause are nonlinear Alfven wave solutions of the collisionless two-fluid plasma equations. In these nonlinear wave solutions, nonlinear steepening is self-consistently balanced by dispersion. Collisionless viscous dissipation is the dominant dissipation in high Mach number shocks, which converts the flow energy into thermal energy. Hybrid simulations show that the collisionless viscous dissipation can result from the reflection and pitch-angle scattering of incoming ions flowing through the magnetic structures in the shock transition region. Collisionless dissipations in hydromagnetic shocks is governed by the magnetic structures in the shock transition region. The dissipation in turn can modify the wave structures and balance the nonlinear steepening. However, such delicate balance of the dispersion, dissipation, and nonlinear steepening has been observed to break down momentarily in high Mach number quasi-parallel shocks. This leads to the so-called cyclic shock front reformation seen in the hybrid simulations. The shock front reformation can be explained in terms of momentary off-balance between the dispersion-dissipation on the one hand and the nonlinear steepening on the other hand. The off-balance occurs after a significant fraction of incoming ions

  10. Steady state risetimes of shock waves in the atmosphere

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    A square wave shape is used in the Pestorius algorithm to calculate the risetime of a step shock in the atmosphere. These results agree closely with steady shock calculations. The healing distance of perturbed shocks due to finite wave effects is then investigated for quasi-steady shocks. Perturbed 100 Pa shocks require on the order of 1.0 km travel distance to return to within 10 percent of their steady shock risetime. For 30 Pa shocks, the minimum recovery distance increases to 3.0 km. It is unlikely that finite wave effects can remove the longer risetimes and irregular features introduced into the sonic boom by turbulent scattering in the planetary boundary layer.

  11. 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.

  12. Laser measurements of bacterial endospore destruction from shock waves

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  13. Cavitation, shock waves and the invasive nature of sonoelectrochemistry.

    PubMed

    Birkin, Peter R; Offin, Douglas G; Joseph, Phillip F; Leighton, Timothy G

    2005-09-08

    The invasive nature of electrodes placed into sound fields is examined. In particular, perturbations of the sound field due to the presence of the electrode support are explored. The effect of an electrode on the drive sound field (at approximately 23 kHz) is shown to be negligible under the conditions investigated in this paper. However, scattering of shock waves produced by cavity collapse is shown to exhibit a significant effect. To demonstrate this, multibubble sonoluminescence (MBSL) and electrochemical erosion measurements are employed. These measurements show an enhancement, due to the reflection by the solid/liquid boundary at the electrode support, of pressure pulses emitted when cavitation bubbles collapse. To first order, this effect can be accounted for by a correction factor. However, this factor requires accurate knowledge of the acoustic impedance of the interface and the electrolyte media. These are measured for two commonly employed substrates (soda glass and epoxy resin, specifically Epofix). A scattering model is developed which is able to predict the acoustic pressure as a function of position over a disk-like electrode substrate. The effects of shock wave reflection and materials employed in the electrode construction are used to clarify the interpretation of the results obtained from different sonoelectrochemical experiments. Given the widespread experimentation involving the insertion of electrodes (or other sensors) into ultrasonic fields, this work represents a significant development to aid the interpretation of the results obtained.

  14. Tandem shock wave cavitation enhancement for extracorporeal lithotripsy

    NASA Astrophysics Data System (ADS)

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

    2002-11-01

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

  15. 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.

  16. Temperature maxima in stable two-dimensional shock waves

    NASA Astrophysics Data System (ADS)

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

    1997-07-01

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

  17. 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.

  18. 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.

  19. Interaction of Isotropic Turbulence with a Shock Wave

    DTIC Science & Technology

    1992-03-01

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

  20. Formation of Chondrules by Shock Waves

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

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

  1. 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.

  2. Observation of interaction of shock wave with gas bubble by image converter camera

    NASA Astrophysics Data System (ADS)

    Yoshii, M.; Tada, M.; Tsuji, T.; Isuzugawa, Kohji

    1995-05-01

    When a spark discharge occurs at the first focal point of a semiellipsoid or a reflector located in water, a spherical shock wave is produced. A part of the wave spreads without reflecting on the reflector and is called direct wave in this paper. Another part reflects on the semiellipsoid and converges near the second focal point, that is named the focusing wave, and locally produces a high pressure. This phenomenon is applied to disintegrators of kidney stone. But it is concerned that cavitation bubbles induced in the body by the expansion wave following the focusing wave will injure human tissue around kidney stone. In this paper, in order to examine what happens when shock waves strike bubbles on human tissue, the aspect that an air bubble is truck by the spherical shock wave or its behavior is visualized by the schlieren system and its photographs are taken using an image converter camera. Besides,the variation of the pressure amplitude caused by the shock wave and the flow of water around the bubble is measured with a pressure probe.

  3. Biomechanical and Biochemical Cellular Response Due to Shock Waves

    DTIC Science & Technology

    2008-12-01

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

  4. Radiant properties of strong shock waves in argon.

    PubMed

    Taylor, W H; Kane, J W

    1967-09-01

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

  5. 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.

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

    PubMed

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

    2009-07-01

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

  7. 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.

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  9. 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.

  10. Shock waves in noble gases and their mixtures

    NASA Astrophysics Data System (ADS)

    Bratos, M.; Herczynski, R.

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  12. Detecting Fragmentation of Kidney Stones in Lithotripsy by Means of Shock Wave Scattering

    NASA Astrophysics Data System (ADS)

    Sapozhnikov, Oleg A.; Trusov, Leonid A.; Owen, Neil R.; Bailey, Michael R.; Cleveland, Robin O.

    2006-05-01

    Although extracorporeal shock wave lithotripsy (a procedure of kidney stone comminution using focused shock waves) has been used clinically for many years, a proper monitoring of the stone fragmentation is still undeveloped. A method considered here is based on recording shock wave scattering signals with a focused receiver placed far from the stone, outside the patient body. When a fracture occurs in the stone or the stone becomes smaller, the elastic waves in the stone will propagate differently (e.g. shear waves will not cross a fracture) which, in turn, will change the scattered acoustic wave in the surrounding medium. Theoretical studies of the scattering phenomenon are based on a linear elastic model to predict shock wave scattering by a stone, with and without crack present in it. The elastic waves in the stone and the nearby liquid were modeled using a finite difference time domain approach. The subsequent acoustic propagation of the scattered waves into the far-field was calculated using the Helmholtz-Kirchhoff integral. Experimental studies were conducted using a research electrohydraulic lithotripter that produced the same acoustic output as an unmodified Dornier HM3 clinical lithotripter. Artificial stones, made from Ultracal-30 gypsum and acrylic, were used as targets. The stones had cylindrical shape and were positioned co-axially with the lithotripter axis. The scattered wave was measured by focused broadband PVDF hydrophone. It was shown that the size of the stone noticeably changed the signature of the reflected wave.

  13. Diffraction of a shock into an expansion wavefront for the transonic self-similar nonlinear wave system in two space dimensions

    NASA Astrophysics Data System (ADS)

    Jang, Juhi; Kim, Eun Heui

    2016-01-01

    We consider a configuration where a planar shock reflects and diffracts as it hits a semi-infinite rigid screen. The diffracted reflected shock meets the diffracted expansion wave, created by the incident shock that does not hit the screen, and changes continuously from a shock into an expansion. The governing equation changes its type and becomes degenerate as the wave changes continuously from a shock to an expansion. Furthermore the governing equation has multiple free boundaries (transonic shocks) and an additional degenerate sonic boundary (the expansion wave). We develop an analysis to understand the solution structure near which the shock strength approaches zero and the shock turns continuously into an expansion wavefront, and show the existence of the global solution to this configuration for the nonlinear wave system. Moreover we provide an asymptotic analysis to estimate the position of the change of the wave, and present intriguing numerical results.

  14. 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

  15. 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.

  16. Shock waves in cosmic space and planetary materials

    NASA Astrophysics Data System (ADS)

    Miura, Y.; Kato, T.

    1993-08-01

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

  17. Full wave-field reflection coefficient inversion.

    PubMed

    Dettmer, Jan; Dosso, Stan E; Holland, Charles W

    2007-12-01

    This paper develops a Bayesian inversion for recovering multilayer geoacoustic (velocity, density, attenuation) profiles from a full wave-field (spherical-wave) seabed reflection response. The reflection data originate from acoustic time series windowed for a single bottom interaction, which are processed to yield reflection coefficient data as a function of frequency and angle. Replica data for inversion are computed using a wave number-integration model to calculate the full complex acoustic pressure field, which is processed to produce a commensurate seabed response function. To address the high computational cost of calculating short range acoustic fields, the inversion algorithms are parallelized and frequency averaging is replaced by range averaging in the forward model. The posterior probability density is interpreted in terms of optimal parameter estimates, marginal distributions, and credibility intervals. Inversion results for the full wave-field seabed response are compared to those obtained using plane-wave reflection coefficients. A realistic synthetic study indicates that the plane-wave assumption can fail, producing erroneous results with misleading uncertainty bounds, whereas excellent results are obtained with the full-wave reflection inversion.

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

    PubMed

    Malaguti, Stefania; Conforti, Matteo; Trillo, Stefano

    2014-10-01

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

  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. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

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

  2. 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.

  3. 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.

  4. Investigation of interaction between reflected shocks and growing perturbation on an interface

    NASA Astrophysics Data System (ADS)

    Chebotareva, E. I.; Aleshin, A. N.; Zaytsev, S. G.; Sergeev, S. V.

    This paper reports the result of investigation into Richtmyer-Meshkov instability (RMI) resulting from multiple interactions of shock waves with the interface between two media of different densities. The instability growth rates were measured after the interactions of the mixing zone with the refracted shock and the first and the second shocks reflected from the endwall. It was shown that for the contribution of separate shock-interface interactions to the instability growth rate, the condition of additivity is not realized. The values of the factor ψ , accounting for the decrease in the RMI growth rate due to the thickening of the mixing zone, have been determined for a continuous interface and for a turbulent mixing zone.

  5. Time-dependent simulation of reflected-shock/boundary layer interaction

    NASA Technical Reports Server (NTRS)

    Wilson, Gregory J.; Sharma, Surendra P.; Gillespie, Walter D.

    1993-01-01

    An initial numerical/experimental investigation has been done to better understand multi-dimensional flow phenomena inside pulse facilities. Time-dependent quasi-one-dimensional and axisymmetric numerical simulations of complete shock tube flow are compared with experimental pressure traces recorded at the NASA Ames electric-arc driven shock tube facility (from cold driver shots). Of particular interest is the interaction between the reflected shock wave and the boundary layer. Evidence of the shock bifurcation caused by this interaction is clearly seen in the present experimental data. The axisymmetric simulations reproduce this phenomenon and demonstrate how this interaction can provide a mechanism for driver gas to contaminate the stagnation region. The simulations incorporate finite-rate chemistry, a moving mesh and laminar viscosity.

  6. 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.

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

    NASA Astrophysics Data System (ADS)

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

    1992-03-01

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

  8. 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.

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

    NASA Technical Reports Server (NTRS)

    Ribner, H S

    1954-01-01

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

  10. 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.

  11. Computer Simulation Of Shock-Wave Propagation In Anisotropic Tectonic Structures

    NASA Astrophysics Data System (ADS)

    Gouliaev, V. I.; Lugovoy, P. Z.

    1997-07-01

    The problem of short shock waves propagating in anisotropic elastic layered media is investigated on a basis of the ray method. To determine the geometric parameters of the shock wave front, an analog of the eikonal equation is deduced whereby the first order partial differential equations are obtained. At each step of the numerical process we calculate for each numerical zone the orientation of the wave front, the types of quasi-longitudinal and quasi-shear waves and the directions and values of their propagation velocities. Thereafter, transition to the next step in the evolution of the shock wave front is carried out. Calculation of the stress intensity on the wave front and the value of the impulse carried by the wave is performed on the basis of conditions of energy and momentum conservation in a specified region. The outlined approach is used to study the reflection and penetration of shock and seismic waves through anisotropic media interfaces, and to investigate their propagation in natural tectonic wave guides.

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

    PubMed

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

    1991-01-01

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

  13. 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.

  14. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  16. Nonlinear shock acceleration. III - Finite wave velocity, wave pressure, and entropy generation via wave damping

    NASA Technical Reports Server (NTRS)

    Eichler, D.

    1985-01-01

    The nonlinear theory of shock acceleration developed in earlier papers, which treated the waves as being completely frozen into the fluid, is generalized to include wave dynamics. In the limit where damping keeps the wave amplitude small, it is found that a finite phase velocity (V sub ph) of the scattering waves through the background fluid, tempers the acceleration generated by high Mach number shocks. Asymptotic spectra proportional to 1/E sq are possible only when the ratio of wave velocity to shock velocity is less than 0.13. For a given asymptotic spectrum, the efficiency of relativistic particle production is found to be practically independent of the value of V sub ph, so that earlier results concerning its value remain valid for finite V sub ph. In the limit where there is no wave damping, it is shown that for modest Alfven Mach numbers, approximately greater than 4 and less than 6, the magnetic field is amplified by the energetic particles to the point of being in rough equipartition with them, as models of synchrotron emission frequently take the field to be. In this case, the disordering and amplification of field energy may play a major role in the shock transition.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. Shock waves from an open-ended shock tube with different shapes

    NASA Astrophysics Data System (ADS)

    Yu, Q.; Grönig, H.

    1996-11-01

    A new method for decreasing the attenuation of a shock wave emerging from an open-ended shock tube exit into a large free space has been developed to improve the shock wave technique for cleaning deposits on the surfaces in industrial equipments by changing the tube exit geometry. Three tube exits (the simple tube exit, a tube exit with ring and a coaxial tube exit) were used to study the propagation processes of the shock waves. The detailed flow features were experimentally investigated by use of a two-dimensional color schlieren method and by pressure measurements. By comparing the results for different tube exits, it is shown that the expansion of the shock waves near the mouth can be restricted by using the tube exit with ring or the coaxial tube exit. Thus, the attenuation of the shock waves is reduced. The time histories of overpressure have illustrated that the best results are obtained for the coaxial tube exit. But the pressure signals for the tube exit with ring showed comparable results with the advantage of a relatively simple geometry. The flow structures of diffracting shock waves have also been simulated by using an upwind finite volume scheme based on a high order extension of Godunov's method as well as an adaptive unstructured triangular mesh refinement/unrefinement algorithm. The numerical results agree remarkably with the experimental ones.

  3. Acetabular augmentation induced by extracorporeal shock waves in rabbits.

    PubMed

    Saisu, Takashi; Kamegaya, Makoto; Wada, Yuichi; Takahashi, Kenji; Mitsuhashi, Shigeru; Moriya, Hideshige; Maier, Markus

    2005-05-01

    We conducted this animal study to demonstrate whether exposing the acetabulum in immature rabbits to extracorporeal shock waves induces bone formation in the acetabulum. Five thousand shock waves of 100 MPa each were directed, from outside, at the acetabular roof of eight immature rabbits. At each of two time points (4 and 8 weeks) after treatment, the pelvises of four rabbits were removed and evaluated morphologically. Woven bone formation was observed on the lateral margin of the acetabular roof at 4 weeks after treatment, and the breadth of the acetabular roof in the coronal plane was significantly increased. Eight weeks after treatment, the woven bone disappeared; the breadth of the acetabular roof, however, was significantly increased. These findings demonstrated that extracorporeal shock waves induced acetabular augmentation in rabbits. We conclude that extracorporeal shock waves, perhaps, could be applied clinically for the treatment of acetabular dysplasia.

  4. 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

  5. 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.

  6. A new class of solutions for interstellar magnetohydrodynamic shock waves

    NASA Technical Reports Server (NTRS)

    Roberge, W. G.; Draine, B. T.

    1990-01-01

    An analysis is presented of the equations of motion for steady MHD shock waves proopagating in interstellar clouds, for boundary conditions that preclude C shocks. In addition to J shocks, in which the neutral fluid component becomes subsonic at an adiabatic jump front, the equations admit a new class of solutions, called C-asterisk shocks, in which the transition to subsonic flow occurs continuously at a sonic point. Numerical methods are developed for computing the structure of J and C-asterisk shocks propagating in diffuse interstellar clouds. The effects of chemical, ionization, and recombination processes are included in this treatment. An alternative numerical method, which uses artificial viscosity to facilitate integration through sonic points, is analyzed and shown to be invalid. A set of exemplary solutions, computed for realistic shock parameters, shows that C-asterisk shocks occur for a broad range of conditions relevant to diffuse interstellar clouds.

  7. 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.

  8. Grain Destruction in a Supernova Remnant Shock Wave

    NASA Astrophysics Data System (ADS)

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

  9. 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.

  10. Statistical Case Study of Extracorporeal Shock Wave Lithotripsy

    DTIC Science & Technology

    2007-11-02

    Shock Wave Lithotripsy (ESWL) is one of the recent, most common ways of treating patients with urinary (renal and ureteric) stones through non...Page 1 of 3 Statistical Case Study of Extracorporeal Shock Wave Lithotripsy Hani M. Amasha1 and Basel M. Al-Eideh2 1Department of...invasive destruction of stones [1]. Many reports and studies have shown its safety and success. It offers the patient less pain; much less discomfort and

  11. Observation and Control of Shock Waves in Individual Nanoplasmas

    DTIC Science & Technology

    2014-03-18

    Observation and Control of Shock Waves in Individual Nanoplasmas Daniel D. Hickstein,1 Franklin Dollar,1 Jim A. Gaffney,2 Mark E. Foord,2 George M...distribution of individual, isolated 100-nm-scale plasmas, we make the first experimental observation of shock waves in nanoplasmas . We demonstrate that...i Nanoscale plasmas ( nanoplasmas ) offer enhanced laser absorption compared to solid or gas targets [1], enabling high-energy physics with tabletop

  12. 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.

  13. 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.

  14. More efficient focusing for extracorporeal shock wave lithotripsy

    NASA Astrophysics Data System (ADS)

    Loske, Achim M.; Prieto, Fernando E.

    2001-10-01

    The purpose of this study was to generate alternative pressure waveforms in order to increase efficiency during non-invasive treatments of nephrolithiasis. Two new systems for electrohydraulic shock wave generators were tested. These devices generate two pressure pulses, instead of only one positive peak, followed by a trough, as in conventional systems. Pressure measurements and stone fragmentation efficiency were compared to that of conventional shock wave generators, using needle hydrophones and kidney-stone models.

  15. T-wave oversensing and inappropriate shocks: a case report.

    PubMed

    Srivathsan, Komandoor; Scott, Luis R; Altemose, Gregory T

    2008-05-01

    A 27-year-old male with congenital long QT syndrome, SCN5A mutation experienced recurrent inappropriate exercise-related implantable cardioverter defibrillator (ICD) shocks. This device showed T-wave oversensing with double, which lead to these device discharges. Dynamic T-wave oversensing was reproducibly provoked at exercise treadmill testing and was confirmed as the mechanism leading to double counting. The insertion of a new pacing and sensing lead with increased R-wave amplitude did not solve the problem. Exchanging the existing ICD generator with one capable of automatic sensitivity control (Biotronik, Lexos DR, Biotronik, Berlin, Germany) completely eliminated T-wave oversensing and inappropriate shocks.

  16. 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.

  17. Wind Observations of Wave Heating and/or Particle Energization at Supercritical Interplanetary Shocks

    NASA Technical Reports Server (NTRS)

    Wilson, Lynn Bruce, III; Szabo, Adam; Koval, Andriy; Cattell, Cynthia A.; Kellogg, Paul J.; Goetz, Keith; Breneman, Aaron; Kersten, Kris; Kasper, Justin C.; Pulupa, Marc

    2011-01-01

    We present the first observations at supercritical interplanetary shocks of large amplitude (> 100 mV/m pk-pk) solitary waves, approx.30 mV/m pk-pk waves exhibiting characteristics consistent with electron Bernstein waves, and > 20 nT pk-pk electromagnetic lower hybrid-like waves, with simultaneous evidence for wave heating and particle energization. The solitary waves and the Bernstein-like waves were likely due to instabilities driven by the free energy provided by reflected ions [Wilson III et al., 2010]. They were associated with strong particle heating in both the electrons and ions. We also show a case example of parallel electron energization and perpendicular ion heating due to a electromagnetic lower hybrid-like wave. Both studies provide the first experimental evidence of wave heating and/or particle energization at interplanetary shocks. Our experimental results, together with the results of recent Vlasov [Petkaki and Freeman, 2008] and PIC [Matsukyo and Scholer, 2006] simulations using realistic mass ratios provide new evidence to suggest that the importance of wave-particle dissipation at shocks may be greater than previously thought.

  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. 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).

  20. 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.

  1. 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.

  2. Oblique ion acoustic shock waves in a magnetized plasma

    SciTech Connect

    Shahmansouri, M.; Mamun, A. A.

    2013-08-15

    Ion acoustic (IA) shock waves are studied in a magnetized plasma consisting of a cold viscous ion fluid and Maxwellian electrons. The Korteweg–de Vries–Burgers equation is derived by using the reductive perturbation method. It is shown that the combined effects of external magnetic field and obliqueness significantly modify the basic properties (viz., amplitude, width, speed, etc.) of the IA shock waves. It is observed that the ion-viscosity is a source of dissipation, and is responsible for the formation of IA shock structures. The implications of our results in some space and laboratory plasma situations are discussed.

  3. Nonstandard Analysis and Jump Conditions for Converging Shock Waves

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

  4. Nonstandard analysis and jump conditions for converging shock waves

    NASA Astrophysics Data System (ADS)

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

    2008-06-01

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

  5. 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

  6. Generation of Focused Shock Waves in Water for Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Lukeš, Petr; Šunka, Pavel; Hoffer, Petr; Stelmashuk, Vitaliy; Beneš, Jiří; Poučková, Pavla; Zadinová, Marie; Zeman, Jan

    The physical characteristics of focused two-successive (tandem) shock waves (FTSW) in water and their biological effects are presented. FTSW were ­generated by underwater multichannel electrical discharges in a highly conductive saline solution using two porous ceramic-coated cylindrical electrodes of different diameter and surface area. The primary cylindrical pressure wave generated at each composite electrode was focused by a metallic parabolic reflector to a common focal point to form two strong shock waves with a variable time delay between the waves. The pressure field and interaction between the first and the second shock waves at the focus were investigated using schlieren photography and polyvinylidene fluoride (PVDF) shock gauge sensors. The largest interaction was obtained for a time delay of 8-15 μs between the waves, producing an amplitude of the negative pressure phase of the second shock wave down to -80 MPa and a large number of cavitations at the focus. The biological effects of FTSW were demonstrated in vitro on damage to B16 melanoma cells, in vivo on targeted lesions in the thigh muscles of rabbits and on the growth delay of sarcoma tumors in Lewis rats treated in vivo by FTSW, compared to untreated controls.

  7. 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.

  8. Explosive-driven shock wave and vortex ring interaction with a propane flame

    NASA Astrophysics Data System (ADS)

    Giannuzzi, P. M.; Hargather, M. J.; Doig, G. C.

    2016-11-01

    Experiments were performed to analyze the interaction of an explosively driven shock wave and a propane flame. A 30 g explosive charge was detonated at one end of a 3-m-long, 0.6-m-diameter shock tube to produce a shock wave which propagated into the atmosphere. A propane flame source was positioned at various locations outside of the shock tube to investigate the effect of different strength shock waves. High-speed retroreflective shadowgraph imaging visualized the shock wave motion and flame response, while a synchronized color camera imaged the flame directly. The explosively driven shock tube was shown to produce a repeatable shock wave and vortex ring. Digital streak images show the shock wave and vortex ring propagation and expansion. The shadowgrams show that the shock wave extinguishes the propane flame by pushing it off of the fuel source. Even a weak shock wave was found to be capable of extinguishing the flame.

  9. 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.

  10. Burnett-Cattaneo continuum theory for shock waves

    NASA Astrophysics Data System (ADS)

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

    2011-02-01

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

  11. Growth and decay of weak shock waves in magnetogasdynamics

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

    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.

  12. Plane shock wave structure in a dilute granular gas

    NASA Astrophysics Data System (ADS)

    Reddy, M. H. Lakshminarayana; Alam, Meheboob

    2016-11-01

    We analyse the early time evolution of the Riemann problem of planar shock wave structures for a dilute granular gas by solving Navier-Stokes equations numerically. The one-dimensional reduced Navier-Stokes equations for plane shock wave problem are solved numerically using a relaxation-type numerical scheme. The results on the shock structures in granular gases are presented for different Mach numbers and restitution coefficients. Based on our analysis on early time shock dynamics we conclude that the density and temperature profiles are "asymmetric"; the density maximum and the temperature maximum occur within the shock layer; the absolute magnitudes of longitudinal stress and heat flux which are initially zero at both end states attain maxima in a very short time and thereafter decrease with time.

  13. 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.

  14. Laboratory observations of self-excited dust acoustic shock waves

    NASA Astrophysics Data System (ADS)

    Merlino, Robert L.; Heinrich, Jonathon R.; Kim, Su-Hyun

    2009-11-01

    Dust acoustic waves have been discussed in connection with dust density structures in Saturn's rings and the Earth's mesosphere, and as a possible mechanism for triggering condensation of small grains in dust molecular clouds. Dust acoustic waves are a ubiquitous occurrence in laboratory dusty plasmas formed in glow discharges. We report observations of repeated, self-excited dust acoustic shock waves in a dc glow discharge dusty plasma using high-speed video imaging. Two major observations will be presented: (1) The self-steepening of a nonlinear dust acoustic wave into a saw-tooth wave with sharp gradient in dust density, very similar to those found in numerical solutions [1] of the fully nonlinear fluid equations for nondispersive dust acoustic waves, and (2) the collision and confluence of two dust acoustic shock waves. [4pt] [1] B. Eliasson and P. K. Shukla, Phys. Rev. E 69, 067401 (2004).

  15. Dispersive Nature of High Mach Number Collisionless Plasma Shocks: Poynting Flux of Oblique Whistler Waves

    NASA Astrophysics Data System (ADS)

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

    2012-01-01

    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.

  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. A novel method to transform prokaryotic cells using shock waves

    NASA Astrophysics Data System (ADS)

    Nataraja, K. N.; Udayakumar, M.; Jagadeesh, G.

    The transgenic approach that is being used to study gene function or to improve the efficiency of crop plants/organisms involves transformation of a wide range of cells, tissues, and organisms with nucleic acid. In this study we report a new micro- shock assisted prokaryotic cell transformation technique. An underwater electric discharge based shock wave generator (25 kV; 150 m A; high voltage capacitor) has been designed and fabricated to carry out the prokaryotic cell transformation experiments. Test tubes with bacterial cell suspension with appropriate plasmid DNA, immersed in water are exposed to shock wave loading (typical overpressure 130 bar). The transformation efficiency of samples of the prokaryotic cells exposed to shock waves is very high compared to conventional methods.

  19. Initiating solar system formation through stellar shock waves

    NASA Technical Reports Server (NTRS)

    Boss, A. P.; Myhill, E. A.

    1993-01-01

    Isotopic anomalies in presolar grains and other meteoritical components require nucleosynthesis in stellar interiors, condensation into dust grains in stellar envelopes, transport of the grains through the interstellar medium by stellar outflows, and finally injection of the grains into the presolar nebula. The proximity of the presolar cloud to these energetic stellar events suggests that a shock wave from a stellar outflow might have initiated the collapse of an otherwise stable presolar cloud. We have begun to study the interactions of stellar shock waves with thermally supported, dense molecular cloud cores, using a three spatial dimension (3D) radiative hydrodynamics code. Supernova shock waves have been shown by others to destroy quiescent clouds, so we are trying to determine if the much smaller shock speeds found in, e.g., asymptotic giant branch (AGB) star winds, are strong enough to initiate collapse in an otherwise stable, rotating, solar-mass cloud core, without leading to destruction of the cloud.

  20. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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.

  3. 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.

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

    SciTech Connect

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

    2015-04-01

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

  5. 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://adsabs.harvard.edu/abs/2015PhDT........42L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhDT........42L"><span>Implications of heterogeneity in the <span class="hlt">shock</span> <span class="hlt">wave</span> propagation of dynamically <span class="hlt">shocked</span> materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>LaJeunesse, Jeff</p> <p></p> <p>The field of <span class="hlt">shock</span> physics as a whole has only recently begun to pay particular attention to modeling heterogeneous materials under <span class="hlt">shock</span> loading. These materials are important because of their practicality in terms of creating stronger, more <span class="hlt">shock</span> resistant materials. To understand why they absorb <span class="hlt">shock</span> impact energy better than homogeneous materials means that the small-scale processes that occur during the <span class="hlt">shock</span> loading of these heterogeneous materials needs to be understood. Recent computational experiments, called mesoscale simulations, have shown that explicitly incorporating small-scale heterogeneous features into hydrocode simulations allows the bulk <span class="hlt">shock</span> response of the heterogeneous material to be observed while not requiring the use of empirically determined constitutive equations. Including these features in simulations can offer insights into the irreversible mechanisms that dominate the propagation of <span class="hlt">shock</span> <span class="hlt">waves</span> in heterogeneous materials. Three cases where the mesoscale approach for modeling the dynamic <span class="hlt">shock</span> loading of heterogeneous materials are presented. These materials fall into three categories: granular - dry sand, granular with binder - concrete, and granular contained in a metal foam with a binder - granular explosive contained in an aluminum foam. The processes in which <span class="hlt">shock</span> <span class="hlt">waves</span> propagate through each material are addressed and relationships between the three materials are discussed. Particle velocity profiles for dry sand and concrete was obtained from Harvard University and Eglin Air Force Base, respectively. Mesoscale simulations using CTH are conducted for each type of heterogeneous material and the results are compared to the experimental data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21367305','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21367305"><span>Visualization of <span class="hlt">Shock</span> <span class="hlt">Wave</span> Driven by Millimeter <span class="hlt">Wave</span> Plasma in a Parabolic Thruster</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Yamaguchi, Toshikazu; Shimada, Yutaka; Shiraishi, Yuya; Shibata, Teppei; Komurasaki, Kimiya; Oda, Yasuhisa; Kajiwara, Ken; Takahashi, Koji; Kasugai, Atsushi; Sakamoto, Keishi; Arakawa, Yoshihiro</p> <p>2010-05-06</p> <p>By focusing a high-power millimeter <span class="hlt">wave</span> beam generated by a 170 GHz gyrotron, a breakdown occurred and a <span class="hlt">shock</span> <span class="hlt">wave</span> was driven by plasma heated by following microwave energy. The <span class="hlt">shock</span> <span class="hlt">wave</span> and the plasma around a focal point of a parabolic thruster were visualized by a shadowgraph method, and a transition of structures between the <span class="hlt">shock</span> <span class="hlt">wave</span> and the plasma was observed. There was a threshold local power density to make the transition, and the propagation velocity at the transition was around 800 m/s.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1981CoFl...43..187E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1981CoFl...43..187E"><span>Initiation of detonation by steady planar incident <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>Edwards, D. H.; Thomas, G. O.; Williams, T. L.</p> <p>1981-11-01</p> <p>The initiation of detonation by planar <span class="hlt">shocks</span> is studied in a vertical <span class="hlt">shock</span> tube in which a removable diaphragm allows the generated <span class="hlt">shock</span> to be transmitted into the gas mixture, without any <span class="hlt">reflection</span> at the interface. Streak schlieren photography confirms that a quasi-steady <span class="hlt">shock</span> reaction complex is formed prior to the <span class="hlt">shock</span> acceleration phase. The steady phase enabled the induction delay time to be measured in a direct manner, and microwave interferometry, along with pressure transducers, gave an accurate value for the delay time. The <span class="hlt">shock</span> acceleration was determined from the locus of the exothermic reaction zone, and it is shown that the time coherence of energy release between particles entering the <span class="hlt">shock</span> front at different times leads to the formation of reactive centers which are characteristic of mild ignition. Ignition delay data obtained by the incident <span class="hlt">shock</span> method for oxyacetylene, diluted with nitrogen, are compared with those obtained by the <span class="hlt">reflected</span> <span class="hlt">shock</span> technique and shown to have advantages in high heat capacity systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JGRA..117.8223I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JGRA..117.8223I"><span>Hybrid simulation of the <span class="hlt">shock</span> <span class="hlt">wave</span> trailing the Moon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Israelevich, P.; Ofman, L.</p> <p>2012-08-01</p> <p>A standing <span class="hlt">shock</span> <span class="hlt">wave</span> behind the Moon was predicted by Michel (1967) but never observed nor simulated. We use 1D hybrid code in order to simulate the collapse of the plasma-free cavity behind the Moon and for the first time to model the formation of this <span class="hlt">shock</span>. Starting immediately downstream of the obstacle we consider the evolution of plasma expansion into the cavity in the frame of reference moving along with the solar wind. Well-known effects as electric charging of the cavity affecting the plasma flow and counterstreaming ion beams in the wake are reproduced. Near the apex of the inner Mach cone where the plasma flows from the opposite sides of the obstacle meet, a <span class="hlt">shock</span> <span class="hlt">wave</span> arises. We expect the <span class="hlt">shock</span> to be produced at periods of high electron temperature solar wind streams (Ti ≪ Te ˜ 100 eV). The <span class="hlt">shock</span> is produced by the interaction of oppositely directed proton beams in the plane containing solar wind velocity and interplanetary magnetic field vectors. In the direction across the magnetic field and the solar wind velocity, the <span class="hlt">shock</span> results from the interaction of the plasma flow with the region of the enhanced magnetic field inside the cavity that plays the role of the magnetic barrier. The appearance of the standing <span class="hlt">shock</span> <span class="hlt">wave</span> is expected at the distance of ˜7RM downstream of the Moon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140010226','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140010226"><span>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/2016APS..DFD.H5001H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFD.H5001H"><span>The role of granular <span class="hlt">shocks</span> in dust-layer dispersal 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>Houim, Ryan; Ugarte, Orlando; Oran, Elaine</p> <p>2016-11-01</p> <p>Exactly how dust-layers are lifted and dispersed by <span class="hlt">shocks</span> has been a longstanding question in compressible multiphase flow. Understanding the mechanism for this, however, is extremely important for early control of dust explosions. We address this problem by numerically solving a set of equations that couples a fully compressible representation of a gas with a kinetic-theory model for a granular medium (see) to simulate a <span class="hlt">shock</span> propagating along the surface of a dust layer. The results show that the majority of the dispersed dust is lifted by hydrodynamic shear directly behind the <span class="hlt">shock</span> <span class="hlt">wave</span>. Simultaneously, large forces are produced behind the <span class="hlt">shock</span> that compact the dust layer and create a granular <span class="hlt">shock</span>. The effects from this granular <span class="hlt">shock</span> on the surface of the dust layer destabilize the gas-dust boundary layer, which, in turn, enhances turbulence and the rate of dust dispersal.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6053909','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6053909"><span>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://adsabs.harvard.edu/abs/2012epsc.conf...39I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012epsc.conf...39I"><span>Hybrid simulation of the <span class="hlt">shock</span> <span class="hlt">wave</span> formation behind the Moon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Israelevich, P.; Ofman, L.</p> <p>2012-09-01</p> <p>A standing <span class="hlt">shock</span> <span class="hlt">wave</span> behind the Moon was predicted by Michel (1967) but never observed nor simulated. We use 1D hybrid code in order to simulate the collapse of the plasma-free cavity behind the Moon and for the first time to model the formation of this <span class="hlt">shock</span>. Starting immediately downstream of the obstacle we consider the evolution of plasma expansion into the cavity in the frame of reference moving along with the solar wind. Wellknown effects as electric charging of the cavity affecting the plasma flow and counter streaming ion beams in the wake are reproduced. Near the apex of the inner Mach cone where the plasma flows from the opposite sides of the obstacle meet, a <span class="hlt">shock</span> <span class="hlt">wave</span> arises. The <span class="hlt">shock</span> is produced by the interaction of oppositely directed proton beams in the plane containing solar wind velocity and interplanetary magnetic field vectors. In the direction across the magnetic field and the solar wind velocity, the <span class="hlt">shock</span> results from the interaction of the plasma flow with the region of the enhanced magnetic field inside the cavity that plays the role of the magnetic barrier. Simulations with lower electron temperatures (Te~20eV) show weakened <span class="hlt">shock</span> formation behind the moon at much greater distances. The <span class="hlt">shock</span> disappears for typical solar wind conditions (Ti ~ Te) Therefore, in order to observe the trailing <span class="hlt">shock</span>, a satellite should have a trajectory passing very close to the wake axis during the period of hot solar wind streams. We expect the <span class="hlt">shock</span> to be produced at periods of high electron temperature solar wind streams (Ti<<Te~100eV). The appearance of the standing <span class="hlt">shock</span> <span class="hlt">wave</span> is expected at the distance of ~ 7RM downstream of the Moon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012ShWav..22..253S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012ShWav..22..253S"><span>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://adsabs.harvard.edu/abs/2005PhDT.......189B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005PhDT.......189B"><span>Lagrangian averaging, nonlinear <span class="hlt">waves</span>, and <span class="hlt">shock</span> regularization</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bhat, Harish S.</p> <p></p> <p>In this thesis, we explore various models for the flow of a compressible fluid as well as model equations for <span class="hlt">shock</span> formation, one of the main features of compressible fluid flows. We begin by reviewing the variational structure of compressible fluid mechanics. We derive the barotropic compressible Euler equations from a variational principle in both material and spatial frames. Writing the resulting equations of motion requires certain Lie-algebraic calculations that we carry out in detail for expository purposes. Next, we extend the derivation of the Lagrangian averaged Euler (LAE-alpha) equations to the case of barotropic compressible flows. The derivation in this thesis involves averaging over a tube of trajectories etaepsilon centered around a given Lagrangian flow eta. With this tube framework, the LAE-alpha equations are derived by following a simple procedure: start with a given action, expand via Taylor series in terms of small-scale fluid fluctuations xi, truncate, average, and then model those terms that are nonlinear functions of xi. We then analyze a one-dimensional subcase of the general models derived above. We prove the existence of a large family of traveling <span class="hlt">wave</span> solutions. Computing the dispersion relation for this model, we find it is nonlinear, implying that the equation is dispersive. We carry out numerical experiments that show that the model possesses smooth, bounded solutions that display interesting pattern formation. Finally, we examine a Hamiltonian partial differential equation (PDE) that regularizes the inviscid Burgers equation without the addition of standard viscosity. Here alpha is a small parameter that controls a nonlinear smoothing term that we have added to the inviscid Burgers equation. We show the existence of a large family of traveling front solutions. We analyze the initial-value problem and prove well-posedness for a certain class of initial data. We prove that in the zero-alpha limit, without any standard viscosity</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DPPUP2096N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DPPUP2096N"><span>Collisionless <span class="hlt">shock</span> <span class="hlt">waves</span> mediated by Weibel Instability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Naseri, Neda; Ruan, Panpan; Zhang, Xi; Khudik, Vladimir; Shvets, Gennady</p> <p>2015-11-01</p> <p>Relativistic collisionless <span class="hlt">shocks</span> are common events in astrophysical environments. They are thought to be responsible for generating ultra-high energy particles via the Fermi acceleration mechanism. It has been conjectured that the formation of collisionless <span class="hlt">shocks</span> is mediated by the Weibel instability that takes place when two initially cold, unmagnetized plasma shells counter-propagate into each other with relativistic drift velocities. Using a PIC code, VLPL, which is modified to suppress numerical Cherenkov instabilities, we study the <span class="hlt">shock</span> formation and evolution for asymmetric colliding shells with different densities in their own proper reference frame. Plasma instabilities in the region between the <span class="hlt">shock</span> and the precursor are also investigated using a moving-window simulation that advances the computational domain at the <span class="hlt">shock</span>'s speed. This method helps both to save computation time and avoid severe numerical Cherenkov instabilities, and it allows us to study the <span class="hlt">shock</span> evolution in a longer time period. Project is supported by US DOE grants DE-FG02-04ER41321 and DE-FG02-07ER54945.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860026497&hterms=Sound+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DSound%2Bwaves','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860026497&hterms=Sound+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DSound%2Bwaves"><span>Cylindrical sound <span class="hlt">wave</span> generated by <span class="hlt">shock</span>-vortex interaction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ribner, H. S.</p> <p>1985-01-01</p> <p>The passage of a columnar vortex broadside through a <span class="hlt">shock</span> is investigated. This has been suggested as a crude, but deterministic, model of the generation of '<span class="hlt">shock</span> noise' by the turbulence in supersonic jets. The vortex is decomposed by Fourier transform into plane sinusoidal shear <span class="hlt">waves</span> disposed with radial symmetry. The plane sound <span class="hlt">waves</span> produced by each shear <span class="hlt">wave/shock</span> interaction are recombined in the Fourier integral. The <span class="hlt">waves</span> possess an envelope that is essentially a growing cylindrical sound <span class="hlt">wave</span> centered at the transmitted vortex. The pressure jump across the nominal radius R = ct attenuates with time as 1/(square root of R) and varies around the arc in an antisymmetric fashion resembling a quadrupole field. Very good agreement, except near the <span class="hlt">shock</span>, is found with the antisymmetric component of reported interferometric measurements in a <span class="hlt">shock</span> tube. Beyond the front r approximately equals R is a precursor of opposite sign, that decays like 1/R, generated by the 1/r potential flow around the vortex core. The present work is essentially an extension and update of an early approximate study at M = 1.25. It covers the range (R/core radius) = 10, 100, 1000, and 10,000 for M = 1.25 and (in part) for M = 1.29 and, for fixed (R/core radius) = 1000, the range M = 1.01 to infinity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003ASAJ..114.2463W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003ASAJ..114.2463W"><span>Treatment of nonunions of long bone fractures with <span class="hlt">shock</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Ching-Jen</p> <p>2003-10-01</p> <p>A prospective clinical study investigated the effectiveness of <span class="hlt">shock</span> <span class="hlt">waves</span> in the treatment of 72 patients with 72 nonunions of long bone fractures (41 femurs, 19 tibias, 7 humeri, 1 radius, 3 ulnas and 1 metatarsal). The doses of <span class="hlt">shock</span> <span class="hlt">waves</span> were 6000 impulses at 28 kV for the femur and tibia, 3000 impulses at 28 kV for the humerus, 2000 impulses at 24 kV for the radius and ulna, and 1000 impulses at 20 kV for the metatarsal. The results of treatment were assessed clinically, and fracture healing was assessed with plain x-rays and tomography. The rate of bony union was 40% at 3 months, 60.9% at 6 months and 80% at 12 months followup. <span class="hlt">Shock</span> <span class="hlt">wave</span> treatment was most successful in hypertrophic nonunions and nonunions with a defect and was least effective in atrophic nonunions. There were no systemic complications or device-related problems. Local complications included petechiae and hematoma formation that resolved spontaneously. In the author's experience, the results of the <span class="hlt">shock</span> <span class="hlt">wave</span> treatment were similar to the results of surgical treatment for chronic nonunions with no surgical risks. <span class="hlt">Shock</span> <span class="hlt">wave</span> treatment is a safe and effective alternative method in the treatment of chronic nonunions of long bones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AIPC.1503....2K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AIPC.1503....2K"><span>Effects of low-dose extracorporeal <span class="hlt">shock</span> <span class="hlt">waves</span> on microcirculation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khaled, Walaa; Goertz, Ole; Lauer, Henrik; Lehnhardt, Marcus; Hauser, Jörg</p> <p>2012-11-01</p> <p>The extended wounds of burn patients remain a challenge due to wound infection and following septicemia. The aim of this study was to analyze microcirculation, angiogenesis and leukocyte endothelium interaction after burn injury with and without extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> application (ESWA). A novel shockwave system was developed based on a commercially available device for orthopedics (Dornier Aries®) that was equipped with a newly developed applicator. This system is based on the electromagnetic <span class="hlt">shock</span> <span class="hlt">wave</span> emitter (EMSE) technology and was introduced to accomplish a localized treatment for wound healing. The system includes a novel field of focus for new applications, with high precision and ease of use. In the animal study, full-thickness burns were inflicted on to the ears of hairless mice (n=51). Intravital fluorescent microscopy was used to assess microcirculatory parameters, angiogenesis and leukocyte behavior. ESWA was performed on day 1, 3 and 7. Values were obtained immediately after burn, as well as at days 1, 3, 7, and 12 post burn. All shockwave treated groups showed an accelerated angiogenesis with a less non-perfused area and an improved blood flow after burn injury compared to the placebo control group. After three treatments, the <span class="hlt">shock</span> <span class="hlt">waves</span> increased the number of rolling leukocytes significantly compared to the non-treated animals. <span class="hlt">Shock</span> <span class="hlt">waves</span> seem to have a positive effect on several parameters of wound healing after burn injury. However, further investigations are necessary to detect positive influence of <span class="hlt">shock</span> <span class="hlt">waves</span> on microcirculation after burn injuries.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PThPS.187...96K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PThPS.187...96K"><span><span class="hlt">Shock</span> <span class="hlt">Wave</span> Collisions and Thermalization in AdS_5</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kovchegov, Y. V.</p> <p></p> <p>We study heavy ion collisions at strong 't Hooft coupling usingAdS/CFT correspondence. According to the AdS/CFT dictionary heavy ion collisions correspond to gravitational <span class="hlt">shock</span> <span class="hlt">wave</span> collisions in AdS_5. We construct the metric in the forward light cone after the collision perturbatively through expansion of Einstein equations in graviton exchanges. We obtain an analytic expression for the metric including all-order graviton exchanges with one <span class="hlt">shock</span> <span class="hlt">wave</span>, while keeping the exchanges with another <span class="hlt">shock</span> <span class="hlt">wave</span> at the lowest order. We read off the corresponding energy-momentum tensor of the produced medium. Unfortunately this energy-momentum tensor does not correspond to ideal hydrodynamics, indicating that higher order graviton exchanges are needed to construct the full solution of the problem. We also show that <span class="hlt">shock</span> <span class="hlt">waves</span> must completely stop almost immediately after the collision in AdS_5, which, on the field theory side, corresponds to complete nuclear stopping due to strong coupling effects, likely leading to Landau hydrodynamics. Finally, we perform trapped surface analysis of the <span class="hlt">shock</span> <span class="hlt">wave</span> collisions demonstrating that a bulk black hole, corresponding to ideal hydrodynamics on the boundary, has to be created in such collisions, thus constructing a proof of thermalization in heavy ion collisions at strong coupling.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1087699','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1087699"><span>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('http://adsabs.harvard.edu/abs/2011MNRAS.416.1284G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011MNRAS.416.1284G"><span><span class="hlt">Shock</span> formation in stellar perturbations and tidal <span class="hlt">shock</span> <span class="hlt">waves</span> in binaries</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gundlach, Carsten; Murphy, Jeremiah W.</p> <p>2011-09-01</p> <p>We investigate whether tidal forcing can result in sound <span class="hlt">waves</span> steepening into <span class="hlt">shocks</span> at the surface of a star. To model the sound <span class="hlt">waves</span> and <span class="hlt">shocks</span>, we consider adiabatic non-spherical perturbations of a Newtonian perfect fluid star. Because tidal forcing of sound <span class="hlt">waves</span> is naturally treated with linear theory, but the formation of <span class="hlt">shocks</span> is necessarily non-linear, we consider the perturbations in two regimes. In most of the interior, where tidal forcing dominates, we treat the perturbations as linear, while in a thin layer near the surface we treat them in full non-linearity but in the approximation of plane symmetry, fixed gravitational field and a barotropic equation of state. Using a hodograph transformation, this non-linear regime is also described by a linear equation. We show that the two regimes can be matched to give rise to a single-mode equation which is linear but models non-linearity in the outer layers. This can then be used to obtain an estimate for the critical mode amplitude at which a <span class="hlt">shock</span> forms near the surface. As an application, we consider the tidal <span class="hlt">waves</span> raised by the companion in an irrotational binary system in circular orbit. We find that <span class="hlt">shocks</span> form at the same orbital separation where Roche lobe overflow occurs, and so <span class="hlt">shock</span> formation is unlikely to occur.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/970576','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/970576"><span><span class="hlt">Shock</span> <span class="hlt">wave</span> structure for a fully ionized plasma</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Masser, Thomas O; Wohibier, John G; Lowrie, Robert B</p> <p>2009-01-01</p> <p>We study the structure of planar <span class="hlt">shock</span> <span class="hlt">waves</span> in a two-temperature model of a fully ionized plasma that includes electron heat conduction and energy exchange between electrons and ions. For steady flow in a reference frame moving with the <span class="hlt">shock</span>, the model reduces to an autonomous system of ordinary differential equations which can be numerically integrated. A phase space analysis of the ODEs provides additional insight into the structure of the solutions. For example, below a threshold mach number the model produces fully dispersed <span class="hlt">shocks</span>; while above another threshold mach number, the solutions contain embedded hydrodynamic <span class="hlt">shocks</span>. Between these two threshold values, the appearance of embedded <span class="hlt">shocks</span> depends on the electron diffusivity and the electron-ion coupling term. We also find that the ion temperature may continue to increase after the <span class="hlt">shock</span> and reaches a maximum near the isothermal sonic point. We summarize the methodology for solving for two-temperature <span class="hlt">shocks</span>, and show results for several values of <span class="hlt">shock</span> strength and material parameters to quantify the <span class="hlt">shock</span> structure and explore the range of possible solutions. Such solutions may be used to verify hydrodynamic codes that use similar plasma physics models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1981swan.rept.....D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1981swan.rept.....D"><span>A <span class="hlt">shock</span> <span class="hlt">wave</span> approach to the noise of supersonic propellers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dittmar, J. H.; Rice, E. J.</p> <p>1981-12-01</p> <p>To model propeller noise expected for a turboprop aircraft, the pressure ratio across the <span class="hlt">shock</span> at the propeller tip was calculated and compared with noise data from three propellers. At helical tip Mach numbers over 1.0, using only the tip <span class="hlt">shock</span> <span class="hlt">wave</span>, the model gave a fairly good prediction of the noise for a bladed propeller and for a propeller swept for aerodynamic purposes. However for another propeller, which was highly swept and designed to have noise cancellations from the inboard propeller sections, the <span class="hlt">shock</span> strength from the tip over predicted the noise. In general the good agreement indicates that <span class="hlt">shock</span> theory is a viable method for predicting the noise from these supersonic propellers but that the <span class="hlt">shock</span> strengths from all of the blade sections need to be properly included.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011APS..SHK.U6002J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011APS..SHK.U6002J"><span>Resolving the <span class="hlt">Shock</span> <span class="hlt">Wave</span> Profile in Viscous Fluids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jordan, Kenneth; Borg, John</p> <p>2011-06-01</p> <p>Capturing and modeling <span class="hlt">shock</span> <span class="hlt">wave</span> profiles has a long history in computational analysis. Often artificial irreversibilities and/or smearing schemes are implemented in order to stabilize and resolve the <span class="hlt">shock</span>. This work presents a direct numeric simulation of the full Navier-Stokes equations where the <span class="hlt">shock</span> profile is completely resolved without the use of artificial viscosity or <span class="hlt">shock</span> smearing techniques. Several viscosity models are employed to study the role of viscosity on this second order accurate finite difference scheme. The results are compared to an analytic solutions and experimental results. The results indicated that the <span class="hlt">shock</span> front thickness and entropy production are in good agreement with simple analytic solutions and experimental results. The extension of this technique to solid and granular materials will be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730015974','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730015974"><span>Ion streaming instabilities with application to collisionless <span class="hlt">shock</span> <span class="hlt">wave</span> structure</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Golden, K. I.; Linson, L. M.; Mani, S. A.</p> <p>1973-01-01</p> <p>The electromagnetic dispersion relation for two counterstreaming ion beams of arbitrary relative strength flowing parallel to a dc magnetic field is derived. The beams flow through a stationary electron background and the dispersion relation in the fluid approximation is unaffected by the electron thermal pressure. The dispersion relation is solved with a zero net current condition applied and the regions of instability in the k-U space (U is the relative velocity between the two ion beams) are presented. The parameters are then chosen to be applicable for parallel <span class="hlt">shocks</span>. It was found that unstable <span class="hlt">waves</span> with zero group velocity in the <span class="hlt">shock</span> frame can exist near the leading edge of the <span class="hlt">shock</span> for upstream Alfven Mach numbers greater than 5.5. It is suggested that this mechanism could generate sufficient turbulence within the <span class="hlt">shock</span> layer to scatter the incoming ions and create the required dissipation for intermediate strength <span class="hlt">shocks</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1982Natur.300..237M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1982Natur.300..237M"><span>Measurements on a <span class="hlt">shock</span> <span class="hlt">wave</span> generated by a solar flare</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maxwell, A.; Dryer, M.</p> <p>1982-11-01</p> <p><span class="hlt">Shock</span> <span class="hlt">waves</span> generated by intense solar flares may be driven by a large amount of ejected mass, about 5 x 10 to the 16th g, and the total energy involved may be of the order of 10 to the 32nd erg. The <span class="hlt">shocks</span> may have initial velocities of the order of 2,000 km/s and, in their exodus through the corona, may be accompanied by fast-moving optical transients, the emission of highly characteristic radio signatures and the acceleration of particles to quasi-relativistic velocities. Here, a review is presented of data on a high-velocity <span class="hlt">shock</span> generated by a flare on 18 August 1979, 1400 UT, and comments are provided on some previously deduced velocities for the <span class="hlt">shock</span>. Attention is given to a model, based on current computer programs to account for the overall characteristics of the <span class="hlt">shock</span> as it propagated through the corona and the interplanetary plasma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19830033736&hterms=exodus&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dexodus','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830033736&hterms=exodus&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dexodus"><span>Measurements on a <span class="hlt">shock</span> <span class="hlt">wave</span> generated by a solar flare</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Maxwell, A.; Dryer, M.</p> <p>1982-01-01</p> <p><span class="hlt">Shock</span> <span class="hlt">waves</span> generated by intense solar flares may be driven by a large amount of ejected mass, about 5 x 10 to the 16th g, and the total energy involved may be of the order of 10 to the 32nd erg. The <span class="hlt">shocks</span> may have initial velocities of the order of 2,000 km/s and, in their exodus through the corona, may be accompanied by fast-moving optical transients, the emission of highly characteristic radio signatures and the acceleration of particles to quasi-relativistic velocities. Here, a review is presented of data on a high-velocity <span class="hlt">shock</span> generated by a flare on 18 August 1979, 1400 UT, and comments are provided on some previously deduced velocities for the <span class="hlt">shock</span>. Attention is given to a model, based on current computer programs to account for the overall characteristics of the <span class="hlt">shock</span> as it propagated through the corona and the interplanetary plasma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Ap%26SS.362...58G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Ap%26SS.362...58G"><span><span class="hlt">Shock</span> <span class="hlt">waves</span> in dusty plasma with two temperature superthermal ions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ghai, Yashika; Saini, N. S.</p> <p>2017-03-01</p> <p>An investigation of dust acoustic <span class="hlt">shock</span> <span class="hlt">waves</span> in dusty plasma containing two temperature ions is presented. The present investigation is motivated by the observations of Geotail spacecraft that report the occurrence of two temperature ion populations in Earth's magnetotail. We have derived Burgers equation to study dust acoustic <span class="hlt">shock</span> structures in an unmagnetized plasma with two temperature superthermal ions. We have also derived the modified Burgers equation at critical values of physical parameters for which nonlinear coefficient (A) of Burgers equation vanishes. The numerical analysis is performed in context with observations in Earth's magnetotail and the influence of various plasma parameters viz. ions temperature ratio, superthermality of hot and cold ions, kinematic viscosity etc. has been observed on characteristics of DA <span class="hlt">shocks</span>. It is observed that the amplitude of positive <span class="hlt">shocks</span> via Burgers equation decreases whereas that of modified <span class="hlt">shocks</span> with higher order nonlinearity increases with increase in superthermality of cold ions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AIPC.1821j0001S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AIPC.1821j0001S"><span>Elimination of cavitation-related attenuation in <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sankin, G. N.; Lautz, J. M.; Simmons, W. N.; Zhong, P.; Frank, S. T.; Szeri, A. J.</p> <p>2017-03-01</p> <p>In <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy (SWL), acoustic pulses with a leading compression <span class="hlt">wave</span> followed by a tensile <span class="hlt">wave</span> are delivered into the patient's body using a water-filled coupling cushion. Cavitation-related acoustic energy loss in the coupling unit depends critically on water conditions, e.g. dissolved gas concentration and exchange flow rate. We have systematically investigated the attenuation mechanism in the coupling water via pressure measurements and cavitation characterization. In non-degassed water the bubble cluster became progressively dense (i.e., proliferated because of gas diffusion into bubbles and splitting of bubbles into many daughter bubbles) in <span class="hlt">shock</span> <span class="hlt">waves</span> delivered at 1 Hz leading to reduction in the tensile <span class="hlt">wave</span> duration from a nominal value of 4.6 to 1.8 µs. To reduce cavitation in the coupling water along the beam path, we have used a continuous jet flow to remove residual daughter bubbles between consecutive <span class="hlt">shocks</span>. As a result, stone fragmentation efficiency was increased from 16±4% to 30±5% (p = 0.002) after 250 <span class="hlt">shocks</span>. Such a hydrodynamic approach for tensile <span class="hlt">wave</span> attenuation in the coupling water may be used to provide a flexible means for a novel treatment strategy with tissue protection.</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>Air bubble-<span class="hlt">shock</span> <span class="hlt">wave</span> interaction adjacent to gelantine surface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lush, P. A.; Tomita, Y.; Onodera, O.; Takayama, K.; Sanada, N.; Kuwahara, M.; Ioritani, N.; Kitayama, O.</p> <p>1990-07-01</p> <p>The interaction between a <span class="hlt">shock</span> <span class="hlt">wave</span> and an air bubble-adjacent to a gelatine surface is investigated in order to simulate human tissue damage resulting from extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy. Using high speed cine photography it is found that a <span class="hlt">shock</span> <span class="hlt">wave</span> of strength 11 MPa causes 1-3 mm diameter bubbles to produce high velocity microjets with penetration rates of approximately 110 m/s and penetration depths approximately equal to twice the initial bubble diameter. Theoretical considerations for liquid impact on soft solid of similar density indicate that microjet velocities will be twice the penetration rate, i.e. 220 m/s in the present case. Such events are the probable cause of observed renal tissue damage.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10025241','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10025241"><span>[High energy <span class="hlt">shock</span> <span class="hlt">wave</span> treatment of the painful heel spur].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Perlick, L; Boxberg, W; Giebel, G</p> <p>1998-12-01</p> <p>Extracorporal <span class="hlt">shock</span> <span class="hlt">wave</span> application (ESWA) has been used in the treatment of stones located in kidneys, bile, pancreas and the glandula parotis. In the last 2 years several studies have shown the benefit of the ESWA on the treatment of soft tissue disorders. The aim of this study was to explore the effect of high energy extracorporal <span class="hlt">shock</span> <span class="hlt">waves</span> in patients with painful calcaneus spurs. 83 patients who underwent medicophysical treatment without benefit were treated with 3000 impulses of 0.30 mj/mm2. Follow-ups after 12 weeks and 12 months showed that 51 of 83 patients became pain-free and 20 patients improved from the treatment. The results are showing the benefit of the high energy extracorporal <span class="hlt">shock</span> <span class="hlt">wave</span> application in the treatment of chronic plantar fasciitis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14733349','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14733349"><span>Effect of extracorporeal <span class="hlt">shock</span> <span class="hlt">waves</span> on calcaneal bone spurs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lee, Gregory P; Ogden, John A; Cross, G Lee</p> <p>2003-12-01</p> <p>In a prospective study of 435 patients with chronic proximal plantar fasciitis, 283 (65%) had an inferior calcaneal bone spur of variable size evident prior to treatment with electrohydraulic high-energy extracorporeal <span class="hlt">shock</span> <span class="hlt">waves</span> (ESW). This included 308 patients who received extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> treatments and 127 placebo (sham control) patients. At both initial (3 months) and final (12 months) evaluations after receiving ESW, no patient who received <span class="hlt">shock</span> <span class="hlt">wave</span> applications had significant disappearance or change in the radiographic appearance of the heel spur. Clinical outcome after ESW was satisfactory in 168 patients (82%) with a radiographically demonstrable inferior heel spur and in 81 patients (79%) without such a heel spur. The results showed no correlation between the presence or absence of the heel spur and the eventual treatment outcome.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19830044689&hterms=PROBLEMS+RESOLVED+ACOUSTICS&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DPROBLEMS%2BRESOLVED%2BACOUSTICS','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830044689&hterms=PROBLEMS+RESOLVED+ACOUSTICS&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DPROBLEMS%2BRESOLVED%2BACOUSTICS"><span>Finite difference solutions to <span class="hlt">shocked</span> acoustic <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Walkington, N. J.; Eversman, W.</p> <p>1983-01-01</p> <p>The MacCormack, Lambda and split flux finite differencing schemes are used to solve a one dimensional acoustics problem. Two duct configurations were considered, a uniform duct and a converging-diverging nozzle. Asymptotic solutions for these two ducts are compared with the numerical solutions. When the acoustic amplitude and frequency are sufficiently high the acoustic signal <span class="hlt">shocks</span>. This condition leads to a deterioration of the numerical solutions since viscous terms may be required if the <span class="hlt">shock</span> is to be resolved. A continuous uniform duct solution is considered to demonstrate how the viscous terms modify the solution. These results are then compared with a <span class="hlt">shocked</span> solution with and without viscous terms. Generally it is found that the most accurate solutions are those obtained using the minimum possible viscosity coefficients. All of the schemes considered give results accurate enough for acoustic power calculations with no one scheme performing significantly better than the others.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.2121I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.2121I"><span>Hybrid simulation of the <span class="hlt">shock</span> <span class="hlt">wave</span> trailing the Moon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Israelevich, P.; Ofman, L.</p> <p>2012-04-01</p> <p>Standing <span class="hlt">shock</span> <span class="hlt">wave</span> behind the Moon was predicted be Michel (1967) but never observed nor simulated. We use 1D hybrid code in order to simulate the collapse of the plasma-free cavity behind the Moon and for the first time to model the formation of this <span class="hlt">shock</span>. Starting immediately downstream of the obstacle we consider the evolution of plasma expansion into the cavity in the frame of reference moving along with the solar wind. Well-known effects as electric charging of the cavity affecting the plasma flow and counter streaming ion beams in the wake are reproduced. Near the apex of the inner Mach cone where the plasma flows from the opposite sides of the obstacle meet, a <span class="hlt">shock</span> <span class="hlt">wave</span> arises. The <span class="hlt">shock</span> is produced by the interaction of oppositely directed proton beams in the plane containing solar wind velocity and interplanetary magnetic field vectors. In the direction across the magnetic field and the solar wind velocity, the <span class="hlt">shock</span> results from the interaction of the plasma flow with the region of the enhanced magnetic field inside the cavity that plays the role of magnetic barrier. The appearance of the standing <span class="hlt">shock</span> <span class="hlt">wave</span> is expected at the distance of ~ 7RM downstream of the Moon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950052353&hterms=Ryszard&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DRyszard','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950052353&hterms=Ryszard&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DRyszard"><span>Supernova remnants and the physics of strong <span class="hlt">shock</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ellison, Donald C.; Reynolds, Stephen P.; Borkowski, Kazimierz; Chevalier, Roger; Cox, Donald P.; Dickel, John R.; Pisarski, Ryszard; Raymond, John; Spangler, Stephen R.; Volk, Heinrich J.</p> <p>1994-01-01</p> <p>This paper reports on a Workshop on Supernova Remnants and the Physics of Strong <span class="hlt">Shock</span> <span class="hlt">Waves</span> hosted by North Carolina State University at Raleigh, North Carolina, September 16-18, 1993. The workshop brought together observers, <span class="hlt">shock</span> theorists, cosmic-ray specialists, and simulators to address the role supernova remnants can play in furthering our understanding of the complex plasma physics associated with collisionless <span class="hlt">shocks</span> and particle acceleration. Over fifty scientists presented papers on various aspects of supernova remnants. In lieu of a proceedings volume, we present here a synopsis of the workshop, in the form of brief summaries of each workshop session.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980223576','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980223576"><span>Effect of Surface Roughness on Characteristics of Spherical <span class="hlt">Shock</span> <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Huber, Paul W.; McFarland, Donald R.</p> <p>1959-01-01</p> <p>Measurements of peak overpressure and Mach stem height were made at four burst heights. Data were obtained with instrumentation capable of directly observing the variation of <span class="hlt">shock</span> <span class="hlt">wave</span> movement with time. Good similarity of free air <span class="hlt">shock</span> peak overpressure with larger scale data was found to exist. The net effect of surface roughness on <span class="hlt">shock</span> peak overpressures slightly. Surface roughness delayed the Mach stem formation at the greatest charge height and lowered the growth at all burst heights. A similarity parameter was found which approximately correlates the triple point path at different burst heights.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860041641&hterms=ohms+law&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dohms%2Blaw','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860041641&hterms=ohms+law&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dohms%2Blaw"><span>Hybrid simulation codes with application to <span class="hlt">shocks</span> and upstream <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Winske, D.</p> <p>1985-01-01</p> <p>Hybrid codes in which part of the plasma is represented as particles and the rest as a fluid are discussed. In the past few years such codes with particle ions and massless, fluid electrons have been applied to space plasmas, especially to collisionless <span class="hlt">shocks</span>. All of these simulation codes are one-dimensional and similar in structure, except for how the field equations are solved. The various approaches that are used (resistive Ohm's law, predictor-corrector, Hamiltonian) are described in detail and results from the various codes are compared with examples taken from collisionless <span class="hlt">shocks</span> and low frequency <span class="hlt">wave</span> phenomena upstream of <span class="hlt">shocks</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000086187&hterms=ortho&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dortho','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000086187&hterms=ortho&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dortho"><span>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('https://www.osti.gov/scitech/biblio/22036754','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22036754"><span>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> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ShWav.tmp...83H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ShWav.tmp...83H"><span>Transition boundary between regular and Mach <span class="hlt">reflections</span> for a moving <span class="hlt">shock</span> interacting with a wedge in inviscid and polytropic air</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hryniewicki, M. K.; Gottlieb, J. J.; Groth, C. P. T.</p> <p>2016-12-01</p> <p>The transition boundary separating the region of regular <span class="hlt">reflection</span> from the regions of single-, transitional-, and double-Mach <span class="hlt">reflections</span> for a planar <span class="hlt">shock</span> <span class="hlt">wave</span> moving in air and interacting with an inclined wedge in a <span class="hlt">shock</span> tube is studied by both analytical methods and computational-fluid-dynamic simulations. The analytical solution for regular <span class="hlt">reflection</span> and the corresponding solutions from the extreme-angle (detachment), sonic, and mechanical-equilibrium transition criteria by von Neumann (Oblique <span class="hlt">reflection</span> of <span class="hlt">shocks</span>, Explosive Research Report No. 12, Navy Department, Bureau of Ordnance, U.S. Dept. Comm. Tech. Serv. No. PB37079 (1943). Also, John von Neumann, Collected Works, Pergamon Press 6, 238-299, 1963) are first revisited and revised. The boundary between regular and Mach <span class="hlt">reflection</span> is then determined numerically using an advanced computational-fluid-dynamics algorithm to solve Euler's inviscid equations for unsteady motion in two spatial dimensions. This numerical transition boundary is determined by post-processing many closely stationed flow-field simulations, to determine the transition point when the Mach stem of the Mach-<span class="hlt">reflection</span> pattern just disappears and this pattern then transcends into that of regular <span class="hlt">reflection</span>. The new numerical transition boundary is shown to agree well with von Neumann's closely spaced sonic and extreme-angle boundaries for weak incident <span class="hlt">shock</span> Mach numbers from 1.0 to 1.6, but this new boundary trends upward and above von Neumann's sonic and extreme-angle boundaries by a couple of degrees at larger <span class="hlt">shock</span> Mach numbers from 1.6 to 4.0. Furthermore, the new numerically determined transition boundary is shown to agree well with very few available experimental data obtained from previous experiments designed to <span class="hlt">reflect</span> two symmetrical moving oblique <span class="hlt">shock</span> <span class="hlt">waves</span> along a plane without a shear or boundary layer.</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>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('https://ntrs.nasa.gov/search.jsp?R=19910046931&hterms=polish&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dpolish','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910046931&hterms=polish&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dpolish"><span>Plasma <span class="hlt">wave</span> generation near the inner heliospheric <span class="hlt">shock</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Macek, W. M.; Cairns, I. H.; Kurth, W. S.; Gurnett, D. A.</p> <p>1991-01-01</p> <p>There is mounting evidence that the Voyager 1 and 2 and Pioneer 11 spacecraft may approach the inner (termination) heliospheric <span class="hlt">shock</span> near the end of this century. It is argued here, by analogy with planetary bow <span class="hlt">shocks</span>, that energetic electrons backstreaming from the heliospheric <span class="hlt">shock</span> along the magnetic field should be unstable to the generation of Langmuir <span class="hlt">waves</span> by the electron beam instability. Analytic expressions for the cutoff velocity, corresponding to the beam speed of the electrons backstreaming from the <span class="hlt">shock</span>, are derived for a standard solar wind model. At the front side of the heliosphere the maximum beam velocity is expected to be at the meridian passing through the nose of the <span class="hlt">shock</span>, which is assumed to be aligned with the Very Local Inter-Stellar Medium flow. This foreshock region and the associated Langmuir <span class="hlt">waves</span> are relevant to both the expected in situ observations of the heliospheric boundaries, and to the low-frequency (2-3 kHz) radio emissions observed by the Voyager spacecraft in the outer heliosphere. Provided that these radio emissions are generated by Langmuir <span class="hlt">waves</span>, the minimum Langmuir <span class="hlt">wave</span> electric fields at the remote source are estimated to be greater than about 3 - 30 microV/m.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990008041&hterms=Uranus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DUranus','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990008041&hterms=Uranus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DUranus"><span>A Study of Uranus' Bow <span class="hlt">Shock</span> Motions Using Langmuir <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Xue, S.; Cairns, I. H.; Smith, C. W.; Gurnett, D. A.</p> <p>1996-01-01</p> <p>During the Voyager 2 flyby of Uranus, strong electron plasma oscillations (Langmuir <span class="hlt">waves</span>) were detected by the plasma <span class="hlt">wave</span> instrument in the 1.78-kHz channel on January 23-24, 1986, prior to the inbound bow <span class="hlt">shock</span> crossing. Langmuir <span class="hlt">waves</span> are excited by energetic electrons streaming away from the bow <span class="hlt">shock</span>. The goal of this work is to estimate the location and motion of Uranus' bow <span class="hlt">shock</span> using Langmuir <span class="hlt">wave</span> data, together with the spacecraft positions and the measured interplanetary magnetic field. The following three remote sensing analyses were performed: the basic remote sensing method, the lag time method, and the trace-back method. Because the interplanetary magnetic field was highly variable, the first analysis encountered difficulties in obtaining a realistic estimation of Uranus' bow <span class="hlt">shock</span> motion. In the lag time method developed here, time lags due to the solar wind's finite convection speed are taken into account when calculating the <span class="hlt">shock</span>'s standoff distance. In the new trace-back method, limits on the standoff distance are obtained as a function of time by reconstructing electron paths. Most of the results produced by the latter two analyses are consistent with predictions based on the standard theoretical model and the measured solar wind plasma parameters. Differences between our calculations and the theoretical model are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993P%26SS...41..183S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993P%26SS...41..183S"><span>Simultaneous plasma <span class="hlt">wave</span> and electron flux observations upstream of the Martian bow <span class="hlt">shock</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Skalsky, A.; Grard, R.; Kiraly, P.; Klimov, S.; Kopanyi, V.; Schwingenschuh, K.; Trotignon, J. G.</p> <p>1993-03-01</p> <p>Flux enhancements of electrons with energies between 100 and 530 eV are observed simultaneously with electron plasma <span class="hlt">waves</span> in the upstream region of the Martian bow <span class="hlt">shock</span>. The electron flux appears to reach its maximum when the pitch angle is close to 0 deg, which corresponds to particles <span class="hlt">reflected</span> from the <span class="hlt">shock</span> region and backstreaming in the solar wind along the magnetic field. The correlation between high-frequency <span class="hlt">waves</span> and enhanced electron fluxes is reminiscent of several studies on the electron foreshock of the Earth. Such a similarity indicates that, in spite of major differences between the global <span class="hlt">shock</span> structures, the microscopic processes operating in the foreshocks of Earth and Mars are probably identical.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870025302&hterms=berkeley&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dberkeley','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870025302&hterms=berkeley&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dberkeley"><span><span class="hlt">Shock</span> <span class="hlt">waves</span> and <span class="hlt">shock</span> tubes; Proceedings of the Fifteenth International Symposium, Berkeley, CA, July 28-August 2, 1985</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bershader, D. (Editor); Hanson, R. (Editor)</p> <p>1986-01-01</p> <p>A detailed survey is presented of <span class="hlt">shock</span> tube experiments, theoretical developments, and applications being carried out worldwide. The discussions explore <span class="hlt">shock</span> tube physics and the related chemical, physical and biological science and technology. Extensive attention is devoted to <span class="hlt">shock</span> <span class="hlt">wave</span> phenomena in dusty gases and other multiphase and heterogeneous systems, including chemically reactive mixtures. Consideration is given to techniques for measuring, visualizing and theoretically modeling flowfield, <span class="hlt">shock</span> <span class="hlt">wave</span> and rarefaction <span class="hlt">wave</span> characteristics. Numerical modeling is explored in terms of the application of computational fluid dynamics techniques to describing flowfields in <span class="hlt">shock</span> tubes. <span class="hlt">Shock</span> interactions and propagation, in both solids, fluids, gases and mixed media are investigated, along with the behavior of <span class="hlt">shocks</span> in condensed matter. Finally, chemical reactions that are initiated as the result of passage of a <span class="hlt">shock</span> <span class="hlt">wave</span> are discussed, together with methods of controlling the evolution of laminar separated flows at concave corners on advanced reentry vehicles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ShWav..26..385G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ShWav..26..385G"><span><span class="hlt">Shock</span> <span class="hlt">wave</span> emission during the collapse of cavitation bubbles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Garen, W.; Hegedűs, F.; Kai, Y.; Koch, S.; Meyerer, B.; Neu, W.; Teubner, U.</p> <p>2016-07-01</p> <p><span class="hlt">Shock</span> <span class="hlt">wave</span> emission induced by intense laser pulses is investigated experimentally. The present work focuses on the conditions of <span class="hlt">shock</span> <span class="hlt">wave</span> emission in glycerine and distilled water during the first bubble collapse. Experimental investigations are carried out in liquids as a function of temperature and viscosity. Comparison is made with the theoretical work of Poritsky (Proc 1st US Natl Congress Appl Mech 813-821, 1952) and Brennen (Cavitation and bubble dynamics, Oxford University Press 1995). To the best knowledge of the authors, this is the first experimental verification of those theories.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20655341','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20655341"><span>The importance of microjet vs <span class="hlt">shock</span> <span class="hlt">wave</span> formation in sonophoresis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wolloch, Lior; Kost, Joseph</p> <p>2010-12-01</p> <p>Low-frequency ultrasound application has been shown to greatly enhance transdermal drug delivery. Skin exposed to ultrasound is affected in a heterogeneous manner, thus mass transport through the stratum corneum occurs mainly through highly permeable localized transport regions (LTRs). <span class="hlt">Shock</span> <span class="hlt">waves</span> and microjets generated during inertial cavitations are responsible for the transdermal permeability enhancement. In this study, we evaluated the effect of these two phenomena using direct and indirect methods, and demonstrated that the contribution of microjets to skin permeability enhancement is significantly higher than <span class="hlt">shock</span> <span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19730050328&hterms=embedded+type&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dembedded%2Btype','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19730050328&hterms=embedded+type&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dembedded%2Btype"><span>Analysis of embedded <span class="hlt">shock</span> <span class="hlt">waves</span> calculated by relaxation methods.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Murman, E. M.</p> <p>1973-01-01</p> <p>The requirements for uniqueness of the calculated jump conditions across embedded <span class="hlt">shock</span> <span class="hlt">waves</span> are investigated for type-dependent difference systems used in transonic flow studies. A mathematical analysis shows that sufficient conditions are (1) the equations should be differenced in conservative form and (2) a special difference operator should be used when switching from a hyperbolic to an elliptic operator. The latter results in a consistency condition on the integral equations, rather than the differential, at these points. Calculated jump conditions for several embedded and detached <span class="hlt">shock</span> <span class="hlt">waves</span> are analyzed in the physical and hodograph planes. Comparisons are made with previous results, a time-dependent calculation, and data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005APS..SHK.C5001K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005APS..SHK.C5001K"><span>Failure <span class="hlt">waves</span> in <span class="hlt">shock</span>-compressed glasses</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kanel, Gennady I.</p> <p>2005-07-01</p> <p>The failure <span class="hlt">wave</span> is a network of cracks that are nucleated on the surface and propagate into the elastically stressed body. It is a mode of catastrophic fracture in an elastically stressed media whose relevance is not limited to impact events. In the presentation, main properties of the failure <span class="hlt">waves</span> are summarized and discussed. It has been shown that the failure <span class="hlt">wave</span> is really a <span class="hlt">wave</span> process which is characterized by small increase of the longitudinal stress and corresponding increments of the particle velocity and the density. The propagation velocity of the failure <span class="hlt">wave</span> is less than the sound speed; it is not directly related to the compressibility but is determined by the crack growth speed. Transformation of elastic compression <span class="hlt">wave</span> followed by the failure <span class="hlt">wave</span> in a thick glass plate into typical two-<span class="hlt">wave</span> configuration in a pile of thin glass plates confirms crucial role of the surfaces. The latter, as well as specific kinematics of the process distinguishes the failure <span class="hlt">wave</span> from a time-dependent inelastic compressive behavior of brittle materials. The failure <span class="hlt">wave</span> is steady if the stress state ahead of it is supported unchanging. Mechanism of this self-supporting propagation of compressive fracture is not quite clear as yet. On the other hand, collected data about its kinematics allow formulating phenomenological models of the phenomenon. In some sense the process is similar to the diffusion of cracks from a source on the glass surface. However, the diffusion-like models contradict to observed steady propagation of the failure <span class="hlt">wave</span>. Analogy with a subsonic combustion <span class="hlt">wave</span> looks more fruitful. Computer simulations based on the phenomenological combustion-like model reproduces well all kinematical aspects of the phenomenon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980228372','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980228372"><span>Structure of Weak <span class="hlt">Shock</span> <span class="hlt">Waves</span> in a Monatomic Gas</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sherman, F. S.; Talbot, L.</p> <p>1959-01-01</p> <p>The profiles and thicknesses of normal <span class="hlt">shock</span> <span class="hlt">waves</span> in argon at Mach numbers of 1.335, 1.454, 1.576, and 1-713 were determined experimentally by means of a free-molecule probe whose equilibrium temperature is related by kinetic theory to the local flow properties and their gradients. Comparisons were made between the experimental <span class="hlt">shock</span> profiles and the theoretical profiles calculated from the Navier-Stokes equations, the Grad 13-moment equations, and the Burnett equations. New, very accurate numerical integrations of the Burnett equations were obtained for this purpose with results quite different from those found by Zoller, to whom the solution of this problem is frequently attributed. The experimental <span class="hlt">shock</span> profiles were predicted with approximately equal success by the Navier-Stokes and Burnett theories, while the 13-moment method was definitely less satisfactory. A surprising feature of the theoretical results is the relatively small difference in predictions between the Navier-Stokes and Burnett theories in the present range of <span class="hlt">shock</span> strengths and the contrastingly large difference between predictions of Burnett and the 13-moment theories. It is concluded that the Navier-Stokes equations are correct for weak <span class="hlt">shocks</span> and that within the present <span class="hlt">shock</span> strength range the Burnett equations make no improvement which merits the trouble of solving them. For <span class="hlt">shocks</span> of noticeably greater strength, say with a <span class="hlt">shock</span> Mach number of more than 2.5, it remains fundamentally doubtful that any of these theories can be correct.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960021262&hterms=energy+Solar&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Denergy%2BSolar','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960021262&hterms=energy+Solar&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Denergy%2BSolar"><span>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('https://www.osti.gov/scitech/biblio/20875777','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20875777"><span>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/2016SPIE.9894E..0TL','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SPIE.9894E..0TL"><span>Traveling solitary <span class="hlt">wave</span> induced by nonlocality in dispersive <span class="hlt">shock</span> <span class="hlt">wave</span> generation (Conference Presentation)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Louis, Hélène; Odent, Vincent; Louvergneaux, Eric</p> <p>2016-04-01</p> <p><span class="hlt">Shock</span> <span class="hlt">waves</span> are well-known nonlinear <span class="hlt">waves</span>, displaying an abrupt discontinuity. Observation can be made in a lot of physical fields, as in water <span class="hlt">wave</span>, plasma and nonlinear optics. <span class="hlt">Shock</span> <span class="hlt">waves</span> can either break or relax through either catastrophic or regularization phenomena. In this work, we restrain our study to dispersive <span class="hlt">shock</span> <span class="hlt">waves</span>. This regularization phenomenon implies the emission of dispersive <span class="hlt">waves</span>. We demonstrate experimentally and numerically the generation of spatial dispersive <span class="hlt">shock</span> <span class="hlt">waves</span> in a nonlocal focusing media. The generation of dispersive <span class="hlt">shock</span> <span class="hlt">wave</span> in a focusing media is more problematic than in a defocusing one. Indeed, the modulational instability has to be frustrated to observe this phenomenon. In 2010, the dispersive <span class="hlt">shock</span> <span class="hlt">wave</span> was demonstrated experimentally in a focusing media with a partially coherent beam [1]. Another way is to use a nonlocal media [2]. The impact of nonlocality is more important than the modulational instability frustration. Here, we use nematic liquid crystals (NLC) as Kerr-like nonlocal medium. To achieve <span class="hlt">shock</span> formation, we use the Riemann condition as initial spatial condition (edge at the beam entrance of the NLC cell). In these experimental conditions, we generate, experimentally and numerically, <span class="hlt">shock</span> <span class="hlt">waves</span> that relax through the emission of dispersive <span class="hlt">waves</span>. Associated with this phenomenon, we evidence the emergence of a localized <span class="hlt">wave</span> that travels through the transverse beam profile. The beam steepness, which is a good indicator of the <span class="hlt">shock</span> formation, is maximal at the <span class="hlt">shock</span> point position. This latter follows a power law versus the injected power as in [3]. Increasing the injected power, we found multiple <span class="hlt">shock</span> points. We have good agreements between the numerical simulations and the experimental results. [1] W. Wan, D. V Dylov, C. Barsi, and J. W. Fleischer, Opt. Lett. 35, 2819 (2010). [2] G. Assanto, T. R. Marchant, and N. F. Smyth, Phys. Rev. A - At. Mol. Opt. Phys. 78, 1 (2008). [3] N. Ghofraniha, L. S</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840008422','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840008422"><span><span class="hlt">Shock</span> conditions and <span class="hlt">shock</span> <span class="hlt">wave</span> structures in a steady flow in a dissipative fluid</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Germain, P.; Guiraud, J. P.</p> <p>1983-01-01</p> <p>More precisely, calling xi the reciprocal of the Reynolds number based on the <span class="hlt">shock</span> <span class="hlt">wave</span> curvature radius, the xi terms of the first order are systematically taken into account. The most important result is a system of formulas giving a correction of order xi for the various RANKINE-HUGONIOT conditions. The suggested formulas may for instance have to be used instead of the conventional ones to evaluate the loss of the total pressure across the detached <span class="hlt">shock</span> <span class="hlt">wave</span> which is found at the nose of a very small probe in supersonic flow.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010PhRvE..82e1915S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010PhRvE..82e1915S"><span><span class="hlt">Shock</span> <span class="hlt">wave</span> initiated by an ion passing through liquid water</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Surdutovich, Eugene; Solov'Yov, Andrey V.</p> <p>2010-11-01</p> <p>We investigate the <span class="hlt">shock</span> <span class="hlt">wave</span> produced by an energetic ion in liquid water. This <span class="hlt">wave</span> is initiated by a rapid energy loss when the ion moves through the Bragg peak. The energy is transferred from the ion to secondary electrons, which then transfer it to the water molecules. The pressure in the overheated water increases by several orders of magnitude and drives a cylindrical <span class="hlt">shock</span> <span class="hlt">wave</span> on a nanometer scale. This <span class="hlt">wave</span> eventually weakens as the front expands further; but before that, it may contribute to DNA damage due to large pressure gradients developed within a few nanometers from the ion’s trajectory. This mechanism of DNA damage may be a very important contribution to the direct chemical effects of low-energy electrons and holes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22252089','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22252089"><span>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('https://www.osti.gov/scitech/biblio/22403239','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22403239"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/21918295','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21918295"><span><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>2011-10-07</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://adsabs.harvard.edu/abs/2016ShWav..26...69H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ShWav..26...69H"><span>Response of ocean bottom dwellers exposed to underwater <span class="hlt">shock</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hosseini, S. H. R.; Kaiho, Kunio; Takayama, Kazuyoshi</p> <p>2016-01-01</p> <p>The paper reports results of experiments to estimate the mortality of ocean bottom dwellers, ostracoda, against underwater <span class="hlt">shock</span> <span class="hlt">wave</span> exposures. This study is motivated to verify the possible survival of ocean bottom dwellers, foraminifera, from the devastating underwater <span class="hlt">shock</span> <span class="hlt">waves</span> induced mass extinction of marine creatures which took place at giant asteroid impact events. Ocean bottom dwellers under study were ostracoda, the replacement of foraminifera, we readily sampled from ocean bottoms. An analogue experiment was performed on a laboratory scale to estimate the domain and boundary of over-pressures at which marine creatures' mortality occurs. Ostracods were exposed to underwater <span class="hlt">shock</span> <span class="hlt">waves</span> generated by the explosion of 100mg PETN pellets in a chamber at <span class="hlt">shock</span> over-pressures ranging up to 44MPa. Pressure histories were measured simultaneously on 113 samples. We found that bottom dwellers were distinctively killed against overpressures of 12MPa and this value is much higher than the usual <span class="hlt">shock</span> over-pressure threshold value for marine-creatures having lungs and balloons.</p> </li> </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/2016EGUGA..1810637M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1810637M"><span>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>Bubbles with <span class="hlt">shock</span> <span class="hlt">waves</span> and ultrasound: a review.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ohl, Siew-Wan; Klaseboer, Evert; Khoo, Boo Cheong</p> <p>2015-10-06</p> <p>The study of the interaction of bubbles with <span class="hlt">shock</span> <span class="hlt">waves</span> and ultrasound is sometimes termed 'acoustic cavitation'. It is of importance in many biomedical applications where sound <span class="hlt">waves</span> are applied. The use of <span class="hlt">shock</span> <span class="hlt">waves</span> and ultrasound in medical treatments is appealing because of their non-invasiveness. In this review, we present a variety of acoustics-bubble interactions, with a focus on <span class="hlt">shock</span> <span class="hlt">wave</span>-bubble interaction and bubble cloud phenomena. The dynamics of a single spherically oscillating bubble is rather well understood. However, when there is a nearby surface, the bubble often collapses non-spherically with a high-speed jet. The direction of the jet depends on the 'resistance' of the boundary: the bubble jets towards a rigid boundary, splits up near an elastic boundary, and jets away from a free surface. The presence of a <span class="hlt">shock</span> <span class="hlt">wave</span> complicates the bubble dynamics further. We shall discuss both experimental studies using high-speed photography and numerical simulations involving <span class="hlt">shock</span> <span class="hlt">wave</span>-bubble interaction. In biomedical applications, instead of a single bubble, often clouds of bubbles appear (consisting of many individual bubbles). The dynamics of such a bubble cloud is even more complex. We shall show some of the phenomena observed in a high-intensity focused ultrasound (HIFU) field. The nonlinear nature of the sound field and the complex inter-bubble interaction in a cloud present challenges to a comprehensive understanding of the physics of the bubble cloud in HIFU. We conclude the article with some comments on the challenges ahead.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22408340','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22408340"><span><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('https://www.ncbi.nlm.nih.gov/pubmed/24607758','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24607758"><span>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://adsabs.harvard.edu/abs/2005ASAJ..117.2372C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005ASAJ..117.2372C"><span>Secondary <span class="hlt">shock</span> <span class="hlt">wave</span> emissions from cavitation in lithotripsy</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>2005-04-01</p> <p>We investigate the role of secondary <span class="hlt">shock</span> <span class="hlt">waves</span> (SSWs) generated by cavitation in lithotripsy. Acoustic pressure was measured with a fiber optic probe hydrophone and cavitation using a dual passive cavitation detector (PCD) consisting of two confocal transducers. An artificial stone (~7 mm diameter and ~9 mm length) was placed at the focus of an electrohydraulic lithotripter. The fiber was inserted through a hole drilled through the stone so that the tip was at the proximal surface. SSWs were identified by matching the time of arrival to that of the inertial collapse signature acquired by the PCD. Measurements of SSWs were obtained for 50% of SWs fired at 20 kV and 1 Hz. The peak positive pressure for the SSW was p+=33.7+/-14.8 MPa, which was comparable to the pressure induced by the incident SW (p+=42.6+/-6 MPa). The peak pressure in water was p+=23.2+/-4.4 MPa. The PCD also recorded acoustic emissions from forced collapse of pre-existing bubbles caused by the incident SW. We propose that both the <span class="hlt">reflection</span> from the semi-rigid stone boundary and SSW from the forced collapse contribute to the observed increase in the peak pressure of the incident SW in presence of a stone. [Work supported by NIH.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22130476','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22130476"><span><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('https://www.ncbi.nlm.nih.gov/pubmed/8687173','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/8687173"><span>[Biochemical evaluation of renal lesions produced by electrohydraulic <span class="hlt">shock</span> <span class="hlt">waves</span>].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rodriguez Vela, L; Abadia Bayona, T; Lazaro Castillo, J; Guallar Labrador, A; Rioja Sanz, C; Rioja Sanz, L A</p> <p>1995-01-01</p> <p>The authors present a biochemical study of the renal lesions produced during extracorporeal electrohydraulic <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy (ESWL). The sequential variation (before and after ESWL) of various biochemical parameters of the blood and 24-hour urine was analysed in 50 patients. A significant increase of urinary N-Acetyl-Glucosaminidase (NAG), urinary NAG/urinary creatinine quotient, proteinuria, serum creatinine and potassium was detected during the 24 hours following ESWL. A significant fall in creatinine clearance, urinary osmolarity and uric acid clearance was also detected. A positive correlation was observed between these alterations, the number of <span class="hlt">shocks</span> and the kilovoltage used. On the 7th and 15th days, no significant difference was observed compared to the baseline values before ESWL. This can be explained by the fact that the lesions caused by <span class="hlt">shock</span> <span class="hlt">waves</span> are already in the repair phase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5184169','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5184169"><span><span class="hlt">Shock</span> <span class="hlt">wave</span> compression and metallization of simple molecules</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ross, M.; Radousky, H.B.</p> <p>1988-03-01</p> <p>In this paper we combine <span class="hlt">shock</span> <span class="hlt">wave</span> studies and metallization of simple molecules in a single overview. The unifying features are provided by the high <span class="hlt">shock</span> temperatures which lead to a metallic-like state in the rare gases and to dissociation of diatomic molecules. In the case of the rare gases, electronic excitation into the conduction band leads to a metallic-like inert gas state at lower than metallic densities and provides information regarding the closing of the band gap. Diatomic dissociation caused by thermal excitation also leads to a final metallic-like or monatomic state. Ina ddition, <span class="hlt">shock</span> <span class="hlt">wave</span> data can provide information concerning the short range intermolecular force of the insulator that can be useful for calculating the metallic phase transition as for example in the case of hydrogen. 69 refs., 36 figs., 2 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910067030&hterms=1092&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D%2526%25231092','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910067030&hterms=1092&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D%2526%25231092"><span>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://adsabs.harvard.edu/abs/2017AAS...22915002R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AAS...22915002R"><span><span class="hlt">Shock</span> <span class="hlt">waves</span> and particle acceleration in clusters of galaxies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ryu, Dongsu; Kang, Hyesung; Ha, Ji-Hoon</p> <p>2017-01-01</p> <p>During the formation of the large-scale structure of the universe, intracluster media (ICMs), which fills the volume of galaxy clusters and is composed of hot, high-beta plasma, are continuously disturbed by major and minor mergers of clumps as well as infall along filaments of the warm-hot intergalactic medium (WHIM). Such activities induce <span class="hlt">shock</span> <span class="hlt">waves</span>, which are observed in radio and X-ray mostly in cluster outskirts. These <span class="hlt">shocks</span> are collisionless, as in other astrophysical environments, and are thought to accelerate cosmic rays (CRs) via diffusive <span class="hlt">shock</span> acceleration (DSA) mechanism. Here, we present the properties of <span class="hlt">shocks</span> in ICMs and their roles in the generation of nonthermal particles, studied with high-resolution simulations. We also discuss the implications on the observations of diffuse radio emission from galaxy clusters, such as radio relics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830025956','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830025956"><span>Numerical computations of turbulence amplification in <span class="hlt">shock</span> <span class="hlt">wave</span> interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zang, T. A.; Hussaini, M. Y.; Bushnell, D. M.</p> <p>1983-01-01</p> <p>Numerical computations are presented which illustrate and test various effects pertinent to the amplification and generation of turbulence in <span class="hlt">shock</span> <span class="hlt">wave</span> turbulent boundary layer interactions. Several fundamental physical mechanisms are identified. Idealizations of these processes are examined by nonlinear numerical calculations. The results enable some limits to be placed on the range of validity of existing linear theories.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/3578316','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/3578316"><span>Principles and application of extracorporeal <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>Robinson, S N; Crane, V S; Jones, D G; Cochran, J S; Williams, O B</p> <p>1987-04-01</p> <p>The physics, instrumentation, and patient-care aspects of extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy (ESWL) in the treatment of kidney stone disease are described. The kidney stone is located through the use of two integrated roentgenographic imaging systems. The x-ray tubes, fixed on either side of a tub of water in which the patient is partially immersed, are directed upward. The patient is maneuvered until the imaging systems indicate the kidney stone is within the second focus of the reflector and within the 1.5-cu cm target area. Once within this alignment, the stone is ready for <span class="hlt">shock</span> <span class="hlt">wave</span> treatment; general or regional anesthesia is used to immobilize the patient so that the position of the stone can be maintained within the focus of the <span class="hlt">shock</span> <span class="hlt">wave</span>. When the stone is repeatedly subjected to this high-energy force, it begins to disintegrate until fragments of less than 1 mm are left. ESWL can (1) disintegrate kidney stones of all types, (2) be efficiently transmitted over distances that allow the <span class="hlt">shock</span> <span class="hlt">wave</span> source to be outside the body, (3) safely pass through living tissue, and (4) be precisely controlled and focused into a small target area. ESWL is a safe, effective, and cost-saving treatment that can be used for 90% of all kidney stone disease that previously required surgery.</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>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.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2145985','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2145985"><span>Treatment of Renal Calculi with Extracorporeal <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>Eberwein, P. M.; Denstedt, J. D.</p> <p>1992-01-01</p> <p>In 12 years, extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy has replaced other treatment techniques for most surgical calculi in the upper urinary tract. Worldwide clinical series have documented its efficacy. Technological advances and modifications have significantly expanded the clinical applications of this technique. Imagesp1673-aFigure 3 PMID:21221368</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA630780','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA630780"><span>Effects of Surf Zone Sediment Properties on <span class="hlt">Shock</span> <span class="hlt">Wave</span> Behavior</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2016-06-07</p> <p>mines is critically dependent upon the propagation effectiveness of <span class="hlt">shock</span> <span class="hlt">waves</span> from the charge to the mine . Data and modeling show that this...doing performance prediction for the Navy mine neutralization systems currently undergoing operational evaluation. TRANSITIONS The data has been...response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing</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>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('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>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.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>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://hdl.handle.net/2060/20150003513','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150003513"><span>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://adsabs.harvard.edu/abs/2016APS..DFD.L5007R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFD.L5007R"><span>Regularized Moment Equations and <span class="hlt">Shock</span> <span class="hlt">Waves</span> for Rarefied Granular Gas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Reddy, Lakshminarayana; Alam, Meheboob</p> <p>2016-11-01</p> <p>It is well-known that the <span class="hlt">shock</span> structures predicted by extended hydrodynamic models are more accurate than the standard Navier-Stokes model in the rarefied regime, but they fail to predict continuous <span class="hlt">shock</span> structures when the Mach number exceeds a critical value. Regularization or parabolization is one method to obtain smooth <span class="hlt">shock</span> profiles at all Mach numbers. Following a Chapman-Enskog-like method, we have derived the "regularized" version 10-moment equations ("R10" moment equations) for inelastic hard-spheres. In order to show the advantage of R10 moment equations over standard 10-moment equations, the R10 moment equations have been employed to solve the Riemann problem of plane <span class="hlt">shock</span> <span class="hlt">waves</span> for both molecular and granular gases. The numerical results are compared between the 10-moment and R10-moment models and it is found that the 10-moment model fails to produce continuous <span class="hlt">shock</span> structures beyond an upstream Mach number of 1 . 34 , while the R10-moment model predicts smooth <span class="hlt">shock</span> profiles beyond the upstream Mach number of 1 . 34 . The density and granular temperature profiles are found to be asymmetric, with their maxima occurring within the <span class="hlt">shock</span>-layer.</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://hdl.handle.net/2060/19840009453','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840009453"><span><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/2016PhyD..333..310X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhyD..333..310X"><span>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://adsabs.harvard.edu/abs/2016EGUGA..18..200S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18..200S"><span>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('https://www.osti.gov/scitech/biblio/22486428','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22486428"><span>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/abs/2017PhRvB..95c5418K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvB..95c5418K"><span>Plasmonic <span class="hlt">shock</span> <span class="hlt">waves</span> and solitons in a nanoring</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koshelev, K. L.; Kachorovskii, V. Yu.; Titov, M.; Shur, M. S.</p> <p>2017-01-01</p> <p>We apply the hydrodynamic theory of electron liquid to demonstrate that a circularly polarized radiation induces the diamagnetic, helicity-sensitive dc current in a ballistic nanoring. This current is dramatically enhanced in the vicinity of plasmonic resonances. The resulting magnetic moment of the nanoring represents a giant increase of the inverse Faraday effect. With increasing radiation intensity, linear plasmonic excitations evolve into the strongly nonlinear plasma <span class="hlt">shock</span> <span class="hlt">waves</span>. These excitations produce a series of the well-resolved peaks at the THz frequencies. We demonstrate that the plasmonic <span class="hlt">wave</span> dispersion transforms the <span class="hlt">shock</span> <span class="hlt">waves</span> into solitons. The predicted effects should enable multiple applications in a wide frequency range (from the microwave to terahertz band) using optically controlled ultralow-loss electric, photonic, and magnetic devices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20719181','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20719181"><span>Energetic Particle Transport in Strong Compressive <span class="hlt">Wave</span> Turbulence Near <span class="hlt">Shocks</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Le Roux, J.A.; Zank, G.P.; Li, G.; Webb, G.M.</p> <p>2005-08-01</p> <p>Strong interplanetary coronal mass ejection driven <span class="hlt">shocks</span> are often accompanied by high levels of low frequency compressive <span class="hlt">wave</span> turbulence. This might require a non-linear kinetic theory approach to properly describe energetic particle transport in their vicinity. We present a non-linear diffusive kinetic theory for suprathermal particle transport and stochastic acceleration along the background magnetic field in strong compressive dynamic <span class="hlt">wave</span> turbulence to which small-scale Alfven <span class="hlt">waves</span> are coupled. Our theory shows that the standard cosmic-ray transport equation must be revised for low suprathermal particle energies to accommodate fundamental changes in spatial diffusion (standard diffusion becomes turbulent diffusion) as well as modifications to particle convection, and adiabatic energy changes. In addition, a momentum diffusion term, which generates accelerated suprathermal particle spectra with a hard power law, must be added. Such effective first stage acceleration possibly leads to efficient injection of particles into second stage diffusive <span class="hlt">shock</span> acceleration as described by standard theory.</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>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/2016APS..DFD.H5002K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFD.H5002K"><span>Simulations of <span class="hlt">Shock</span> <span class="hlt">Wave</span> Interaction with a Particle Cloud</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koneru, Rahul; Rollin, Bertrand; Ouellet, Frederick; Annamalai, Subramanian; Balachandar, S.'Bala'</p> <p>2016-11-01</p> <p>Simulations of a <span class="hlt">shock</span> <span class="hlt">wave</span> interacting with a cloud of particles are performed in an attempt to understand similar phenomena observed in dispersal of solid particles under such extreme environment as an explosion. We conduct numerical experiments in which a particle curtain fills only 87% of the <span class="hlt">shock</span> tube from bottom to top. As such, the particle curtain upon interaction with the <span class="hlt">shock</span> <span class="hlt">wave</span> is expected to experience Kelvin-Helmholtz (KH) and Richtmyer-Meshkov (RM) instabilities. In this study, the initial volume fraction profile matches with that of Sandia Multiphase <span class="hlt">Shock</span> Tube experiments, and the <span class="hlt">shock</span> Mach number is limited to M =1.66. In these simulations we use a Eulerian-Lagrangian approach along with state-of-the-art point-particle force and heat transfer models. Measurements of particle dispersion are made at different initial volume fractions of the particle cloud. A detailed analysis of the evolution of the particle curtain with respect to the initial conditions is presented. This work was supported by the U.S. Department of Energy, National Nuclear Security Administration, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, Contract No. DE-NA0002378.</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>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('https://www.ncbi.nlm.nih.gov/pubmed/17467154','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17467154"><span>Acoustic field of a ballistic <span class="hlt">shock</span> <span class="hlt">wave</span> therapy device.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cleveland, Robin O; Chitnis, Parag V; McClure, Scott R</p> <p>2007-08-01</p> <p><span class="hlt">Shock</span> <span class="hlt">wave</span> therapy (SWT) refers to the use of focused <span class="hlt">shock</span> <span class="hlt">waves</span> for treatment of musculoskeletal indications including plantar fascitis and dystrophic mineralization of tendons and joint capsules. Measurements were made of a SWT device that uses a ballistic source. The ballistic source consists of a handpiece within which compressed air (1-4 bar) is used to fire a projectile that strikes a metal applicator placed on the skin. The projectile generates stress <span class="hlt">waves</span> in the applicator that transmit as pressure <span class="hlt">waves</span> into tissue. The acoustic fields from two applicators were measured: one applicator was 15 mm in diameter and the surface slightly convex and the second was 12 mm in diameter the surface was concave. Measurements were made in a water tank and both applicators generated a similar pressure pulse consisting of a rectangular positive phase (4 micros duration and up to 8 MPa peak pressure) followed by a predominantly negative tail (duration of 20 micros and peak negative pressure of -6 MPa), with many oscillations. The rise times of the waveforms were around 1 micros and were shown to be too long for the pulses to be considered <span class="hlt">shock</span> <span class="hlt">waves</span>. Measurements of the field indicated that region of high pressure was restricted to the near-field (20-40 mm) of the source and was consistent with the Rayleigh distance. The measured acoustic field did not display focusing supported by calculations, which demonstrated that the radius of curvature of the concave surface was too large to effect a focusing gain. Other SWT devices use electrohydraulic, electromagnetic and piezoelectric sources that do result in focused <span class="hlt">shock</span> <span class="hlt">waves</span>. This difference in the acoustic fields means there is potentially a significant mechanistic difference between a ballistic source and other SWT devices.</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>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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ShWav..27..179Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ShWav..27..179Z"><span>Experimental research on dust lifting by propagating <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>Żydak, P.; Oleszczak, P.; Klemens, R.</p> <p>2017-03-01</p> <p>The aim of the presented work was to study the dust lifting process from a layer of dust behind a propagating <span class="hlt">shock</span> <span class="hlt">wave</span>. The experiments were conducted with the use of a <span class="hlt">shock</span> tube and a specially constructed, five-channel laser optical device enabling measurements at five positions located in one vertical plane along the height of the tube. The system enabled measurements of the delay in lifting up of the dust from the layer, and the vertical velocity of the dust cloud was calculated from the dust concentration measurements. The research was carried out for various initial conditions and for three fractions of black coal dust. In the presented tests, three <span class="hlt">shock</span> <span class="hlt">wave</span> velocities: 450, 490 and 518 m/s and three dust layer thicknesses, equal to 1.0, 1.5 and 2.0 mm, were taken into consideration. On the grounds of the obtained experimental results, it was assumed that the vertical component of the lifted dust velocity is a function of the dust particle diameter, the velocity of the air flow in the channel, the layer thickness and the dust bulk density. It appeared, however, that lifting up of the dust from the thick layers, thicker than 1 mm, is a more complex process than that from thin layers and still requires further research. A possible explanation is that the <span class="hlt">shock</span> <span class="hlt">wave</span> action upon the thick layer results in its aggregation in the first stage of the dispersing process, which suppresses the dust lifting process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/12444','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/12444"><span>Iron sound velocities in <span class="hlt">shock</span> <span class="hlt">wave</span> experiments</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Holmes, N C; Nguyen, J H</p> <p>1999-08-20</p> <p>We have performed a series of sound velocity measurements in iron at earth's core pressures. Experiments were carried out at <span class="hlt">shock</span> pressures as high as 400 GPa, with particular emphasis on the pressure range between 175 GPa and 275 GPa. The measured sound velocities of iron at elevated pressures exhibit a single discontinuity near 250 GPa, corresponding to the vanishing of shear strength as the iron melts. A second discontinuity reported by Brown and McQueen in their previous iron sound velocity studies was not observed in our study. Our results are consistent with their data otherwise. Experimental details and error propagation techniques essential to determining the melting point will also be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005shwa.book.1113A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005shwa.book.1113A"><span>Development of the hybrid numerical simulation to clarify <span class="hlt">shock</span> viscosity effects in a plastic <span class="hlt">shock</span> <span class="hlt">wave</span> front</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Abe, A.</p> <p></p> <p><span class="hlt">Shock</span> viscous stress can be defined as the stress differences between the stress on Rayleigh line and the equilibrium stress at the same strain. The <span class="hlt">shock</span> viscous stress is one of the important parameters with respect to rising times of elastic and plastic <span class="hlt">shock</span> <span class="hlt">wave</span> fronts [1]. Swegle and Grady took the routine program of the <span class="hlt">shock</span> viscous stress into their one-dimensional finite difference <span class="hlt">wave</span> code, and they predicted the <span class="hlt">shock</span> <span class="hlt">wave</span> rise times occurred in several kind of materials with relatively small stress impacts [2]. Their numerical results seemed to represent the experimental results measured by the velocity interferometer system (VISAR). Strictly speaking, however, their method was not sufficiently accurate because their expression of the <span class="hlt">shock</span> viscous stress was the stress differences between Rayleigh line and Hugoniot. Recently, we had proposed a new analytical method to get temperature in steady <span class="hlt">shock</span> <span class="hlt">wave</span> fronts and the effects were ascertained for a ceramic material and some metals [3-6]. When we derive the temperature in <span class="hlt">shock</span> <span class="hlt">wave</span> fronts by our method, we can also get the quasistatic (equilibrium) stresses. Therefore, it is possible to obtain the <span class="hlt">shock</span> viscous stress analytically. The structured variations in the <span class="hlt">shock</span> <span class="hlt">wave</span> rising process are closely related to the dissipative processes in the material, and it is interesting to investigate these structured characteristics.</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>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://hdl.handle.net/2060/19930002418','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930002418"><span>Turbulence modeling in <span class="hlt">shock</span> <span class="hlt">wave</span>/turbulent boundary layer interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smits, A. J.</p> <p>1992-01-01</p> <p>The research performed was an experimental program to help develop turbulence models for <span class="hlt">shock</span> <span class="hlt">wave</span> boundary layer interactions. The measurements were taken in a Mach 3, 16 deg compression corner interaction, at a unit Reynolds number of 63 x 10(exp 6)/m. The data consisted of heat transfer data taken upstream and downstream of the interaction, hot wire measurements of the instantaneous temperature and velocity fluctuations to verify the Strong Reynolds Analogy, and single- and double-pulsed Rayleigh scattering images to study the development of the instantaneous <span class="hlt">shock</span>/turbulence interaction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA433330','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA433330"><span>Detonation Initiation by Annular Jets and <span class="hlt">Shock</span> <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2007-11-02</p> <p>11,12,13,14,15,16,17,18, 19,20,21,22 to better understand the <span class="hlt">shock</span> implosion process. The current interest in air-breathing pulse detonation engines ( PDEs ) has led...This technology has yet to be realized and, as a result, current PDEs use initiator tubes sensitized with oxygen 23 or detonate more sensitive mixtures... Detonation Initiation by Annular Jets and <span class="hlt">Shock</span> <span class="hlt">Waves</span> Final Report for Award ONR N00014-03 -0931 Joseph E. Shepherd Aeronautics California Institute</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><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://adsabs.harvard.edu/abs/2015shw1.conf...83M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015shw1.conf...83M"><span><span class="hlt">Shock</span> Tube Simulation of Low Mach Number Blast <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>Morgan, R. G.; Gildfind, D. E.</p> <p></p> <p>The underground mining environment has always been high risk due to the presence of solid and gaseous flammables, and the potential for the creation of detonablemixtures. Following explosions in confined spaces, <span class="hlt">shock</span> <span class="hlt">waves</span> are generated and may propagate through the tunnel system, causing injuries and possibly initiating further combusting or detonating events. The ability to generate the conditions which exist post <span class="hlt">shock</span> is a useful experimental tool for the study of such processes, and for the evaluation of techniques to control and limit propagation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://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="https://ntrs.nasa.gov/search.jsp?R=19720052777&hterms=organic+synthesis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dorganic%2Bsynthesis"><span>'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> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24765974','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24765974"><span><span class="hlt">Shock-wave</span> compression and Joule-Thomson expansion.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hoover, Wm G; Hoover, Carol G; Travis, Karl P</p> <p>2014-04-11</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('https://ntrs.nasa.gov/search.jsp?R=19830012590&hterms=Atmospheric+Absorption+spectrum+Infrared&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DAtmospheric%2BAbsorption%2Bspectrum%2B%2BInfrared','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830012590&hterms=Atmospheric+Absorption+spectrum+Infrared&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DAtmospheric%2BAbsorption%2Bspectrum%2B%2BInfrared"><span><span class="hlt">Shock</span> <span class="hlt">waves</span>, atmospheric structure and mass loss in Miras</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Willson, L. A.; Pierce, J. N.</p> <p>1981-01-01</p> <p>Large amplitude <span class="hlt">shock</span> <span class="hlt">waves</span> are observed to be present in the atmospheres of the Mira variables: spectral line doubling with Delta v 30 km/s is present in infrared spectra. Even the visible spectra contain some evidence for such <span class="hlt">shocks</span>. These <span class="hlt">shocks</span> are sufficiently large to clearly dominate the energy balance of the atmosphere. Mira variables also show symptoms of substantial mass loss rates: they are strong maser and infrared continuum sources and have strong circumstellar absorption features. The pulsation induced <span class="hlt">shocks</span> which are seen to be present are obvious suspects for causing or enhancing the mass loss from these stars. The Miras thus present an ideal case for the study of dynamical effects on atmospheric structure, since both the dynamics and the results are clearly observable. The results are given of calculations of the thermalization and cooling of the <span class="hlt">shock</span> heated material passing through <span class="hlt">shock</span> fronts whose properties were selected to be consistent with both the isothermal models and the spectroscopic observations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1266106','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1266106"><span>Potential theory for <span class="hlt">shock</span> <span class="hlt">reflection</span> by a large-angle wedge</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Chen, Gui-Qiang; Feldman, Mikhail</p> <p>2005-01-01</p> <p>When a plane <span class="hlt">shock</span> hits a wedge head on, it experiences a <span class="hlt">reflection</span>, and then a self-similar <span class="hlt">reflected</span> <span class="hlt">shock</span> moves outward as the original <span class="hlt">shock</span> moves forward in time. Experimental, computational, and asymptotic analysis has shown that various patterns of <span class="hlt">reflected</span> <span class="hlt">shocks</span> may occur, including regular and Mach <span class="hlt">reflection</span>. However, most fundamental issues for <span class="hlt">shock</span> <span class="hlt">reflection</span> phenomena have not been understood, such as the transition among the different patterns of <span class="hlt">shock</span> <span class="hlt">reflection</span>; therefore, it is essential to establish a global existence and stability theory for <span class="hlt">shock</span> <span class="hlt">reflection</span>. On the other hand, there has been no rigorous mathematical result on the global existence and stability of solutions to <span class="hlt">shock</span> <span class="hlt">reflection</span>, especially for potential flow, which has widely been used in aerodynamics. The theoretical problems involve several challenging difficulties in the analysis of nonlinear partial differential equations including elliptic-hyperbolic mixed type, free-boundary problems, and corner singularity, especially when an elliptic degenerate curve meets a free boundary. Here we develop a potential theory to overcome these difficulties and to establish the global existence and stability of solutions to <span class="hlt">shock</span> <span class="hlt">reflection</span> by a large-angle wedge for potential flow. The techniques and ideas developed will be useful to other nonlinear problems involving similar difficulties. PMID:16230619</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950039618&hterms=lead+generation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dlead%2Bgeneration','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950039618&hterms=lead+generation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dlead%2Bgeneration"><span><span class="hlt">Shock</span> propagation and the generation of magnetohydrodynamic <span class="hlt">wave</span> fields in inhomogeneous molecular clouds</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Miesch, Mark S.; Zweibel, Ellen G.</p> <p>1994-01-01</p> <p>We develop a simple one-dimensional model for the interaction of a steady, thin, planar <span class="hlt">shock</span> <span class="hlt">wave</span> with a nonrigid cloud which may be in motion relative to the surrounding medium, and we apply the model to <span class="hlt">shocks</span> impinging on, and propagating through, molecular clouds. Both 'adiabatic' (gamma = 5/3) and radiative (gamma = 1) <span class="hlt">shocks</span> are considered and we allow for the presence of a uniform magnetic field directed either parallel or perpendicular to the <span class="hlt">shock</span> normal. The former field orientation is equivalent to the hydrodynamic case, and the latter involves only fast MHD <span class="hlt">shocks</span>. We focus on the manner in which such <span class="hlt">shocks</span> can generate internal kinetic motions in the cloud on a range of size and density scales through the direct acceleration of cores and clumps by <span class="hlt">shocks</span> transmitted into them and through the generation of an MHD wavefield via the <span class="hlt">reflection</span> of the incident <span class="hlt">shock</span> at clump boundaries. We find that stronger incident Mach numbers and smaller density contrasts lead to more efficient cloud acceleration, as do isothermal intercloud <span class="hlt">shocks</span> and small intercloud magnetic field strengths. The acceleration efficiency is insensitive to the adiabatic index and the magnetic field strength in the cloud itself. For typical parameter choices, the direct acceleration of clouds and clumps by strong <span class="hlt">shocks</span> is found to be substantial and could at least in part account for their observed velocity dispersions. If the <span class="hlt">shocks</span> are moderately weak, the final velocity of the cloud is linearly related to its initial velocity, with higher acceleration giving shallower slopes (i.e., final velocity distributions which are less sensitive to the initial distribution). Compared to the kinetic energy of the postshock cloud, the energy given to the wavefield at each encounter is small, and the heating of the interclump medium by the dissipation of this wavefield is found to be insufficient to balance the cooling rate in the cloud as a whole (although it may be important in particular</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005ASAJ..117.2370P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005ASAJ..117.2370P"><span><span class="hlt">Shock</span> <span class="hlt">wave</span> lithotripsy at 60 or 120 <span class="hlt">shocks</span> per minute: A randomized, double-blinded trial</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pace, Kenneth; Ghiculete, Daniela; Harju, Melanie; Honey, R. John</p> <p>2005-04-01</p> <p>Rate of <span class="hlt">shock</span> <span class="hlt">wave</span> administration is a factor in the per-<span class="hlt">shock</span> efficiency of SWL. Decreasing <span class="hlt">shock</span> <span class="hlt">wave</span> frequency from 120 <span class="hlt">shocks</span> per minute (s/m) may improve stone fragmentation. This study is the first to test this hypothesis in vivo. Patients with previously untreated radio-opaque kidney stones were randomized to SWL at 60 or 120 s/m and followed at 2 weeks and 3 months. Primary outcome was success rate, defined as stone-free or asymptomatic fragments 5 mm in size 3 months post-treatment. 111 patients were randomized to 60 s/m and 109 to 120 s/m. The groups were comparable on age, gender, BMI, stent status, and initial stone area. Success rate was higher for 60 s/m (75% versus 61%, p=0.027). Patients with stone area 100 mm2 experienced the greatest benefit: success rates were 71% for 60 s/m versus 32% (p=0.002), and stone-free rates were 60% versus 28% (p=0.015). Repeat SWL treatment was required in 32% treated at 120 s/m versus 18% (p=0.018). Fewer <span class="hlt">shocks</span> were required (2423 versus 2906, p=0.001), but treatment time was longer (40.6 versus 24.2 minutes, p=0.001). SWL treatment at 60 s/m yields better outcomes than 120 s/m, particularly for stones 100 mm2.</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>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/2060/19980214919','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980214919"><span>Transonic <span class="hlt">Shock-Wave</span>/Boundary-Layer Interactions on an Oscillating Airfoil</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Davis, Sanford S.; Malcolm, Gerald N.</p> <p>1980-01-01</p> <p>Unsteady aerodynamic loads were measured on an oscillating NACA 64A010 airfoil In the NASA Ames 11 by 11 ft Transonic Wind Tunnel. Data are presented to show the effect of the unsteady <span class="hlt">shock-wave</span>/boundary-layer interaction on the fundamental frequency lift, moment, and pressure distributions. The data show that weak <span class="hlt">shock</span> <span class="hlt">waves</span> induce an unsteady pressure distribution that can be predicted quite well, while stronger <span class="hlt">shock</span> <span class="hlt">waves</span> cause complex frequency-dependent distributions due to flow separation. An experimental test of the principles of linearity and superposition showed that they hold for weak <span class="hlt">shock</span> <span class="hlt">waves</span> while flows with stronger <span class="hlt">shock</span> <span class="hlt">waves</span> cannot be superimposed.</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>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('https://ntrs.nasa.gov/search.jsp?R=19750035255&hterms=lead+generation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dlead%2Bgeneration','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19750035255&hterms=lead+generation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dlead%2Bgeneration"><span>A model for generation of bow-<span class="hlt">shock</span>-associated upstream <span class="hlt">waves</span>. [in solar wind</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fredricks, R. W.</p> <p>1975-01-01</p> <p>A model is proposed for the generation of upstream hydromagnetic <span class="hlt">waves</span> by proton beams <span class="hlt">reflected</span> at the earth's bow <span class="hlt">shock</span>. It is assumed that the <span class="hlt">reflection</span> process can produce some gyrophase bunching of the protons, thus creating a gyrophase disturbance that propagates with the beam as it streams back along interplanetary field lines. This leads to the production of driven hydromagnetic <span class="hlt">waves</span> in the left-hand mode. The resulting theory predicts a <span class="hlt">wave</span> amplitude, frequency, and polarization in the solar wind rest frame. The amplitude depends on the fraction of protons assumed to be phase coherent in their gyromotion and on the plasma beta, beam velocity, temperatures, and the Alfven Mach number. The theory also predicts the Doppler-shifted frequencies and the apparent sense of polarization that would be observed in satellite measurement frames.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005ASAJ..117.3389T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005ASAJ..117.3389T"><span>A note on <span class="hlt">reflection</span> of spherical <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>Taraldsen, Gunnar</p> <p>2005-06-01</p> <p>In 1909 Sommerfeld gave an exact solution for the <span class="hlt">reflection</span> of a spherical <span class="hlt">wave</span> from a plane surface in terms of an oscillatory integral and also presented an asymptotic solution for the case where both source and receiver are at the boundary. Weyl (1919) presented an alternative solution and also an asymptotic solution for the case where the source is at the boundary. It is known that the general case is solved if a general solution for the case where the source is at the boundary is known. Here it is demonstrated that it is sufficient to have the general solution for the case where both source and receiver are at the boundary. This is mainly of theoretical interest, but may have practical applications. As an example it is demonstrated that Sommerfeld's approximate solution gives Ingard's (1951) approximate solution which is valid for arbitrary source and receiver heights. .</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930035432&hterms=asme&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dasme','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930035432&hterms=asme&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dasme"><span>Hypersonic flow separation in <span class="hlt">shock</span> <span class="hlt">wave</span> boundary layer interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hamed, A.; Kumar, Ajay</p> <p>1992-01-01</p> <p>An assessment is presented for the experimental data on separated flow in <span class="hlt">shock</span> <span class="hlt">wave</span> turbulent boundary layer interactions at hypersonic and supersonic speeds. The data base consists mainly of two dimensional and axisymmetric interactions in compression corners or cylinder-flares, and externally generated oblique <span class="hlt">shock</span> interactions with boundary layers over flat plates or cylindrical surfaces. The conditions leading to flow separation and the subsequent changes in the flow empirical correlations for incipient separation are reviewed. The effects of the Mach number, Reynolds number, surface cooling and the methods of detecting separation are discussed. The pertinent experimental data for the separated flow characteristics in separated turbulent boundary layer <span class="hlt">shock</span> interaction are also presented and discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19740043047&hterms=streaming&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dstreaming','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19740043047&hterms=streaming&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dstreaming"><span>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. Magnetic effects on the ion beams are included, but the electrons are treated as a magnetized fluid. 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. These results are extensions of Kovner's analysis for weak beams. The parameters are then chosen to be applicable for parallel <span class="hlt">shocks</span>. It is 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.</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>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/2002PhDT.........5M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002PhDT.........5M"><span>Particle Acceleration at Relativistic and Ultra-Relativistic <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>Meli, A.</p> <p></p> <p>We perform Monte Carlo simulations using diffusive <span class="hlt">shock</span> acceleration at relativistic and ultra-relativistic <span class="hlt">shock</span> <span class="hlt">waves</span>. High upstream flow gamma factors are used, Γ=(1-uup2/c2)-0.5, which are relevant to models of ultra-relativistic particle <span class="hlt">shock</span> acceleration in the central engines and relativistic jets of Active Galactic Nuclei (AGN) and in Gamma-Ray Burst (GRB) fireballs. Numerical investigations are carried out on acceleration properties in the relativistic and ultra-relativistic flow regime (Γ ˜ 10-1000) concerning angular distributions, acceleration time scales, particle energy gain versus number of crossings and spectral shapes. We perform calculations for both parallel and oblique sub-luminal and super-luminal <span class="hlt">shocks</span>. For parallel and oblique sub-luminal <span class="hlt">shocks</span>, the spectra depend on whether or not the scattering is represented by pitch angle diffusion or by large angle scattering. The large angle case exhibits a distinctive structure in the basic power-law spectrum not nearly so obvious for small angle scattering. However, both cases yield a significant 'speed-up' of acceleration rate when compared with the conventional, non-relativistic expression, tacc=[c/(uup-udown)] (λup/uup+λdown/udown). An energization by a factor Γ2 for the first crossing cycle and a large energy gains for subsequent crossings as well as the high 'speed-up' factors found, are important in supporting past works, especially the models developed by Vietri and Waxman on ultra-high energy cosmic ray, neutrino and gamma-ray production in GRB. For oblique super-luminal <span class="hlt">shocks</span>, we calculate the energy gain and spectral shape for a number of different inclinations. For this case the acceleration of particles is 'pictured' by a <span class="hlt">shock</span> drift mechanism. We use high gamma flows with Lorentz factors in the range 10-40 which are relevant to ultra-relativistic <span class="hlt">shocks</span> in AGN accretion disks and jets. In all investigations we closely follow the particle's trajectory along the magnetic field</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhDT........41O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhDT........41O"><span>Oblique <span class="hlt">Shock</span> <span class="hlt">Wave</span> Effects on Impulsively Accelerated Heavy Gas Column</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Olmstead, Dell T.</p> <p></p> <p>An experimental study was performed to elucidate the fundamental physics of <span class="hlt">shock</span>-induced mixing for a simple three-dimensional interface. The interface studied consists of a gravity stabilized SF6-based heavy gas jet that produced a circular column with a diffuse interface into the surrounding air. The effects of density gradient (Atwood number, A), <span class="hlt">shock</span> strength (Mach number, M), and column inclination angle (theta) were examined. Concentration was measured using Planar Laser Induced Fluorescence (PLIF) of an acetone vapor tracer mixed with the heavy gas jet and illuminated by a pulsed Nd-YAG laser. <span class="hlt">Shocks</span> with Mach numbers of 1.13, 1.5, 1.7, and 2.0 were used for inclinations of 0° (planar normal <span class="hlt">shock</span> <span class="hlt">wave</span>), 20° and 30°. Columns with Atwood numbers of 0.25, 0.4, and 0.60 were tested at Mach 1.7 for inclinations of 0° and 20°. The oblique <span class="hlt">shock</span>-accelerated cylindrical interface produced a typical Richtmyer-Meshkov instability (RMI) consisting of a primary counter-rotating vortices. The streamwise extent of the vortex pair in the centerline plane (cross-section) images of the column is proportional to √A/√ M, regardless of oblique <span class="hlt">shock</span> angle for theta < 20. A heretofore unseen manifestation of Kelvin-Helmholtz (K-H) <span class="hlt">waves</span> on the upstream edge of the column appear for oblique <span class="hlt">shock</span> acceleration. The upstream edge K-H <span class="hlt">waves</span> were observed in images from a vertical plane through the center of the column. The wavelength of the upstream edge K-H <span class="hlt">waves</span> is proportional to theta/M ˙ √A. This upstream edge K-H instability (KHI) caused earlier onset of secondary instabilities in the primary RMI vortices seen in the centerline plane images. The combination of more rapid onset of secondary instabilities in the RMI and upstream edge KHI accelerated transition to turbulence and thus reduced the time to achieve well-mixed flow. Time to reach well-mixed flow was inversely related to Atwood number, and had a weak correlation with Mach number for M>1.13. Transition to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930093827','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930093827"><span>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>1955-01-01</p> <p>An investigation has been conducted on a small-scale test layout in which direct observation of the <span class="hlt">shock</span> <span class="hlt">wave</span> movement with time could be made in order to determine the effects of surface roughness on the characteristics of spherical <span class="hlt">shock</span> <span class="hlt">waves</span>. Data were obtained with 15-gram pentolite charges at four heights of burst, both for a smooth surface and for a surface completely covered with pyramid-shaped roughness elements. The observations resulted in determinations of <span class="hlt">shock</span> peak overpressure and Mach stem height as a function of distance for each test. Comparison of the smooth-surface data with those obtained for the extremely rough condition showed a small net effort of roughness on the <span class="hlt">shock</span> peak overpressures at the surface for all burst heights, the effect being to lower the overpressures. The effect of surface roughness on the Mach stem formation and growth was to delay the formation at the greatest charge height and to lower the height of the Mach stem for all heights.Comparison of the free-air <span class="hlt">shock</span> peak overpressures with larger scale data showed good similarity of the overpressure-distance relationships. The data did not fit a geometrical similarity parameter for the path of the triple point at different heights of burst suggested by other investigators. A simple similarity parameter (relating the horizontal distance to the theoretical point of Mach formation) was found which showed only a small influence of burst height on the path of the triple point. While the data presented provide knowledge of the effect of many surface-roughness elements on the overall <span class="hlt">shock</span> characteristics, the data do not provide insight into the details of the air-flow characteristics along the surface, nor the relative contribution of individual roughness elements to the results obtained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JAP...109g3103S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JAP...109g3103S"><span><span class="hlt">Shock</span> induced damage and damage threshold of optical K9 glass investigated by laser-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>Song, Yunfei; Yu, Guoyang; Jiang, Lilin; Zheng, Xianxu; Liu, Yuqiang; Yang, Yanqiang</p> <p>2011-04-01</p> <p>The <span class="hlt">shock</span> <span class="hlt">wave</span> driven by short laser pulse is used to study the damage of brittle material K9 glass. The damage morphology of K9 glass surface indicates that the material has experienced different loading modes, respectively, at the central area and the surrounding area of the <span class="hlt">shock</span> <span class="hlt">wave</span>. At the central area of <span class="hlt">shock</span> <span class="hlt">wave</span>, the wavefront is plane and has a uniform pressure distribution, the material mainly suffers a longitudinal <span class="hlt">shock</span> pressure; but on the edge the <span class="hlt">shock</span> <span class="hlt">wave</span>, the wavefront is approximately spherical, besides longitudinal pressure, transverse tensile stress will emerge inside the material. In the latter case, the damage threshold of the material is much smaller than that in the case of compressing by longitudinal pressure only. According to the relationship between damage area and <span class="hlt">shock</span> pressure, an experimental method is proposed to measure the damage threshold of materials under <span class="hlt">shock</span> loading. The damage threshold of K9 glass under spherical <span class="hlt">shock</span> <span class="hlt">wave</span> is measured to be about 1.12 GPa; and the damage threshold under plane <span class="hlt">shock</span> <span class="hlt">wave</span> is estimated to be between 1.82 and 1.98 GPa. They are much bigger than the damage threshold under static pressure. This method could also be used to measure the damage threshold of other materials when loaded by dynamic pressure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ExFl...56..113G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ExFl...56..113G"><span>High-resolution PIV measurements of a transitional <span class="hlt">shock</span> <span class="hlt">wave</span>-boundary layer interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Giepman, R. H. M.; Schrijer, F. F. J.; van Oudheusden, B. W.</p> <p>2015-06-01</p> <p>This study investigates the effects of boundary layer transition on an oblique <span class="hlt">shock</span> <span class="hlt">wave</span> <span class="hlt">reflection</span>. The Mach number was 1.7, the unit Reynolds number was 35 × 106 m-1, and the pressure ratio over the interaction was 1.35. Particle image velocimetry is used as the main flow diagnostics tool, supported by oil-flow and Schlieren visualizations. At these conditions, the thickness of the laminar boundary layer is only 0.2 mm, and seeding proved to be problematic as practically no seeding was recorded in the lower 40 % of the boundary layer. The top 60 % could, however, still be resolved with good accuracy and is found to be in good agreement with the compressible Blasius solution. Due to the effects of turbulent mixing, the near-wall seeding deficiency disappears when the boundary layer transitions to a turbulent state. This allowed the seeding distribution to be used as an indicator for the state of the boundary layer, permitting to obtain an approximate intermittency distribution for the boundary layer transition region. This knowledge was then used for positioning the oblique <span class="hlt">shock</span> <span class="hlt">wave</span> in the laminar, transitional (50 % intermittency) or turbulent region of the boundary layer. Separation is only recorded for the laminar and transitional interactions. For the laminar interaction, a large separation bubble is found, with a streamwise length of 96. The incoming boundary layer is lifted over the separation bubble and remains in a laminar state up to the impingement point of the <span class="hlt">shock</span> <span class="hlt">wave</span>. After the <span class="hlt">shock</span>, transition starts and a turbulent profile is reached approximately 80-90 downstream of the <span class="hlt">shock</span>. Under the same <span class="hlt">shock</span> conditions, the transitional interaction displays a smaller separation bubble (43), and transition is found to be accelerated over the separation bubble.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15083118','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15083118"><span>Effects of extracorporeal <span class="hlt">shock</span> <span class="hlt">waves</span> on immature rabbit femurs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Saisu, Takashi; Takahashi, Kenji; Kamegaya, Makoto; Mitsuhashi, Shigeru; Wada, Yuichi; Moriya, Hideshige</p> <p>2004-05-01</p> <p>We hypothesized that extracorporeal <span class="hlt">shock</span> <span class="hlt">waves</span> induce overgrowth and local increases in bone mineral content (BMC) in immature long bones. Immature male rabbits (n=14; 9 weeks old) were randomized equally between group I, which received 1000 100 MPa <span class="hlt">shock</span> <span class="hlt">waves</span> on the femoral shaft and group II, which received 5000. Unexposed femurs were used as controls. No fractures occurred in group I; three occurred in group II. Six weeks after exposure, the length and width were significantly larger (1.0 and 14.9%, respectively), and the BMC was significantly higher (22.8%) than those of control femurs in group I. These results of differences in width and BMC might be clinically useful.</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>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> </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/2017PhyD..342...45A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhyD..342...45A"><span>Optical dispersive <span class="hlt">shock</span> <span class="hlt">waves</span> in defocusing colloidal media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>An, X.; Marchant, T. R.; Smyth, N. F.</p> <p>2017-03-01</p> <p>The propagation of an optical dispersive <span class="hlt">shock</span> <span class="hlt">wave</span>, generated from a jump discontinuity in light intensity, in a defocusing colloidal medium is analysed. The equations governing nonlinear light propagation in a colloidal medium consist of a nonlinear Schrödinger equation for the beam and an algebraic equation for the medium response. In the limit of low light intensity, these equations reduce to a perturbed higher order nonlinear Schrödinger equation. Solutions for the leading and trailing edges of the colloidal dispersive <span class="hlt">shock</span> <span class="hlt">wave</span> are found using modulation theory. This is done for both the perturbed nonlinear Schrödinger equation and the full colloid equations for arbitrary light intensity. These results are compared with numerical solutions of the colloid equations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhSen...7....1Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhSen...7....1Z"><span>Material measurement method based on femtosecond laser plasma <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>Zhong, Dong; Li, Zhongming</p> <p>2017-03-01</p> <p>The acoustic emission signal of laser plasma <span class="hlt">shock</span> <span class="hlt">wave</span>, which comes into being when femtosecond laser ablates pure Cu, Fe, and Al target material, has been detected by using the fiber Fabry-Perot (F-P) acoustic emission sensing probe. The spectrum characters of the acoustic emission signals for three kinds of materials have been analyzed and studied by using Fourier transform. The results show that the frequencies of the acoustic emission signals detected from the three kinds of materials are different. Meanwhile, the frequencies are almost identical for the same materials under different ablation energies and detection ranges. Certainly, the amplitudes of the spectral character of the three materials show a fixed pattern. The experimental results and methods suggest a potential application of the plasma <span class="hlt">shock</span> <span class="hlt">wave</span> on-line measurement based on the femtosecond laser ablating target by using the fiber F-P acoustic emission sensor probe.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JEMat..41.1595B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JEMat..41.1595B"><span><span class="hlt">Shock-Wave</span> Consolidation of Nanostructured Bismuth Telluride Powders</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Beck, Jan; Alvarado, Manuel; Nemir, David; Nowell, Mathew; Murr, Lawrence; Prasad, Narasimha</p> <p>2012-06-01</p> <p>Nanostructured thermoelectric powders can be produced using a variety of techniques. However, it is very challenging to build a bulk material from these nanopowders without losing the nanostructure. In the present work, nanostructured powders of the bismuth telluride alloy system are obtained in kilogram quantities via a gas atomization process. These powders are characterized using a variety of methods including scanning electron microscopy, transition electron microscopy, and x-ray diffraction analysis. Then the powders are consolidated into a dense bulk material using a <span class="hlt">shock-wave</span> consolidation technique whereby a nanopowder-containing tube is surrounded by explosives and then detonated. The resulting <span class="hlt">shock</span> <span class="hlt">wave</span> causes rapid fusing of the powders without the melt and subsequent grain growth of other techniques. We describe the test setup and consolidation results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21455272','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21455272"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/11400894','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11400894"><span><span class="hlt">Shock</span> <span class="hlt">wave</span> therapy for chronic proximal plantar fasciitis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ogden, J A; Alvarez, R; Levitt, R; Cross, G L; Marlow, M</p> <p>2001-06-01</p> <p>Three hundred two patients with chronic heel pain caused by proximal plantar fasciitis were enrolled in a study to assess the treatment effects consequent to administration of electrohydraulicall-generated extracorporeal <span class="hlt">shock</span> <span class="hlt">waves</span>. Symptoms had been present from 6 months to 18 years. Each treated patient satisfied numerous inclusion and exclusion criteria before he or she was accepted into this study, which was approved by the Food and Drug Administration as a randomized, double-blind evaluation of the efficacy of <span class="hlt">shock</span> <span class="hlt">wave</span> therapy for this disorder. Overall, at the predetermined evaluation period 3 months after one treatment, 56% more of the treated patients had a successful result by all four of the evaluation criteria when compared with the patients treated with a placebo. This difference was significant and corroborated the fact that this difference in the results was specifically attributable to the <span class="hlt">shock</span> <span class="hlt">wave</span> treatment, rather than any natural improvement caused by the natural history of the condition. The current study showed that the directed application of electrohydraulic-generated <span class="hlt">shock</span> <span class="hlt">waves</span> to the insertion of the plantar fascia onto the calcaneus is a safe and effective nonsurgical method for treating chronic, recalcitrant heel pain syndrome that has been present for at least 6 months and has been refractory to other commonly used nonoperative therapies. This technology, when delivered using the OssaTron (High Medical Technology, Kreuz-lingen, Switzerland), has been approved by the Food and Drug Administration specifically for the treatment of chronic proximal plantar fasciitis. The results suggest that this therapeutic modality should be considered before any surgical options, and even may be preferable to cortisone injection, which has a recognized risk of rupture of the plantar fascia and recurrence of symptoms.</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>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/2015APS..DPPUP2052J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DPPUP2052J"><span>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('https://www.osti.gov/scitech/biblio/22522514','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22522514"><span>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://www.osti.gov/scitech">SciTech Connect</a></p> <p>Slavin, Jonathan D.; Dwek, Eli; Jones, Anthony P.</p> <p>2015-04-10</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., 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{sup −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 ∼2 compared to those of Jones et al., who assumed a hot gas dominated ISM. Recent estimates of supernova rates and ISM mass lead to another factor of ∼3 increase in the destruction timescales, resulting in a silicate grain destruction timescale of ∼2–3 Gyr. These increases, while not able to resolve the problem of the discrepant timescales for silicate grain destruction and creation, are an important step toward understanding the origin and evolution of dust in the ISM.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22043623','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22043623"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/27182751','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27182751"><span>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>2016-06-02</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('https://www.osti.gov/scitech/biblio/1295510','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1295510"><span>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/scitech">SciTech Connect</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, Sebastien; Guillet, Serge A. H.; Curtis, Robin H.; Vetter, Sharon L.; Loos, Henrik; Turner, James L.; Decker, Franz -Josef</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 MPa 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1295510-negative-pressures-spallation-water-drops-subjected-nanosecond-shock-waves','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1295510-negative-pressures-spallation-water-drops-subjected-nanosecond-shock-waves"><span>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.; ...</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('https://www.osti.gov/scitech/biblio/22410459','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22410459"><span>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('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2768123','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2768123"><span>Assessment of <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripters via cavitation potential</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Iloreta, Jonathan I.; Zhou, Yufeng; Sankin, Georgy N.; Zhong, Pei; Szeri, Andrew J.</p> <p>2008-01-01</p> <p>A method to characterize <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripters by examining the potential for cavitation associated with the lithotripter <span class="hlt">shock</span> <span class="hlt">wave</span> (LSW) has been developed. The method uses the maximum radius achieved by a bubble subjected to a LSW as a representation of the cavitation potential for that region in the lithotripter. It is found that the maximum radius is determined by the work done on a bubble by the LSW. The method is used to characterize two reflectors: an ellipsoidal reflector and an ellipsoidal reflector with an insert. The results show that the use of an insert reduced the −6 dB volume (with respect to peak positive pressure) from 1.6 to 0.4 cm3, the −6 dB volume (with respect to peak negative pressure) from 14.5 to 8.3 cm3, and reduced the volume characterized by high cavitation potential (i.e., regions characterized by bubbles with radii larger than 429 µm) from 103 to 26 cm3. Thus, the insert is an effective way to localize the potentially damaging effects of <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy, and suggests an approach to optimize the shape of the reflector. PMID:19865493</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26687540','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26687540"><span>Modeling secondary accidents identified by traffic <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>Junhua, Wang; Boya, Liu; Lanfang, Zhang; Ragland, David R</p> <p>2016-02-01</p> <p>The high potential for occurrence and the negative consequences of secondary accidents make them an issue of great concern affecting freeway safety. Using accident records from a three-year period together with California interstate freeway loop data, a dynamic method for more accurate classification based on the traffic <span class="hlt">shock</span> <span class="hlt">wave</span> detecting method was used to identify secondary accidents. Spatio-temporal gaps between the primary and secondary accident were proven be fit via a mixture of Weibull and normal distribution. A logistic regression model was developed to investigate major factors contributing to secondary accident occurrence. Traffic <span class="hlt">shock</span> <span class="hlt">wave</span> speed and volume at the occurrence of a primary accident were explicitly considered in the model, as a secondary accident is defined as an accident that occurs within the spatio-temporal impact scope of the primary accident. Results show that the <span class="hlt">shock</span> <span class="hlt">waves</span> originating in the wake of a primary accident have a more significant impact on the likelihood of a secondary accident occurrence than the effects of traffic volume. Primary accidents with long durations can significantly increase the possibility of secondary accidents. Unsafe speed and weather are other factors contributing to secondary crash occurrence. It is strongly suggested that when police or rescue personnel arrive at the scene of an accident, they should not suddenly block, decrease, or unblock the traffic flow, but instead endeavor to control traffic in a smooth and controlled manner. Also it is important to reduce accident processing time to reduce the risk of secondary accident.</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>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://adsabs.harvard.edu/abs/2016PhPl...23e2706V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhPl...23e2706V"><span>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/2010SCPMA..53..279W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010SCPMA..53..279W"><span>A study on compressive <span class="hlt">shock</span> <span class="hlt">wave</span> propagation in metallic foams</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Zhihua; Zhang, Yifen; Ren, Huilan; Zhao, Longmao</p> <p>2010-02-01</p> <p>Metallic foam can dissipate a large amount of energy due to its relatively long stress plateau, which makes it widely applicable in the design of structural crashworthiness. However, in some experimental studies, stress enhancement has been observed when the specimens are subjected to intense impact loads, leading to severe damage to the objects being protected. This paper studies this phenomenon on a 2D mass-spring-bar model. With the model, a constitutive relationship of metal foam and corresponding loading and unloading criteria are presented; a nonlinear kinematics equilibrium equation is derived, where an explicit integration algorithm is used to calculate the characteristic of the compressive <span class="hlt">shock</span> <span class="hlt">wave</span> propagation within the metallic foam; the effect of heterogeneous distribution of foam microstructures on the <span class="hlt">shock</span> <span class="hlt">wave</span> features is also included. The results reveal that under low impact pulses, considerable energy is dissipated during the progressive collapse of foam cells, which then reduces the crush of objects. When the pulse is sufficiently high, on the other hand, stress enhancement may take place, especially in the heterogeneous foams, where high peak stresses usually occur. The characteristics of compressive <span class="hlt">shock</span> <span class="hlt">wave</span> propagation in the foam and the magnitude and location of the peak stress produced are strongly dependent on the mechanical properties of the foam material, amplitude and period of the pulse, as well as the homogeneity of the microstructures. This research provides valuable insight into the reliability of the metallic foams used as a protective structure.</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>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('http://adsabs.harvard.edu/abs/2012AIPC.1481...76D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AIPC.1481...76D"><span>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> </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/2016EGUGA..1810690M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1810690M"><span>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> <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>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('https://ntrs.nasa.gov/search.jsp?R=19950048201&hterms=polish&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dpolish','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950048201&hterms=polish&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dpolish"><span><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://hdl.handle.net/2060/19950024161','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950024161"><span>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('https://ntrs.nasa.gov/search.jsp?R=19950035611&hterms=McKee&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DMcKee','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950035611&hterms=McKee&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DMcKee"><span>On the hydrodynamic interaction of <span class="hlt">shock</span> <span class="hlt">waves</span> with interstellar clouds. 1: Nonradiative <span class="hlt">shocks</span> in small clouds</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Klein, Richard I.; Mckee, Christopher F.; Colella, Philip</p> <p>1994-01-01</p> <p>The interstellar medium (ISM) is inhomogeneous, with clouds of various temperatures and densities embedded in a tenuous intercloud medium. <span class="hlt">Shocks</span> propagating through the ISM can ablate or destroy the clouds, at the same time significantly altering the properties of the intercloud medium. This paper presents a comprehensive numerical study of the simplest case of the interaction between a <span class="hlt">shock</span> <span class="hlt">wave</span> and a spherical cloud, in which the <span class="hlt">shock</span> far from the cloud is steady and planar, and in which radiative losses, thermal conduction, magnetic fields, and gravitational forces are all neglected. As a result, the problem is completely specified by two numbers: the Mach number of the <span class="hlt">shock</span>, M, and the ratio of the density of the cloud to that of the intercloud medium, Chi. For strong <span class="hlt">shocks</span> we show that the dependence on M scales out, so the primary independent parameter is Chi. Variations from this simple case are also considered: the potential effect of radiative losses is assessed by calculations in which the ratio of specific heats in the cloud is 1.1 instead of 5/3; the effect of the initial shape of the cloud is studied by using a cylindrical cloud instead of a spherical one; and the role of the initial <span class="hlt">shock</span> is determined by considering the case of a cloud embedded in a wind. Local adaptive mesh refinement techniques with a second-order, two-fluid, two-dimensional Godunov hydrodynamic scheme are used to address these problems, allowing heretofore unobtainable numerical resolution. Convergence studies to be described in a subsequent paper demonstrate that about 100 zones per cloud radius are needed for accurate results; previous calculations have generally used about a third of this number. The results of the calculations are analyzed in terms of global quantities which provide an overall description of te <span class="hlt">shocked</span> cloud: the size and shape of the cloud, the mean density, the mean pressure, the mean velocity, the velocity dispersion, and the total circulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930049652&hterms=Radio+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DRadio%2Bwaves','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930049652&hterms=Radio+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DRadio%2Bwaves"><span>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/2060/19880003924','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19880003924"><span>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://www.osti.gov/scitech/servlets/purl/6138630','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6138630"><span>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('http://adsabs.harvard.edu/abs/2015AdSpR..56.2804C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AdSpR..56.2804C"><span><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://adsabs.harvard.edu/abs/2008PhDT........16I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008PhDT........16I"><span>Interactions of <span class="hlt">shock</span> <span class="hlt">waves</span> with material interfaces in lithotripsy and inertial confinement fusion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Iloreta, Jonathan Ian</p> <p></p> <p>This dissertation focuses on the interaction of <span class="hlt">shock</span> <span class="hlt">wave</span> with material interfaces in <span class="hlt">shock</span> <span class="hlt">wave</span> lithotrispsy (SWL) and inertial confinement fusion (ICF). In the area of SWL, a method to characterize <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripters by examining the potential for cavitation associated with the lithotripter <span class="hlt">shock</span> <span class="hlt">wave</span> (LSW) has been developed. The method uses the maximum radius achieved by a bubble subjected to a LSW as a representation of the cavitation potential for that region in the lithotripter. It is found that the maximum radius is determined by the work done on a bubble by the LSW. The method is used to characterize two reflectors: an ellipsoidal reflector and an ellipsoidal reflector with an insert. The results show that the use of an insert reduced the ---6 dB volume (with respect to peak positive pressure) from 1.6 cm3 to 0.4 cm3, the -6 dB volume (with respect to peak negative pressure) from 14.5 cm3 to 8.3 cm3, and reduced the volume characterized by high cavitation potential (i.e. regions characterized by bubbles with radii larger than 429 microm) from 103 cm3 to 26 cm3. Thus, the insert is an effective way to localize the potentially damaging effects of <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy, and suggests an approach to optimize the shape of the reflector. Also in the area of SWL, the dynamics of bubbles near a kidney stone subjected to a lithotripter <span class="hlt">shock</span> <span class="hlt">wave</span> are considered to address the effect of kidney stone geometry and composition on the cavitation potential near the stone in a <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripter. Results of the <span class="hlt">reflection</span> of the LSW from cylindrical kidney stones with proximal surfaces of varying geometry show that the presence of the stone enhances bubble growth near the stone and decreases growth further away, due to constructive and destructive interference, respectively. These effects hold true regardless of the shape and curvature of the face, and are strongest for stones with concave faces and higher <span class="hlt">reflection</span> coefficients. An interesting consequence of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005ASAJ..117.2370T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005ASAJ..117.2370T"><span>In vitro comparison of <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy machines</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Teichman, Joel M.; Cecconi, Patricia P.; Pearle, Margaret S.; Clayman, Ralph V.</p> <p>2005-04-01</p> <p>We tested the hypothesis that <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy machines vary in the ability to fragment stones to small size. Calcium oxalate monohydrate, calcium phosphate, cystine and struvite calculi were fragmented in vitro with the Dornier HM3, Storz Modulith SLX, Siemens Lithostar C, Medstone STS-T, HealthTronics LithoTron 160, Dornier Doli S and Medispec Econolith lithotriptors. Stones were given 2000 <span class="hlt">shocks</span> or the FDA limit. Post-lithotripsy fragment size was compared. Struvite calculi were completely fragmented by all devices. The mean incidence of calcium phosphate dihydrate, calcium oxalate monohydrate, and cystine stones rendered into fragments greater than 2 mm was 0% for the HM3, Modulith SLX and Lithostar C, 10% for the STS-T, 3% for the LithoTron 160, 29% for the Doli and 18% for the Econolith (p=0.04); 0% for the HM3, Modulith SLX, Lithostar C, STS-T and LithoTron 160, 4% for the Doli and 9% for the Econolith (p=0.15); 1% for the HM3, 0% for the Modulith SLX, 1% for the Lithostar C, 10% for the STS-T, 14% for the LithoTron 160, 3% for the Doli and 9% for the Econolith (p=0.44), respectively. <span class="hlt">Shock</span> <span class="hlt">wave</span> lithotriptors vary in fragmentation ability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AIPC.1426.1215H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AIPC.1426.1215H"><span>Burnett-Cattaneo continuum theory for <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>Holian, Brad Lee; Mareschal, Michel; Ravelo, R.</p> <p>2012-03-01</p> <p>We model strong shockwave propagation, both in the ideal gas and in the dense Lennard- Jones fluid, using a refinement of earlier work, which accounts for the cold compression in the early stages of the <span class="hlt">shock</span> rise by a nonlinear, Burnett-like, strain-rate dependence of the thermal conductivity, and relaxation of kinetic temperature components on the hot, compressed side of the <span class="hlt">shock</span> front. The relaxation of the disequilibrium among the three components of the kinetic temperature, namely, the difference between the component in the direction of a planar <span class="hlt">shock</span> <span class="hlt">wave</span> and those in the transverse directions, particularly in the region near the <span class="hlt">shock</span> front, is accomplished at a much more quantitative level by the first-ever rigorous application of the Cattaneo-Maxwell relaxation equation to a reference solution, namely, the steady shockwave solution of linear Navier- Stokes-Fourier theory, along with the nonlinear Burnett heat-flux term. Our new continuum theory is in nearly quantitative agreement with non-equilibrium molecular-dynamics simulations under strong shockwave conditions, using relaxation parameters obtained from the reference solution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011APS..SHK.C3006H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011APS..SHK.C3006H"><span>Burnett-Cattaneo continuum theory for <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>Holian, Brad Lee; Mareschal, Michel; Ravelo, Ramon</p> <p>2011-06-01</p> <p>We model strong shockwave propagation, both in the ideal gas and in the dense Lennard-Jones fluid, using a refinement of earlier work, which accounts for the cold compression in the early stages of the <span class="hlt">shock</span> rise by a nonlinear, Burnett-like, strain-rate dependence of the thermal conductivity, and relaxation of kinetic temperature components on the hot, compressed side of the <span class="hlt">shock</span> front. The relaxation of the disequilibrium among the three components of the kinetic temperature, namely, the difference between the component in the direction of a planar <span class="hlt">shock</span> <span class="hlt">wave</span> and those in the transverse directions, particularly in the region near the <span class="hlt">shock</span> front, is accomplished at a much more quantitative level by the first-ever rigorous application of the Cattaneo-Maxwell relaxation equation to a reference solution, namely, the steady shockwave solution of linear Navier-Stokes-Fourier theory, along with the nonlinear Burnett heat-flux term. Our new continuum theory is in nearly quantitative agreement with non-equilibrium molecular-dynamics simulations under strong shockwave conditions, using relaxation parameters obtained from the reference solution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17360268','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17360268"><span><span class="hlt">Wave</span> breaking and <span class="hlt">shock</span> <span class="hlt">waves</span> for a periodic shallow water equation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Escher, Joachim</p> <p>2007-09-15</p> <p>This paper is devoted to the study of a recently derived periodic shallow water equation. We discuss in detail the blow-up scenario of strong solutions and present several conditions on the initial profile, which ensure the occurrence of <span class="hlt">wave</span> breaking. We also present a family of global weak solutions, which may be viewed as global periodic <span class="hlt">shock</span> <span class="hlt">waves</span> to the equation under discussion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003APh....19..649M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003APh....19..649M"><span>Particle acceleration in ultra-relativistic 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>Meli, A.; Quenby, J. J.</p> <p>2003-08-01</p> <p>We perform Monte Carlo simulations of diffusive <span class="hlt">shock</span> acceleration at highly relativistic oblique <span class="hlt">shock</span> <span class="hlt">waves</span>. High upstream flow Lorentz gamma factors ( Γ) are used, which are relevant to models of ultra-relativistic particle <span class="hlt">shock</span> acceleration in active galactic nuclei (AGN) central engines and relativistic jets and gamma ray burst (GRB) fireballs. We investigate numerically the acceleration properties in the relativistic and ultra-relativistic flow regime ( Γ˜10-10 3), such as angular distribution, acceleration time constant, particle energy gain versus number of crossings and spectral shapes. We perform calculations for sub-luminal and super-luminal <span class="hlt">shocks</span>. For the first case, the dependence on whether or not the scattering is pitch angle diffusion or large angle scattering is studied. The large angle model exhibits a distinctive structure in the basic power-law spectrum which is not nearly so obvious for small angle scattering. However, both models yield significant 'speed-up' or faster acceleration rates when compared with the conventional, non-relativistic expression for the time constant, or alternatively with the time scale rg/ c where rg is Larmor radius. The Γ2 energization for the first crossing cycle and the significantly large energy gain for subsequent crossings as well as the high 'speed-up' factors found, are important in supporting the Vietri and Waxman work on GRB ultra-high energy cosmic ray, neutrino and gamma-ray output. Secondly, for super-luminal <span class="hlt">shocks</span>, we calculate the energy gain for a number of different inclinations and the spectral shapes of the accelerated particles are given. In this investigation we consider only large angle scattering, partly because of computational time limitations and partly because this model provides the most favourable situation for acceleration. We use high gamma flows with Lorentz factors in the range 10-40, which are relevant to AGN accretion disks and jet ultra-relativistic <span class="hlt">shock</span> configurations. We</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19720051948&hterms=heat+shock+method&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dheat%2Bshock%2Bmethod','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19720051948&hterms=heat+shock+method&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dheat%2Bshock%2Bmethod"><span><span class="hlt">Shock-wave</span> structure using nonlinear model Boltzmann equations.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Segal, B. M.; Ferziger, J. H.</p> <p>1972-01-01</p> <p>The structure of strong plane <span class="hlt">shock</span> <span class="hlt">waves</span> in a perfect monatomic gas was studied using four nonlinear models of the Boltzmann equation. The models involved the use of a simplified collision operator with velocity-independent collision frequency, in place of the complicated Boltzmann collision operator. The models employed were the BGK and ellipsoidal models developed by earlier authors, and the polynomial and trimodal gain function models developed during the work. An exact set of moment equations was derived for the density, velocity, temperature, viscous stress, and heat flux within the <span class="hlt">shock</span>. This set was reduced to a pair of coupled nonlinear integral equations and solved using specially adapted numerical techniques. A new and simple Gauss-Seidel iteration was developed during the work and found to be as efficient as the best earlier iteration methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..SHK.E1003G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..SHK.E1003G"><span>Estimating explosive performance from laser-induced <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>Gottfried, Jennifer</p> <p>2015-06-01</p> <p>A laboratory-scale method for predicting explosive performance (e.g., detonation velocity and pressure) based on milligram quantities of material is currently being developed. This technique is based on schlieren imaging of the <span class="hlt">shock</span> <span class="hlt">wave</span> generated in air by the formation of a laser-induced plasma on the surface of an energetic material. A large suite of pure and composite conventional energetic materials has been tested. Based on the observed linear correlation between the laser-induced <span class="hlt">shock</span> velocity and the measured performance from full-scale detonation testing, this method is a potential screening tool for the development of new energetic materials and formulations prior to detonation testing. Recent results on the extension of this method to metal-containing energetic materials will be presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007JThSc..16...97D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007JThSc..16...97D"><span><span class="hlt">Shock</span> <span class="hlt">wave</span> strength reduction by passive control using perforated plates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Doerffer, Piotr; Szulc, Oskar</p> <p>2007-05-01</p> <p>Strong, normal <span class="hlt">shock</span> <span class="hlt">wave</span>, terminating a local supersonic area on an airfoil, not only limits aerodynamic performance but also becomes a source of a high-speed impulsive helicopter noise. The application of a passive control system (a cavity covered by a perforated plate) on a rotor blade should reduce the noise created by a moving <span class="hlt">shock</span>. This article covers the numerical implementation of the Bohning/Doerffer transpiration law into the SPARC code and includes an extended validation against the experimental data for relatively simple geometries of transonic nozzles. It is a first step towards a full simulation of a helicopter rotor equipped with a noise reducing passive control device in hover and in forward flight conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AIPC.1793b0002F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AIPC.1793b0002F"><span>Material response mechanisms are needed to obtain highly accurate experimental <span class="hlt">shock</span> <span class="hlt">wave</span> data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Forbes, Jerry W.</p> <p>2017-01-01</p> <p>The field of <span class="hlt">shock</span> <span class="hlt">wave</span> compression of matter has provided a simple set of equations relating thermodynamic and kinematic parameters that describe the conservation of mass, momentum and energy across a steady plane <span class="hlt">shock</span> <span class="hlt">wave</span> with one-dimensional flow. Well-known condensed matter <span class="hlt">shock</span> <span class="hlt">wave</span> experimental results will be reviewed to see whether the assumptions required for deriving these simple R-H equations are satisfied. Note that the material compression model is not required for deriving the 1-D conservation flow equations across a steady plane <span class="hlt">shock</span> front. However, this statement is misleading from a practical experimental viewpoint since obtaining small systematic errors in <span class="hlt">shock</span> <span class="hlt">wave</span> measured parameters requires the material compression and release mechanisms to be known. A review will be presented on errors in <span class="hlt">shock</span> <span class="hlt">wave</span> data from common experimental techniques for elastic-plastic solids. Issues related to time scales of experiments, steady <span class="hlt">waves</span> with long rise times and detonations will also be discussed</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20711703','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20711703"><span>Influence of dielectric barrier discharges on low Mach number <span class="hlt">shock</span> <span class="hlt">waves</span> at low to medium pressures</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bletzinger, P.; Ganguly, B.N.; Garscadden, A.</p> <p>2005-06-01</p> <p>For <span class="hlt">shock</span> <span class="hlt">wave</span> propagation in nonequilibrium plasmas, it has been shown that when the electron Debye length exceeds the <span class="hlt">shock</span> <span class="hlt">wave</span> discontinuity dimension, strong double layers are generated, propagating with the <span class="hlt">shock</span> <span class="hlt">wave</span>. Strong double layer formation leads to the enhancement of the local excitation, ionization, and local neutral gas heating which increases the <span class="hlt">shock</span> <span class="hlt">wave</span> velocity. It is shown that dielectric barrier discharges (DBD) in pure N{sub 2} also increase the <span class="hlt">shock</span> <span class="hlt">wave</span> velocity and broaden the <span class="hlt">shock</span> <span class="hlt">wave</span>. The DBD is considerably more energy efficient in producing these effects compared to a dc glow discharge and can operate over a wide pressure range. It is shown that these effects are also operative in the pure N{sub 2} discharge afterglow, allowing a wide range of pulse repetition frequencies.</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.ncbi.nlm.nih.gov/pubmed/17313015','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17313015"><span>[Preliminary summarization of a new method, extrinsic <span class="hlt">shock</span> <span class="hlt">wave</span> acupuncture and moxibustion].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Everke, Heinrich</p> <p>2006-12-01</p> <p>In medical field, extrinsic <span class="hlt">shock</span> <span class="hlt">wave</span> is only used to crush kidney stone to pieces. In recent years, a new instrument has been produced, which outputs a more gentle extrinsic <span class="hlt">shock</span> <span class="hlt">wave</span> that also can be used for treatment of pain excitation region in the muscular system. This <span class="hlt">shock</span> <span class="hlt">wave</span> is called rectilinear ballistic extrinsic <span class="hlt">shock</span> <span class="hlt">wave</span>. In 2002, the author designed an instrument, which could generate the rectilinear ballistic extrinsic <span class="hlt">shock</span> <span class="hlt">wave</span> and was used at acupoints. The author used the instrument for treatment of over 500 patients and proved that the method had a better effect than that of simple acupuncture and moxibustion for many kinds of diseases. Extrinsic <span class="hlt">shock</span> <span class="hlt">wave</span> acupuncture and moxibustion is another method for stimulating acupoints, besides acupuncture, moxihustion, massage of acupoints, electroacupuncture and laser acupuncture.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPC.1786k0004B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1786k0004B"><span>Simulations of condensation flows induced by <span class="hlt">reflection</span> of weak <span class="hlt">shocks</span> from liquid surfaces</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barbante, Paolo; Frezzotti, Aldo</p> <p>2016-11-01</p> <p>The condensation of a vapor onto a planar liquid surface, caused by the <span class="hlt">reflection</span> of a weak <span class="hlt">shock</span> <span class="hlt">wave</span>, is studied by three different simulation method. The first one is based on molecular dynamics (MD) simulations of the Lennard-Jones fluid which are supposed to provide reference solutions. The second method is based on a Diffuse Interface Model (DIM), consistent with the thermodynamic properties of the Lennard-Jones fluid as well as with its transport properties. The third method is based on a hybrid model (HM) in which the liquid is described by a purely hydrodynamic approach, whereas the vapor is described by the Boltzmann equation. The two phases are connected by kinetic boundary conditions. The results show that DIM fails to accurately predict the condensation rate when the vapor is dilute but becomes more accurate when the vapor phase gets denser. HM reproduces MD simulations of nearly ideal vapor condensations with good accuracy, assuming unit condensation coefficient.</p> </li> <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><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('https://www.ncbi.nlm.nih.gov/pubmed/24237537','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24237537"><span>Measurement of elastic <span class="hlt">waves</span> induced by the <span class="hlt">reflection</span> of light.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Požar, Tomaž; Možina, Janez</p> <p>2013-11-01</p> <p>The <span class="hlt">reflection</span> of light from the surface of an elastic solid gives rise to various types of elastic <span class="hlt">waves</span> that propagate inside the solid. The weakest <span class="hlt">waves</span> are generally those that are generated by the radiation pressure acting during the <span class="hlt">reflection</span> of the light. Here, we present the first quantitative measurement of such light-pressure-induced elastic <span class="hlt">waves</span> inside an ultrahigh-<span class="hlt">reflectivity</span> mirror. Amplitudes of a few picometers were observed at the rear side of the mirror with a displacement-measuring conical piezoelectric sensor when laser pulses with a fluence of 1 J/cm(2) were <span class="hlt">reflected</span> from the front side of the mirror.</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>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://adsabs.harvard.edu/abs/1992PhDT........61C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992PhDT........61C"><span>An experimental investigation of <span class="hlt">shock</span> <span class="hlt">wave</span>/vortex interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cattafesta, Louis Nicholas, III</p> <p></p> <p>Although <span class="hlt">shock</span> <span class="hlt">wave</span>/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 <span class="hlt">shock</span> <span class="hlt">wave</span> has been 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 <span class="hlt">shock</span> <span class="hlt">waves</span> 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 <span class="hlt">shock</span> is perturbed locally into an unsteady 'bubble' <span class="hlt">shock</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMSH33A1476A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMSH33A1476A"><span>Observation of energetic protons penetrating previous <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>Al-Sawad, A.; Saloniemi, O.; Laitinen, T. L.; Kocharov, L. G.; Valtonen, E.</p> <p>2009-12-01</p> <p>We report new evidence on energetic protons penetrating previous <span class="hlt">shock</span> <span class="hlt">wave</span>. We have chosen four Multi Eruption Solar Energetic Particle (MESEP) events from the list presented by Al-Sawad 2007, and observed by Energetic and Relativistic Nuclei and Electron (ERNE) instrument on the Solar and Heliospheric Observatory (SOHO). Two events were studied in details, the event of 2001 October 19-21, which was in association with two X1.6/2B solar flares and halo CMEs separated by ~15 hours and the event of 2000 April 04, which was associated with two CMEs separated by ~8 hours. The other two new MESEP events were on 2000 February 17-19 and 2005 August 22-25. The first event was associated with two CMEs. The first halo CME was associated with M 1.3 solar flare at S29E07 Hα location from the NOAA AR 8827, and with metric and later D-H type II radio bursts, indicating a formation of <span class="hlt">shock</span> <span class="hlt">wave</span>, which was later passed near the Earth's orbit and registered, by SOHO, ACE and Wind spacecrafts. The second CME erupted from the south-west after ~13 hours. The second event was associated with two halo CMEs separated by ~16 and erupted from same NOAA AR 10798 in association with M class solar flares. The first halo was in association with metric type II but both were in association with D-H type II. In both events the first CME was decelerating and both events can be classified as gradual SEP events. Our analysis for proton flux anisotropy data, He/P ratio and possible velocity dispersion in the second peak of the intensity-time profile are related to the second CME in both events. This suggests that the energetic protons > 10 MeV penetrate the first <span class="hlt">shock</span> <span class="hlt">waves</span> associated with first CMEs in order to reach 1 AU and thus, these observations indicate that capability of interplanetary <span class="hlt">shock</span> to accelerate high-energy protons gradually declines as <span class="hlt">shock</span> travels from near the Sun to beyond 1~AU.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998PhDT.......239C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998PhDT.......239C"><span>Transient cavitation produced by extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cioanta, Iulian</p> <p>1998-12-01</p> <p>Two decades ago, a new medical procedure was introduced, allowing the fragmentation of kidney stones from outside the human body (noninvasively) using a <span class="hlt">shock</span> <span class="hlt">wave</span> device termed lithotripter ('stone crusher'). Considered as one of the most important medical inventions of this century, lithotripsy is currently used in more than 80% of urolithiasis cases. Experimental studies have shown that transient or inertial cavitation is generated by this procedure near the stones and in renal tissue. To find a correlation between the number of <span class="hlt">shocks</span> delivered and the treatment efficiency, the acoustic emission (AE) generated by the oscillation of cavitation bubbles, and its relation with stone fragmentation and tissue damage during <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy were studied. In vitro experiments were carried out to identify the correlation between the AE signals and the expansion and collapse of cavitation bubbles, which were captured by high-speed photography (20,000 frames per second). This correlation has been verified on four different electrohydraulic lithotripters, under multiple experimental conditions. The effects of tissue attenuation on AE and stone fragmentation were also studied. The in vitro results have further allowed the interpretation of AE signals from in vivo experiments with pigs. Although similar in general trend, in vivo AE signals are found to be shorter in expansion and longer in the total ringing times (including the rebound phenomenon) than for in vitro AE signals, indicating a tissue constraining effect on bubble oscillation. Based on this observation a new mechanism for renal vascular and tubular injury is proposed. In addition, changes in AE signals have been observed as the total number of <span class="hlt">shocks</span> increases, and this dose dependence feature has allowed the determination of a threshold value for extended tissue injury at 20 kV. This result has been confirmed by histological analysis and by results of a theoretical model study of bubble oscillation in a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995SPIE.2393...94K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995SPIE.2393...94K"><span>Comparative <span class="hlt">shock</span> <span class="hlt">wave</span> analysis during corneal ablation with an excimer laser, picosecond laser, and femtosecond laser</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Krueger, Ronald R.; Juhasz, Tibor</p> <p>1995-05-01</p> <p>With the event of topographic steep central islands following excimer laser surgery and the potential damage to the corneal endothelium, <span class="hlt">shock</span> <span class="hlt">waves</span> are playing an increasingly important role in laser refractive surgery. With this in mind, we performed a comparative <span class="hlt">shock</span> <span class="hlt">wave</span> analysis in corneal tissue using an excimer laser, picosecond laser, and femtosecond laser. We used a Lambda Physik excimer laser at 308 nm wavelength, a Nd:YLF picosecond laser at 1053 nm wavelength and a synchronously pumped linear cavity femtosecond laser at 630 nm wavelength. The pulse widths of the corresponding lasers were 8 ns, 18 ps, 150 fs, respectively. The energy density of irradiation was 2.5 to 8 times the threshold level being 2 J/cm2 (excimer laser), 86 J/cm2 (picosecond laser) and 10.3 J/cm2 (femtosecond laser). <span class="hlt">Shock</span> <span class="hlt">wave</span> dynamics were analyzed using time-resolved photography on a nanosecond time scale using the picosecond laser in corneal tissue, water and air. <span class="hlt">Shock</span> <span class="hlt">wave</span> dynamics using the femtosecond laser were studied in water only while the excimer laser induced <span class="hlt">shock</span> <span class="hlt">wave</span> during corneal ablation was studied in air only. We found the dynamics of <span class="hlt">shock</span> <span class="hlt">waves</span> to be similar in water and corneal tissue indicating that water is a good model to investigate <span class="hlt">shock</span> <span class="hlt">wave</span> effects in the cornea. The magnitude of the <span class="hlt">shock</span> <span class="hlt">wave</span> velocity and pressure decays over time to that of a sound <span class="hlt">wave</span>. The distance over which it decays is 3 mm in air with the excimer laser and 600 - 700 micrometers in air with the picosecond laser. In water, the picosecond laser <span class="hlt">shock</span> <span class="hlt">wave</span> decays over a distance of 150 micrometers compared to the femtosecond laser <span class="hlt">shock</span> <span class="hlt">wave</span> which decays over a distance of 30 micrometers . Overall the excimer laser <span class="hlt">shock</span> <span class="hlt">wave</span> propagates 5 times further than that of the picosecond laser and the picosecond laser <span class="hlt">shock</span> <span class="hlt">wave</span> propagates 5 times further than that of the femtosecond laser. In this preliminary comparison, the time and distance for <span class="hlt">shock</span> <span class="hlt">wave</span> decay appears to be directly</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22492655','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22492655"><span>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/2015AIPC.1685i0011K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AIPC.1685i0011K"><span>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://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Karzova, M.; Yuldashev, P.; Ollivier, S.; Khokhlova, V.; Blanc-Benon, Ph.</p> <p>2015-10-01</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/2006AIPC..829..440C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AIPC..829..440C"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/12120271','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12120271"><span>Successful extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy for sibling pancreatic duct stones.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kitajima, Y; Ohiwa, T; Yamada, T; Sano, H; Ohara, H; Nakazawa, T; Ando, H; Hashimoto, T; Nakamura, S; Nomura, T; Joh, T; Yokoyama, Y; Itoh, M</p> <p>2001-01-01</p> <p>We present a case of 2 brothers with idiopathic chronic pancreatitis associated with pancreatic duct stones which could be successfully disintegrated by extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy (ESWL). An obvious etiology for the pancreatolithiasis, like alcohol or biliary disease, was lacking and point mutations of the cationic trypsinogen gene exons 2 and 3 were not detected in the long arm of the 7th chromosome. However, a hereditary etiology could not be precluded since pancreatolithiasis occurred in the siblings. There has been no recurrence of pancreatic stones during 42 months of follow-up periods, for both. ESWL, the least invasive therapy, appeared applicable and effective for pancreatolithiasis in the present cases.</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>[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('https://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="https://ntrs.nasa.gov/search.jsp?R=19860045471&hterms=informatique&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dinformatique"><span>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('https://www.osti.gov/scitech/biblio/21476310','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21476310"><span>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('http://hdl.handle.net/2060/19940011005','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940011005"><span>On the interaction between the <span class="hlt">shock</span> <span class="hlt">wave</span> attached to a wedge and freestream disturbances</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Duck, Peter W.; Lasseigne, D. Glenn; Hussaini, M. Y.</p> <p>1993-01-01</p> <p>A study of the interaction of small amplitude, unsteady, freestream disturbances with a <span class="hlt">shock</span> <span class="hlt">wave</span> induced by a wedge in supersonic flow is presented. These disturbances may be acoustic <span class="hlt">waves</span>, vorticity <span class="hlt">waves</span>, or entropy <span class="hlt">waves</span> (or indeed a combination of all three). Their interactions then generate behind the <span class="hlt">shock</span> disturbances of all three classes, an aspect that is investigated in some detail, our motivation being to investigate possible mechanisms for boundary-layer receptivity, caused through the amplification and modification of freestream turbulence through the <span class="hlt">shock</span>-body coupling. Also, the possibility of enhanced mixing owing to additional vorticity produced by the <span class="hlt">shock</span>-body coupling is investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21743529','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21743529"><span>Effect of focusing conditions on laser-induced <span class="hlt">shock</span> <span class="hlt">waves</span> at titanium-water interface.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nath, Arpita; Khare, Alika</p> <p>2011-07-01</p> <p>The spatial and temporal evolution of laser-induced <span class="hlt">shock</span> <span class="hlt">waves</span> at a titanium-water interface was analyzed using a beam deflection setup. The focusing conditions of the source laser were varied, and its effect onto the dynamics of <span class="hlt">shock</span> <span class="hlt">waves</span> was elucidated. For a tightly focused condition, the speed of the <span class="hlt">shock</span> <span class="hlt">wave</span> was ~6.4 Km/s, whereas for a defocused condition the velocities reduced to <3 km/s at the vicinity of the titanium-water interface. When the laser is focused a few millimeters above the target, i.e., within the water, the emission of dual <span class="hlt">shock</span> <span class="hlt">waves</span> was observed toward the rear side of the focal volume. These <span class="hlt">shock</span> <span class="hlt">waves</span> originate from the titanium-water interface as well as from the pure water breakdown region, respectively. The <span class="hlt">shock</span> <span class="hlt">wave</span> pressure is estimated from the <span class="hlt">shock</span> <span class="hlt">wave</span> velocity using the Newton's second law across a <span class="hlt">shock</span> <span class="hlt">wave</span> discontinuity. The <span class="hlt">shock</span> <span class="hlt">wave</span> pressure for a tightly focused condition was 18 GPa, whereas under a defocused condition the pressure experienced was ≤1 GPa in the proximity of target.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22036636','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22036636"><span>Effect of focusing conditions on laser-induced <span class="hlt">shock</span> <span class="hlt">waves</span> at titanium-water interface</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Nath, Arpita; Khare, Alika</p> <p>2011-07-01</p> <p>The spatial and temporal evolution of laser-induced <span class="hlt">shock</span> <span class="hlt">waves</span> at a titanium-water interface was analyzed using a beam deflection setup. The focusing conditions of the source laser were varied, and its effect onto the dynamics of <span class="hlt">shock</span> <span class="hlt">waves</span> was elucidated. For a tightly focused condition, the speed of the <span class="hlt">shock</span> <span class="hlt">wave</span> was {approx}6.4 Km/s, whereas for a defocused condition the velocities reduced to <3 km/s at the vicinity of the titanium-water interface. When the laser is focused a few millimeters above the target, i.e., within the water, the emission of dual <span class="hlt">shock</span> <span class="hlt">waves</span> was observed toward the rear side of the focal volume. These <span class="hlt">shock</span> <span class="hlt">waves</span> originate from the titanium-water interface as well as from the pure water breakdown region, respectively. The <span class="hlt">shock</span> <span class="hlt">wave</span> pressure is estimated from the <span class="hlt">shock</span> <span class="hlt">wave</span> velocity using the Newton's second law across a <span class="hlt">shock</span> <span class="hlt">wave</span> discontinuity. The <span class="hlt">shock</span> <span class="hlt">wave</span> pressure for a tightly focused condition was 18 GPa, whereas under a defocused condition the pressure experienced was {<=}1 GPa in the proximity of target.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5300798','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5300798"><span>A histomorphometric study of necrotic femoral head in rabbits treated with extracorporeal <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>Ma, Huan-Zhi; Zhou, Dong-Sheng; Li, Dong; Zhang, Wei; Zeng, Bing-Fang</p> <p>2017-01-01</p> <p>[Purpose] This study aimed to determine the effectiveness and mechanisms of extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> therapy in the treatment of femoral head osteonecrosis. [Subjects and Methods] Histomorphometric analysis of necrotic femoral head in rabbits treated with <span class="hlt">shock</span> <span class="hlt">waves</span> was performed. Bilateral osteonecrosis of femoral heads was induced with methylprednisolone and lipopolysaccharide in eight rabbits. The left limb (study side) received <span class="hlt">shock</span> <span class="hlt">waves</span> to the femoral head. The right limb (control side) received no <span class="hlt">shock</span> <span class="hlt">waves</span>. Biopsies of the femoral heads were performed at 12 weeks after <span class="hlt">shock</span> <span class="hlt">wave</span> therapy. [Results] Necrotic femoral heads treated with <span class="hlt">shock</span> <span class="hlt">waves</span>, compared with controls, had higher bone volume per tissue volume, trabecular thickness, trabecular number, osteoblast surface/bone surface, osteoid surface/bone surface, osteoid thickness, mineralizing surface/bone surface, mineralizing apposition rate, and bone formation rate. However, trabecular separation was lower in <span class="hlt">shock</span> <span class="hlt">wave</span>-treated femoral heads than in controls. Eroded surface/bone surface and osteoclast surface/bone surface did not differ significantly between groups. [Conclusion] The bone mass of necrotic femoral heads treated with <span class="hlt">shock</span> <span class="hlt">waves</span> increases. Extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> may promote bone repair in necrotic femoral heads through the proliferation and activation of osteoblasts. PMID:28210032</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('https://www.ncbi.nlm.nih.gov/pubmed/27550074','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27550074"><span><span class="hlt">Shock</span> <span class="hlt">Wave</span>-Induced Damage and Poration in Eukaryotic Cell Membranes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>López-Marín, Luz M; Millán-Chiu, Blanca E; Castaño-González, Karen; Aceves, Carmen; Fernández, Francisco; Varela-Echavarría, Alfredo; Loske, Achim M</p> <p>2017-02-01</p> <p><span class="hlt">Shock</span> <span class="hlt">waves</span> are known to permeabilize eukaryotic cell membranes, which may be a powerful tool for a variety of drug delivery applications. However, the mechanisms involved in <span class="hlt">shock</span> <span class="hlt">wave</span>-mediated membrane permeabilization are still poorly understood. In this study, the effects on both the permeability and the ultrastructural features of two human cell lineages were investigated after the application of underwater <span class="hlt">shock</span> <span class="hlt">waves</span> in vitro. Scanning Electron Microscopy of cells derived from a human embryo kidney (HEK)-293 and Michigan Cancer Foundation (MCF)-7 cells, an immortalized culture derived from human breast adenocarcinoma, showed a small amount of microvilli (as compared to control cells), the presence of hole-like structures, and a decrease in cell size after <span class="hlt">shock</span> <span class="hlt">wave</span> exposure. Interestingly, these effects were accompanied by the permeabilization of acid and macromolecular dyes and gene transfection. Trypan blue exclusion assays indicated that cell membranes were porated during <span class="hlt">shock</span> <span class="hlt">wave</span> treatment but resealed after a few seconds. Deformations of the cell membrane lasted for at least 5 min, allowing their observation in fixed cells. For each cell line, different <span class="hlt">shock</span> <span class="hlt">wave</span> parameters were needed to achieve cell membrane poration. This difference was correlated to successful gene transfection by <span class="hlt">shock</span> <span class="hlt">waves</span>. Our results demonstrate, for the first time, that <span class="hlt">shock</span> <span class="hlt">waves</span> induce transient micro- and submicrosized deformations at the cell membrane, leading to cell transfection and cell survival. They also indicate that ultrastructural analyses of cell surfaces may constitute a useful way to match the use of <span class="hlt">shock</span> <span class="hlt">waves</span> to different cells and settings.</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>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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JAP...106g3307W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JAP...106g3307W"><span>Investigation on oblique <span class="hlt">shock</span> <span class="hlt">wave</span> control by arc discharge plasma in supersonic airflow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Jian; Li, Yinghong; Xing, Fei</p> <p>2009-10-01</p> <p>Wedge oblique <span class="hlt">shock</span> <span class="hlt">wave</span> control by arc discharge plasma in supersonic airflow was investigated theoretically, experimentally, and numerically in this paper. Using thermal choking model, the change in oblique <span class="hlt">shock</span> <span class="hlt">wave</span> was deduced, which refer that the start point of <span class="hlt">shock</span> <span class="hlt">wave</span> shifts upstream, the <span class="hlt">shock</span> <span class="hlt">wave</span> angle decreases, and its intensity weakens. Then the theoretical results were validated experimentally in a Mach 2.2 wind tunnel. On the test conditions of arc discharge power of ˜1 kW and arc plasma temperature of ˜3000 K, schlieren photography and gas pressure measurements indicated that the start point of <span class="hlt">shock</span> <span class="hlt">wave</span> shifted upstream of ˜4 mm, the <span class="hlt">shock</span> <span class="hlt">wave</span> angle decreased 8.6%, and its intensity weakened 8.8%. The deduced theoretical results match the test results qualitatively, so thermal mechanism and thermal choking model are rational to explain the problem of oblique <span class="hlt">shock</span> <span class="hlt">wave</span> control by arc discharge plasma. Finally, numerical simulation was developed. Based on thermal mechanism, the arc discharge plasma was simplified as a thermal source term that added to the Navier-Stokes equations. The simulation results of the change in oblique <span class="hlt">shock</span> <span class="hlt">wave</span> were consistent with the test results, so the thermal mechanism indeed dominates the oblique <span class="hlt">shock</span> <span class="hlt">wave</span> control process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21361857','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21361857"><span>Investigation on oblique <span class="hlt">shock</span> <span class="hlt">wave</span> control by arc discharge plasma in supersonic airflow</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wang Jian; Li Yinghong; Xing Fei</p> <p>2009-10-01</p> <p>Wedge oblique <span class="hlt">shock</span> <span class="hlt">wave</span> control by arc discharge plasma in supersonic airflow was investigated theoretically, experimentally, and numerically in this paper. Using thermal choking model, the change in oblique <span class="hlt">shock</span> <span class="hlt">wave</span> was deduced, which refer that the start point of <span class="hlt">shock</span> <span class="hlt">wave</span> shifts upstream, the <span class="hlt">shock</span> <span class="hlt">wave</span> angle decreases, and its intensity weakens. Then the theoretical results were validated experimentally in a Mach 2.2 wind tunnel. On the test conditions of arc discharge power of approx1 kW and arc plasma temperature of approx3000 K, schlieren photography and gas pressure measurements indicated that the start point of <span class="hlt">shock</span> <span class="hlt">wave</span> shifted upstream of approx4 mm, the <span class="hlt">shock</span> <span class="hlt">wave</span> angle decreased 8.6%, and its intensity weakened 8.8%. The deduced theoretical results match the test results qualitatively, so thermal mechanism and thermal choking model are rational to explain the problem of oblique <span class="hlt">shock</span> <span class="hlt">wave</span> control by arc discharge plasma. Finally, numerical simulation was developed. Based on thermal mechanism, the arc discharge plasma was simplified as a thermal source term that added to the Navier-Stokes equations. The simulation results of the change in oblique <span class="hlt">shock</span> <span class="hlt">wave</span> were consistent with the test results, so the thermal mechanism indeed dominates the oblique <span class="hlt">shock</span> <span class="hlt">wave</span> control process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1813612R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813612R"><span>Nonlinear <span class="hlt">reflection</span> of internal gravity <span class="hlt">wave</span> onto a slope</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Raja, Keshav; Sommeria, Joel; Staquet, Chantal; Leclair, Matthieu; Grisouard, Nicolas; Gostiaux, Louis</p> <p>2016-04-01</p> <p>The interaction of internal <span class="hlt">waves</span> on sloping topography is one of the processes that cause mixing and transport in oceans. The mixing caused by internal <span class="hlt">waves</span> is considered to be an important source of energy that is needed to bring back deep, dense water from the abyss to the surface of the ocean, across constant density surfaces. Apart from the vertical transport of heat (downwards) and mass (upwards), internal <span class="hlt">waves</span> are also observed to irreversibly induce a mean horizontal flow. Mixing and <span class="hlt">wave</span> induced mean flow may be considered as the processes that transfer <span class="hlt">wave</span> induced energy to smaller and larger scales respectively. The process of mixing has been a subject of intense research lately. However, the process of <span class="hlt">wave</span> induced mean flow and their dynamic impact await thorough study. The present study involves this <span class="hlt">wave</span> induced mean flow, its generation and energetics. The nonlinear subcritical <span class="hlt">reflection</span> of internal <span class="hlt">waves</span> from a sloping boundary is studied using laboratory experiments carried out on the Coriolis Platform at Grenoble and, 2D and 3D numerical simulations done using a non-hydrostatic code. In the experiment, a plane <span class="hlt">wave</span> is produced using a <span class="hlt">wave</span> generator and is made to <span class="hlt">reflect</span> normally on a sloping bottom in a uniformly stratified fluid. We consider both rotating and non-rotating cases. The numerical simulation mimicks the laboratory setup with an initial condition of an analytical plane <span class="hlt">wave</span> solution in a vertical plane limited by a smooth envelope to simulate the finite <span class="hlt">wave</span> generator. The interaction of the incident and <span class="hlt">reflected</span> <span class="hlt">waves</span> produce, apart from higher harmonics, an irreversible <span class="hlt">wave</span> induced mean flow which grows in time and is localised in the interacting region. The finite extent of the <span class="hlt">wave</span> generator allows the mean flow to recirculate in the horizontal plane, resulting in a dipolar potential vorticity field. Moreover, the generation of mean flow and higher harmonics, along with dissipative effects, diminishes the amplitude of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22489307','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22489307"><span>Photoacoustic <span class="hlt">shock</span> <span class="hlt">wave</span> emission and cavitation from structured optical fiber tips</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mohammadzadeh, M.; Gonzalez-Avila, S. R.; Ohl, C. D.; Wan, Y. C.; Wang, X.; Zheng, H.</p> <p>2016-01-11</p> <p>Photoacoustic <span class="hlt">waves</span> generated at the tip of an optical fiber consist of a compressive <span class="hlt">shock</span> <span class="hlt">wave</span> followed by tensile diffraction <span class="hlt">waves</span>. These tensile <span class="hlt">waves</span> overlap along the fiber axis and form a cloud of cavitation bubbles. We demonstrate that shaping the fiber tip through micromachining alters the number and direction of the emitted <span class="hlt">waves</span> and cavitation clouds. <span class="hlt">Shock</span> <span class="hlt">wave</span> emission and cavitation patterns from five distinctively shaped fiber tips have been studied experimentally and compared to a linear <span class="hlt">wave</span> propagation model. In particular, multiple <span class="hlt">shock</span> <span class="hlt">wave</span> emission and generation of strong tension away from the fiber axis have been realized using modified fiber tips. These altered waveforms may be applied for novel microsurgery protocols, such as fiber-based histotripsy, by utilizing bubble-<span class="hlt">shock</span> <span class="hlt">wave</span> interaction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/870050','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/870050"><span>Fiber optic sensor employing successively destroyed coupled points or reflectors for detecting <span class="hlt">shock</span> <span class="hlt">wave</span> speed and damage location</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Weiss, Jonathan D.</p> <p>1995-01-01</p> <p>A <span class="hlt">shock</span> velocity and damage location sensor providing a means of measuring <span class="hlt">shock</span> speed and damage location. The sensor consists of a long series of time-of-arrival "points" constructed with fiber optics. The fiber optic sensor apparatus measures <span class="hlt">shock</span> velocity as the fiber sensor is progressively crushed as a <span class="hlt">shock</span> <span class="hlt">wave</span> proceeds in a direction along the fiber. The light received by a receiving means changes as time-of-arrival points are destroyed as the sensor is disturbed by the <span class="hlt">shock</span>. The sensor may comprise a transmitting fiber bent into a series of loops and fused to a receiving fiber at various places, time-of-arrival points, along the receiving fibers length. At the "points" of contact, where a portion of the light leaves the transmitting fiber and enters the receiving fiber, the loops would be required to allow the light to travel backwards through the receiving fiber toward a receiving means. The sensor may also comprise a single optical fiber wherein the time-of-arrival points are comprised of <span class="hlt">reflection</span> planes distributed along the fibers length. In this configuration, as the <span class="hlt">shock</span> front proceeds along the fiber it destroys one reflector after another. The output received by a receiving means from this sensor may be a series of downward steps produced as the <span class="hlt">shock</span> <span class="hlt">wave</span> destroys one time-of-arrival point after another, or a nonsequential pattern of steps in the event time-of-arrival points are destroyed at any point along the sensor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/100985','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/biblio/100985"><span>Fiber optic sensor employing successively destroyed coupled points or reflectors for detecting <span class="hlt">shock</span> <span class="hlt">wave</span> speed and damage location</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Weiss, J.D.</p> <p>1995-08-29</p> <p>A <span class="hlt">shock</span> velocity and damage location sensor providing a means of measuring <span class="hlt">shock</span> speed and damage location is disclosed. The sensor consists of a long series of time-of-arrival ``points`` constructed with fiber optics. The fiber optic sensor apparatus measures <span class="hlt">shock</span> velocity as the fiber sensor is progressively crushed as a <span class="hlt">shock</span> <span class="hlt">wave</span> proceeds in a direction along the fiber. The light received by a receiving means changes as time-of-arrival points are destroyed as the sensor is disturbed by the <span class="hlt">shock</span>. The sensor may comprise a transmitting fiber bent into a series of loops and fused to a receiving fiber at various places, time-of-arrival points, along the receiving fibers length. At the ``points`` of contact, where a portion of the light leaves the transmitting fiber and enters the receiving fiber, the loops would be required to allow the light to travel backwards through the receiving fiber toward a receiving means. The sensor may also comprise a single optical fiber wherein the time-of-arrival points are comprised of <span class="hlt">reflection</span> planes distributed along the fibers length. In this configuration, as the <span class="hlt">shock</span> front proceeds along the fiber it destroys one reflector after another. The output received by a receiving means from this sensor may be a series of downward steps produced as the <span class="hlt">shock</span> <span class="hlt">wave</span> destroys one time-of-arrival point after another, or a nonsequential pattern of steps in the event time-of-arrival points are destroyed at any point along the sensor. 6 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016CMMPh..56.1096A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016CMMPh..56.1096A"><span>Numerical investigation of interactions of multiple spherical <span class="hlt">shock</span> <span class="hlt">waves</span> between themselves and with the underlying surface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Andrushchenko, V. A.; Murashkin, I. V.; Shevelev, Yu. D.</p> <p>2016-06-01</p> <p>Within the investigation of various aspects of asteroid and comet danger and, in particular, the explosion of several fragments of meteoroids in the atmosphere above the Earth surface, the toy problem about four point explosions in the case of their special arrangement above the underlying surface is numerically solved. Complex interactions of primary and secondary <span class="hlt">shock</span> <span class="hlt">waves</span> between themselves, with the hard surface, and with tangential discontinuities are examined. The structure of flow inside gas regions disturbed by the explosions—the occurrence of eddy structures in them and the influence of <span class="hlt">reflected</span> <span class="hlt">shocks</span> <span class="hlt">waves</span> on them—are investigated. The tendency of the external <span class="hlt">wave</span> fronts of each explosion to form a unified front and the tendency of their internal hot domains to merge into a joined configuration (where the second process proceeds a little later than the first one) is revealed. This unified front and joined configuration are qualitatively identical to the external internal structure for the solitary explosion. The specially arranged explosions are chosen because the effects of multiple diffraction, interference, and, the main thing, cumulation of spherical <span class="hlt">waves</span> are manifested more clearly in this caseTwo variants with different altitude of the explosions above the surface are calculated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27176524','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27176524"><span>Observation of Dispersive <span class="hlt">Shock</span> <span class="hlt">Waves</span>, Solitons, and Their Interactions in Viscous Fluid Conduits.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Maiden, Michelle D; Lowman, Nicholas K; Anderson, Dalton V; Schubert, Marika E; Hoefer, Mark A</p> <p>2016-04-29</p> <p>Dispersive <span class="hlt">shock</span> <span class="hlt">waves</span> and solitons are fundamental nonlinear excitations in dispersive media, but dispersive <span class="hlt">shock</span> <span class="hlt">wave</span> studies to date have been severely constrained. Here, we report on a novel dispersive hydrodynamic test bed: the effectively frictionless dynamics of interfacial <span class="hlt">waves</span> between two high viscosity contrast, miscible, low Reynolds number Stokes fluids. This scenario is realized by injecting from below a lighter, viscous fluid into a column filled with high viscosity fluid. The injected fluid forms a deformable pipe whose diameter is proportional to the injection rate, enabling precise control over the generation of symmetric interfacial <span class="hlt">waves</span>. Buoyancy drives nonlinear interfacial self-steepening, while normal stresses give rise to the dispersion of interfacial <span class="hlt">waves</span>. Extremely slow mass diffusion and mass conservation imply that the interfacial <span class="hlt">waves</span> are effectively dissipationless. This enables high fidelity observations of large amplitude dispersive <span class="hlt">shock</span> <span class="hlt">waves</span> in this spatially extended system, found to agree quantitatively with a nonlinear <span class="hlt">wave</span> averaging theory. Furthermore, several highly coherent phenomena are investigated including dispersive <span class="hlt">shock</span> <span class="hlt">wave</span> backflow, the refraction or absorption of solitons by dispersive <span class="hlt">shock</span> <span class="hlt">waves</span>, and the multiphase merging of two dispersive <span class="hlt">shock</span> <span class="hlt">waves</span>. The complex, coherent, nonlinear mixing of dispersive <span class="hlt">shock</span> <span class="hlt">waves</span> and solitons observed here are universal features of dissipationless, dispersive hydrodynamic flows.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvL.116q4501M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvL.116q4501M"><span>Observation of Dispersive <span class="hlt">Shock</span> <span class="hlt">Waves</span>, Solitons, and Their Interactions in Viscous Fluid Conduits</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maiden, Michelle D.; Lowman, Nicholas K.; Anderson, Dalton V.; Schubert, Marika E.; Hoefer, Mark A.</p> <p>2016-04-01</p> <p>Dispersive <span class="hlt">shock</span> <span class="hlt">waves</span> and solitons are fundamental nonlinear excitations in dispersive media, but dispersive <span class="hlt">shock</span> <span class="hlt">wave</span> studies to date have been severely constrained. Here, we report on a novel dispersive hydrodynamic test bed: the effectively frictionless dynamics of interfacial <span class="hlt">waves</span> between two high viscosity contrast, miscible, low Reynolds number Stokes fluids. This scenario is realized by injecting from below a lighter, viscous fluid into a column filled with high viscosity fluid. The injected fluid forms a deformable pipe whose diameter is proportional to the injection rate, enabling precise control over the generation of symmetric interfacial <span class="hlt">waves</span>. Buoyancy drives nonlinear interfacial self-steepening, while normal stresses give rise to the dispersion of interfacial <span class="hlt">waves</span>. Extremely slow mass diffusion and mass conservation imply that the interfacial <span class="hlt">waves</span> are effectively dissipationless. This enables high fidelity observations of large amplitude dispersive <span class="hlt">shock</span> <span class="hlt">waves</span> in this spatially extended system, found to agree quantitatively with a nonlinear <span class="hlt">wave</span> averaging theory. Furthermore, several highly coherent phenomena are investigated including dispersive <span class="hlt">shock</span> <span class="hlt">wave</span> backflow, the refraction or absorption of solitons by dispersive <span class="hlt">shock</span> <span class="hlt">waves</span>, and the multiphase merging of two dispersive <span class="hlt">shock</span> <span class="hlt">waves</span>. The complex, coherent, nonlinear mixing of dispersive <span class="hlt">shock</span> <span class="hlt">waves</span> and solitons observed here are universal features of dissipationless, dispersive hydrodynamic flows.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AIPC..845..896U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AIPC..845..896U"><span>Tension of Ethyl Alcohol and Hexadecane 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>Utkin, A. V.; Sosikov, V. A.; Fortov, V. E.</p> <p>2006-07-01</p> <p>The influences of strain rate and <span class="hlt">shock</span> <span class="hlt">wave</span> amplitude on the negative pressure in ethyl alcohol, and hexadecane have been investigated. The method of spall strength measurements was applied and <span class="hlt">wave</span> profiles were registered by laser interferometer VISAR. Unlike other liquids the process of destruction in methyl alcohol and hexadecane are double staged. At the first stage formation of cavities starts and there is a kinked at free velocity profile was observed. At the second stage the cavity grow rate increases and the spall pulse occurs. The dependence of negative pressure from the strain rate was instigated. The value of the negative pressure correspondent to the kinked at free velocity profile was practically constant and equal to 14MPa for methyl alcohol, and the maximal strength value may be much higher and equal to about 50MPa. Theory of homogeneous bubble nucleation was used to explain the experimental results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApGeo..13..667F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApGeo..13..667F"><span>Boundary-<span class="hlt">reflected</span> <span class="hlt">waves</span> and ultrasonic coda <span class="hlt">waves</span> in rock physics experiments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fu, Bo-Ye; Fu, Li-Yun; Wei, Wei; Zhang, Yan</p> <p>2016-12-01</p> <p>Ultrasonic coda <span class="hlt">waves</span> are widely used to study high-frequency scattering. However, ultrasonic coda <span class="hlt">waves</span> are strongly affected by interference from by boundary-<span class="hlt">reflected</span> <span class="hlt">waves</span>. To understand the effect of boundary-<span class="hlt">reflected</span> <span class="hlt">waves</span>, we performed ultrasonic experiments using aluminum and shale samples, and the rotating staggered-mesh finite-difference method to simulate the wavefield. We analyzed the wavefield characteristics at the different receiving points and the interference characteristics of the boundary-<span class="hlt">reflected</span> <span class="hlt">waves</span> with the ultrasonic coda <span class="hlt">wave</span>, and the effect of sample geometry on the ultrasonic coda <span class="hlt">waves</span>. The increase in the aspect ratio of the samples delays the interference effect of the laterally <span class="hlt">reflected</span> <span class="hlt">waves</span> and reduces the effect on the ultrasonic coda <span class="hlt">waves</span>. The main <span class="hlt">waves</span> interfering with the ultrasonic coda <span class="hlt">waves</span> are laterally <span class="hlt">reflected</span> PP-, PS-, PPP-, and PPS-<span class="hlt">waves</span>. The scattering and attenuation of the high-frequency energy in actual rocks can weaken the interference of laterally <span class="hlt">reflected</span> <span class="hlt">waves</span> with the ultrasonic coda <span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JMEP...23...49G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JMEP...23...49G"><span>Meso-scale Computational Investigation of <span class="hlt">Shock-Wave</span> Attenuation by Trailing Release <span class="hlt">Wave</span> in Different Grades of Polyurea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grujicic, Mica; Snipes, J. S.; Ramaswami, S.; Yavari, R.; Ramasubramanian, M. K.</p> <p>2014-01-01</p> <p>Over the past several years, considerable research efforts have been made toward investigating polyurea, a segmented thermoplastic elastomer, and particularly its <span class="hlt">shock</span>-mitigation capacity, i.e., an ability to attenuate and disperse <span class="hlt">shock-waves</span>. These research efforts have clearly established that the <span class="hlt">shock</span>-mitigation capacity of polyurea is closely related to its chemistry, processing route, and the resulting microstructure. Polyurea typically possesses a nano-segregated microstructure consisting of (high glass transition temperature, T g) hydrogen-bonded discrete hard domains and a (low T g) contiguous soft matrix. While the effect of polyurea microstructure on its <span class="hlt">shock</span>-mitigation capacity is well-established, it is not presently clear what microstructure-dependent phenomena and processes control its <span class="hlt">shock</span>-mitigation capacity. To help identify these phenomena and processes, meso-scale simulations of the formation of nano-segregated microstructure and its interaction with a leading <span class="hlt">shock-wave</span> and a trailing release-<span class="hlt">wave</span> is analyzed in the present work. The results obtained revealed that <span class="hlt">shock</span>-induced hard-domain densification makes an important contribution to the superior <span class="hlt">shock</span>-mitigation capacity of polyurea, and that the extent of densification is a sensitive function of the polyurea soft-segment molecular weight. In particular, the ability of release-<span class="hlt">waves</span> to capture and neutralize <span class="hlt">shock-waves</span> has been found to depend strongly on the extent of <span class="hlt">shock</span>-induced hard-domain densification and, thus, on the polyurea soft-segment molecular weight.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004A%26A...420..699C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004A%26A...420..699C"><span>Properties of longitudinal flux tube <span class="hlt">waves</span>. II. Limiting <span class="hlt">shock</span> strength behavior</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cuntz, M.</p> <p>2004-06-01</p> <p>We extend our previous work on analytic evaluations of properties of longitudinal tube <span class="hlt">waves</span> to <span class="hlt">waves</span> propagating in gravitational atmospheres. We derive an expression for the limiting <span class="hlt">shock</span> strength and discuss the behavior of the <span class="hlt">shock</span> strength in tubes of different geometry. It is found that a height-independent value for the limiting strength is attained for constant cross-section tubes and exponential tubes, whereas for wine-glass tubes the limiting <span class="hlt">shock</span> strength increases with height due to the increase of the tube cross section. The limiting <span class="hlt">shock</span> strength is well reproduced by time-dependent simulations. The derived limiting <span class="hlt">shock</span> strength as well as the energy dissipation rate of the <span class="hlt">waves</span> show significant similarities to acoustic <span class="hlt">waves</span>. The limiting <span class="hlt">shock</span> strength allows to estimate the heating potential of <span class="hlt">waves</span> in the absence of detailed time-dependent computations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011APS..MARQ31004H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011APS..MARQ31004H"><span>Burnett-Cattaneo Continuum Theory for <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>Holian, B. L.; Mareschal, M.; Ravelo, R.</p> <p>2011-03-01</p> <p>We model strong shockwave propagation, both in the ideal gas and in the dense Lennard-Jones fluid, using a refinement of earlier work, which accounts for the cold compression by a nonlinear, Burnett-like, strain-rate dependence of the thermal conductivity, and relaxation of temperature components on the hot, compressed side of the <span class="hlt">shock</span> front. The relaxation of the disequilibrium among the three components of the kinetic temperature, namely, the difference between the temperature in the direction of a planar <span class="hlt">shock</span> <span class="hlt">wave</span> and those in the transverse directions, particularly in the region near the <span class="hlt">shock</span> front, is accomplished by a rigorous application of the Cattaneo-Maxwell relaxation equation to a reference state, namely, the steady shockwave solution of linear Navier-Stokes-Fourier theory, along with the nonlinear Burnett heat-flux term. Our new continuum theory is in nearly quantitative agreement with non-equilibrium molecular-dynamics simulations under strong shockwave conditions. Part of this work supported by the U.S. Department of Energy under contract DE-AC5206NA25396.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015TESS....130502D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015TESS....130502D"><span>Plasma and <span class="hlt">wave</span> properties downstream of Martian bow <span class="hlt">shock</span>: Hybrid simulations and MAVEN observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dong, Chuanfei; Winske, Dan; Cowee, Misa; Bougher, Stephen W.; Andersson, Laila; Connerney, Jack; Epley, Jared; Ergun, Robert; McFadden, James P.; Ma, Yingjuan; Toth, Gabor; Curry, Shannon; Nagy, Andrew; Jakosky, Bruce</p> <p>2015-04-01</p> <p>Two-dimensional hybrid simulation codes are employed to investigate the kinetic properties of plasmas and <span class="hlt">waves</span> downstream of the Martian bow <span class="hlt">shock</span>. The simulations are two-dimensional in space but three dimensional in field and velocity components. Simulations show that ion cyclotron <span class="hlt">waves</span> are generated by temperature anisotropy resulting from the <span class="hlt">reflected</span> protons around the Martian bow <span class="hlt">shock</span>. These proton cyclotron <span class="hlt">waves</span> could propagate downward into the Martian ionosphere and are expected to heat the O+ layer peaked from 250 to 300 km due to the <span class="hlt">wave</span>-particle interaction. The proton cyclotron <span class="hlt">wave</span> heating is anticipated to be a significant source of energy into the thermosphere, which impacts atmospheric escape rates. The simulation results show that the specific dayside heating altitude depends on the Martian crustal field orientations, solar cycles and seasonal variations since both the cyclotron resonance condition and the non/sub-resonant stochastic heating threshold depend on the ambient magnetic field strength. The dayside magnetic field profiles for different crustal field orientation, solar cycle and seasonal variations are adopted from the BATS-R-US Mars multi-fluid MHD model. The simulation results, however, show that the heating of O+ via proton cyclotron <span class="hlt">wave</span> resonant interaction is not likely in the relatively weak crustal field region, based on our simplified model. This indicates that either the drift motion resulted from the transport of ionospheric O+, or the non/sub-resonant stochastic heating mechanism are important to explain the heating of Martian O+ layer. We will investigate this further by comparing the simulation results with the available MAVEN data. These simulated ion cyclotron <span class="hlt">waves</span> are important to explain the heating of Martian O+ layer and have significant implications for future observations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005ASAJ..117.2371M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005ASAJ..117.2371M"><span>Detecting cavitation in vivo from <span class="hlt">shock-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>Matula, Thomas J.; Yu, Jinfei; Bailey, Michael R.</p> <p>2005-04-01</p> <p>Extracorporeal <span class="hlt">shock-wave</span> therapy (ESWT) has been used as a treatment for plantar faciitis, lateral epicondylitis, shoulder tendonitis, non-unions, and other indications where conservative treatments have been unsuccessful. However, in many areas, the efficacy of SW treatment has not been well established, and the mechanism of action, particularly the role of cavitation, is not well understood. Research indicates cavitation plays an important role in other ultrasound therapies, such as lithotripsy and focused ultrasound surgery, and in some instances, cavitation has been used as a means to monitor or detect a biological effect. Although ESWT can generate cavitation easily in vitro, it is unknown whether or not cavitation is a significant factor in vivo. The purpose of this investigation is to use diagnostic ultrasound to detect and monitor cavitation generated by ESWT devices in vivo. Diagnostic images are collected at various times during and after treatment. The images are then post-processed with image-processing algorithms to enhance the contrast between bubbles and surrounding tissue. The ultimate goal of this research is to utilize cavitation as a means for optimizing <span class="hlt">shock</span> <span class="hlt">wave</span> parameters such as amplitude and pulse repetition frequency. [Work supported by APL internal funds and NIH DK43881 and DK55674.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011SPIE.8008E..15C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011SPIE.8008E..15C"><span>Wireless device for activation of an underground <span class="hlt">shock</span> <span class="hlt">wave</span> absorber</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chikhradze, M.; Akhvlediani, I.; Bochorishvili, N.; Mataradze, E.</p> <p>2011-10-01</p> <p>The paper describes the mechanism and design of the wireless device for activation of energy absorber for localization of blast energy in underground openings. The statistics shows that the greatest share of accidents with fatal results associate with explosions in coal mines due to aero-methane and/or air-coal media explosion. The other significant problem is terrorist or accidental explosions in underground structures. At present there are different protective systems to reduce the blast energy. One of the main parts of protective Systems is blast Identification and Registration Module. The works conducted at G. Tsulukidze Mining Institute of Georgia enabled to construct the wireless system of explosion detection and mitigation of <span class="hlt">shock</span> <span class="hlt">waves</span>. The system is based on the constant control on overpressure. The experimental research continues to fulfill the system based on both threats, on the constant control on overpressure and flame parameters, especially in underground structures and coal mines. Reaching the threshold value of any of those parameters, the system immediately starts the activation. The absorber contains a pyrotechnic device ensuring the discharge of dispersed water. The operational parameters of wireless device and activation mechanisms of pyrotechnic element of <span class="hlt">shock</span> <span class="hlt">wave</span> absorber are discussed in the paper.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22090371','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22090371"><span>[Medical and Economic Aspects of Extracorporeal <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>Knoll, T; Fritsche, H-M; Rassweiler, J</p> <p>2011-11-01</p> <p>Extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy (ESWL) is the method of choice for most renal and ureteral calculi. However, endoscopic procedures such as ureteroscopy or percutaneous nephrolithotomy are being more and more performed as primary treatment alternatives in clinical routine. This development may result from the sometimes unsatisfying results of ESWL. While this is often explained by a lower efficacy of last-generation machines, an often unrecognized explanation is the impact of a less well trained urologist. To achieve best results it is mandatory that fundamental knowledge about <span class="hlt">shock</span> <span class="hlt">wave</span> physics and disintegration mechanisms are available. In Germany, the reimbursement system between outpatient and inpatient departments is totally separate. This leads to difficulties in clinical practice. We believe that patients at risk for complications, such as ureteral stones, urinary tract infections or high age, benefit from inpatient treatment, while uncomplicated renal stones can safely be treated on an outpatient basis. Regular application and training of ESWL will aid an optimization of its results and acceptance.</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/1990AIPC..208..185I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990AIPC..208..185I"><span>Renal tissue damage induced by focused <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>Ioritani, N.; Kuwahara, M.; Kambe, K.; Taguchi, K.; Saitoh, T.; Shirai, S.; Orikasa, S.; Takayama, K.; Lush, P. A.</p> <p>1990-07-01</p> <p>Biological evidence of renal arterial wall damage induced by the microjet due to <span class="hlt">shock</span> <span class="hlt">wave</span>-cavitation bubble interaction was demonstrated in living dog kidneys. We also intended to clarify the mechanism of renal tissue damage and the effects of different conditions of <span class="hlt">shock</span> <span class="hlt">wave</span> exposure (peak pressure of focused area, number of shots, exposure rate) on the renal tissue damage in comparison to stone disintegration. Disruption of arterial wall was the most remarkable histological change in the focused area of the kidneys. This lesion appeared as if the wall had been punctured by a needle. Large hematoma formation in the renal parenchym, and interstitial hemorrhage seemed to be the results of the arterial lesion. This arterial disorder also led to ischemic necrosis of the tubules surrounding the hematoma. Micro-angiographic examination of extracted kidneys also proved such arterial puncture lesions and ischemic lesions. The number of shots required for model stone disintegration was not inversely proportional to peak pressure. It decreased markedly when peak pressure was above 700 bar. Similarly thenumber of shots for hematoma formation was not inversely proportional to peak pressure, however, this decreased markedly above 500 bar. These results suggested that a hematoma could be formed under a lower peak pressure than that required for stone disintegration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AIPC.1049..249H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AIPC.1049..249H"><span>Effect of <span class="hlt">Shock</span> <span class="hlt">Wave</span> Lithotripsy on Renal Hemodynamics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Handa, Rajash K.; Willis, Lynn R.; Evan, Andrew P.; Connors, Bret A.</p> <p>2008-09-01</p> <p>Extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy (SWL) can injure tissue and decrease blood flow in the SWL-treated kidney, both tissue and functional effects being largely localized to the region targeted with <span class="hlt">shock</span> <span class="hlt">waves</span> (SWs). A novel method of limiting SWL-induced tissue injury is to employ the "protection" protocol, where the kidney is pretreated with low-energy SWs prior to the application of a standard clinical dose of high-energy SWs. Resistive index measurements of renal vascular resistance/impedance to blood flow during SWL treatment protocols revealed that a standard clinical dose of high-energy SWs did not alter RI during SW application. However, there was an interaction between low- and high-energy SWL treatment phases of the "protection" protocol such that an increase in RI (vasoconstriction) was observed during the later half of SW application, a time when tissue damage is occurring during the standard high-energy SWL protocol. We suggest that renal vasoconstriction may be responsible for reducing the degree of tissue damage that normally results from a standard clinical dose of high-energy SWs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4841477','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4841477"><span>Radiating dispersive <span class="hlt">shock</span> <span class="hlt">waves</span> in non-local optical media</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>El, Gennady A.</p> <p>2016-01-01</p> <p>We consider the step Riemann problem for the system of equations describing the propagation of a coherent light beam in nematic liquid crystals, which is a general system describing nonlinear <span class="hlt">wave</span> propagation in a number of different physical applications. While the equation governing the light beam is of defocusing nonlinear Schrödinger (NLS) equation type, the dispersive <span class="hlt">shock</span> <span class="hlt">wave</span> (DSW) generated from this initial condition has major differences from the standard DSW solution of the defocusing NLS equation. In particular, it is found that the DSW has positive polarity and generates resonant radiation which propagates ahead of it. Remarkably, the velocity of the lead soliton of the DSW is determined by the classical <span class="hlt">shock</span> velocity. The solution for the radiative wavetrain is obtained using the Wentzel–Kramers–Brillouin approximation. It is shown that for sufficiently small initial jumps the nematic DSW is asymptotically governed by a Korteweg–de Vries equation with the fifth-order dispersion, which explicitly shows the resonance generating the radiation ahead of the DSW. The constructed asymptotic theory is shown to be in good agreement with the results of direct numerical simulations. PMID:27118911</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/8945854','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/8945854"><span>High-efficiency <span class="hlt">shock-wave</span> generator for extracorporeal lithotripsy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Broyer, P; Cathignol, D; Theillère, Y; Mestas, J L</p> <p>1996-09-01</p> <p>In extracorporeal lithotripsy, the electro-acoustic efficiency of electrohydraulic generators is limited by the inductance of the electrical discharge circuit. A new <span class="hlt">shock-wave</span> generator is described that uses a coaxial discharge line enabling electro-acoustic efficiency to be greatly increased. The line is built using a para-electric ceramic with a relative dielectric constant of 1700, manufactured for use in high-voltage impulse mode. A coaxial spark gap, with minimal inductance, has been developed to obtain the triggered breakdown of the discharge line. <span class="hlt">Shock</span> <span class="hlt">waves</span> are created with a coaxial electrode plugged directly into the spark gap and immersed in an electrolyte of degassed saline. Electrode gap and electrolyte resistivity are adjusted to match the resistivity of the electrolyte volume between the underwater electrodes to the characteristic impedance of the line. The discharge line generates in the medium a rectangular current pulse with an amplitude of about 6000 A and a rise time of 50 ns. Compared with conventional generators, measurements of the expansive peak pressure pulse show an increase of 105% at 10 kV, 86.5% at 12 kV and 34.5% at 14 kV charging voltage. Electro-acoustic efficiency is found to be 11% instead of 5.5% for a conventional discharge circuit.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/2709649','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/2709649"><span>Extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy: a study of renal stone differences.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Powers, C J; Tinterow, M M; Burpee, J F</p> <p>1989-01-01</p> <p>The extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> lithotriptor (ESWL or lithotriptor) is a new, revolutionary, noninvasive method of treating renal calculi. It offers a safer, cheaper and more effective method of treatment compared to the traditional open surgery. Its history dates back only to 1980--and to 1985 at HCA Wesley Medical Center in Wichita, where research is just beginning. Initial research focused on ESWL versus traditional open surgery, but more recent research is investigating elements within the ESWL treatment. This article presents an investigation of renal stone size in relation to number of ESWL treatments needed per stone, number of <span class="hlt">shock</span> <span class="hlt">waves</span> per treatment, length of hospital stay post-lithotripsy, and hospital costs per length of stay during HCA Wesley's first year of operation. The subjects in this study consisted of approximately every third patient who received an ESWL treatment and were grouped according to stone sizes of less than 2 cm and those greater than 2 cm. A questionnaire was used, and after data were collected from the patient's charts and billing, a t-test for independent samples was used for analysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DPPUO6015H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DPPUO6015H"><span><span class="hlt">Shock-Wave</span> Acceleration of Protons on OMEGA EP</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Haberberger, D.; Froula, D. H.; Pak, A.; Link, A.; Patel, P.; Fiuza, F.; Tochitsky, S.; Joshi, C.</p> <p>2016-10-01</p> <p>The creation of an electrostatic <span class="hlt">shock</span> <span class="hlt">wave</span> and ensuing ion acceleration is studied on the OMEGA EP Laser System at the Laboratory for Laser Energetics. Previous work using a 10- μm CO2 laser in a H2 gas jet shows promising results for obtaining narrow spectral features in the accelerated proton spectra. Scaling the <span class="hlt">shock-wave</span> acceleration mechanism to the 1- μm-wavelength drive laser makes it possible to use petawatt-scale laser systems such as OMEGA-EP, but involves tailoring of the plasma profile. To accomplish the necessitated sharp rise to near-critical plasma density and a long exponential fall, an 1- μm-thick CH foil is illuminated on the back side by thermal x rays produced from an irradiated gold foil. The plasma density is measured using the fourth-harmonic probe system, the accelerating fields are probed using an orthogonal proton source, and the accelerated protons and ions are detected with a Thomson parabola. These results will be presented and compared with particle-in-cell simulations. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944 and LLNL's Laboratory Directed Research and Development program under project 15-LW-095.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhRvE..92b3028N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvE..92b3028N"><span>Passage of a <span class="hlt">shock</span> <span class="hlt">wave</span> through inhomogeneous media and its impact on gas-bubble deformation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nowakowski, A. F.; Ballil, A.; Nicolleau, F. C. G. A.</p> <p>2015-08-01</p> <p>The paper investigates <span class="hlt">shock</span>-induced vortical flows within inhomogeneous media of nonuniform thermodynamic properties. Numerical simulations are performed using a Eulerian type mathematical model for compressible multicomponent flow problems. The model, which accounts for pressure nonequilibrium and applies different equations of state for individual flow components, shows excellent capabilities for the resolution of interfaces separating compressible fluids as well as for capturing the baroclinic source of vorticity generation. The developed finite volume Godunov type computational approach is equipped with an approximate Riemann solver for calculating fluxes and handles numerically diffused zones at flow component interfaces. The computations are performed for various initial conditions and are compared with available experimental data. The initial conditions promoting a <span class="hlt">shock</span>-bubble interaction process include weak to high planar <span class="hlt">shock</span> <span class="hlt">waves</span> with a Mach number ranging from 1.2 to 3 and isolated cylindrical bubble inhomogeneities of helium, argon, nitrogen, krypton, and sulphur hexafluoride. The numerical results reveal the characteristic features of the evolving flow topology. The impulsively generated flow perturbations are dominated by the <span class="hlt">reflection</span> and refraction of the <span class="hlt">shock</span>, the compression, and acceleration as well as the vorticity generation within the medium. The study is further extended to investigate the influence of the ratio of the heat capacities on the interface deformation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA561812','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA561812"><span><span class="hlt">Wave</span> <span class="hlt">Reflection</span> on a Two-Slope Steep Beach</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2012-03-01</p> <p>ABSTRACT (maximum 200 words) <span class="hlt">Wave</span> <span class="hlt">reflection</span> of sea-swell (0.05–0.20 Hz) energy on a two-slope (1/7.6 nearshore and 1/19 offshore) steep beach with no...amplitude long period <span class="hlt">waves</span> produced energy <span class="hlt">reflection</span> coefficients up to 80%, with most in the 30–50% range. There was a measured increase in the...PAGE INTENTIONALLY LEFT BLANK v ABSTRACT <span class="hlt">Wave</span> <span class="hlt">reflection</span> of sea-swell (0.05–0.20 Hz) energy on a two-slope (1/7.6 nearshore and 1/19 offshore) steep</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22136573','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22136573"><span>DIFFRACTION, REFRACTION, AND <span class="hlt">REFLECTION</span> OF AN EXTREME-ULTRAVIOLET <span class="hlt">WAVE</span> OBSERVED DURING ITS INTERACTIONS WITH REMOTE ACTIVE REGIONS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Shen Yuandeng; Liu Yu; Zhao Ruijuan; Tian Zhanjun; Su Jiangtao; Li Hui; Ichimoto, Kiyoshi; Shibata, Kazunari</p> <p>2013-08-20</p> <p>We present observations of the diffraction, refraction, and <span class="hlt">reflection</span> of a global extreme-ultraviolet (EUV) <span class="hlt">wave</span> propagating in the solar corona. These intriguing phenomena are observed when the <span class="hlt">wave</span> interacts with two remote active regions, and together they exhibit properties of an EUV <span class="hlt">wave</span>. When the <span class="hlt">wave</span> approached AR11465, it became weaker and finally disappeared in the active region, but a few minutes later a new wavefront appeared behind the active region, and it was not concentric with the incoming <span class="hlt">wave</span>. In addition, a <span class="hlt">reflected</span> <span class="hlt">wave</span> was also simultaneously observed on the <span class="hlt">wave</span> incoming side. When the <span class="hlt">wave</span> approached AR11459, it transmitted through the active region directly and without <span class="hlt">reflection</span>. The formation of the new wavefront and the transmission could be explained with diffraction and refraction effects, respectively. We propose that the different behaviors observed during the interactions may be caused by different speed gradients at the boundaries of the two active regions. We find that the EUV <span class="hlt">wave</span> formed ahead of a group of expanding loops a few minutes after the start of the loops' expansion, which represents the initiation of the associated coronal mass ejection (CME). Based on these results, we conclude that the EUV <span class="hlt">wave</span> should be a nonlinear magnetosonic <span class="hlt">wave</span> or <span class="hlt">shock</span> driven by the associated CME, which propagated faster than the ambient fast mode speed and gradually slowed down to an ordinary linear <span class="hlt">wave</span>. Our observations support the hybrid model that includes both fast <span class="hlt">wave</span> and slow non-<span class="hlt">wave</span> components.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPhCS.751a2020K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPhCS.751a2020K"><span>Rigid polyurethane foam as an efficient material for <span class="hlt">shock</span> <span class="hlt">wave</span> attenuation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Komissarov, P. V.; Borisov, A. A.; Sokolov, G. N.; Lavrov, V. V.</p> <p>2016-09-01</p> <p>A new method for reducing parameters of blast <span class="hlt">waves</span> generated by explosions of HE charges on ground is presented. Most of the traditional techniques reduce the <span class="hlt">wave</span> parameters at a certain distance from the charge, i.e. as a matter of fact the damping device interacts with a completely formed <span class="hlt">shock</span> <span class="hlt">wave</span>. The proposed approach is to use rigid polyurethane foam coating immediately the explosive charge. A distributed structure of such a foam block that provides most efficient <span class="hlt">shock</span> <span class="hlt">wave</span> attenuation is suggested. Results of experimental <span class="hlt">shock</span> <span class="hlt">wave</span> investigations recorded in tests in which HE charges have been exploded with damping devices and without it are compared.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014APS..DPPCP8076S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APS..DPPCP8076S"><span>Ion-acoustic <span class="hlt">Shocks</span> with <span class="hlt">Reflected</span> Ions: Implications for laser-based proton accelerators</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sagdeev, Roald; Malkov, Mikhail; Dudnikova, Galina; Liseykina, Tatyana; Diamond, Patrick; Liu, C.-S.; Su, J.-J.</p> <p>2014-10-01</p> <p>Analytic solution for an ion-acoustic collisionless <span class="hlt">shock</span> with <span class="hlt">reflected</span> ions is obtained. Its relation to classical non-<span class="hlt">reflecting</span> solitons propagating at Mach numbers strictly limited by M <M* ~ 1 . 6 (Boltzmann electrons) and M* ~ 3 . 1 (trapped electrons), is quantified. Above M =M* the soliton begins to <span class="hlt">reflect</span> upstream ions and turns into a <span class="hlt">shock</span>. The <span class="hlt">shock</span> has a double-structure consisting of two receding transitions. The first transition is the ion-acoustic <span class="hlt">shock</span> itself formed in place of the soliton. The <span class="hlt">shock</span> <span class="hlt">reflected</span> ions progressively fill up an extended foot region ending with the second transition that propagates faster than the rear <span class="hlt">shock</span> but slower than the most of <span class="hlt">reflected</span> ions. A small fraction of these ions still remains trapped in the transition to maintain charge neutrality. Most of them pass through this front transition, and accelerate whereas their distribution becomes noteworthily monoenergetic. The obtained solution may thus have interesting implications for the laser-based ion accelerators. Applications to particle acceleration in geophysical and astrophysical <span class="hlt">shocks</span> are discussed. Partially supported by NASA, ATP NNX14AH36G, and the US DoE.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20975385','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20975385"><span>The evolution and cellular structure of a detonation subsequent to a head-on interaction with 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>Botros, Barbara B.; Zhu, YuJian; Lee, John H.S.; Ng, Hoi Dick; Ju, Yiguang</p> <p>2007-12-15</p> <p>This paper analyzes the results of a head-on collision between a detonation and a planar <span class="hlt">shock</span> <span class="hlt">wave</span>. The evolution of the detonation cellular structure subsequent to the frontal collision was examined through smoked foil experiments. It is shown that a large reduction in cell size is observed following the frontal collision, and that the detonation cell widths are correlated well with the chemical kinetic calculations from the ZND model. From chemical kinetic calculations, the density increase caused by <span class="hlt">shock</span> compression appears to be the main factor leading to the significant reduction in cell size. It was found that depending on the initial conditions, the transition to the final cellular pattern can be either smooth or spotty. This phenomenon appears to be equivalent to Oppenheim's strong and mild <span class="hlt">reflected</span> <span class="hlt">shock</span> ignition experiments. The difference between these two transitions is, however, more related to the stability of the incident detonation and the strength of the perturbation generated by the incident <span class="hlt">shock</span>. (author)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26990289','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26990289"><span>Time-Resolved Broadband Cavity-Enhanced Absorption Spectroscopy behind <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>Matsugi, Akira; Shiina, Hiroumi; Oguchi, Tatsuo; Takahashi, Kazuo</p> <p>2016-04-07</p> <p>A fast and sensitive broadband absorption technique for measurements of high-temperature chemical kinetics and spectroscopy has been developed by applying broadband cavity-enhanced absorption spectroscopy (BBCEAS) in a <span class="hlt">shock</span> tube. The developed method has effective absorption path lengths of 60-200 cm, or cavity enhancement factors of 12-40, over a wavelength range of 280-420 nm, and is capable of simultaneously recording absorption time profiles over an ∼32 nm spectral bandpass in a single experiment with temporal and spectral resolutions of 5 μs and 2 nm, respectively. The accuracy of the kinetic and spectroscopic measurements was examined by investigating high-temperature reactions and absorption spectra of formaldehyde behind <span class="hlt">reflected</span> <span class="hlt">shock</span> <span class="hlt">waves</span> using 1,3,5-trioxane as a precursor. The rate constants obtained for the thermal decomposition reactions of 1,3,5-trioxane (to three formaldehyde molecules) and formaldehyde (to HCO + H) agreed well with the literature data. High-temperature absorption cross sections of formaldehyde between 280 and 410 nm have been determined at the post-<span class="hlt">reflected-shock</span> temperatures of 955, 1265, and 1708 K. The results demonstrate the applicability of the BBCEAS technique to time- and wavelength-resolved sensitive absorption measurements at high temperatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005ASAJ..118.2667C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005ASAJ..118.2667C"><span>Modeling elastic <span class="hlt">wave</span> propagation in kidney stones with application to <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cleveland, Robin O.; Sapozhnikov, Oleg A.</p> <p>2005-10-01</p> <p>A time-domain finite-difference solution to the equations of linear elasticity was used to model the propagation of lithotripsy <span class="hlt">waves</span> in kidney stones. The model was used to determine the loading on the stone (principal stresses and strains and maximum shear stresses and strains) due to the impact of lithotripsy <span class="hlt">shock</span> <span class="hlt">waves</span>. The simulations show that the peak loading induced in kidney stones is generated by constructive interference from shear <span class="hlt">waves</span> launched from the outer edge of the stone with other <span class="hlt">waves</span> in the stone. Notably the shear <span class="hlt">wave</span> induced loads were significantly larger than the loads generated by the classic Hopkinson or spall effect. For simulations where the diameter of the focal spot of the lithotripter was smaller than that of the stone the loading decreased by more than 50%. The constructive interference was also sensitive to <span class="hlt">shock</span> rise time and it was found that the peak tensile stress reduced by 30% as rise time increased from 25 to 150 ns. These results demonstrate that shear <span class="hlt">waves</span> likely play a critical role in stone comminution and that lithotripters with large focal widths and short rise times should be effective at generating high stresses inside kidney stones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21072682','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21072682"><span><span class="hlt">Reflection</span> of Alfven <span class="hlt">waves</span> from boundaries with different conductivities</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Leneman, D.</p> <p>2007-12-15</p> <p>The <span class="hlt">reflection</span> of Alfven <span class="hlt">waves</span> from the ionosphere plays a crucial role because the <span class="hlt">reflected</span> <span class="hlt">wave</span> can reduce or enhance the electric field pattern of the incident <span class="hlt">wave</span>. The ionosphere is typically treated as a conducting surface, which has a height integrated Pederson conductivity. This approximation is appropriate in considering the <span class="hlt">reflection</span> of Alfven <span class="hlt">waves</span> because the wavelengths along the magnetic field are large compared to the height of the ionosphere. Shear Alfven <span class="hlt">wave</span> <span class="hlt">reflection</span> experiments have been performed in the large plasma device [W. Gekelman, H. Pfister, Z. Lucky, J. Bamber, D. Leneman, and J. Maggs, Rev. of Sci. Instrum. 62, 2875 (1991)] at the University of California, Los Angeles. A single frequency <span class="hlt">wave</span> is launched from an antenna and <span class="hlt">reflects</span> from a large plate inserted into the plasma column. By alternatively using a conducting and an insulating plate, the two extremes of conductivity relative to the Alfven conductivity, 1/({mu}{sub o}v{sub A}) are tested. The data are compared with the expected theoretical behavior of the interference pattern of incident and <span class="hlt">reflected</span> <span class="hlt">waves</span>. Perhaps due to experimental effects, the conducting reflector is found to behave in much the same fashion as the insulator.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19720027237&hterms=level+crossing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dlevel%2Bcrossing','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19720027237&hterms=level+crossing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dlevel%2Bcrossing"><span>Pioneer 8 plasma-<span class="hlt">wave</span> measurements at distant bow-<span class="hlt">shock</span> crossings.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Scarf, F. L.</p> <p>1971-01-01</p> <p>Evaluation of enhanced low-frequency plasma-<span class="hlt">wave</span> levels detected near the Pioneer 8 multiple bow-<span class="hlt">shock</span> crossings encountered beyond 120 earth radii (Bavassano et al., 1971) and of high-frequency plasma <span class="hlt">waves</span> detected in the upstream region. It is suggested that the distant interaction of the solar wind and the magnetosheath produced nonthermal electrons of the type commonly found upstream from the subsolar <span class="hlt">shock</span>. The bow-<span class="hlt">shock</span> position is compared with fluid model predictions, and some distinctions between the standing bow <span class="hlt">shock</span> and the propagating interplanetary <span class="hlt">shock</span> are considered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19760063661&hterms=Media+law&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DMedia%2Blaw','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19760063661&hterms=Media+law&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DMedia%2Blaw"><span>Frequency modulation at a moving material interface and a conservation law for <span class="hlt">wave</span> number. [acoustic <span class="hlt">wave</span> <span class="hlt">reflection</span> and transmission</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kleinstein, G. G.; Gunzburger, M. D.</p> <p>1976-01-01</p> <p>An integral conservation law for <span class="hlt">wave</span> numbers is considered. In order to test the validity of the proposed conservation law, a complete solution for the <span class="hlt">reflection</span> and transmission of an acoustic <span class="hlt">wave</span> impinging normally on a material interface moving at a constant speed is derived. The agreement between the frequency condition thus deduced from the dynamic equations of motion and the frequency condition derived from the jump condition associated with the integral equation supports the proposed law as a true conservation law. Additional comparisons such as amplitude discontinuities and Snells' law in a moving media further confirm the stated proposition. Results are stated concerning frequency and <span class="hlt">wave</span> number relations across a <span class="hlt">shock</span> front as predicted by the proposed conservation law.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992ATJFE.114...58F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992ATJFE.114...58F"><span>Inlet boundary conditions for <span class="hlt">shock</span> <span class="hlt">wave</span> propagation problems in air ducts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fashbaugh, R. H.</p> <p>1992-03-01</p> <p><span class="hlt">Shock</span> <span class="hlt">waves</span> propagating into air ducting systems are numerically studied using data from Kriebel (1972). Small-scale junctions mounted in <span class="hlt">shock</span> tubes with an incident <span class="hlt">shock</span> <span class="hlt">wave</span> are considered. The stagnation pressure ratio through a duct inlet is evaluated for various junction types. The logarithm of this ratio varies linearly with the Mach number of the flow behind the incident <span class="hlt">shock</span> <span class="hlt">wave</span>. The static pressure inside the inlet is established using experimental data with given Mach numbers of the incident and inlet flows. A constant stagnation enthalpy through the inlet junction is assumed to establish inflow to the duct.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AIPC.1022..460P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AIPC.1022..460P"><span>Bubble Proliferation in <span class="hlt">Shock</span> <span class="hlt">Wave</span> Lithotripsy Occurs during Inertial Collapse</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pishchalnikov, Yuri A.; McAteer, James A.; Pishchalnikova, Irina V.; Williams, James C.; Bailey, Michael R.; Sapozhnikov, Oleg A.</p> <p>2008-06-01</p> <p>In <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy (SWL), firing <span class="hlt">shock</span> pulses at slow pulse repetition frequency (0.5 Hz) is more effective at breaking kidney stones than firing <span class="hlt">shock</span> <span class="hlt">waves</span> (SWs) at fast rate (2 Hz). Since at fast rate the number of cavitation bubbles increases, it appears that bubble proliferation reduces the efficiency of SWL. The goal of this work was to determine the basis for bubble proliferation when SWs are delivered at fast rate. Bubbles were studied using a high-speed camera (Imacon 200). Experiments were conducted in a test tank filled with nondegassed tap water at room temperature. Acoustic pulses were generated with an electromagnetic lithotripter (DoLi-50). In the focus of the lithotripter the pulses consisted of a ˜60 MPa positive-pressure spike followed by up to -8 MPa negative-pressure tail, all with a total duration of about 7 μs. Nonlinear propagation steepened the <span class="hlt">shock</span> front of the pulses to become sufficiently thin (˜0.03 μm) to impose differential pressure across even microscopic bubbles. High-speed camera movies showed that the SWs forced preexisting microbubbles to collapse, jet, and break up into daughter bubbles, which then grew rapidly under the negative-pressure phase of the pulse, but later coalesced to re-form a single bubble. Subsequent bubble growth was followed by inertial collapse and, usually, rebound. Most, if not all, cavitation bubbles emitted micro-jets during their first inertial collapse and re-growth. After jetting, these rebounding bubbles could regain a spherical shape before undergoing a second inertial collapse. However, either upon this second inertial collapse, or sometimes upon the first inertial collapse, the rebounding bubble emerged from the collapse as a cloud of smaller bubbles rather than a single bubble. These daughter bubbles could continue to rebound and collapse for a few cycles, but did not coalesce. These observations show that the positive-pressure phase of SWs fragments preexisting bubbles but this initial</p> </li> <li> <p><a target="_blank" onclick="trackOutboun