Paton, R. T.; Skews, B. W.; Rubidge, S.; Snow, J.
2013-07-01
The behaviour of conical shock waves imploding axisymmetrically was first studied numerically by Hornung (J Fluid Mech 409:1-12, 2000) and this prompted a limited experimental investigation into these complex flow patterns by Skews et al. (Shock Waves 11:323-326, 2002). Modification of the simulation boundary conditions, resulting in the loss of self-similarity, was necessary to image the flow experimentally. The current tests examine the temporal evolution of these flows utilising a converging conical gap of fixed width fed by a shock wave impinging at its entrance, supported by CFD simulations. The effects of gap thickness, angle and incident shock strength were investigated. The wave initially diffracts around the outer lip of the gap shedding a vortex which, for strong incident shock cases, can contain embedded shocks. The converging shock at exit reflects on the axis of symmetry with the reflected wave propagating outwards resulting in a triple point developing on the incident wave together with the associated shear layer. This axisymmetric shear layer rolls up into a mushroom-shaped toroidal vortex ring and forward-facing jet. For strong shocks, this deforms the Mach disk to the extent of forming a second triple point with the primary shock exhibiting a double bulge. Separate features resembling the Richtmeyer-Meshkov and Kelvin-Helmholtz instabilities were noted in some tests. Aside from the incident wave curvature, the reflection patterns demonstrated correspond well with the V- and DV-types identified by Hornung although type S was not clearly seen, possibly due to the occlusion of the reflection region by the outer diffraction vortex at these early times. Some additional computational work explicitly exploring the limits of the parameter space for such systems has demonstrated the existence of a possible further reflection type, called vN-type, which is similar to the von Neumann reflection for plane waves. It is recommended that the parameter space be
Jiang, Z
2005-01-01
The International Symposium on Shock Waves (ISSW) is a well established series of conferences held every two years in a different location. A unique feature of the ISSW is the emphasis on bridging the gap between physicists and engineers working in fields as different as gas dynamics, fluid mechanics and materials sciences. The main results presented at these meetings constitute valuable proceedings that offer anyone working in this field an authoritative and comprehensive source of reference.
Shock Wave Structure in Polyurethane Foam
ONODERA, Hideki; TAKAYAMA, Kazuyoshi
1994-01-01
Shock wave propagation in polyurethane (PU(R)) foam was experimentally studied. The experiment was conducted in a shock tube by measuring pressure along the PU(R) foam in a shock tube, by means of holographic interferometry and streak camera recording. It was found that the stress-strain curve of PU(R) has an inflection point. When the pressure behind the incident shock wave was below the inflection-point pressure P_c, the wave impedance ratio of the incident shock wave and transmitted pressu...
Directory of Open Access Journals (Sweden)
Abdolrahman Razani
2007-11-01
Full Text Available Shock wave theory was studied in literature by many authors. This article presents a survey with references about various topics related to shock waves: Hyperbolic conservation laws, Well-posedness theory, Compactness theory, Shock and reaction-diffusion wave, The CJ and ZND theory, Existence of detonation in Majda's model, Premixed laminar flame, Multidimensional gas flows, Multidimensional Riemann problem.
Shock wave treatment in medicine
Indian Academy of Sciences (India)
Urology has long been the only medical field for shock waves in medicine. Meanwhile shock waves have been used in orthopedics and traumatology to treat insertion tendinitis, avascular necrosis of the head of femur and other necrotic bone alterations. Another field of shock wave application is the treatment of tendons, ...
Shock wave treatment in medicine
Indian Academy of Sciences (India)
Unknown
compared to urology where shock waves are used for disintegration. [Shrivastava S K and Kailash 2005 Shock wave treatment in medicine; J. Biosci. 30 269–275]. 1. Introduction. Extracorporeal generated shock waves have been intro- duced for medical therapy approximately 20 years back to disintegrate kidney stones.
Fascinating World of Shock Waves
Indian Academy of Sciences (India)
Srimath
travelling at supersonic speeds (more than the sound speed at local temperature) then one can see a shock wave around the body as shown in Figure 1. Dissipation of energy, rapid changes in velocity, presure, temperature and flow turning are some of the features associated with shock waves. Obviously the word 'shock.
Bubble Dynamics and Shock Waves
2013-01-01
This volume of the Shock Wave Science and Technology Reference Library is concerned with the interplay between bubble dynamics and shock waves. It is divided into four parts containing twelve chapters written by eminent scientists. Topics discussed include shock wave emission by laser generated bubbles (W Lauterborn, A Vogel), pulsating bubbles near boundaries (DM Leppinen, QX Wang, JR Blake), interaction of shock waves with bubble clouds (CD Ohl, SW Ohl), shock propagation in polydispersed bubbly liquids by model equations (K Ando, T Colonius, CE Brennen. T Yano, T Kanagawa, M Watanabe, S Fujikawa) and by DNS (G Tryggvason, S Dabiri), shocks in cavitating flows (NA Adams, SJ Schmidt, CF Delale, GH Schnerr, S Pasinlioglu) together with applications involving encapsulated bubble dynamics in imaging (AA Doinikov, A Novell, JM Escoffre, A Bouakaz), shock wave lithotripsy (P Zhong), sterilization of ships’ ballast water (A Abe, H Mimura) and bubbly flow model of volcano eruptions ((VK Kedrinskii, K Takayama...
Sachdev, PL
2004-01-01
Understanding the causes and effects of explosions is important to experts in a broad range of disciplines, including the military, industrial and environmental research, aeronautic engineering, and applied mathematics. Offering an introductory review of historic research, Shock Waves and Explosions brings analytic and computational methods to a wide audience in a clear and thorough way. Beginning with an overview of the research on combustion and gas dynamics in the 1970s and 1980s, the author brings you up to date by covering modeling techniques and asymptotic and perturbative methods and ending with a chapter on computational methods.Most of the book deals with the mathematical analysis of explosions, but computational results are also included wherever they are available. Historical perspectives are provided on the advent of nonlinear science, as well as on the mathematical study of the blast wave phenomenon, both when visualized as a point explosion and when simulated as the expansion of a high-pressure ...
Shock Waves in Supernova Ejecta
Raymond, J. C.
2018-02-01
Astrophysical shock waves are a major mechanism for dissipating energy, and by heating and ionizing the gas they produce emission spectra that provide valuable diagnostics for the shock parameters, for the physics of collisionless shocks, and for the composition of the shocked material. Shocks in SN ejecta in which H and He have been burned to heavier elements behave differently than shocks in ordinary astrophysical gas because of their very large radiative cooling rates. In particular, extreme departures from thermal equilibrium among ions and electrons and from ionization equilibrium may arise. This paper discusses the consequences of the enhanced metal abundances for the structure and emission spectra of those shocks.
Oscillating nonlinear acoustic shock waves
DEFF Research Database (Denmark)
Gaididei, Yuri; Rasmussen, Anders Rønne; Christiansen, Peter Leth
2016-01-01
We investigate oscillating shock waves in a tube using a higher order weakly nonlinear acoustic model. The model includes thermoviscous effects and is non isentropic. The oscillating shock waves are generated at one end of the tube by a sinusoidal driver. Numerical simulations show...... that at resonance a stationary state arise consisting of multiple oscillating shock waves. Off resonance driving leads to a nearly linear oscillating ground state but superimposed by bursts of a fast oscillating shock wave. Based on a travelling wave ansatz for the fluid velocity potential with an added 2'nd order...... polynomial in the space and time variables, we find analytical approximations to the observed single shock waves in an infinitely long tube. Using perturbation theory for the driven acoustic system approximative analytical solutions for the off resonant case are determined....
Giammarinaro, Bruno; Espíndola, David; Coulouvrat, François; Pinton, Gianmarco
2018-01-01
Focusing is a ubiquitous way to transform waves. Recently, a new type of shock wave has been observed experimentally with high-frame-rate ultrasound: shear shock waves in soft solids. These strongly nonlinear waves are characterized by a high Mach number, because the shear wave velocity is much slower, by 3 orders of magnitude, than the longitudinal wave velocity. Furthermore, these waves have a unique cubic nonlinearity which generates only odd harmonics. Unlike longitudinal waves for which only compressional shocks are possible, shear waves exhibit cubic nonlinearities which can generate positive and negative shocks. Here we present the experimental observation of shear shock wave focusing, generated by the vertical motion of a solid cylinder section embedded in a soft gelatin-graphite phantom to induce linearly vertically polarized motion. Raw ultrasound data from high-frame-rate (7692 images per second) acquisitions in combination with algorithms that are tuned to detect small displacements (approximately 1 μ m ) are used to generate quantitative movies of gel motion. The features of shear shock wave focusing are analyzed by comparing experimental observations with numerical simulations of a retarded-time elastodynamic equation with cubic nonlinearities and empirical attenuation laws for soft solids.
30th International Symposium on Shock Waves
Sadot, Oren; Igra, Ozer
2017-01-01
These proceedings collect the papers presented at the 30th International Symposium on Shock Waves (ISSW30), which was held in Tel-Aviv Israel from July 19 to July 24, 2015. The Symposium was organized by Ortra Ltd. The ISSW30 focused on the state of knowledge of the following areas: Nozzle Flow, Supersonic and Hypersonic Flows with Shocks, Supersonic Jets, Chemical Kinetics, Chemical Reacting Flows, Detonation, Combustion, Ignition, Shock Wave Reflection and Interaction, Shock Wave Interaction with Obstacles, Shock Wave Interaction with Porous Media, Shock Wave Interaction with Granular Media, Shock Wave Interaction with Dusty Media, Plasma, Magnetohyrdrodynamics, Re-entry to Earth Atmosphere, Shock Waves in Rarefied Gases, Shock Waves in Condensed Matter (Solids and Liquids), Shock Waves in Dense Gases, Shock Wave Focusing, Richtmyer-Meshkov Instability, Shock Boundary Layer Interaction, Multiphase Flow, Blast Waves, Facilities, Flow Visualization, and Numerical Methods. The two volumes serve as a reference ...
INTERFERENCE OF COUNTERPROPAGATING SHOCK WAVES
Directory of Open Access Journals (Sweden)
P. V. Bulat
2015-03-01
Full Text Available The subject of study. We examined the interaction of counterpropagating shock waves. The necessity of counterpropagating shock waves studying occurs at designing of high Mach number modern internal compression air intakes, Ramjets with subsonic and supersonic combustion, in asymmetrical supersonic nozzles and in some other cases. In a sense, this problem is a generalization of the case of an oblique shock reflection from the wall or from the plane of symmetry. With the renewed vigor, the interest to this problem emerged at the end of the 90s. This was due to the start of the programs for flight study at hypersonic speeds. The first experiments performed with air intakes, which realized the interaction of counterpropagating shock waves have shown that the change in flow velocity is accompanied by abrupt alteration of shock-wave structure, the occurrence of nonstationary and oscillatory phenomena. With an increase of flow velocity these phenomena undesirable for aircraft structure became more marked. The reason is that there are two fundamentally different modes of interaction of counterpropagating shock waves: a four-wave regular and a five-wave irregular. The transition from one mode to another can be nonstationary abrupt or gradual, it can also be accompanied by hysteresis. Main results. Criteria for the transition from regular reflection of counterpropagating shock waves to irregular are described: the criterion of von Neumann and the stationary Mach configuration criterion. We described areas in which the transition from one reflection type to another is possible only in abrupt way, as well as areas of possible gradual transition. Intensity dependences of the reflected shock waves from the intensity of interacting counterpropagating shocks were given. Qualitative pictures of shock-wave structures arising from the interaction of counterpropagating shock waves were shown. Calculation results of the intensity of outgoing gas
Shock wave treatment in medicine
Indian Academy of Sciences (India)
Unknown
to open surgery, the cost of the ESWT is very reasonable. But nevertheless it is necessary to improve the basic un ... In second group, shock waves are used to measure distances because of the low energy loss over large distances ... pared to a piezoelectric hydrophone. The rise time of an electrohydraulic generated shock ...
Shock wave dynamics derivatives and related topics
Emanuel, George
2012-01-01
"...this monograph develops an esoteric niche within shock wave theory. …treats shock waves from an analytical approach assuming perfect gas. Emanuel has made significant contributions to the theory of shock waves and has selected a number of topics that reflect those contributions."-Shock Waves, 2013.
A collisionless shock wave experiment
International Nuclear Information System (INIS)
Winske, D.; Jones, M.E.; Sgro, A.G.; Thomas, V.A.
1995-01-01
Collisionless shock waves are a very important heating mechanism for plasmas and are commonly found in space and astrophysical environments. Collisionless shocks were studied in the laboratory more than 20 years ago, and more recently in space via in situ satellite measurements. The authors propose a new laboratory shock wave experiment to address unresolved issues related to the differences in the partition of plasma heating between electrons and ions in space and laboratory plasmas, which can have important implications for a number of physical systems
Three-Dimensional Unsteady Laminar Shock-Wave/Boundary Layer Interaction
National Research Council Canada - National Science Library
Boin, J-P; Robinet, Jean-Christophe
2004-01-01
.... To this end, the authors decided to study the evolution of the interaction between an incident shock wave and a laminar boundary layer developing over a flat plate when the incident shock angle...
Fascinating World of Shock Waves
Indian Academy of Sciences (India)
Srimath
elements in a fluid approach one another with a velocity higher than the local ... observed in nature. The dissipation of mechanical, nuclear, chemi- cal, and electrical energy in a limited space will usually result in the formation of a shock wave. Because of ..... aerodynamics, chemical kinetics, medicine, process engineering,.
EXTRACORPOREAL SHOCK WAVE LITHOTRIPSY AS ...
African Journals Online (AJOL)
Objective To evaluate extracorporeal shock wave lithotripsy (ESWL) as a monotherapy for urolithiasis in patients with solitary kidney and to determine the factors that may affect its results. Patients and Methods Using the Dornier MFL 5000 lithotriptor, 106 patients with solitary kidney (80 men and 26 women) were treated for ...
Attenuation of Shock Waves using Perforated Plates
Pavan Kumar, CH V. L. C. S.; Hitesh Reddy, C.; Rahul Sai, L.; Dharani Kumar, K. S. S.; Nagaraja, S. R.
2017-08-01
The shock/blast waves generated due to explosions cause wide spread damage to the objects in its path. Different techniques have been used to attenuate shock wave over pressure, to reduce the catastrophic effects. Perforated plates can be used effectively to attenuate the shock wave pressure. In this paper shock wave interaction with perforated plates is simulated using COMSOL multiphysics software. The pressure drop varied from 43.75% to 26% for porosity varying from 10% to 40.
Kasimov, Aslan R.
2013-03-08
We propose the following model equation, ut+1/2(u2−uus)x=f(x,us) that predicts chaotic shock waves, similar to those in detonations in chemically reacting mixtures. The equation is given on the half line, x<0, and the shock is located at x=0 for any t≥0. Here, us(t) is the shock state and the source term f is taken to mimic the chemical energy release in detonations. This equation retains the essential physics needed to reproduce many properties of detonations in gaseous reactive mixtures: steady traveling wave solutions, instability of such solutions, and the onset of chaos. Our model is the first (to our knowledge) to describe chaos in shock waves by a scalar first-order partial differential equation. The chaos arises in the equation thanks to an interplay between the nonlinearity of the inviscid Burgers equation and a novel forcing term that is nonlocal in nature and has deep physical roots in reactive Euler equations.
29th International Symposium on Shock Waves
Ranjan, Devesh
2015-01-01
This proceedings present the results of the 29th International Symposium on Shock Waves (ISSW29) which was held in Madison, Wisconsin, U.S.A., from July 14 to July 19, 2013. It was organized by the Wisconsin Shock Tube Laboratory, which is part of the College of Engineering of the University of Wisconsin-Madison. The ISSW29 focused on the following areas: Blast Waves, Chemically Reactive Flows, Detonation and Combustion, Facilities, Flow Visualization, Hypersonic Flow, Ignition, Impact and Compaction, Industrial Applications, Magnetohydrodynamics, Medical and Biological Applications, Nozzle Flow, Numerical Methods, Plasmas, Propulsion, Richtmyer-Meshkov Instability, Shock-Boundary Layer Interaction, Shock Propagation and Reflection, Shock Vortex Interaction, Shock Waves in Condensed Matter, Shock Waves in Multiphase Flow, as well as Shock Waves in Rarefield Flow. The two Volumes contain the papers presented at the symposium and serve as a reference for the participants of the ISSW 29 and individuals interes...
Experimental methods of shock wave research
Seiler, Friedrich
2016-01-01
This comprehensive and carefully edited volume presents a variety of experimental methods used in Shock Waves research. In 14 self contained chapters this 9th volume of the “Shock Wave Science and Technology Reference Library” presents the experimental methods used in Shock Tubes, Shock Tunnels and Expansion Tubes facilities. Also described is their set-up and operation. The uses of an arc heated wind tunnel and a gun tunnel are also contained in this volume. Whenever possible, in addition to the technical description some typical scientific results obtained using such facilities are described. Additionally, this authoritative book includes techniques for measuring physical properties of blast waves and laser generated shock waves. Information about active shock wave laboratories at different locations around the world that are not described in the chapters herein is given in the Appendix, making this book useful for every researcher involved in shock/blast wave phenomena.
SHOCK WAVE IN IONOSPHERE DURING EARTHQUAKE
Directory of Open Access Journals (Sweden)
V.V. Kuznetsov
2016-11-01
Full Text Available Fundamentally new model of the shock wave (SW generation in atmosphere and ionosphere during earthquake is proposed. The model proceeds from the idea of cooperative shock water crystallization in a cloud
Errors when shock waves interact due to numerical shock width
Energy Technology Data Exchange (ETDEWEB)
Menikoff, R.
1993-03-04
A simple test problem proposed by Noh, a strong shock reflecting from a rigid wall, demonstrates a generic problem with numerical shock capturing algorithms at boundaries that Noh called ``excess wall heating.`` We show that the same type of numerical error occurs in general when shock waves interact. The underlying cause is the non-uniform convergence to the hyperbolic solution of the inviscid limit of the solution to the PDEs with viscosity. The error can be understood from an analysis of the asymptotic solution. For a propagating shock, there is a difference in the total energy of the parabolic wave relative to the hyperbolic shock. Moreover, the relative energy depends on the strength of the shock. The error when shock waves interact is due to the difference in the relative energies between the incoming and outgoing shock waves. It is analogous to a phase shift in a scattering matrix. A conservative differencing scheme correctly describes the Hugoniot jump conditions for a steady propagating shock. Therefore, the error from the asymptotics occurs in the transient when the waves interact. The entropy error that occurs in the interaction region remains localized but does not dissipate. A scaling argument shows that as the viscosity coefficient goes to zero, the error shrinks in spatial extend but is constant in magnitude. Noh`s problem of the reflection of a shock from a rigid wall is equivalent to the symmetric impact of two shock waves of the opposite family. The asymptotic argument shows that the same type of numerical error would occur when the shocks are of unequal strength. Thus, Noh`s problem is indicative of a numerical error that occurs when shocks interact due to the numerical shock width.
Errors when shock waves interact due to numerical shock width
Energy Technology Data Exchange (ETDEWEB)
Menikoff, R.
1993-03-04
A simple test problem proposed by Noh, a strong shock reflecting from a rigid wall, demonstrates a generic problem with numerical shock capturing algorithms at boundaries that Noh called excess wall heating.'' We show that the same type of numerical error occurs in general when shock waves interact. The underlying cause is the non-uniform convergence to the hyperbolic solution of the inviscid limit of the solution to the PDEs with viscosity. The error can be understood from an analysis of the asymptotic solution. For a propagating shock, there is a difference in the total energy of the parabolic wave relative to the hyperbolic shock. Moreover, the relative energy depends on the strength of the shock. The error when shock waves interact is due to the difference in the relative energies between the incoming and outgoing shock waves. It is analogous to a phase shift in a scattering matrix. A conservative differencing scheme correctly describes the Hugoniot jump conditions for a steady propagating shock. Therefore, the error from the asymptotics occurs in the transient when the waves interact. The entropy error that occurs in the interaction region remains localized but does not dissipate. A scaling argument shows that as the viscosity coefficient goes to zero, the error shrinks in spatial extend but is constant in magnitude. Noh's problem of the reflection of a shock from a rigid wall is equivalent to the symmetric impact of two shock waves of the opposite family. The asymptotic argument shows that the same type of numerical error would occur when the shocks are of unequal strength. Thus, Noh's problem is indicative of a numerical error that occurs when shocks interact due to the numerical shock width.
Experimental investigation of shock wave - bubble interaction
Energy Technology Data Exchange (ETDEWEB)
Alizadeh, Mohsen
2010-04-09
In this work, the dynamics of laser-generated single cavitation bubbles exposed to lithotripter shock waves has been investigated experimentally. The energy of the impinging shock wave is varied in several steps. High-speed photography and pressure field measurements simultaneously with image acquisition provide the possibility of capturing the fast bubble dynamics under the effect of the shock wave impact. The pressure measurement is performed using a fiber optic probe hydrophone (FOPH) which operates based on optical diagnostics of the shock wave propagating medium. After a short introduction in chapter 1 an overview of the previous studies in chapter 2 is presented. The reported literatures include theoretical and experimental investigations of several configurations of physical problems in the field of bubble dynamics. In chapter 3 a theoretical description of propagation of a shock wave in a liquid like water has been discussed. Different kinds of reflection of a shock wave at an interface are taken into account. Undisturbed bubble dynamics as well as interaction between a planar shock wave and an initially spherical bubble are explored theoretically. Some physical parameters which are important in this issue such as the velocity of the shock-induced liquid jet, Kelvin impulse and kinetic energy are explained. The shock waves are generated in a water filled container by a focusing piezoelectric generator. The shock wave profile has a positive part with pulse duration of ∼1 μs followed by a longer tension tail (i.e. ∼3 μs). In chapter 4 high-speed images depict the propagation of a shock wave in the water filled tank. The maximum pressure is also derived for different intensity levels of the shock wave generator. The measurement is performed in the free field (i.e. in the absence of laser-generated single bubbles). In chapter 5 the interaction between lithotripter shock waves and laserinduced single cavitation bubbles is investigated experimentally. An
Physics of Collisionless Shocks Space Plasma Shock Waves
Balogh, André
2013-01-01
The present book provides a contemporary systematic treatment of shock waves in high-temperature collisionless plasmas as are encountered in near Earth space and in Astrophysics. It consists of two parts. Part I develops the complete theory of shocks in dilute hot plasmas under the assumption of absence of collisions among the charged particles when the interaction is mediated solely by the self-consistent electromagnetic fields. Such shocks are naturally magnetised implying that the magnetic field plays an important role in their evolution and dynamics. This part treats both subcritical shocks, which dissipate flow energy by generating anomalous resistance or viscosity, and supercritical shocks. The main emphasis is, however, on super-critical shocks where the anomalous dissipation is insufficient to retard the upstream flow. These shocks, depending on the direction of the upstream magnetic field, are distinguished as quasi-perpendicular and quasi-parallel shocks which exhibit different behaviours, reflecti...
PENETRATION OF A SHOCK WAVE IN A FLAME FRONT
Directory of Open Access Journals (Sweden)
Dan PANTAZOPOL
2009-09-01
Full Text Available The present paper deals with the interactions between a fully supersonic flame front, situated in a supersonic two-dimensional flow of an ideal homogeneous combustible gas mixture, and an incident shock wawe, which is penetrating in the space of the hot burnt gases. A possible configuration, which was named ,,simple penetration” is examined. For the anlysis of the interference phenomena, shock polar and shock-combustion polar are used. At the same time, the paper shows the possibility to produce similar but more complicated configurations, which may contain expansion fans and reflected shock waves.
Introduction to Shock Waves and Shock Wave Research
Energy Technology Data Exchange (ETDEWEB)
Anderson, William Wyatt [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2017-02-02
M-9 and a number of other organizations at LANL and elsewhere study materials in dynamic processes. Often, this is described as “shock wave research,” but in reality is broader than is implied by that term. Most of our work is focused on dynamic compression and associated phenomena, but you will find a wide variety of things we do that, while related, are not simple compression of materials, but involve a much richer variety of phenomena. This tutorial will introduce some of the underlying physics involved in this work, some of the more common types of phenomena we study, and common techniques. However, the list will not be exhaustive by any means.
Intense Shock Waves and Strongly Coupled Plasmas
Fortov, Vladimir
2005-07-01
The report presents the recent results of experimental investigations of equations of state, compositions, thermodynamical and transport properties, electrical conductivity and opacity of strongly coupled plasmas generated by intense shock and rarefaction waves. The experimental methods for generation of high energy densities in matter, drivers for shock waves and fast diagnostic tools are discussed. Application of intense shock waves to solid and porous targets generates nonideal plasmas in megabar-gigabar pressure range. Compression of plasma by a series of reverberating shock waves allows us to decrease irreversible heating effects. To increase the irreversibility effects and to generate high temperature plasma states the experiments on shock compression of porous samples (fine metal powder, aerogels) were performed. The adiabatic expansion of matter initially compressed by intense shocks up to megabars allows investigating the intermediate region between the solid and vapor phase of nonideal plasmas, including the metal-insulator transition phase and the high temperature saturation curve with critical points of metals. The shock-wave-induced non-equilibrium phenomena at fast melting, spallation and adiabatic condensation are analyzed in the framework of the interspinodal decomposition model. The spall strength of single and polycrystal metals at extremely fast deformation produced by fast shock waves is discussed. The ``pressure ionization'' phenomena in hydrogen, helium, argon, xenon, krypton, neon, iodine, silica, sulfur, fullerenes, and some metals are analyzed on the base of multiple shock compression experiments. For some simple metals (Li, Na, Ca) the effect of ``dielectrization'' as a result of multiple shock compression are discussed.
The microphysics of collisionless shock waves
DEFF Research Database (Denmark)
Marcowith, Alexandre; Bret, Antoine; Bykov, Andrei
2016-01-01
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...
Reflection of curved shock waves
Mölder, S.
2017-09-01
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.
Spherical shock waves in general relativity
International Nuclear Information System (INIS)
Nutku, Y.
1991-01-01
We present the metric appropriate to a spherical shock wave in the framework of general relativity. This is a Petrov type-N vacuum solution of the Einstein field equations where the metric is continuous across the shock and the Riemann tensor suffers a step-function discontinuity. Spherical gravitational waves are described by type-N Robinson-Trautman metrics. However, for shock waves the Robinson-Trautman solutions are unacceptable because the metric becomes discontinuous in the Robinson-Trautman coordinate system. Other coordinate systems that have so far been introduced for describing Robinson-Trautman solutions also suffer from the same defect. We shall present the C 0 -form of the metric appropriate to spherical shock waves using Penrose's approach of identification with warp. Further extensions of Penrose's method yield accelerating, as well as coupled electromagnetic-gravitational shock-wave solutions
Shock wave velocity and shock pressure for low density powders : A novel approach
Dijken, D.K.; Hosson, J.Th.M. De
1994-01-01
A novel approach is presented to predict the shock wave velocity as well as the shock wave pressure in powder materials. It is shown that the influence of the specific volume behind the shock wave on shock wave velocity and shock pressure decreases with decreasing initial powder density. The new
SHOCK-WAVE VELOCITY AND SHOCK PRESSURE FOR LOW-DENSITY POWDERS - A NOVEL-APPROACH
DIJKEN, DK; DEHOSSON, JTM
1994-01-01
A novel approach is presented to predict the shock wave velocity as well as the shock wave pressure in powder materials. It is shown that the influence of the specific volume behind the shock wave on shock wave velocity and shock pressure decreases with decreasing initial powder density. The new
28th International Symposium on Shock Waves
2012-01-01
The University of Manchester hosted the 28th International Symposium on Shock Waves between 17 and 22 July 2011. The International Symposium on Shock Waves first took place in 1957 in Boston and has since become an internationally acclaimed series of meetings for the wider Shock Wave Community. The ISSW28 focused on the following areas: Blast Waves, Chemically Reacting Flows, Dense Gases and Rarefied Flows, Detonation and Combustion, Diagnostics, Facilities, Flow Visualisation, Hypersonic Flow, Ignition, Impact and Compaction, Multiphase Flow, Nozzle Flow, Numerical Methods, Propulsion, Richtmyer-Meshkov, Shockwave Boundary Layer Interaction, Shock Propagation and Reflection, Shock Vortex Interaction, Shockwave Phenomena and Applications, as well as Medical and Biological Applications. The two Volumes contain the papers presented at the symposium and serve as a reference for the participants of the ISSW 28 and individuals interested in these fields.
Dense particle cloud dispersion by a shock wave
Kellenberger, M.; Johansen, C.; Ciccarelli, G.; Zhang, F.
2013-09-01
A dense particle flow is generated by the interaction of a shock wave with an initially stationary packed granular bed. High-speed particle dispersion research is motivated by the energy release enhancement of explosives containing solid particles. The initial packed granular bed is produced by compressing loose powder into a wafer with a particle volume fraction of . The wafer is positioned inside the shock tube, uniformly filling the entire cross-section. This results in a clean experiment where no flow obstructing support structures are present. Through high-speed shadowgraph imaging and pressure measurements along the length of the channel, detailed information about the particle shock interaction was obtained. Due to the limited strength of the incident shock wave, no transmitted shock wave is produced. The initial solid-like response of the particle wafer acceleration forms a series of compression waves that eventually coalesce to form a shock wave. Breakup is initiated along the periphery of the wafer as the result of shear that forms due to the fixed boundary condition. Particle breakup is initiated by local failure sites that result in the formation of particle jets that extend ahead of the accelerating, largely intact, wafer core. In a circular tube, the failure sites are uniformly distributed along the wafer circumference. In a square channel, the failure sites, and the subsequent particle jets, initially form at the corners due to the enhanced shear. The wafer breakup subsequently spreads to the edges forming a highly non-uniform particle cloud.
Sound waves and shock waves in high-density deuterium
International Nuclear Information System (INIS)
Inoue, Kazuko; Ariyasu, Tomio
1991-01-01
The possibility of compressing the cryogenic hollow pellet of inertial confinement nuclear fusion with multiple adiabatic shock waves is discussed, on the basis of the estimation of the properties of a high-density deuterium plasma (10 24 -10 27 cm -3 , 10 -1 -10 4 eV), such as the velocity and the attenuation constant of the adiabatic sound wave, the width of the shock wave, and the surface tension. It is found that in the course of compression the wavelength of the adiabatic sound wave and the width of the weak shock wave sometimes become comparable to or exceed the fuel shell width of the pellet, and that the surface tension is negative. These results show that it is rather difficult to compress stably the hollow pellet with successive weak shock waves. (author)
Shock Wave Science and Technology Reference Library
2007-01-01
Shock waves in multiphase flows refers to a rich variety of phenomena of interest to physicists, chemists, and fluid dynamicists, as well as mechanical, biomedical and aeronautical engineers. This volume treats shock and expansion waves in (bullet) complex, bubbly liquids (L van Wijngaarden, Y Tomita, V Kedrinskii) and (bullet) cryogenic liquids (M Murakami) and examines the relationship of shock waves with (bullet) phase transitions (A Guha, CF Delale, G Schnerr, MEH van Dongen) (bullet) induced phase transitions (GEA Meier) as well as their interaction with (bullet) solid foams, textiles, porous and granular media (B Skews, DMJ Smeulders, MEH van Dongen, V Golub, O Mirova) All chapters are self-contained, so they can be read independently, although they are of course thematically interrelated. Taken together, they offer a timely reference on shock waves in multiphase flows, including new viewpoints and burgeoning developments. The book will appeal to beginners as well as professional scientists and engineer...
Medical and biomedical applications of shock waves
Loske, Achim M
2017-01-01
This book provides current, comprehensive, and clear explanations of the physics behind medical and biomedical applications of shock waves. Extracorporeal shock wave lithotripsy is one of the greatest medical advances of our time, and its techniques and clinical devices are continuously evolving. Further research continues to improve the understanding of calculi fragmentation and tissue-damaging mechanisms. Shock waves are also used in orthopedics and traumatology. Possible applications in oncology, cardiology, dentistry, gene therapy, cell transfection, transformation of fungi and bacteria, as well as the inactivation of microorganisms are promising approaches for clinical treatment, industrial applications and research. Medical and Biomedical Applications of Shock Waves is useful as a guide for students, technicians and researchers working in universities and laboratories. Chemists, biologists, physicians and veterinarians, involved in research or clinical practice will find useful advice, but also engineer...
Shock wave mitigation using Newtonian and non-Newtonian fluids
Tao, Xingtian; Colvert, Brendan; Eliasson, Veronica
2014-11-01
The effectiveness of a wall of liquid as a blast mitigation device is examined using a shock tube and a custom-designed and -built shock test chamber. High-speed schlieren photography and high-frequency pressure sensors allow measurement during the relevant shock interaction time periods of the liquid-gas interface. The characteristic quantities that reflect these effects include reflected-to-incident shock strength ratio, transmitted-to-incident shock strength ratio, transmitted and reflected impulse, and peak pressure reduction. In particular, the effects of viscous properties of the fluid are considered when using non-Newtonian dilatant and pseudoplastic fluids. Experiments have been performed with both Newtonian and non-Newtonian fluids. The impact of a shock waves on Non-newtonian fluids is compared to that of Newtonian fluids. Experiments show that non-Newtonian fluids have very strong reflection properties, acting like solid walls under the impact of a shock wave. Further work is to be performed to compare quantitatively the properties of Newtonian vs. non-Newtonian fluids.
Shock waves in helium at low temperatures
International Nuclear Information System (INIS)
Liepmann, H.W.; Torczynski, J.R.
1986-01-01
Results are reported from studies of the properties of low temperature He-4 using shock waves as a probe. Ideal shock tube theory is used to show that sonic speeds of Mach 40 are attainable in He at 300 K. Viscosity reductions at lower temperatures minimize boundary layer effects at the side walls. A two-fluid model is described to account for the phase transition which He undergoes at temperatures below 2.2 K, after which the quantum fluid (He II) and the normal compressed superfluid (He I) coexist. Analytic models are provided for pressure-induced shocks in He I and temperature-induced shock waves (called second sound) which appear in He II. The vapor-fluid interface of He I is capable of reflecting second and gasdynamic sound shocks, which can therefore be used as probes for studying phase transitions between He I and He II. 17 references
Shock wave science and technology reference library
2009-01-01
This book, as a volume of the Shock Wave Science and Technology Reference Library, is primarily concerned with detonation waves or compression shock waves in reactive heterogeneous media, including mixtures of solid, liquid and gas phases. The topics involve a variety of energy release and control processes in such media - a contemporary research field that has found wide applications in propulsion and power, hazard prevention as well as military engineering. The six extensive chapters contained in this volume are: - Spray Detonation (SB Murray and PA Thibault) - Detonation of Gas-Particle Flow (F Zhang) - Slurry Detonation (DL Frost and F Zhang) - Detonation of Metalized Composite Explosives (MF Gogulya and MA Brazhnikov) - Shock-Induced Solid-Solid Reactions and Detonations (YA Gordopolov, SS Batsanov, and VS Trofimov) - Shock Ignition of Particles (SM Frolov and AV Fedorov) Each chapter is self-contained and can be read independently of the others, though, they are thematically interrelated. They offer a t...
Shock parameter calculations at weak interplanetary shock waves
Directory of Open Access Journals (Sweden)
J. M. Gloag
2005-02-01
Full Text Available A large set of interplanetary shock waves observed using the Ulysses spacecraft is analysed in order to determine their local parameters. For the first time a detailed analysis is extended to the thermodynamic properties of a large number of events. The intention is to relate the shock parameters to the requirements set by MHD shock theory. A uniform approach is adopted in the selection of up and downstream regions for this analysis and applied to all the shock waves. Initially, the general case of a 3 component adiabatic plasma is considered. However, the calculation of magnetosonic and Alfvénic Mach numbers and the ratio of downstream to upstream entropy produce some unexpected results. In some cases there is no clear increase in entropy across the shock and also the magnetosonic Mach number can be less than 1. It is found that a more discerning use of data along with an empirical value for the polytropic index can raise the distribution of downstream to upstream entropy ratios to a more acceptable level. However, it is also realised that many of these shocks are at the very weakest end of the spectrum and associated phenomena may also contribute to the explanation of these results.
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.
Experimental study of wall conductivity influence on shock wave reflection
Skews, Beric; Berry, Richard
2017-12-01
In the conventional von Neumann theoretical treatment of two-dimensional shock wave reflection off a surface, it is assumed that the flow is inviscid and that the reflecting surface is perfectly smooth, rigid, non-porous, and adiabatic. These theoretical predictions have been found to be good predictions of reflection over a significant range where regular reflection exists and for a limited range around Mach 2 for strong shocks in the case of Mach reflection. However, experiments on regular reflection have shown that this pattern persists to a small extent beyond what the theory predicts. This effect has been ascribed to the development of a viscous boundary layer behind the point of reflection, and some studies have been done on the effect of surface roughness on reflection topology. The possibility of thermal effects and heat transfer from the shock-heated gas to the wall and on the boundary layer has, on the other hand, been almost totally neglected. To study this, two surfaces of different conductivities have been placed at the same angle, symmetrically in a shock tube, and impacted by a single plane shock wave and the reflection patterns examined. Tests were conducted over a range of Mach numbers between 1.28 and 1.4, and incident shock wave angles between 36° and 70° covering both regular and Mach reflection. Both quantitative and qualitative tests show that there is a difference in the angles between the reflected waves and the reflecting surfaces based on the material thermal conductivity. In the quantitative tests the value of this angle was larger for materials with a lower thermal conductivity, and vice versa. A material, such as aluminium, with mid-range thermal conductivity had angles that lay within the limits of the two extreme values for glass and copper. The qualitative images supported these findings, showing asymmetry in reflection topography, with the intersection of the two reflected shock waves lying closer to the material with a higher
Shock wave science and technology reference library
2009-01-01
This book is the second of several volumes on solids in the Shock Wave Science and Technology Reference Library. These volumes are primarily concerned with high-pressure shock waves in solid media, including detonation and high-velocity impact and penetration events. Of the four extensive chapters in this volume, the first two describe the reactive behavior of condensed phase explosives, - Condensed-Phase Explosives: Shock Initiation and Detonation Phenomena (SA Sheffield and R Engelke) - First Principles Molecular Simulations of Energetic Materials at High-Pressures (F Zhang, S Alavi, and TK Woo), and the remaining two discuss the inert, mechanical response of solid materials. - Combined Compression and Shear Plane Waves (ZP Tang and JB Aidun), and - Dynamic Fragmentation of Solids (D Grady). All chapters are each self-contained, and can be read independently of each other. They offer a timely reference, for beginners as well as professional scientists and engineers, on the foundations of detonation phenomen...
Bifurcation parameters of a reflected shock wave in cylindrical channels of different roughnesses
Penyazkov, O.; Skilandz, A.
2018-03-01
To investigate the effect of bifurcation on the induction time in cylindrical shock tubes used for chemical kinetic experiments, one should know the parameters of the bifurcation structure of a reflected shock wave. The dynamics and parameters of the shock wave bifurcation, which are caused by reflected shock wave-boundary layer interactions, are studied experimentally in argon, in air, and in a hydrogen-nitrogen mixture for Mach numbers M = 1.3-3.5 in a 76-mm-diameter shock tube without any ramp. Measurements were taken at a constant gas density behind the reflected shock wave. Over a wide range of experimental conditions, we studied the axial projection of the oblique shock wave and the pressure distribution in the vicinity of the triple Mach configuration at 50, 150, and 250 mm from the endwall, using side-wall schlieren and pressure measurements. Experiments on a polished shock tube and a shock tube with a surface roughness of 20 {μ }m Ra were carried out. The surface roughness was used for initiating small-scale turbulence in the boundary layer behind the incident shock wave. The effect of small-scale turbulence on the homogenization of the transition zone from the laminar to turbulent boundary layer along the shock tube perimeter was assessed, assuming its influence on a subsequent stabilization of the bifurcation structure size versus incident shock wave Mach number, as well as local flow parameters behind the reflected shock wave. The influence of surface roughness on the bifurcation development and pressure fluctuations near the wall, as well as on the Mach number, at which the bifurcation first develops, was analyzed. It was found that even small additional surface roughness can lead to an overshoot in pressure growth by a factor of two, but it can stabilize the bifurcation structure along the shock tube perimeter.
Shock wave compression of condensed matter a primer
Forbes, Jerry W
2012-01-01
This book introduces the core concepts of the shock wave physics of condensed matter, taking a continuum mechanics approach to examine liquids and isotropic solids. The text primarily focuses on one-dimensional uniaxial compression in order to show the key features of condensed matter’s response to shock wave loading. The first four chapters are specifically designed to quickly familiarize physical scientists and engineers with how shock waves interact with other shock waves or material boundaries, as well as to allow readers to better understand shock wave literature, use basic data analysis techniques, and design simple 1-D shock wave experiments. This is achieved by first presenting the steady one-dimensional strain conservation laws using shock wave impedance matching, which insures conservation of mass, momentum and energy. Here, the initial emphasis is on the meaning of shock wave and mass velocities in a laboratory coordinate system. An overview of basic experimental techniques for measuring pressure...
Critical point anomalies include expansion shock waves
Nannen, N.R.; Guardone, A.; Colonna, P.
2014-01-01
From first-principle fluid dynamics, complemented by a rigorous state equation accounting for critical anomalies, we discovered that expansion shock waves may occur in the vicinity of the liquid-vapor critical point in the two-phase region. Due to universality of near-critical thermodynamics, the
Success of electromagnetic shock wave lithotripter asmonotherapy ...
African Journals Online (AJOL)
Objectives: To evaluate the success of shock wave lithotripsy (SWL) as monotherapy for solitary renalstones larger than 2 cm without ureteral stenting. Hence, if our study result demonstrates acceptable successand safety, we can recommend ESWL as a treatment option for patients with large renal calculi. Subjects and ...
Extracorporeal shock wave therapy (ESWT) in urology
DEFF Research Database (Denmark)
Fojecki, Grzegorz Lukasz; Thiessen, Stefan; Osther, Palle Jörn Sloth
2017-01-01
PURPOSE: The objective was to evaluate high-level evidence studies of extracorporeal shock wave therapy (ESWT) for urological disorders. METHODS: We included randomized controlled trials reporting outcomes of ESWT in urology. Literature search on trials published in English using EMBASE, Medline...
Geodesics analysis of colliding gravitational shock waves
International Nuclear Information System (INIS)
Pozdeeva, E.
2011-01-01
Full text: (author)We consider collision of charged gravitational shock waves with infinite transverse extension (charged gravitational walls). We study the influence of the charges on the trapped surface formation in the charged walls collision. This consideration has applications in the in heavy ion collisions using a holographic approach in which the charge plays the role of the chemical potential
Interstellar shock waves with magnetic precursors
International Nuclear Information System (INIS)
Draine, B.T.
1980-01-01
The structure of steady, radiative, one-dimensional shock waves in partially ionized gas with a transverse magnetic field B 0 is investigated. Under a broad range of conditions applicable to the interstellar medium it is found that such shocks may be preceded by a magnetic precursor which heats and compresses the medium ahead of the front where the neutral gas undergoes a discontinuous change of state; indeed, if B 0 is sufficiently large, a shock can exist with no discontinuities in hydrodynamical variables. Within this magnetic precursor both ions and electrons stream through the neutral fluid with velocities which may be a significant fraction of the shock speed. The physical processes operative in such shocks are examined, including the effects of charged dust grains in dense molecular clouds. Numerical examples are shown for v/sub s/ = 10 km s -1 shocks propagating into diffuse H I or H 2 . Shocks with magnetic precursors may have important consequences for the interstellar medium, some of which are briefly considered
High Temperature Phenomena in Shock Waves
2012-01-01
The high temperatures generated in gases by shock waves give rise to physical and chemical phenomena such as molecular vibrational excitation, dissociation, ionization, chemical reactions and inherently related radiation. In continuum regime, these processes start from the wave front, so that generally the gaseous media behind shock waves may be in a thermodynamic and chemical non-equilibrium state. This book presents the state of knowledge of these phenomena. Thus, the thermodynamic properties of high temperature gases, including the plasma state are described, as well as the kinetics of the various chemical phenomena cited above. Numerous results of measurement and computation of vibrational relaxation times, dissociation and reaction rate constants are given, and various ionization and radiative mechanisms and processes are presented. The coupling between these different phenomena is taken into account as well as their interaction with the flow-field. Particular points such as the case of rarefied flows an...
Shock Wave Attenuation Using Foam Obstacles: Does Geometry Matter?
Directory of Open Access Journals (Sweden)
Hongjoo Jeon
2015-06-01
Full Text Available A shock wave impact study on open and closed cell foam obstacles was completed to assess attenuation effects with respect to different front face geometries of the foam obstacles. Five different types of geometries were investigated, while keeping the mass of the foam obstacle constant. The front face, i.e., the side where the incident shock wave impacts, were cut in geometries with one, two, three or four convergent shapes, and the results were compared to a foam block with a flat front face. Results were obtained by pressure sensors located upstream and downstream of the foam obstacle, in addition to high-speed schlieren photography. Results from the experiments show no significant difference between the five geometries, nor the two types of foam.
Ren, Zhaoxin; Wang, Bing; Zheng, Longxi
2018-03-01
The analysis on the interactions of a large-scale shearing vortex, an incident oblique shock wave, and a chemical reaction in a planar shear layer is performed by numerical simulations. The reacting flows are obtained by directly solving the multi-species Navier-Stokes equations in the Eulerian frame, and the motions of individual point-mass fuel droplets are tracked in the Lagrangian frame considering the two-way coupling. The influences of shock strength and spray equivalence ratio on the shock-vortex interaction and the induced combustion are further studied. Under the present conditions, the incident shock is distorted by the vortex evolution to form the complicated waves including an incident shock wave, a multi-refracted wave, a reflected wave, and a transmitted wave. The local pressure and temperature are elevated by the shock impingement on the shearing vortex, which carries flammable mixtures. The chemical reaction is mostly accelerated by the refracted shock across the vortex. Two different exothermal reaction modes could be distinguished during the shock-vortex interaction as a thermal mode, due to the additional energy from the incident shock, and a local quasi detonation mode, due to the coupling of the refracted wave with reaction. The former mode detaches the flame and shock wave, whereas the latter mode tends to occur when the incident shock strength is higher and local equivalence ratio is higher approaching to the stoichiometric value. The numerical results illustrate that those two modes by shock-vortex interaction depend on the structure of the post-shock flame kernel, which may be located either in the vortex-braids of post-shock flows or in the shock-vortex interaction regime.
Shock waves in binary oxides memristors
Tesler, Federico; Tang, Shao; Dobrosavljević, Vladimir; Rozenberg, Marcelo
2017-09-01
Progress of silicon based technology is nearing its physical limit, as minimum feature size of components is reaching a mere 5 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, it has been mainly the result of empirical trial and error. Hence, gaining theoretical insight is of essence. In the present work we report a new connection between the resistive switching and shock wave formation, a classic topic of non-linear dynamics. We argue that the profile of oxygen ions that migrate during the commutation in insulating binary oxides may form a shock wave, which propagates through a poorly conductive region of the device. We validate the scenario by means of model simulations.
Material Point Methods for Shock Waves
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.
Bacterial transformation using micro-shock waves.
Divya Prakash, G; Anish, R V; Jagadeesh, G; Chakravortty, Dipshikha
2011-12-15
Shock waves are one of the most competent mechanisms of energy dissipation observed in nature. We have developed a novel device to generate controlled micro-shock waves using an explosive-coated polymer tube. In this study, we harnessed these controlled micro-shock waves to develop a unique bacterial transformation method. The conditions were optimized for the maximum transformation efficiency in Escherichia coli. The maximum transformation efficiency was obtained when we used a 30 cm length polymer tube, 100 μm thick metal foil, 200 mM CaCl(2), 1 ng/μl plasmid DNA concentration, and 1×10(9) cell density. The highest transformation efficiency achieved (1×10(-5) transformants/cell) was at least 10 times greater than the previously reported ultrasound-mediated transformation (1×10(-6) transformants/cell). This method was also successfully employed for the efficient and reproducible transformation of Pseudomonas aeruginosa and Salmonella typhimurium. This novel method of transformation was shown to be as efficient as electroporation with the added advantage of better recovery of cells, reduced cost (40 times cheaper than a commercial electroporator), and growth phase independent transformation. Copyright © 2011 Elsevier Inc. All rights reserved.
Feshbach resonance induced shock waves in Bose-Einstein condensates
International Nuclear Information System (INIS)
Perez-Garcia, Victor M.; Konotop, Vladimir V.; Brazhnyi, Valeriy A.
2004-01-01
We propose a method for generating shock waves in Bose-Einstein condensates by rapidly increasing the value of the nonlinear coefficient using Feshbach resonances. We show that in a cigar-shaped condensate there exist primary (transverse) and secondary (longitudinal) shock waves. We analyze how the shocks are generated in multidimensional scenarios and describe the related phenomenology
Dust acoustic solitary and shock waves in strongly coupled dusty ...
Indian Academy of Sciences (India)
mal vortex-like ion distribution and strongly correlated grains in a liquid-like state and discussed about the properties of shock ... shock waves in coupled dusty plasma with Boltzmann distribution of ions. Ghosh et al have studied the effect of ... ues of parameters where the nonlinear term is zero. Also new kind of shock wave.
Dust acoustic shock wave at high dust density
International Nuclear Information System (INIS)
Ghosh, Samiran; Sarkar, Susmita; Khan, Manoranjan; Avinash, K.; Gupta, M. R.
2003-01-01
Dust acoustic (DA) shock wave at high dust density, i.e., the dust electroacoustic (DEA) or dust Coulomb (DC) shock wave has been investigated incorporating the nonadiabatic dust charge variation. The nonlinear DEA (DC) shock wave is seen to be governed by the Korteweg-de Vries Burger equation, in which the Burger term is proportional to the nonadiabaticity generated dissipation. It is seen that the shock strength decreases but after reaching minimum, it increases as the dust space charge density |q d n d | increases and the shock strength of DA wave is greater than that of DEA (DC) wave. Moreover the DEA (DC) shock width increases appreciably with increase mass m i of the ion component of the dusty plasma but for DA shock wave the effect is weak
Effect of target-fixture geometry on shock-wave compacted copper powders
Kim, Wooyeol; Ahn, Dong-Hyun; Yoon, Jae Ik; Park, Lee Ju; Kim, Hyoung Seop
2018-01-01
In shock compaction with a single gas gun system, a target fixture is used to safely recover a powder compact processed by shock-wave dynamic impact. However, no standard fixture geometry exists, and its effect on the processed compact is not well studied. In this study, two types of fixture are used for the dynamic compaction of hydrogen-reduced copper powders, and the mechanical properties and microstructures are investigated using the Vickers microhardness test and electron backscatter diffraction, respectively. With the assistance of finite element method simulations, we analyze several shock parameters that are experimentally hard to control. The results of the simulations indicate that the target geometry clearly affects the characteristics of incident and reflected shock waves. The hardness distribution and the microstructure of the compacts also show their dependence on the geometry. With the results of the simulations and the experiment, it is concluded that the target geometry affects the shock wave propagation and wave interaction in the specimen.
Modeling Propagation of Shock Waves in Metals
Howard, W. M.; Molitoris, J. D.
2006-07-01
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 ˜ 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 ˜ 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.
Energy Technology Data Exchange (ETDEWEB)
Hull, Lawrence Mark [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Miller, Phillip Isaac [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Moro, Erik Allan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
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”.
EXPERIMENTAL STUDY OF SHOCK WAVE DYNAMICS IN MAGNETIZED PLASMAS
International Nuclear Information System (INIS)
Podder, Nirmol K.
2009-01-01
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
The Shock Wave in the ionosphere during an Earthquake
Directory of Open Access Journals (Sweden)
Kuznetsov Vladimir
2016-01-01
Full Text Available Fundamentally new model of the shock wave (SW generation in atmosphere and ionosphere during earthquake is proposed. The model proceeds from the idea of cooperative shock water crystallization in a cloud.
CT evaluation of the kidneys following extracorporeal shock wave lithotripsy
International Nuclear Information System (INIS)
Rubin, J.I.; Arger, P.H.; Pollack, H.M.; Banner, M.P.; Coleman, B.G.; Mintz, M.C.; Van Arsdalen, K.N.
1986-01-01
CT scans of the kidneys were obtained iln 50 patients before and after extracorporeal shock wave lithotripsy (ESWL). Post-ESWL scans demonstrated subcapsular hematomas in eight (15%) and intrarenal hematomas in two (4%) patients. Water-density subcapsular collections were seen in three (6%) patients. Treated kidneys showed a mean increase in renal size of 9%. Perinephric stranding and fascial thickening were seen in 37 (70%) of 53 treated renal fossae. While most patients undergoing ESWL will show some posttreatment abnormality on CT, the procedure appears to be associated with a low incidence of serious renal trauma
Shock Waves Science and Technology Library
2012-01-01
This book, as a volume of the Shock Wave Science and Technology Reference Library, is primarily concerned with the fundamental theory of detonation physics in gaseous and condensed phase reactive media. The detonation process involves complex chemical reaction and fluid dynamics, accompanied by intricate effects of heat, light, electricity and magnetism - a contemporary research field that has found wide applications in propulsion and power, hazard prevention as well as military engineering. The seven extensive chapters contained in this volume are: - Chemical Equilibrium Detonation (S. Bastea and LE Fried) - Steady One-Dimensional Detonations (A Higgins) - Detonation Instability (HD Ng and F Zhang) - Dynamic Parameters of Detonation (AA Vasiliev) - Multi-Scaled Cellular Detonation (D Desbordes and HN Presles) - Condensed Matter Detonation: Theory and Practice (C Tarver) - Theory of Detonation Shock Dynamics (JB Bdzil and DS Stewart) The chapters are thematically interrelated in a systematic descriptive appro...
Dust acoustic solitary and shock waves in strongly coupled dusty ...
Indian Academy of Sciences (India)
between nonlinear and dispersion effects can result in the formation of symmetrical solitary waves. Also shock ... et al have studied the effect of nonadiabatic dust charge variation on the nonlinear dust acoustic wave with ..... Figure 5 presents the border between oscillatory- and monotonic-type shock waves as functions of ...
Study on Reflected Shock Wave/Boundary Layer Interaction in a Shock Tube
Energy Technology Data Exchange (ETDEWEB)
Kim, Dong Wook; Kim, Tae Ho; Kim, Heuy Dong [Andong Nat’l Univ., Andong (Korea, Republic of)
2017-07-15
The interaction between a shock wave and a boundary layer causes boundary layer separation, shock train, and in some cases, strong unsteadiness in the flow field. Such a situation is also observed in a shock tube, where the reflected shock wave interacts with the unsteady boundary layer. However, only a few studies have been conducted to investigate the shock train phenomenon in a shock tube. In the present study, numerical studies were conducted using the two-dimensional axisymmetric domain of a shock tube, and compressible Navier-Stokes equations were solved to clarify the flow characteristics of shock train phenomenon inside a shock tube. A detailed wave diagram was developed based on the present computational results, which were validated with existing experimental data.
On the interplay between cosmological shock waves and their environment
Martin-Alvarez, Sergio; Planelles, Susana; Quilis, Vicent
2017-05-01
Cosmological shock waves are tracers of the thermal history of the structures in the Universe. They play a crucial role in redistributing the energy within the cosmic structures and are also amongst the main ingredients of galaxy and galaxy cluster formation. Understanding this important function requires a proper description of the interplay between shocks and the different environments where they can be found. In this paper, an Adaptive Mesh Refinement (AMR) Eulerian cosmological simulation is analysed by means of a shock-finding algorithm that allows to generate shock wave maps. Based on the population of dark matter halos and on the distribution of density contrast in the simulation, we classify the shocks in five different environments. These range from galaxy clusters to voids. The shock distribution function and the shocks power spectrum are studied for these environments dynamics. We find that shock waves on different environments undergo different formation and evolution processes, showing as well different characteristics. We identify three different phases of formation, evolution and dissipation of these shock waves, and an intricate migration between distinct environments and scales. Shock waves initially form at external, low density regions and are merged and amplified through the collapse of structures. Shock waves and cosmic structures follow a parallel evolution. Later on, shocks start to detach from them and dissipate. We also find that most of the power that shock waves dissipate is found at scales of k ˜0.5 Mpc^{-1}, with a secondary peak at k ˜8 Mpc^{-1}. The evolution of the shocks power spectrum confirms that shock waves evolution is coupled and conditioned by their environment.
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.
The isolated perfused kidney of the pig: new model to evaluate shock wave-induced lesions.
Köhrmann, K U; Back, W; Bensemann, J; Florian, J; Weber, A; Kahmann, F; Rassweiler, J; Alken, P
1994-04-01
Little is known about the mechanisms and determining factors of shock wave-induced kidney trauma. After classification of the renal lesion in a canine model, we attempted to establish an ex vivo model using the isolated kidney of the pig perfused by Tyrode's solution under physiologic conditions. After shock wave application on the Modulith SL 20, vessel lesions were evaluated by microangiography to determine the size and frequency of dye extravasation in the different areas of the organ. Variation of the focus localization caused different patterns of lesions that characterized the pathway of the shock wave. In particular, constant petechial extravasation in the cortex was observed. The generator voltage correlated with the diameter and the frequency of the lesion area. The number of shock waves primarily affected the incidence of vessel rupture in the regions adjacent to the focal zone. Light microscopy revealed dose-dependent necrosis of tubular cells up to gap-like parenchymal defects. Even after application of the minimal shock wave doses, electron microscopy demonstrated vacuolization of tubular cells in the shock wave focus. Traumatic junctions between capillaries and the tubulur system can explain clinically observed macrohematuria without renal hematomas. With this model, it was possible to evaluate localization and dose dependence of shock wave-induced kidney trauma with high sensitivity and reproducibility. Further advantages of the model were easy availability and the fact that studies on living animals were not necessary. Therefore, standardization and comparison of different lithotripters becomes possible.
Velocity of interplanetary shock waves according to radioastronomical data
International Nuclear Information System (INIS)
Vlasov, V.I.
1988-01-01
Velocities of 34 interplanetary shock waves are estimated by the method of radioastronomical cartography of scintillation indices of cosmic radiosources. The velocity of shock waves within the limits of approximately 0.2-1.2 a.e. is shown to decrease as far as they are far from the Sun at a distance equalling 1/r α , where 0.25 < or approx. α ≤ 1. In this case the degree of shock wave slowing-down dependences on their initial velocity; the velocity radial gradient is approximately proportional to the square of the shock wave initial velocity
In vitro comparison of shock wave lithotripsy machines
Teichman, Joel M.; Cecconi, Patricia P.; Pearle, Margaret S.; Clayman, Ralph V.
2005-04-01
We tested the hypothesis that shock wave 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 shocks 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. Shock wave lithotriptors vary in fragmentation ability.
Shock Wave Diffraction Phenomena around Slotted Splitters
Directory of Open Access Journals (Sweden)
Francesca Gnani
2015-01-01
Full Text Available In the field of aerospace engineering, the study of the characteristics of vortical flows and their unsteady phenomena finds numerous engineering applications related to improvements in the design of tip devices, enhancement of combustor performance, and control of noise generation. A large amount of work has been carried out in the analysis of the shock wave diffraction around conventional geometries such as sharp and rounded corners, but the employment of splitters with lateral variation has hardly attracted the attention of researchers. The investigation of this phenomenon around two-dimensional wedges has allowed the understanding of the basic physical principles of the flow features. On the other hand, important aspects that appear in the third dimension due to the turbulent nature of the vortices are omitted. The lack of studies that use three-dimensional geometries has motivated the current work to experimentally investigate the evolution of the shock wave diffraction around two splitters with spike-shaped structures for Mach numbers of 1.31 and 1.59. Schlieren photography was used to obtain an insight into the sequential diffraction processes that take place in different planes. Interacting among them, these phenomena generate a complicated turbulent cloud with a vortical arrangement.
The characteristic response of whistler mode waves to interplanetary shocks
Yue, C.; Chen, L.; Bortnik, J.; Ma, Q.; Thorne, R. M.; Angelopoulos, V.; Li, J.; An, X.; Zhou, C.
2017-12-01
Magnetospheric whistler mode waves play a key role in regulating the dynamics of the electron radiation belts. Recent satellite observations indicate a significant influence of interplanetary (IP) shocks on whistler mode wave power in the inner magnetosphere. In this study, we statistically investigate the response of whistler mode chorus and plasmaspheric hiss to IP shocks based on Van Allen Probes and THEMIS satellite observations. Immediately after the IP shock arrival, chorus wave power is usually intensified, often at dawn, while plasmaspheric hiss wave power predominantly decreases near the dayside but intensifies near the nightside. We conclude that chorus wave intensification outside the plasmasphere is probably associated with the suprathermal electron flux enhancement caused by the IP shock. On the other hand, the solar wind dynamic pressure increase changes the magnetic field configuration to favor ray penetration into the nightside and promote ray refraction away from the dayside, explaining the magnetic local time (MLT) dependent responses of plasmaspheric hiss waves following IP shock arrivals.
Effects of shock waves on Rayleigh-Taylor instability
International Nuclear Information System (INIS)
Zhang Yongtao; Shu Chiwang; Zhou Ye
2006-01-01
A numerical simulation of two-dimensional compressible Navier-Stokes equations using a high-order weighted essentially nonoscillatory finite difference shock capturing scheme is carried out in this paper, to study the effect of shock waves on the development of Rayleigh-Taylor instability. Shocks with different Mach numbers are introduced ahead or behind the Rayleigh-Taylor interface, and their effect on the transition to instability is demonstrated and compared. It is observed that shock waves can speed up the transition to instability for the Rayleigh-Taylor interface significantly. Stronger shocks are more effective in this speed-up process
Shock wave focusing in water inside convergent structures
Directory of Open Access Journals (Sweden)
C Wang
2016-09-01
Full Text Available Experiments on shock focusing in water-filled convergent structures have been performed. A shock wave in water is generated by means of a projectile, launched from a gas gun, which impacts a water-filled convergent structure. Two types of structures have been tested; a bulk material and a thin shell structure. The geometric shape of the convergent structures is given by a logarithmic spiral, and this particular shape is chosen because it maximizes the amount of energy reaching the focal region. High-speed schlieren photography is used to visualize the shock dynamics during the focusing event. Results show that the fluid-structure interaction between the thin shell structure and the shock wave in the water is different from that of a bulk structure; multiple reflections of the shock wave inside the thin shell are reflected back into the water, thus creating a wave train, which is not observed for shock focusing in a bulk material.
Biological effects of tandem shock waves demonstrated on magnetic resonance
Czech Academy of Sciences Publication Activity Database
Beneš, J.; Zeman, J.; Poučková, P.; Zadinová, M.; Šunka, Pavel; Lukeš, Petr
Roč. 113, č. 6 ( 2012 ), s. 335-338 ISSN 0006-9248 R&D Projects: GA ČR GA202/09/1151 Institutional research plan: CEZ:AV0Z20430508 Keywords : electrical discharges in water * focused shock waves * cavitations * tandem shock waves Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.472, year: 2012
Acceleration mechanisms flares, magnetic reconnection and shock waves
International Nuclear Information System (INIS)
Colgate, S.A.
1979-01-01
Several mechanisms are briefly discussed for the acceleration of particles in the astrophysical environment. Included are hydrodynamic acceleration, spherically convergent shocks, shock and a density gradient, coherent electromagnetic acceleration, the flux tube origin, symmetries and instabilities, reconnection, galactic flares, intergalactic acceleration, stochastic acceleration, and astrophysical shocks. It is noted that the supernova shock wave models still depend critically on the presupernova star structure and the assumption of highly compact presupernova models for type I supernovae. 37 references
On cylindrically converging shock waves shaped by obstacles
Energy Technology Data Exchange (ETDEWEB)
Eliasson, V; Henshaw, W D; Appelo, D
2007-07-16
Motivated by recent experiments, numerical simulations were performed of cylindrically converging shock waves. The converging shocks impinged upon a set of zero to sixteen regularly space obstacles. For more than two obstacles the resulting diffracted shock fronts formed polygonal shaped patterns near the point of focus. The maximum pressure and temperature as a function of number of obstacles were studied. The self-similar behavior of cylindrical, triangular and square-shaped shocks were also investigated.
THE EFFECTS OF AREA CONTRACTION ON SHOCK WAVE STRENGTH AND PEAK PRESSURE IN SHOCK TUBE
Directory of Open Access Journals (Sweden)
A. M. Mohsen
2012-06-01
Full Text Available This paper presents an experimental investigation into the effects of area contraction on shock wave strength and peak pressure in a shock tube. The shock tube is an important component of the short duration, high speed fluid flow test facility, available at the Universiti Tenaga Nasional (UNITEN, Malaysia. The area contraction was facilitated by positioning a bush adjacent to the primary diaphragm section, which separates the driver and driven sections. Experimental measurements were performed with and without the presence of the bush, at various diaphragm pressure ratios, which is the ratio of air pressure between the driver (high pressure and driven (low pressure sections. The instantaneous static pressure variations were measured at two locations close to the driven tube end wall, using high sensitivity pressure sensors, which allow the shock wave strength, shock wave speed and peak pressure to be analysed. The results reveal that the area contraction significantly reduces the shock wave strength, shock wave speed and peak pressure. At a diaphragm pressure ratio of 10, the shock wave strength decreases by 18%, the peak pressure decreases by 30% and the shock wave speed decreases by 8%.
A new shock wave assisted sandalwood oil extraction technique
Arunkumar, A. N.; Srinivasa, Y. B.; Ravikumar, G.; Shankaranarayana, K. H.; Rao, K. S.; Jagadeesh, G.
A new shock wave assisted oil extraction technique from sandalwood has been developed in the Shock Waves Lab, IISc, Bangalore. The fragrant oil extracted from sandalwood finds variety of applications in medicine and perfumery industries. In the present method sandal wood specimens (2.5mm diameter and 25mm in length)are subjected to shock wave loading (over pressure 15 bar)in a constant area shock tube, before extracting the sandal oil using non-destructive oil extraction technique. The results from the study indicates that both the rate of extraction as well as the quantity of oil obtained from sandal wood samples exposed to shock waves are higher (15-40 percent) compared to non-destructive oil extraction technique. The compressive squeezing of the interior oil pockets in the sandalwood specimen due to shock wave loading appears to be the main reason for enhancement in the oil extraction rate. This is confirmed by the presence of warty structures in the cross-section and micro-fissures in the radial direction of the wood samples exposed to shock waves in the scanning electron microscopic investigation. In addition the gas chromatographic studies do not show any change in the q uality of sandal oil extracted from samples exposed to shock waves.
Incident shock strength evolution in overexpanded jet flow out of rocket nozzle
Silnikov, Mikhail V.; Chernyshov, Mikhail V.
2017-06-01
The evolution of the incident shock in the plane overexpanded jet flow or in the axisymmetric one is analyzed theoretically and compared at the whole range of governing flow parameters. Analytical results can be applied to avoid jet flow instability and self-oscillation effects at rocket launch, to improve launch safety and to suppress shock-wave induced noise harmful to environment and personnel. The mathematical model of ;differential conditions of dynamic compatibility; was applied to the curved shock in non-uniform plane or axisymmetrical flow. It allowed us to study such features of the curved incident shock and flow downstream it as shock geometrical curvature, jet boundary curvature, local increase or decrease of the shock strength, flow vorticity rate (local pressure gradient) in the vicinity of the nozzle lip, static pressure gradient in the compressed layer downstream the shock, and many others. All these quantities sufficiently depend on the flow parameters (flow Mach number, jet overexpansion rate, nozzle throat angle, and ration of gas specific heats). These dependencies are sometimes unusual, especially at small Mach numbers. It was also surprising that there is no great difference among all these flowfield features in the plane jet and in the axisymmetrical jet flow out of a nozzle with large throat angle, but all these parameters behave in a quite different way in an axisymmetrical jet at small and moderate nozzle throat angles.
Huang, Shi-Wei; Tsai, Chung-You; Wang, Jui; Pu, Yeong-Shiau; Chen, Pei-Chun; Huang, Chao-Yuan; Chien, Kuo-Liong
2017-10-01
Although shock wave lithotripsy is minimally invasive, earlier studies argued that it may increase patients' subsequent risk of hypertension and diabetes mellitus. This study evaluated the association between shock wave lithotripsy and new-onset hypertension or diabetes mellitus. The Taiwanese National Health Insurance Research Database was used to identify 20 219 patients aged 18 to 65 years who underwent the first stone surgical treatment (shock wave lithotripsy or ureterorenoscopic lithotripsy) between January 1999 and December 2011. A Cox proportional model was applied to evaluate associations. Time-varying Cox models were applied to evaluate the association between the number of shock wave lithotripsy sessions and the incidence of hypertension or diabetes mellitus. After a median follow-up of 74.9 and 82.6 months, 2028 and 688 patients developed hypertension in the shock wave lithotripsy and ureterorenoscopic lithotripsy groups, respectively. Patients who underwent shock wave lithotripsy had a higher probability of developing hypertension than patients who underwent ureterorenoscopic lithotripsy, with a hazard ratio of 1.20 (95% confidence interval, 1.10-1.31) after adjusting for covariates. The risk increased as the number of shock wave lithotripsy sessions increased. However, the diabetes mellitus risk was similar in the shock wave lithotripsy and ureterorenoscopic lithotripsy groups. Furthermore, the hazard ratio did not increase as the number of shock wave lithotripsy sessions increased. Shock wave lithotripsy consistently increased the incidence of hypertension on long-term follow-up. Therefore, alternatives to urolithiasis treatment (eg, endoscopic surgery or medical expulsion therapy) could avoid the hypertension risk. Furthermore, avoiding multiple sessions of shock wave lithotripsy could also evade the hypertension risk. © 2017 American Heart Association, Inc.
Measurement of the development and evolution of shock waves in a laser-induced gas breakdown plasma
International Nuclear Information System (INIS)
Chu, T.K.; Johnson, L.C.
1974-12-01
Space- and time-resolved interferometric measurements of electron density in CO 2 -laser produced plasmas in helium or hydrogen are made near the laser focal spot. Immediately after breakdown, a rapidly growing region of approximately uniform plasma density appears at the focal spot. After a few tens of nanoseconds, shock waves are formed, propagating both transverse and parallel to the incident laser beam direction. Behind the transverse propagating shock is an on-axis density minimum, which results in laser-beam self trapping. The shock wave propagating toward the focusing lens effectively shields the interior plasma from the incident beam, because the lower plasma temperature and higher plasma density in the shock allow strong absorption of the incident beam energy. By arranging the laser radiation-plasma interaction to begin at a plasma vacuum interface at the exit of a free-expansion jet, this backward propagating shock wave is eliminated, thus permitting efficient energy deposition in the plasma interior. (auth)
Review of methods to attenuate shock/blast waves
Igra, O.; Falcovitz, J.; Houas, L.; Jourdan, G.
2013-04-01
Quick and reliable shock wave attenuation is the goal of every protection facility and therefore it is not surprising that achieving this has drawn much attention during the past hundred years. Different options have been suggested; their usefulness varying from a reasonable protection to the opposite, a shock enhancement. An example for a suggestion for shock mitigation that turned out to be an enhancement of the impinging shock wave was the idea to cover a protected object with a foam layer. While the pressure behind the reflected shock wave from the foam frontal surface was smaller than that recorded in a similar reflection from a rigid wall [25], the pressure on the “protected” surface, attached to the foam's rear-surface, was significantly higher than that recorded in a similar reflection from a bare, rigid wall [11]. In protecting humans and installations from destructive shock and/or blast waves the prime goal is to reduce the wave amplitude and the rate of pressure increase across the wave front. Both measures result in reducing the wave harmful effects. During the past six decades several approaches for achieving the desired protection have been offered in the open literature. We point out in this review that while some of the suggestions offered are practical, others are impractical. In our discussion we focus on recent schemes for shock/blast wave attenuation, characterized by the availability of reliable measurements (notably pressure and optical diagnostics) as well as high-resolution numerical simulations.
Laminar wave train structure of collisionless magnetic slow shocks
Coroniti, F. V.
1970-01-01
The laminar wave train structure of collisionless magnetic slow shocks is investigated using two fluid hydromagnetics with ion cyclotron radius dispersion. For shock strengths less than the maximally strong switch-off shock, in the shock leading edge dispersive steepening forms a magnetic field gradient, while in the downstream flow dispersive propagation forms a trailing wave train; dispersion scale lengths are the ion inertial length if beta is smaller than 1 and the ion cyclotron radius if beta is greater than 1. In the switch-off slow shock leading edge, dispersion only produced rotations of the magnetic field direction; the gradient of the magnetic field magnitude, and hence the shock steepening length, is determined solely by resistive diffusion. The switch-off shock structure consists of a long trailing of magnetic rotations which are gradually damped by resistivity.
Kinematical Compatibility Conditions for Vorticity Across Shock Waves
Baty, Roy
2015-11-01
This work develops the general kinematical compatibility conditions for vorticity across arbitrary shock waves in compressible, inviscid fluids. The vorticity compatibility conditions are derived from the curl of the momentum equation using singular distributions defined on two-dimensional shock wave surfaces embedded in three-dimensional flow fields. The singular distributions are represented as generalized differential operators concentrated on moving shock wave surfaces. The derivation of the compatibility conditions for vorticity requires the application of second-order generalized derivatives and elementary tensor algebra. The well-known vorticity jump conditions across a shock wave are then shown to follow from the general kinematical compatibility conditions for vorticity by expressing the flow field velocity in vectorial components normal and tangential to a shock surface.
Acceleration of energetic protons by interplanetary shock waves
International Nuclear Information System (INIS)
Pesses, M.E.
1979-01-01
The acceleration of energetic protons in interplanetary magnetosonic fast-mode shock waves is studied via analytical modelling, numerical simulations and in situ observations. It is found that the only physical process by which energetic particles can gain energy from magnetosonic fast-mode shock waves is the one in which the particles cross the shock front several times during a shock encounter and the particle guiding centers gradient B and/or curvature drift at the shock front in the vector V x vector B electric field that exists in the shock rest frame. It is shown that it is physically impossible for charged particles to be Fermi accelerated by MHD shock waves or discontinuities. An analytical model is presented in which the particle-shock interaction is viewed in an intermediate frame in which the upstream and downstream vector V x vector B and partial derivative of vector B with respect to the electric fields are simultaneously zero. It is shown by numerical simulations that both reflected and transmitted particles conserve the first adiabatic invariant in the vector E = 0 frame for quasi-perpendicular shocks psi greater than or equal to 70 0 . The analytical predictions of post-shock energies and pitch angles and shock reflection and transmission coefficients are shown to be in excellent agreement with numerical simulation results. It is found that the 2 to 3 orders of magnitude increases in the Ca 1 MeV proton intensity frequently observed around the time of shock passage apparently cannot be produced by protons encountering the shocks just once, and that the average particle probably encounters the shocks several times prior to observation at Ca 1 MeV. The combination of vector V x vector B electric field mechanism and multiple shock encounters is shown to lead naturally to a differential energy spectrum that is an exponential in momentum
Particle acceleration by coronal and interplanetary shock waves
International Nuclear Information System (INIS)
Pesses, M.E.
1982-01-01
Utilizing many years of observation from deep space and near-earth spacecraft a theoretical understanding has evolved on how ions and electrons are accelerated in interplanetary shock waves. This understanding is now being applied to solar flare-induced shock waves propagating through the solar atmosphere. Such solar flare phenomena as gamma-ray line and neutron emissions, interplanetary energetic electron and ion events, and Type II and moving Type IV radio bursts appear understandable in terms of particle acceleration in shock waves
Shock waves in water at low energy pulsed electric discharges
International Nuclear Information System (INIS)
Pinchuk, M E; Kolikov, V A; Rutberg, Ph G; Leks, A G; Dolinovskaya, R V; Snetov, V N; Stogov, A Yu
2012-01-01
Experimental results of shock wave formation and propagation in water at low energy pulsed electric discharges are presented. To study the hydrodynamic structure of the shock waves, the direct shadow optical diagnostic device with time resolution of 5 ns and spatial resolution of 0.1 mm was designed and developed. Synchronization of the diagnostic and electrodischarge units by the fast optocouplers was carried out. The dependences of shock wave velocities after breakdown of interelectrode gap for various energy inputs (at range of ≤1 J) into discharge were obtained. Based on the experimental results the recommendations for the adjustment parameters of the power supply and load were suggested.
Effects of explosion-generated shock waves in ducts
International Nuclear Information System (INIS)
Busby, M.R.; Kahn, J.E.; Belk, J.P.
1976-01-01
An explosion in a space causes an increase in temperature and pressure. To quantify the challenge that will be presented to essential components in a ventilation system, it is necessary to analyze the dynamics of a shock wave generated by an explosion, with attention directed to the propagation of such a wave in a duct. Using the equations of unsteady flow and shock tube theory, a theoretical model has been formulated to provide flow properties behind moving shock waves that have interacted with various changes in duct geometry. Empirical equations have been derived to calculate air pressure, temperature, Mach number, and velocity in a duct following an explosion
Oscillatory instability of interstellar medium radiative shock waves
International Nuclear Information System (INIS)
Imamura, J.N.
1984-01-01
Observations of the radiative shock waves produced during the late stages of supernova remnant evolution cannot be understood in the context of steady state shock models. As a result, several more complicated scenarios have been suggested. For example, it has been proposed that several shocks are producing the emission or that one shock, which is in the process of making the transition between the adiabatic and the radiative phases of its evolution, produces the emission. In this paper, we suggest another explanation. We propose that supernova remnant shock waves are subject to an oscillatory instability. By an oscillatory instability, we mean one where the postshock cooling region periodically varies in size on a time scale determined by the postshock plasma cooling time. An oscillatory instability may be able to produce the types of behavior exhibited by supernova remnant radiative shocks in a natural way. 16 refs., 1 fig
US evaluation in extracorporeal shock wave lithotripsy
International Nuclear Information System (INIS)
Baumgartner, B.R.; Steinberg, H.V.; Ambrose, S.S.; Walton, K.N.; Bernardino, M.E.
1986-01-01
Real-time US was performed in 100 consecutive patients the day preceding and/or 24 and 48 hours after extracorporeal shock wave lithotripsy (ESWL) therapy. In the 87 treated kidneys containing three or fewer stones, a total of 111 stones were found; 104 were radiopaque. Pre-ESWL US was not available for six stones. Sixty-eight stones (64.5%) were visualized. Of the 37 stones not seen, 10 (27%) were ≤ 5 mm in diameter, and of the larger stones, 19 (51%) were in the ureter or ureteropelvic junction; only six (16%) were in the calyces, and two (5%) were in the renal pelvis. Comparison of pre-ESWL and post-ESWL in 80 kidneys revealed no change in 37 (46%), more stones or fragments detected in 23 (29%), fewer stones or a change in location of stones in 12 (15%), and decreased size of the original stone in eight (10%). The ability of US to detect renal calculi seems to be related not only to stone size but also to location. Hydronephrosis was detected on pre-ESWL US in 16 kidneys (20%). After ESWL the hydronephrosis did not change in seven, decreased or resolved in eight, and increased in only one. Hydronephrosis was noted to develop after ESWL in 21 (26%) other kidneys. Pre-ESWL and post-ESWL hydronephrosis found on US must be considered in conjunction with the clinical picture and other radiographic studies
Exploratory laser-driven shock wave studies
International Nuclear Information System (INIS)
Solem, J.C.; Veeser, L.R.
1977-11-01
We show the results of a feasibility study for investigating shock structure and for measuring equation-of-state parameters using high-energy, short-pulse lasers. We discuss the temporal and spatial structure of the luminosity from laser-driven shock unloading in aluminum foils. We demonstrate that shock velocity can be measured by observing the time interval between shock emergence across two thicknesses and show data for shocks of 1.3 and 2.1 Mbar. The fact that we observe shock fronts cleanly breaking through steps as small as 3 μm indicates that the shock front thickness is very small in the few megabar region; this is the first experimental verification that these fronts are not more than a few micrometers thick. We present approximate measurements of free-surface velocity. Finally, we speculate on the use of these techniques to obtain detailed equation-of-state data
The thickness of the interplanetary collisionless shock waves
International Nuclear Information System (INIS)
Pinter, S.
1980-05-01
The thicknesses of magnetic structures of the interplanetary shock waves related to the upstream solar wind plasma parameters are studied. From this study the following results have been obtained: the measured shock thickness increases for decreasing upstream proton number density and decreases for increasing proton flux energy. The shock thickness strongly depends on the ion plasma β, i.e. for higher values of the β the thickness decreases. (author)
The acceleration of cosmic ray by shock waves
International Nuclear Information System (INIS)
Axford, W.I.; Leer, E.; Skadron, G.
1977-01-01
The acceleration of cosmic rays in flows involving shocks and other compressional waves is considered in terms of one-dimensionl, steady flows and the diffusion approximation. The results suggest that very substantial energy conversion can occur. (author)
Topics in Computational Modeling of Shock and Wave Propagation
National Research Council Canada - National Science Library
Gazonas, George A; Main, Joseph A; Laverty, Rich; Su, Dan; Santare, Michael H; Raghupathy, R; Molinari, J. F; Zhou, F
2006-01-01
This report contains reprints of four papers that focus on various aspects of shock and wave propagation in cellular, viscoelastic, microcracked, and fragmented media that appear in the Proceedings...
Persistence of Precursor Waves in Two-dimensional Relativistic Shocks
Energy Technology Data Exchange (ETDEWEB)
Iwamoto, Masanori; Amano, Takanobu; Hoshino, Masahiro [Department of Earth and Planetary Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Matsumoto, Yosuke, E-mail: iwamoto@eps.s.u-tokyo.ac.jp [Department of Physics, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522 (Japan)
2017-05-01
We investigated the efficiency of coherent upstream large-amplitude electromagnetic wave emission via synchrotron maser instability in relativistic magnetized shocks using two-dimensional particle-in-cell simulations. We considered a purely perpendicular shock in an electron–positron plasma. The coherent wave emission efficiency was measured as a function of the magnetization parameter σ , which is defined as the ratio of the Poynting flux to the kinetic energy flux. The wave amplitude was systematically smaller than that observed in one-dimensional simulations. However, it continued to persist, even at a considerably low magnetization rate, where the Weibel instability dominated the shock transition. The emitted electromagnetic waves were sufficiently strong to disturb the upstream medium, and transverse filamentary density structures of substantial amplitude were produced. Based on this result, we discuss the possibility of the wakefield acceleration model to produce nonthermal electrons in a relativistic magnetized ion–electron shock.
Multi-layer protective armour for underwater shock wave mitigation
Directory of Open Access Journals (Sweden)
Ahmed Hawass
2015-12-01
The strain gauge data and displacement sensors results showed that the multi-layer plates have higher level of underwater shock wave mitigation than the triple aluminum plates with strain and deflection of nearly 50%.
Shock Waves in the Treatment of Muscle Hypertonia and Dystonia
Directory of Open Access Journals (Sweden)
Laura Mori
2014-01-01
Full Text Available Since 1997, focused shock waves therapy (FSWT has been reported to be useful in the treatment of muscle hypertonia and dystonia. More recently, also radial shock wave therapy (RSWT has been successfully used to treat muscle hypertonia. The studies where FSWT and RSWT have been used to treat muscle hypertonia and dystonia are reviewed in this paper. The more consistent and long lasting results were obtained in the lower limb muscles of patients affected by cerebral palsy with both FSWT and RSWT and in the distal upper limb muscles of adult stroke patients using FSWT. The most probable mechanism of action is a direct effect of shock waves on muscle fibrosis and other nonreflex components of muscle hypertonia. However, we believe that up to now the biological effects of shock waves on muscle hypertonia and dystonia cannot be clearly separated from a placebo effect.
Nonstandard jump functions for radically symmetric shock waves
International Nuclear Information System (INIS)
Baty, Roy S.; Tucker, Don H.; Stanescu, Dan
2008-01-01
Nonstandard analysis is applied to derive generalized jump functions for radially symmetric, one-dimensional, magnetogasdynamic shock waves. It is assumed that the shock wave jumps occur on infinitesimal intervals and the jump functions for the physical parameters occur smoothly across these intervals. Locally integrable predistributions of the Heaviside function are used to model the flow variables across a shock wave. The equations of motion expressed in nonconservative form are then applied to derive unambiguous relationships between the jump functions for the physical parameters for two families of self-similar flows. It is shown that the microstructures for these families of radially symmetric, magnetogasdynamic shock waves coincide in a nonstandard sense for a specified density jump function.
High-speed imaging of dynamic shock wave reflection phenomena
CSIR Research Space (South Africa)
Naidoo, K
2010-09-01
Full Text Available Dynamic shock wave reflection generated by a rapidly pitching wedge in a steady supersonic free stream has been studied with numerical simulation previously. An experimental facility was developed for the investigation of these dynamic phenomena...
Shock wave propagation in soda lime glass using optical ...
Indian Academy of Sciences (India)
2016-06-16
Jun 16, 2016 ... out at the Raja Ramanna Centre for Advanced Tech- nology, Indore, India, using the chirped pulse shadow- graphy technique as well as the snap-shot technique, to study the evolution of shock waves in transparent soda lime glass targets and to observe the temporal variation of the shock velocity. A high ...
A new class of solutions for interstellar magnetohydrodynamic shock waves
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.
Grain Destruction in a Supernova Remnant Shock Wave
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.
Tracking kidney stones with sound during shock wave lithotripsy
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.
Experiments on second-sound shock waves in superfluid helium
International Nuclear Information System (INIS)
Cummings, J.C.; Schmidt, D.W.; Wagner, W.J.
1978-01-01
The waveform and velocity of second-sound waves in superfluid helium have been studied experimentally using superconducting, thin-film probes. The second-sound waves were generated with electrical pulses through a resistive film. Variations in pulse power, pulse duration, and bath temperature were examined. As predicted theoretically, the formation of a shock was observed at the leading or trailing edge of the waves depending on bath temperature. Breakdown of the theoretical model was observed for large pulse powers. Accurate data for the acoustic second-sound speed were derived from the measurements of shock-wave velocities and are compared with previous results
Background Oriented Schlieren Method as an Optical Method to Study Shock Waves
Gerasimov, S. I.; Trepalov, N. A.
2017-12-01
Background oriented schlieren method is applied in diagnostics of shock waves in air. The method can be used for visualization of shock waves that are generated after explosion or due to motion at ultrasonic speeds. Experimental data make it possible to observe propagation of a shock wave in space, estimate the asymmetry of energy liberation in explosion, and determine parameters of shock wave.
ULF waves upstream of the Venus bow shock - Properties of one-hertz waves
Orlowski, D. S.; Russell, C. T.
1991-01-01
Pioneer Venus Orbiter data are used here to study the properties of a class of ULF upstream waves with relatively high observed frequencies. These waves show significant similarity to 'one-Hz' waves identified at earth in the ISEE 1 and 2 observations and the whistler waves identified earlier by IMP 6 observations. The waves appear almost immediately after the spacecraft crosses the magnetic field tangent line to the bow shock surface into the region of connected field lines. The wave amplitude decreases with distance from the shock measured along the magnetic field line. Group velocities calculated using the cold plasma dispersion relation indicate that the waves have sufficient upstream velocities to propagate form the shock into the solar wind. The totality of observations seem best explained by a source of right-handed whistler mode waves at the bow shock.
The structure of steady shock waves in porous metals
Czarnota, Christophe; Molinari, Alain; Mercier, Sébastien
2017-10-01
The paper aims at developing an understanding of steady shock wave propagation in a ductile metallic material containing voids. Porosity is assumed to be less than 0.3 and voids are not connected (foams are not considered). As the shock wave is traveling in the porous medium, the voids are facing a rapid collapse. During this dynamic compaction process, material particles are subjected to very high acceleration in the vicinity of voids, thus generating acceleration forces at the microscale that influence the overall response of the porous material. Analyzing how stationary shocks are influenced by these micro-inertia effects is the main goal of this work. The focus is essentially on the shock structure, ignoring oscillatory motion of pores prevailing at the tail of the shock wave. Following the constitutive framework developed by Molinari and Ravichandran (2004) for the analysis of steady shock waves in dense metals, an analytical approach of steady state propagation of plastic shocks in porous metals is proposed. The initial void size appears as a characteristic internal length that scales the overall dynamic response, thereby contributing to the structuring of the shock front. This key feature is not captured by standard damage models where the porosity stands for the single damage parameter with no contribution of the void size. The results obtained in this work provide a new insight in the fundamental understanding of shock waves in porous media. In particular, a new scaling law relating the shock width to the initial void radius is obtained when micro-inertia effects are significant.
Interaction of a conical shock wave with a turbulent boundary layer
Teh, S. L.; Gai, S. L.
The paper reports an investigation on the interaction of an incident conical shock wave with a turbulent boundary layer. Although a conical shock theoretically creates a hyperbolic shock trace on the flat plate, the line joining all the experimental interaction origins takes a different form due to varying upstream influence. The existence of strong pressure gradients in the spanwise direction after the shock leads to the boundary-layer twist. A model based on the upstream influence of the shock when combined with McCabe's secondary-flow theory showed separation to occur at an external flow deflection of 11.8 deg. The oil flow measurements however show this to occur at 9.2 deg. This discrepancy is of the same order as that found by McCabe. Detailed data involving Schlieren and shadowgraph photography, surface-flow visualization, and surface-pressure measurements are presented.
International Nuclear Information System (INIS)
Vassout, P.; Franke, R.; Parmentier, G.; Evrard, G.; Dancer, A.
1987-01-01
A theoretical study on the propagation of a pressure wave in a diphasic medium, when compared to the onset mechanism of pulmonary lesions in subjects exposed to strong shock waves, shows an increase in the incident overpressure at the interface level. Using hydrophones, intracorporal pressure was measured in pigs. The authors recorded the costal wall acceleration on the side directly exposed to the shock wave and calculated the displacement of the costal wall after a shock wave passed by. These experiments were conducted for shock waves in a free field, at an overpressure peak level ranging from 26 kFPa to 380 kPa and for a first positive phase lasting 2 ms. Sensors placed in an intracorporal position detected no increase of the overpressure level for any value of the incident pressure. A comparison of the costal wall displacement, measured experimentally, relative to the theoretical displacement of the entire animal mass indicates that the largest relative displacement of the costal wall could be the origin of the pulmonary lesions found. 5 refs., 13 figs
Hydraulic shock waves in an inclined chute contraction
Jan, C.-D.; Chang, C.-J.
2009-04-01
A chute contraction is a common structure used in hydraulic engineering for typical reasons such as increase of bottom slope, transition from side channel intakes to tunnel spillways, reduction of chute width due to bridges, transition structures in flood diversion works, among others. One of the significant chute contractions in Taiwan is that used in the Yuanshantzu Flood Diversion Project of Keelung River. The diversion project is designed to divert flood water from upper Keelung River into East Sea with a capasity of 1,310 cubic meters per second for mitigating the flood damage of lower part of Keelung River basin in Northern Taiwan. An inclined chute contraction is used to connect Keelung River and a diversion turnel. The inlet and outlet works of the diversion project is located at Ruifang in the Taipei County of north Taiwan. The diameter of diversion tunnel is 12 meters and the total length of tunnel is 2,484 meters. The diversion project has been completed and successfully executed many times since 2004 to lower the water level of Keelung River in typhoon seasons for avioding flooding problems in the lower part of Keelung River basin. Flow in a chute contraction has complicated flow pattern due to the existence of shock waves in it. A simple and useful calculation procedure for the maximum height and its position of shock waves is essentially needed for the preliminary design stage of a chute contraction. Hydraulic shock waves in an inclined chute contraction were experimentally and numerically investigated in this study with the consideration of the effects of sidewall deflection angle, bottom inclination angle and Froude number of approaching flow. The flow pattern of hydraulic shock waves in a chute contraction was observed. The main issue of designing chute contraction is to estimate the height and position of maximum shock wave for the consideration of freeboards. Achieving this aim, the experimental data are adopted and analyzed for the shock angle
Dhar, Nivedita Bhatta; Thornton, Julie; Karafa, Matthew T; Streem, Stevan B
2004-12-01
Subcapsular or perinephric hematoma is one of the most frequent and potentially serious complications of extracorporeal shock wave lithotripsy (SWL). We determined the incidence of and risk factors for renal hematomas following electromagnetic shock wave lithotripsy. Between February 1999 and August 2003, 570 SWL treatments were performed using a Modulith SLX electromagnetic lithotriptor (Storz, St. Louis, Missouri). A total of 415 of these treatments in 317 patients were performed for stones in the renal pelvis or calices and these treatment episodes represent the study group reported. Treatment episodes were reviewed from a prospective institutional review board approved registry and analyzed for patient age, gender, body mass index, mean arterial pressure at induction, stone location, total number of shock waves and peak shock wave intensity. Following these 415 episodes subcapsular or perinephric hematomas developed in 17 patients for an overall incidence of 4.1%. The probability of hematoma after shock wave lithotripsy increased significantly as patient age at treatment increased, such that the probability of hematoma was estimated to be 1.67 times greater for each 10-year incremental increase in patient age. None of the other variables analyzed were significantly related to the incidence of hematoma formation at the 0.05 level. The incidence of renal hematoma formation following electromagnetic SWL for renal calculus was 4.1%. The probability of hematoma increased significantly with increasing patient age but it was not associated with increasing mean arterial pressure at treatment. These findings are in contrast to previous reports of hematoma associated with electrohydraulic SWL. These differences may be a consequence of the smaller focal zone and higher peak pressure associated with Storz Modulith electromagnetic SWL and, just as importantly, a consequence of the difference in the manner in which blood pressure was defined.
Attenuation of shock waves in copper and stainless steel
International Nuclear Information System (INIS)
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
Attenuation of shock waves in copper and stainless steel
Energy Technology Data Exchange (ETDEWEB)
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.
The Characteristic Response of Whistler Mode Waves to Interplanetary Shocks
Yue, Chao; Chen, Lunjin; Bortnik, Jacob; Ma, Qianli; Thorne, Richard M.; Angelopoulos, Vassilis; Li, Jinxing; An, Xin; Zhou, Chen; Kletzing, Craig; Reeves, Geoffrey D.; Spence, Harlan E.
2017-10-01
Magnetospheric whistler mode waves play a key role in regulating the dynamics of the electron radiation belts. Recent satellite observations indicate a significant influence of interplanetary (IP) shocks on whistler mode wave power in the inner magnetosphere. In this study, we statistically investigate the response of whistler mode chorus and plasmaspheric hiss to IP shocks based on Van Allen Probes and THEMIS satellite observations. Immediately after the IP shock arrival, chorus wave power is usually intensified, often at postmidnight to prenoon sector, while plasmaspheric hiss wave power predominantly decreases near the dayside but intensifies near the nightside. We conclude that chorus wave intensification outside the plasmasphere is probably associated with the suprathermal electron flux enhancement caused by the IP shock. Through a simple ray tracing modeling assuming the scenario that plasmaspheric hiss is originated from chorus, we find that the solar wind dynamic pressure increase changes the magnetic field configuration to favor ray penetration in the nightside and promote ray refraction away from the dayside, potentially explaining the magnetic local time-dependent responses of plasmaspheric hiss waves following IP shock arrivals.
Dispersive shock waves in nonlinear and atomic optics
Kamchatnov, Anatoly
2017-10-01
A brief review is given of dispersive shock waves observed in nonlinear optics and dynamics of Bose-Einstein condensates. The theory of dispersive shock waves is developed on the basis of Whitham modulation theory for various situations taking place in these two fields. In particular, the full classification is established for types of wave structures evolving from initial discontinuities for propagation of long light pulses in fibers with account of steepening effect and for dynamics of the polarization mode in two-component Bose-Einstein condensates.
Dispersive shock waves in nonlinear and atomic optics
Directory of Open Access Journals (Sweden)
Kamchatnov Anatoly
2017-01-01
Full Text Available A brief review is given of dispersive shock waves observed in nonlinear optics and dynamics of Bose-Einstein condensates. The theory of dispersive shock waves is developed on the basis of Whitham modulation theory for various situations taking place in these two fields. In particular, the full classification is established for types of wave structures evolving from initial discontinuities for propagation of long light pulses in fibers with account of steepening effect and for dynamics of the polarization mode in two-component Bose-Einstein condensates.
Patient controlled analgesia for extracorporeal shock wave lithotripsy of gallstones.
Schelling, G; Mendl, G; Weber, W; Pauletzki, J; Sackmann, M; Pöppel, E; Peter, K
1992-03-01
Sixty patients undergoing shock wave lithotripsy of gallbladder stones (ESWL) were randomly assigned to receive alfentanil either by infusion controlled by the attending anesthesiologist (standard treatment group, n = 31) or by analgesia controlled by the patient (PCA group, n = 29). Patients using PCA were allowed to self-administer 0.25 mg of alfentanil i.v. every minute as required. Data collected during treatment included the total dose of drug required, transcutaneous pCO2 values, verbal pain and sedation scores, visual analogue scale (VAS) patient satisfaction scores, and the incidence of nausea or vomiting. PCA patients used less alfentanil than the standard treatment group (PCA group: 12.8 micrograms/kg; standard treatment group: 44.3 micrograms/kg; mean values, P = 0.0001), tolerated significantly higher pain intensities and self-administered the narcotic only to moderate levels of pain but not to pronounced analgesia. Standard treatment patients reported lower levels of pain, were more sedated (P less than 0.05) and showed significantly higher transcutaneous pCO2 values. There was a trend towards a lower incidence of nausea or vomiting in PCA patients without reaching statistical significance. No significant difference with regard to patient satisfaction with pain relief could be demonstrated. Self-administered alfentanil during ESWL of gallbladder stones provided adequate analgesia with minimal side effects and high patient satisfaction. ESWL may represent a new and useful indication for PCA.
Dispersion of low frequency plasma waves upstream of the quasi-perpendicular terrestrial bow shock
Directory of Open Access Journals (Sweden)
A. P. Dimmock
2013-08-01
Full Text Available Low frequency waves in the foot of a supercritical quasi-perpendicular shock front have been observed since the very early in situ observations of the terrestrial bow shock (Guha et al., 1972. The great attention that has been devoted to these type of waves since the first observations is explained by the key role attributed to them in the processes of energy redistribution in the shock front by various theoretical models. In some models, these waves play the role of the intermediator between the ions and electrons. It is assumed that they are generated by plasma instability that exist due to the counter-streaming flows of incident and reflected ions. In the second type of models, these waves result from the evolution of the shock front itself in the quasi-periodic process of steepening and overturning of the magnetic ramp. However, the range of the observed frequencies in the spacecraft frame are not enough to distinguish the origin of the observed waves. It also requires the determination of the wave vectors and the plasma frame frequencies. Multipoint measurements within the wave coherence length are needed for an ambiguous determination of the wave vectors. In the main multi-point missions such as ISEE, AMPTE, Cluster and THEMIS, the spacecraft separation is too large for such a wave vector determination and therefore only very few case studies are published (mainly for AMPTE UKS AMPTE IRM pair. Here we present the observations of upstream low frequency waves by the Cluster spacecraft which took place on 19 February 2002. The spacecraft separation during the crossing of the bow shock was small enough to determine the wave vectors and allowed the identification of the plasma wave dispersion relation for the observed waves. Presented results are compared with whistler wave dispersion and it is shown that contrary to previous studies based on the AMPTE data, the phase velocity in the shock frame is directed downstream. The consequences of this
Rogue and shock waves in nonlinear dispersive media
Resitori, Stefania; Baronio, Fabio
2016-01-01
This self-contained set of lectures addresses a gap in the literature by providing a systematic link between the theoretical foundations of the subject matter and cutting-edge applications in both geophysical fluid dynamics and nonlinear optics. Rogue and shock waves are phenomena that may occur in the propagation of waves in any nonlinear dispersive medium. Accordingly, they have been observed in disparate settings – as ocean waves, in nonlinear optics, in Bose-Einstein condensates, and in plasmas. Rogue and dispersive shock waves are both characterized by the development of extremes: for the former, the wave amplitude becomes unusually large, while for the latter, gradients reach extreme values. Both aspects strongly influence the statistical properties of the wave propagation and are thus considered together here in terms of their underlying theoretical treatment. This book offers a self-contained graduate-level text intended as both an introduction and reference guide for a new generation of scientists ...
Extracorporeal shock wave lithotripsy for urinary stones
International Nuclear Information System (INIS)
Shinn, Kyung Sub; Kim, Hyun; Byun, Jae Young; Lee, Myung Hee; Bahk, Yong Whee; Park, Yong Hyun
1988-01-01
Extracorporeal shock wave lithotripsy (ESWL) is a new noninvasive treatment modality for urinary stones, and it sometimes is to necessitate endourologic techniques. ESWL with an Edap lithotripter which uses piezo-electric elements, was performed in 142 cases (130 patients) with urinary stones including 68 in calices, 30 in pelves, and 44 in ureters. Technical factors were 100 storages at 5 to 10 pulse rates/sec and 70-100% adjustable power for about 60 minutes (15-90) for renal stones, and 200 storages at 20 pulse rates/sec and 100% adjustable power for about 60 minutes for ureteral stones in a single treatment under stone localization by 5 MHz ultrasonic sector scanner. All patients were treated at Kangnam St.Mary's Hospital of Catholic University Medical College during the 5 months period from May 1, 1987. Every patient had pre-treatment chest, plain abdomen, intravenous urogram and ultrasonogram studies and post-treatment follow-up abdominal radiograms in 1 to 3 months after ESWL.The overall success rate of ESWL in 142 cases was 94.4%. Eight out of 142 cases were successful. Thus, 134 cases were analysed. Of these, 58 cases (43.3%) received one treatment, 33 cases (24.6%) two treatments, 16 cases (11.9%) three treatments and 27 cases (20.2%) more than four treatments. Renal stones were more successfully treated (98.0%) than ureteral stones (88.1%), and calyceal stones presented the highest success rate (98.5%). The stones as small as 5 to 10 mm in size were easily fragmented and the stones of round of oval shape were more easily pulverized than those of staghorn or amorphous shape. The adjunctive endourlogic techniques such as percutaneous nephrostomy, ureteral catheterization or internal ureteral stenting with a double pigtail catheter were required in 17 cases (11.9%). Complications of ESWL for urolithiasis included hematuria (84.5%), flank pain (8.5%) and fever (5.6%), which were controlled without specific treatment. ESWL using ultrasonic localization was
Cylindrical sound wave generated by shock-vortex interaction
Ribner, H. S.
1985-01-01
The passage of a columnar vortex broadside through a shock is investigated. This has been suggested as a crude, but deterministic, model of the generation of 'shock noise' by the turbulence in supersonic jets. The vortex is decomposed by Fourier transform into plane sinusoidal shear waves disposed with radial symmetry. The plane sound waves produced by each shear wave/shock interaction are recombined in the Fourier integral. The waves possess an envelope that is essentially a growing cylindrical sound wave 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 shock, is found with the antisymmetric component of reported interferometric measurements in a shock 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.
Effects of low-dose extracorporeal shock waves on microcirculation
Khaled, Walaa; Goertz, Ole; Lauer, Henrik; Lehnhardt, Marcus; Hauser, Jörg
2012-11-01
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 shock wave 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 shock wave 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 shock waves increased the number of rolling leukocytes significantly compared to the non-treated animals. Shock waves 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 shock waves on microcirculation after burn injuries.
Radial extracorporeal shock wave treatment harms developing chicken embryos
Kiessling, Maren C.; Milz, Stefan; Frank, Hans-Georg; Korbel, Rüdiger; Schmitz, Christoph
2015-01-01
Radial extracorporeal shock wave treatment (rESWT) has became one of the best investigated treatment modalities for cellulite, including the abdomen as a treatment site. Notably, pregnancy is considered a contraindication for rESWT, and concerns have been raised about possible harm to the embryo when a woman treated with rESWT for cellulite is not aware of her pregnancy. Here we tested the hypothesis that rESWT may cause serious physical harm to embryos. To this end, chicken embryos were exposed in ovo to various doses of radial shock waves on either day 3 or day 4 of development, resembling the developmental stage of four- to six-week-old human embryos. We found a dose-dependent increase in the number of embryos that died after radial shock wave exposure on either day 3 or day 4 of development. Among the embryos that survived the shock wave exposure a few showed severe congenital defects such as missing eyes. Evidently, our data cannot directly be used to draw conclusions about potential harm to the embryo of a pregnant woman treated for cellulite with rESWT. However, to avoid any risks we strongly recommend applying radial shock waves in the treatment of cellulite only if a pregnancy is ruled out. PMID:25655309
Radial extracorporeal shock wave treatment harms developing chicken embryos.
Kiessling, Maren C; Milz, Stefan; Frank, Hans-Georg; Korbel, Rüdiger; Schmitz, Christoph
2015-02-06
Radial extracorporeal shock wave treatment (rESWT) has became one of the best investigated treatment modalities for cellulite, including the abdomen as a treatment site. Notably, pregnancy is considered a contraindication for rESWT, and concerns have been raised about possible harm to the embryo when a woman treated with rESWT for cellulite is not aware of her pregnancy. Here we tested the hypothesis that rESWT may cause serious physical harm to embryos. To this end, chicken embryos were exposed in ovo to various doses of radial shock waves on either day 3 or day 4 of development, resembling the developmental stage of four- to six-week-old human embryos. We found a dose-dependent increase in the number of embryos that died after radial shock wave exposure on either day 3 or day 4 of development. Among the embryos that survived the shock wave exposure a few showed severe congenital defects such as missing eyes. Evidently, our data cannot directly be used to draw conclusions about potential harm to the embryo of a pregnant woman treated for cellulite with rESWT. However, to avoid any risks we strongly recommend applying radial shock waves in the treatment of cellulite only if a pregnancy is ruled out.
International Nuclear Information System (INIS)
Loske, A.M.; Fernandez, F.; Gutierrez, J.
2005-01-01
The non-invasive disintegration of kidney stones using shock waves, referred to as extracorporal shock wave lithotripsy, has been successful for more than twenty years in treating patients having renal and ureteral stones. Two modified shock wave generators are described in this article. The novel systems produce two similar shock waves (tandem shock waves) generated with a short time delay. The second shock wave arrives during collapse of the bubbles generated in the neighborhood of the stone due to the first shock wave. This may increase cavitation bubble collapse and could enhance cavitation-induced damage to kidney stones during shock wave lithotripsy. In vitro comparison of standard systems with the new designs showed that fragmentation efficiency of artificial kidney stones was significantly enhanced using tandem shock waves. (orig.)
Excitation of intense shock waves by soft X-radiation
International Nuclear Information System (INIS)
Branitskij, A.V.; Fortov, V.E.; Danilenko, K.N.; Dyabilin, K.S.; Grabovskij, E.V.; Vorobev, O. Yu.; Lebedev, M.E.; Smirnov, V.P.; Zakharov, A.E.; Persyantsev, I.V.
1996-01-01
Investigation of the shock waves generated by soft x radiation in Al, Sn, Fe, and Pb targets is reported. The soft x radiation was induced by the dynamic compression and heating of the cylindrical z-pinch plasma generated in the ANGARA-5-1 pulsed power machine. The temperature of the z-pinch plasma was as high as 60 - 120 eV, and the duration of the x-ray pulse reached 30 ns FWHM. Thick stepped Al/Pb, Sn/Pb, and pure Pb targets were used. The results of experiments show that uniform intense shock waves can be generated by z-pinch plasma soft x-ray radiation. The uniformity of the shock is very high. At a flux power of the order of several TW/cm 2 , a shock pressure of some hundreds of GPa was achieved. (J.U.). 3 figs., 11 refs
Leading edge effects on boundary layers behind weak shock waves
International Nuclear Information System (INIS)
Deckker, B.E.L.; Singh, D.
1985-01-01
This paper discusses experiments carried out in which normal shock waves of strength M s =1.22 and M s =1.30 were made to impinge on plates of three different thicknesses in order to examine the effects of leading edge thickness on the boundary layers growing from the foot of the shock and from the leading edge. The work describes the anomalous growth of these boundary layers on a slender wedge, supported as a cantilever
Shock-wave structure formation in a dusty plasma
International Nuclear Information System (INIS)
Popel', S.I.; Golub', A.P.; Loseva, T.V.; Bingkhem, R.; Benkadda, S.
2001-01-01
Nonstationary problem on evolution perturbation and its transformation into nonlinear wave structure is considered. The method developed permits finding solution to the system of nonlinear evolution equations describing dust particles with variable charge, Boltzmann electron and inertia ions. An accurate stationary solution as ion-sonic wave structures explained by anomalous dissipation due to electric discharge of dust particles was found. Evolution of two types of initial perturbations was studied, i.e.: soliton and immobile region with increased density of ions - a step. Soliton evolution in plasma with variable charge of dust particles results in the appearance on nonstationary shock-wave structure, whereas the step evolution gives rise to appearance of a shock wave similar to the stationary one along with rarefaction wave [ru
Magnetohydrodynamic shock wave formation: Effect of area and density variation
International Nuclear Information System (INIS)
Sujith, R.I.
2005-01-01
The nonlinear steepening of finite amplitude magnetohydrodynamic (MHD) waves propagating perpendicular to the magnetic field is investigated. The nonlinear evolution of a planar fast magnetosonic wave in a homentropic flow field is understood well through simple waves. However, in situations where the wave is moving through a variable area duct or when the flow field is nonhomentropic, the concept of simple waves cannot be used. In the present paper, the quasi-one-dimensional MHD equations that include the effect of area variation and density gradients are solved using the wave front expansion technique. The analysis is performed for a perfectly conducting fluid and also for a weakly conducting fluid. Closed form solutions are obtained for the nonlinear evolution of the slope of the wave front in the limits of infinitely large and small conductivity. A general criterion for a compression wave to steepen into a shock is obtained. An analytical expression for the location of shock formation is derived. The effect of area variation and density gradient on shock formation is studied and examples highlighting the same are presented
Effect of extracorporeal shock waves on calcaneal bone spurs.
Lee, Gregory P; Ogden, John A; Cross, G Lee
2003-12-01
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 shock waves (ESW). This included 308 patients who received extracorporeal shock wave treatments and 127 placebo (sham control) patients. At both initial (3 months) and final (12 months) evaluations after receiving ESW, no patient who received shock wave 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.
Detonation-to-shock wave transmission at a contact discontinuity
Peace, J. T.; Lu, F. K.
2018-02-01
The one-dimensional interaction of a detonation wave with a contact discontinuity was investigated analytically and experimentally for oxyhydrogen detonations. The analytical and experimental results showed that the transmitted shock through the contact surface and into a non-combustible gas can either be amplified or attenuated depending on the reflection type at the contact surface and on the ratio of acoustic impedance across it. Experiments were performed with a detonation-driven shock tube facility to determine the transmitted shock velocity into a non-combustible He/air mixture. The oxyhydrogen equivalence ratio in the detonation section was varied from 0.5 to 1.5, and the driven section He mole fraction was varied from 0.0 to 1.0 to test a broad range of acoustic impedance ratios ranging from approximately 0.36 to 1.69. The analytical results were shown to have acceptable agreement with the measured transmitted shock wave velocity in the case of a reflected rarefaction from the contact surface. Additionally, the results indicated that the detonation wave reaction zone properties could have an important role that influences the transmitted shock properties in the case of a reflected shock from the contact surface.
Failure waves in shock-compressed glasses
Kanel, Gennady I.
2005-07-01
The failure wave is a network of cracks that are nucleated on the surface and propagate into the elastically stressed body. It is a mode of catastrophic fracture in an elastically stressed media whose relevance is not limited to impact events. In the presentation, main properties of the failure waves are summarized and discussed. It has been shown that the failure wave is really a wave process which is characterized by small increase of the longitudinal stress and corresponding increments of the particle velocity and the density. The propagation velocity of the failure wave is less than the sound speed; it is not directly related to the compressibility but is determined by the crack growth speed. Transformation of elastic compression wave followed by the failure wave in a thick glass plate into typical two-wave configuration in a pile of thin glass plates confirms crucial role of the surfaces. The latter, as well as specific kinematics of the process distinguishes the failure wave from a time-dependent inelastic compressive behavior of brittle materials. The failure wave is steady if the stress state ahead of it is supported unchanging. Mechanism of this self-supporting propagation of compressive fracture is not quite clear as yet. On the other hand, collected data about its kinematics allow formulating phenomenological models of the phenomenon. In some sense the process is similar to the diffusion of cracks from a source on the glass surface. However, the diffusion-like models contradict to observed steady propagation of the failure wave. Analogy with a subsonic combustion wave looks more fruitful. Computer simulations based on the phenomenological combustion-like model reproduces well all kinematical aspects of the phenomenon.
Potential of shock waves to remove calculus and biofilm.
Müller, Philipp; Guggenheim, Bernhard; Attin, Thomas; Marlinghaus, Ernst; Schmidlin, Patrick R
2011-12-01
Effective calculus and biofilm removal is essential to treat periodontitis. Sonic and ultrasonic technologies are used in several scaler applications. This was the first feasibility study to assess the potential of a shock wave device to remove calculus and biofilms and to kill bacteria. Ten extracted teeth with visible subgingival calculus were treated with either shock waves for 1 min at an energy output of 0.4 mJ/mm(2) at 3 Hz or a magnetostrictive ultrasonic scaler at medium power setting for 1 min, which served as a control. Calculus was determined before and after treatment planimetrically using a custom-made software using a grey scale threshold. In a second experiment, multispecies biofilms were formed on saliva-preconditioned bovine enamel discs during 64.5 h. They were subsequently treated with shock waves or the ultrasonic scaler (N = 6/group) using identical settings. Biofilm detachment and bactericidal effects were then assessed. Limited efficiency of the shock wave therapy in terms of calculus removal was observed: only 5% of the calculus was removed as compared to 100% when ultrasound was used (P ≤ 0.0001). However, shock waves were able to significantly reduce adherent bacteria by three orders of magnitude (P ≤ 0.0001). The extent of biofilm removal by the ultrasonic device was statistically similar. Only limited bactericidal effects were observed using both methods. Within the limitations of this preliminary study, the shock wave device was not able to reliably remove calculus but had the potential to remove biofilms by three log steps. To increase the efficacy, technical improvements are still required. This novel noninvasive intervention, however, merits further investigation.
Dynamics of Laser-Driven Shock Waves in Solid Targets
Aglitskiy, Y.; Karasik, M.; Velikovich, A. L.; Serlin, V.; Weaver, J.; Schmitt, A. J.; Obenschain, S. P.; Grun, J.; Metzler, N.; Zalesak, S. T.; Gardner, J. H.; Oh, J.; Harding, E. C.
2009-11-01
Accurate shock timing is a key issue of both indirect- and direct-drive laser fusions. The experiments on the Nike laser at NRL presented here were made possible by improvements in the imaging capability of our monochromatic x-ray diagnostics based on Bragg reflection from spherically curved crystals. Side-on imaging implemented on Nike makes it possible to observe dynamics of the shock wave and ablation front in laser-driven solid targets. We can choose to observe a sequence of 2D images or a continuous time evolution of an image resolved in one spatial dimension. A sequence of 300 ps snapshots taken using vanadium backlighter at 5.2 keV reveals propagation of a shock wave in a solid plastic target. The shape of the shock wave reflects the intensity distribution in the Nike beam. The streak records with continuous time resolution show the x-t trajectory of a laser-driven shock wave in a 10% solid density DVB foam.
Shock Wave Energy Dissipation by Metal-Organic Framework
Zhou, Xuan; Miao, Yurun; Banlusan, Kiettipong; Shaw, William; Strachan, Alejandro; Suslick, Kenneth; Dlott, Dana
2017-06-01
Metal-organic framework (MOF) such as ZIF-8 and UiO-66 show promising shock energy dissipation abilities through mechano-chemical reactions including bond breaking and pore collapse. In this work, we performed quantitative measurements on the shock wave energy attenuated by MOF films using a laser-driven flyer-plate apparatus. Aluminum flyer plates of 75-um thick were accelerated to speeds up to 2.0 km/s by a flat-top pulsed laser to impact the MOF film. The MOF layer was coated on a 200-nm thick gold mirror, which was deposited previously on glass substrate. Photonic Doppler velocimetry (PDV) was used to track the motions of the gold mirror, which can be converted to the energy flux and fluence of the shock wave that transmitted through the MOF layer. We deduced the shock energy that was attenuated by the MOF film by comparing the transmitted energy flux/fluence obtained with and without the presence of the MOF layer. A two-wave-shaped flux-time curve was obtained with the MOF layer because of its nanoporous structure. Studies on the shock wave energy attenuation by ZIF-8 and UiO-66 were carried out under various flyer speeds and sample thicknesses. We used in situ emission spectroscopy to verify that pore collapse was accompanied by chemical bond breakage. Corresponding author:dlott@illinois.edu.
ShockWave science and technology reference library
2007-01-01
This book is the first of several volumes on solids in the Shock Wave Science and Technology Reference Library. These volumes are primarily concerned with high-pressure shock waves in solid media, including detonation, high-velocity impact, and penetration. Of the eight chapters in this volume three chapters survey recent, exciting experimental advances in - ultra-short shock dynamics at the atomic and molecular scale (D.S. More, S.D. Mcgrane, and D.J. Funk), - Z accelerator for ICE and Shock compression (M.D. Knudson), and - failure waves in glass and ceramics (S.J. Bless and N.S. Brar). The subsequent four chapters are foundational, and cover the subjects of - equation of state (R. Menikoff), - elastic-plastic shock waves (R. Menikoff), - continuum plasticity (R. M. Brannon), and - numerical methods (D. J. Benson). The last chapter, but not the least, describes a tour de force illustration of today’s computing power in - modeling heterogeneous reactive solids at the grain scale (M.R. Baer). All chapters a...
Lower hybrid waves at the shock front: a reassessment
Directory of Open Access Journals (Sweden)
S. N. Walker
2008-03-01
Full Text Available The primary process occurring at a collisionless shock is the redistribution of the bulk upstream energy into other degrees of freedom. One part of this process results in the acceleration of electrons at the shock front. Accelerated electrons are observed at the terrestrial and other planetary shocks, comets, and their effects are observed in astrophysical phenomena such as supernova remnants and jets in the form of X-ray bremsstrahlung radiation. One of the physical models for electron acceleration at supercritical shocks is based on low-hybrid turbulence due to the presence of reflected ions in the foot region. Since lower hybrid waves propagate almost perpendicular to the magnetic field they can be simultaneously in resonance with both the unmagnetised ions (ω=Vik⊥ and magnetised electrons (ω=Vek||. In this paper, Cluster observations of the electric field are used to study the occurrence of lower hybrid waves in the front of the terrestrial bow shock. It is shown that the lower hybrid waves exist as isolated wave packets. However, the very low level of the observed lower hybrid turbulence is too small to impart significant energisation to the electron population.
Lower hybrid waves at the shock front: a reassessment
Directory of Open Access Journals (Sweden)
S. N. Walker
2008-03-01
Full Text Available The primary process occurring at a collisionless shock is the redistribution of the bulk upstream energy into other degrees of freedom. One part of this process results in the acceleration of electrons at the shock front. Accelerated electrons are observed at the terrestrial and other planetary shocks, comets, and their effects are observed in astrophysical phenomena such as supernova remnants and jets in the form of X-ray bremsstrahlung radiation. One of the physical models for electron acceleration at supercritical shocks is based on low-hybrid turbulence due to the presence of reflected ions in the foot region. Since lower hybrid waves propagate almost perpendicular to the magnetic field they can be simultaneously in resonance with both the unmagnetised ions (ω=V_{i}k_{⊥} and magnetised electrons (ω=V_{e}k_{||}. In this paper, Cluster observations of the electric field are used to study the occurrence of lower hybrid waves in the front of the terrestrial bow shock. It is shown that the lower hybrid waves exist as isolated wave packets. However, the very low level of the observed lower hybrid turbulence is too small to impart significant energisation to the electron population.
Cosmic Rays Accelerated at Cosmological Shock Waves
Indian Academy of Sciences (India)
2016-01-27
Jan 27, 2016 ... Based on hydrodynamic numerical simulations and diffusive shock acceleration model, we calculated the ratio of cosmic ray (CR) to thermal energy. We found that the CR fraction can be less than ∼ 0.1 in the intracluster medium, while it would be of order unity in the warm-hot intergalactic medium.
The importance of microjet vs shock wave formation in sonophoresis.
Wolloch, Lior; Kost, Joseph
2010-12-01
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). Shock waves 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 shock waves. Copyright © 2010. Published by Elsevier B.V.
Spatiotemporal dynamics of underwater conical shock wave focusing
Czech Academy of Sciences Publication Activity Database
Hoffer, Petr; Lukeš, Petr; Akiyama, H.; Hosseini, H.
2017-01-01
Roč. 27, č. 4 (2017), s. 685-690 ISSN 0938-1287 Grant - others:Rada Programu interní podpory projektů mezinárodní spolupráce AV ČR(CZ) M100431203 Program:M Institutional support: RVO:61389021 Keywords : Underwater shock wave focusing * multichannel * electrohydraulic discharge * conical shock wave reflection * medical application Subject RIV: BI - Acoustics OBOR OECD: Applied mechanics Impact factor: 1.107, year: 2016 https://link.springer.com/article/10.1007/s00193-016-0703-7
Behavior of Metallic Foam under Shock Wave Loading
Directory of Open Access Journals (Sweden)
Zoran Ren
2012-08-01
Full Text Available In this manuscript, the behavior of metallic foam under impact loading and shock wave propagation has been observed. The goal of this research was to investigate the material and structural properties of submerged open-cell aluminum foam under impact loading conditions with particular interest in shock wave propagation and its effects on cellular material deformation. For this purpose experimental tests and dynamic computational simulations of aluminum foam specimens inside a water tank subjected to explosive charge have been performed. Comparison of the results shows a good correlation between the experimental and simulation results.
Have shock waves been observed in nuclear collisions
International Nuclear Information System (INIS)
Gudima, K.K.; Toneev, V.D.
Experimental data on shock wave phenomena in nuclear reactions are analyzed within the kinetic theory rather than that of the hydrodynamic approach. Beginning with a presentation of the model, which is a generalization of the cascade--evaporation model to the case of the interaction of two nuclei, it is then ascertained to what degree the developed approach is valid. Next on the basis of this model the results of experiments performed are examined to find the effects of a shock wave. The results of this analysis and the related set-up of new experiments are discussed also. 34 references
Propagation of acoustic shock waves between parallel rigid boundaries and into shadow zones
Energy Technology Data Exchange (ETDEWEB)
Desjouy, C., E-mail: cyril.desjouy@gmail.com; Ollivier, S.; Dragna, D.; Blanc-Benon, P. [Laboratoire de Mécanique des Fluides et d’Acoustique, UMR CNRS 5509, École Centrale de Lyon, Université de Lyon, 69134 Ecully Cedex (France); Marsden, O. [European Center For Medium Range Weather Forecasts, United Kingdom Shinfield (United Kingdom)
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.
Generalized Sagdeev potential theory for shock waves modeling
Akbari-Moghanjoughi, M.
2017-05-01
In this paper, we develop an innovative approach to study the shock wave propagation using the Sagdeev potential method. We also present an analytical solution for Korteweg de Vries Burgers (KdVB) and modified KdVB equation families with a generalized form of the nonlinearity term which agrees well with the numerical one. The novelty of the current approach is that it is based on a simple analogy of the particle in a classical potential with the variable particle energy providing one with a deeper physical insight into the problem and can easily be extended to more complex physical situations. We find that the current method well describes both monotonic and oscillatory natures of the dispersive-diffusive shock structures in different viscous fluid configurations. It is particularly important that all essential parameters of the shock structure can be deduced directly from the Sagdeev potential in small and large potential approximation regimes. Using the new method, we find that supercnoidal waves can decay into either compressive or rarefactive shock waves depending on the initial wave amplitude. Current investigation provides a general platform to study a wide range of phenomena related to nonlinear wave damping and interactions in diverse fluids including plasmas.
Blast effects physical properties of shock waves
2018-01-01
This book compiles a variety of experimental data on blast waves. The book begins with an introductory chapter and proceeds to the topic of blast wave phenomenology, with a discussion Rankine-Hugoniot equations and the Friedlander equation, used to describe the pressure-time history of a blast wave. Additional topics include arrival time measurement, the initiation of detonation by exploding wires, a discussion of TNT equivalency, and small scale experiments. Gaseous and high explosive detonations are covered as well. The topics and experiments covered were chosen based on the comparison of used scale sizes, from small to large. Each characteristic parameter of blast waves is analyzed and expressed versus scaled distance in terms of energy and mass. Finally, the appendix compiles a number of polynomial laws that will prove indispensable for engineers and researchers.
Shock-wave induced synthesis of few layer graphene nanosheets
Chen, Pengwan; Yin, Hao; Xu, Chunxiao; Gao, Xin; Zhou, Qiang; Qu, Liangti
2017-06-01
Shock wave action combining shock-induced chemical reaction will cause a series of changes of material physical and chemical properties, which is supposed to be a new method for material synthesis and modification. Using solid CO2 (dry ice) as the carbon source, few layer graphene nanosheets were successful synthesized by reduction of CO2 with calcium hydride under detonation-driven flyer impact loading in this study. Furthermore, by adding ammonium nitrate to the reaction system, nitrogen-doped graphene materials were formed in this one-step shock-wave treatment. Similarly, few layer graphene and nitrogen-doped graphene materials were also prepared through the reaction of calcium carbonate and magnesium induced by shock wave. The shock synthesis of graphene nanosheets requires a balance between the growth rate of graphene materials and the formation rate of carbon atoms. Meanwhile, the pressure and temperature are two important factors affecting the synthesis of few layer graphene nanosheets. This work is supported by the National Natural Science Foundation of China under Grant Nos. 11521062 and 11172043.
Response of ocean bottom dwellers exposed to underwater shock waves
Hosseini, S. H. R.; Kaiho, Kunio; Takayama, Kazuyoshi
2016-01-01
The paper reports results of experiments to estimate the mortality of ocean bottom dwellers, ostracoda, against underwater shock wave exposures. This study is motivated to verify the possible survival of ocean bottom dwellers, foraminifera, from the devastating underwater shock waves 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 shock waves generated by the explosion of 100mg PETN pellets in a chamber at shock 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 shock over-pressure threshold value for marine-creatures having lungs and balloons.
Viscoelastic shock wave in ballistic gelatin behind soft body armor.
Liu, Li; Fan, Yurun; Li, Wei
2014-06-01
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 waves at different locations. The observed shock wave 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 shock wave attenuation. Using the characteristic-line method and the spherical wave assumption, the propagation of impact pressure wave front and the subsequent unloading profile can be simulated using the experimental velocity boundary condition. The established viscoelastic model considerably improves the prediction of shock wave attenuation in the ballistic gelatin. Copyright © 2014 Elsevier Ltd. All rights reserved.
Cosmic Rays Accelerated at Cosmological Shock Waves Renyi Ma1 ...
Indian Academy of Sciences (India)
Key words. Cosmic rays—large-scale structure of universe—methods: ... During the formation of large-scale structure of the universe, matters condense into ... A cubic box of comoving size 85h. −1. Mpc was simulated using 10243 grid zones. The details of shock wave identification are described in Kang et al. (2007). 301 ...
Shock wave therapy for spastic plantar flexor muscles in hemiplegic ...
African Journals Online (AJOL)
CP). Spastic equines foot is the most frequent deformity in ambulated children with CP. Shock wave therapy on spastic muscles of the upper limb in stroke patients provided a significant reduction in muscle tone. Aim: The present study aimed to ...
paediatric ureteric calculi: in-situ extracorporeal shock wave lithotripsy
African Journals Online (AJOL)
Objective To evaluate prospectively the efficacy of in-situ extracorporeal shock wave lithotripsy (ESWL) in the treatment of ureteric calculi in the paediatric age group. Patients and Methods Twenty children (aged 2.2 16 years) with 22 ureteric stones were evaluated and treated with in-situ ESWL using the Dornier S lithotripter ...
Stenting and extracorporeal shock wave lithotripsy in chronic pancreatitis
DEFF Research Database (Denmark)
Holm, M; Matzen, Peter
2003-01-01
BACKGROUND: Early observational studies of endoscopic treatment and extracorporeal shock wave lithotripsy (ESWL) reported considerable or complete relief of pain in 50%-80% of patients with chronic pancreatitis. There is no consensus on the measurement of pain, making comparison of observational...
Effect of extracorporeal shock waves on subcondylar mandibular fractures.
Altuntaş, Emine Elif; Oztemur, Zekeriya; Ozer, Hatice; Müderris, Suphi
2012-11-01
The purpose of this pilot study was to evaluate the effects of extracorporeal shock wave therapy on healing of subcondylar mandibular fracture in rats. Unilateral subcondylar fracture in 20 Wistar albino rats was used as a fracture model. Each rat was anesthetized 1 day after surgery, and extracorporeal shock wave therapy was performed. On the 21st day after surgery, animals were killed. Mandibles were dissected, all soft tissues were removed after sacrifice, and fractured and nonfractured hemimandibles were obtained from each rat. Histologic analyses were performed by a single pathologist blinded to the samples. The specimens' mean score in bone fracture healing was 7 (1.09) (range, 6-9) in group 1 and 2.57 (1.62) (range, 1-6) in group 2. With respect to the specimens' bone fracture healing score, there was a statistically significant difference between the 2 groups. As a result, our study showed that extracorporeal shock wave therapy accelerated the improvement of fractures in experimentally induced subcondylar mandibular fracture in the rat mandible. We believe that reducing the duration of improvement in subcondylar mandibular fractures by intermaxillary fixation along with extracorporeal shock wave theraphy would contribute to preventing complications such as ankylosis, fibrosis, and hypomobility occuring because of prolonged fixation.
Nonplanar electrostatic shock waves in an opposite polarity dust ...
Indian Academy of Sciences (India)
A rigorous theoretical investigation has been carried out on the propagation of nonplanar (cylindrical and spherical) dust-acoustic shock waves (DASHWs) in a collisionless four-component unmagnetized dusty plasmasystem containing massive, micron-sized, positively and negatively charged inertial dust grains along with ...
Changing the Window of Shock Wave Application. How it improves ...
African Journals Online (AJOL)
Objectives: The aim of this work is to study the impact of using multiple windows of shock wave application on the results of ESWL therapy for renal calculi. Patients and Methods: Between January 1996 and October 2002, 676 patients with single pelvic stones ≤ 2.5 cm and either no or mild back pressure changes were ...
Shock wave propagation in soda lime glass using optical ...
Indian Academy of Sciences (India)
2016-06-16
Jun 16, 2016 ... from laser-produced plasmas. With the advent of high- power laser systems delivering several hundreds of kilojoules of energy, this transient pressure range is extended from several hundreds of megabars to giga- bars [7–9] through intense shock wave generation for laser intensities of 1013−15 W/cm2.
Collisionless shocks and upstream waves and particles: Introductory remarks
International Nuclear Information System (INIS)
Kennel, C.F.
1981-01-01
We discuss more aspects of collisionless shock theory that might be pertinent to the problem of upstream waves and particles. It is hoped that our qualititive remarks may be a useful guide for the general reader as he goes through the detailed papers to come
Survey of Temperature Measurement Techniques For Studying Underwater Shock Waves
Danehy, Paul M.; Alderfer, David W.
2004-01-01
Several optical methods for measuring temperature near underwater shock waves 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.
The gravitational shock wave of a massless particle
Hooft, G. 't; Dray, T
1985-01-01
The (spherical) gravitational shock wave due to a massless particle moving at the speed of light along the horizon of the Schwarzchild black hole is obtained. Special cases of our procedure yield previous results by Aichelburg and Sexl[1] for a photon in Minkowski vpace and by Penrose [2] for
Transient granular shock waves and upstream motion on a staircase
van der Weele, J.P.; Kanellopoulos, Giorgos; Tsiavos, Christos; van der Meer, Roger M.
2009-01-01
A granular cluster, placed on a staircase setup, is brought into motion by vertical shaking. Molecular dynamics simulations show that the system goes through three phases. After a rapid initial breakdown of the cluster, the particle stream organizes itself in the form of a shock wave moving down the
Dynamic Theory: some shock wave and energy implications
International Nuclear Information System (INIS)
Williams, P.E.
1981-02-01
The Dynamic Theory, a unifying five-dimensional theory of space, time, and matter, is examined. The theory predicts an observed discrepancy between shock wave viscosity measurements at low and high pressures in aluminum, a limiting mass-to-energy conversion rate consistent with the available data, and reduced pressures in electromagneticaly contained controlled-fusion plasmas
Success of electromagnetic shock wave lithotripter as monotherapy ...
African Journals Online (AJOL)
K.S. Meitei
Abstract. Objectives: To evaluate the success of shock wave lithotripsy (SWL) as monotherapy for solitary renal stones larger than 2 cm without ureteral stenting. Hence, if our study result demonstrates acceptable success and safety, we can recommend ESWL as a treatment option for patients with large renal calculi.
Nucleus-acoustic shock waves in white dwarfs
Indian Academy of Sciences (India)
S Jannat
2018-03-09
Mar 9, 2018 ... Abstract. The nucleus-acoustic shock waves (NASWs) propagating in a white dwarf plasma system, which contain non-relativistically or ultrarelativistically degenerate electrons, non-relativistically degenerate, viscous fluid of light nuclei, and immobile nuclei of heavy elements, have been theoretically ...
DESTRUCTION OF INTERSTELLAR DUST IN EVOLVING SUPERNOVA REMNANT SHOCK WAVES
International Nuclear Information System (INIS)
Slavin, Jonathan D.; Dwek, Eli; Jones, Anthony P.
2015-01-01
Supernova generated shock waves 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 shocks, however, that approximation breaks down when the destruction timescale becomes longer than that for the evolution of the supernova remnant (SNR) shock. 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 shock when the thermal history of a shocked gas parcel in the SNR differs significantly from that behind a steady shock. This occurs in shocks with velocities ≳200 km s −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
Destruction of Interstellar Dust in Evolving Supernova Remnant Shock Waves
Slavin, Jonathan D.; Dwek, Eli; Jones, Anthony P.
2015-01-01
Supernova generated shock waves 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 shocks, however that approximation breaks down when the destruction timescale becomes longer than that for the evolution of the supernova remnant (SNR) shock. 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 shock when the thermal history of a shocked gas parcel in the SNR differs significantly from that behind a steady shock. This occurs in shocks 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.
Shock Wave Structure in the Presence of Energetic Particles
Mostafavi, Parisa; Zank, Gary P.; Webb, Gary M.
2017-09-01
Energetic particles that are not equilibrated with the thermal plasma (such as pickup ions (PUIs), anomalous cosmic rays (ACRs) and solar energetic particles (SEPs)) can modify the structure of collisionless shock waves. This is relevant to the inner and outer heliosphere and the Very Local Interstellar Medium (VLISM) where observations of shock waves in the e.g., the inner heliosphere show that the energetic particle component pressure is greater than the both the magnetic field and thermal gas pressure (Lario et al., 2015). Voyager 2 observations revealed that the heliospheric termination shock (HTS) is very broad and mediated by energetic particles. PUIs and SEPs contribute both a collisionless heat flux and a higher-order viscosity. We show that the incorporation of both effects can completely determine the structure of collisionless shocks mediated by energetic ions. Since the reduced form of the PUI mediated plasma model is structurally identical to the classical cosmic ray two-fluid model (Axford et al., (1982)), we note that the presence of viscosity at least formally eliminates the need of a gas sub-shock in the classical two-fluid model, including in that regime where three are possible. By considering parameters upstream of the heliospheric termination shock (HTS), we show that the thermal gas remains relatively cold and the shock is mediated by PUIs. We determine the structure of the weak interstellar shock observed by Voyager 1. We consider the inclusion of the thermal heat flux and viscosity to address the most general form of an energetic particle-thermal plasma two-fluid model.
Comparison of geometrical shock dynamics and kinematic models for shock-wave propagation
Ridoux, J.; Lardjane, N.; Monasse, L.; Coulouvrat, F.
2018-03-01
Geometrical shock dynamics (GSD) is a simplified model for nonlinear shock-wave propagation, based on the decomposition of the shock front into elementary ray tubes. Assuming small changes in the ray tube area, and neglecting the effect of the post-shock flow, a simple relation linking the local curvature and velocity of the front, known as the A{-}M rule, is obtained. More recently, a new simplified model, referred to as the kinematic model, was proposed. This model is obtained by combining the three-dimensional Euler equations and the Rankine-Hugoniot relations at the front, which leads to an equation for the normal variation of the shock Mach number at the wave front. In the same way as GSD, the kinematic model is closed by neglecting the post-shock flow effects. Although each model's approach is different, we prove their structural equivalence: the kinematic model can be rewritten under the form of GSD with a specific A{-}M relation. Both models are then compared through a wide variety of examples including experimental data or Eulerian simulation results when available. Attention is drawn to the simple cases of compression ramps and diffraction over convex corners. The analysis is completed by the more complex cases of the diffraction over a cylinder, a sphere, a mound, and a trough.
Directory of Open Access Journals (Sweden)
AKM Zamanul Islam Bhuiyan
2013-01-01
Full Text Available Background: Renal calculi are frequent causes of ureteric colic. Extracorporeal shock wave lithotripsy is the most common treatment of these stones. It uses focused sound waves to break up stones externally. Objective: To compare the efficiency of slow and fast delivery rate of shock waves on stone fragmentation and treatment outcome in patients with renal calculi. Materials and Methods: This prospective study was done in the department of Urology, National Institute of Kidney diseases and Urology, Sher-e-Bangla Nagar, Dhaka from July 2006 to June 2007. Total 90 patients were treated using the Storz Medical Modulith ® SLX lithotripter. Patients were divided into Group A, Group B and Group C – each group having 30 subjects. Group A was selected for extracorporeal shockwave lithotripsy (ESWL by 60 shock waves per minute, Group B by 90 shock waves per minute and Group C by 120 shock waves per minute. Results: Complete clearance of stone was observed in 24 patients in Group A and 13 patients in both Group B and Group C in first session. In Group A only 3 patients needed second session but in Group B and Group C, 12 and 8 patients needed second session. In Group A only one patient needed third session but third session was required for 3 patients in Group B and 5 patients in Group C for complete clearance of stone. In Group A, subsequent sessions were performed under spinal anesthesia and in Group B under sedation and analgesia (p>0.001. Mean number of sessions for full clearance of stones in group A was 1.37 ± 0.85, in Group B was 1.8 ± 0.887 and in Group C was 2.0 ± 1.083. Significant difference was observed in term of sessions among groups (p>0.05. In first follow-up, complete clearance of stones was seen in 24 patients in Group A and 13 in both Group B and Group C. In second follow-up, 3 patients in Group A, 12 in Group B and 8 in Group C showed complete clearance of stones. It was observed that rate of stone clearance was higher in Group A
Cohen, Z.; Breneman, A. W.; Cattell, C. A.; Davis, L.; Grul, P.; Kersten, K.; Wilson, L. B., III
2017-12-01
Determining the role of plasma waves in providing energy dissipation at shock waves is of long-standing interest. Interplanetary (IP) shocks serve as a large database of low Mach number shocks. We examine electric field waveforms captured by the Time Domain Sampler (TDS) on the STEREO spacecraft during the ramps of IP shocks, with emphasis on captures lasting 2.1 seconds. Previous work has used captures of shorter duration (66 and 131 ms on STEREO, and 17 ms on WIND), which allowed for observation of waves with maximum (minimum) frequencies of 125 kHz (15 Hz), 62.5 kHz (8 Hz), and 60 kHz (59 Hz), respectively. The maximum frequencies are comparable to 2-8 times the plasma frequency in the solar wind, enabling observation of Langmuir waves, ion acoustic, and some whistler-mode waves. The 2 second captures resolve lower frequencies ( few Hz), which allows us to analyze packet structure of the whistler-mode waves and some ion acoustic waves. The longer capture time also improves the resolvability of simultaneous wave modes and of waves with frequencies on the order of 10s of Hz. Langmuir waves, however, cannot be identified at this sampling rate, since the plasma frequency is usually higher than 3.9 kHz. IP shocks are identified from multiple databases (Helsinki heliospheric shock database at http://ipshocks.fi, and the STEREO level 3 shock database at ftp://stereoftp.nascom.nasa.gov/pub/ins_data/impact/level3/). Our analysis focuses on TDS captures in shock ramp regions, with ramp durations determined from magnetic field data taken at 8 Hz. Software is used to identify multiple wave modes in any given capture and classify waves as Langmuir, ion acoustic, whistler, lower hybrid, electron cyclotron drift instability, or electrostatic solitary waves. Relevant frequencies are determined from density and magnetic field data collected in situ. Preliminary results suggest that large amplitude (∼ 5 mV/m) ion acoustic waves are most prevalent in the ramp, in agreement with
Peculiarities of evolution of shock waves generated by boiling coolant
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.
International Nuclear Information System (INIS)
Rodean, H.C.
1977-01-01
The Rankine-Hugoniot relations for shock waves and the empirical linear relation between the shock-wave and particle velocities define an incomplete thermodynamic description of the states along the Hugoniot curve. This incomplete description defines the following along the Hugoniot: (1) internal energy and pressure as functions of specific volume, (2) the ratio of enthalpy to internal energy, (3) the ratio of the changes in enthalpy and internal energy across a shock wave, and (4) the relation between the Grueneisen coefficient and the effective isentropic exponent. We use the Dugdale-MacDonald relation for the Grueneisen coefficient at low pressure, an assumed constant value for the specific heat at constant volume, and reasonable physical assumptions for extremely strong shock waves together with the incomplete thermodynamic state description to define the following along the Hugoniot: (5) the Grueneisen coefficient, (6) the effective isentropic exponent, (7) the ratio of specific heats, and (8) thermal and elastic components of pressure, temperature, and entropy. We present representative numerical values of these parameters as functions of reduced volumetric compression. We show how the solutions for these parameters define tangent planes to the surfaces of the incomplete E,P, and V and P,V, and T equations of state at each point along the Hugoniot curve
Shock waves from non-spherically collapsing cavitation bubbles
Supponen, Outi; Obreschkow, Danail; Farhat, Mohamed
2017-11-01
Combining simultaneous high-speed imaging and hydrophone measurements, we uncover details of the multiple shock wave emission from laser-induced cavitation bubbles collapsing in a non-spherical way. For strongly deformed bubbles collapsing near a free surface, we identify the distinct shock waves caused by the jet impact onto the opposite bubble wall and by the individual collapses of the remaining bubble segments. The energy carried by each of these shocks depends on the level of bubble deformation, quantified by the anisotropy parameter ζ, the dimensionless equivalent of the Kelvin impulse. For jetting bubbles, at ζ hammer pressure is found to be the most energetic shock. Through statistical analysis of the experimental data and theoretical derivations, and by comparing bubbles deformed by different sources (variable gravity achieved on parabolic flights, and neighboring free and rigid surfaces), we find that the shock peak pressure may be approximated as the jet impact-induced water hammer as ph = 0.45 (ρc2 Δp) 1 / 2ζ-1 .
Applications of Shock Wave Research to Developments of Therapeutic Devices.
Takayama, Kazuyoshi
2007-06-01
Underwater shock wave 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 shock waves. 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 shock wave 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 shock 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.
Laser Acceleration of Electrons in Shock Wave Enhanced Gas Jets
Kaganovich, Dmitri; Helle, Michael; Gordon, Daniel; Ting, Antonio
2012-10-01
Controlling the gas density gradient and profile is important for electron and proton acceleration. Using an optimized gas density profile, we have demonstrated 40 times higher electron energy compared to a Gaussian gas jet without lost of charge or stability. Propagation of a shock wave through a gas jet can modify the gas density profile and create sharp density gradients [1, 2]. Using different shock waves energies and shock originating positions, we were able to modify the plasma density profile of a ``typical'' Gaussian gas jet into a variety of profiles, from thin (foil-like) structure to elongated profiles with fast rise and slow fall. We used a plasma bubble Cherenkov diagnostic [3, 4] to optimize the acceleration process. Accelerated electron energy and charge were cross-correlated with the second harmonic diagnostic signal. The optimized gas density profile generated stable 0.5 nC of 40 MeV electrons using a 10 TW laser. The shock wave modified gas jet can be used as a stand alone electron source or as an injector coupled to additional acceleration structures. We demonstrated stable injection of electrons from the shock wave modified gas jet into a lower density plasma. The results are also being studied with numerical simulations. [4pt] [1] D. Kaganovich et al., Physics of Plasmas 18, 120701 (2011)[0pt] [2] D. Kaganovich et al., Applied Physics Letters 97, 191501 (2010)[0pt] [3] D. F. Gordon, et al., Phys. Rev. Lett. 101, 045004 (2008)[0pt] [4] M. H. Helle et al., Phys. Rev. Lett. 105, 105001 (2010)
'Thunder' - Shock waves in pre-biological organic synthesis.
Bar-Nun, A.; Tauber, M. E.
1972-01-01
Theoretical study of the gasdynamics and chemistry of lightning-produced shock waves in a postulated primordial reducing atmosphere. It is shown that the conditions are similar to those encountered in a previously performed shock-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.
Study of shock-wave impingement on perforated plates using high-speed holographic interferometry
Skews, Beric W.; Takayama, Kazuyoshi
1997-05-01
It has recently been established that the porosity of surfaces can have a significant effect on the reflection geometry of shock waves, and thus on the loads that are generated. This paper describes a comprehensive series of tests on the patterns of shock wave reflection from a surface covered with a series of slits, over the full range of angles of incidence from glancing to normal. The use of double-pulse interferometry is shown to be ideally suited to the study of complex compressible flow fields of this type, not only because of the high resolution but also because the tracking of fringes gives a very clear indication of both the general flow field as well as the fine structure, and thus helps clarify the mechanisms whereby the interaction process is modified from the case of reflection off a plane impervious wall. These features of the method allow a number of effects to be established which have not previously been evident, or are in conflict with the assumptions of previous studies. Specifically it is shown that the inflow angle relative to the plate is almost constant (at about 17 degrees) for shock incidence angles from zero to about 50 degrees and that the flow leaves the plate almost normal to the surface; although there is a slight drift in a direction opposite to that of the shock induced flow. Furthermore it is shown that many of the flow variables, and specifically the inflow velocity, exhibit a maximum in the vicinity of transition from regular to Mach reflection. An analysis of the motion of the acoustic waves generated from the lips of the perforations allows estimates to be made of the constancy of the inflow along the surface. These waves are convected with the flow and as they do not meet the wall at a right angle show that the convection is towards the wall. Using this method it is found that the inflow is constant behind the reflected wave in regular reflection but variable for the case of Mach reflection. Photographs of the region under the
Exploring nonlocal observables in shock wave collisions
Energy Technology Data Exchange (ETDEWEB)
Ecker, Christian; Grumiller, Daniel; Stanzer, Philipp; Stricker, Stefan A. [Institut für Theoretische Physik, Technische Universität Wien,Wiedner Hauptstrasse 8-10, A-1040 Vienna (Austria); Schee, Wilke van der [Center for Theoretical Physics, Massachusetts Institute of Technology,77 Massachusetts Avenue, Cambridge, MA 02139 (United States)
2016-11-09
We study the time evolution of 2-point functions and entanglement entropy in strongly anisotropic, inhomogeneous and time-dependent N=4 super Yang-Mills theory in the large N and large ’t Hooft coupling limit using AdS/CFT. On the gravity side this amounts to calculating the length of geodesics and area of extremal surfaces in the dynamical background of two colliding gravitational shockwaves, which we do numerically. We discriminate between three classes of initial conditions corresponding to wide, intermediate and narrow shocks, and show that they exhibit different phenomenology with respect to the nonlocal observables that we determine. Our results permit to use (holographic) entanglement entropy as an order parameter to distinguish between the two phases of the cross-over from the transparency to the full-stopping scenario in dynamical Yang-Mills plasma formation, which is frequently used as a toy model for heavy ion collisions. The time evolution of entanglement entropy allows to discern four regimes: highly efficient initial growth of entanglement, linear growth, (post) collisional drama and late time (polynomial) fall off. Surprisingly, we found that 2-point functions can be sensitive to the geometry inside the black hole apparent horizon, while we did not find such cases for the entanglement entropy.
Towards simulating a collisionless shock wave using the FLASH code
International Nuclear Information System (INIS)
Farley, D.R.; Shigemori K; Azechi, H.
2005-01-01
Full text: In recent years, there has been considerable interest in conducting laser-plasma experiments of relevance to astrophysical research. Results from these experiments can be used to study fundamental physics, as well as benchmark astrophysical codes. The FLASH code, a robust hydrodynamics code produced by the University of Chicago under the Accelerated Strategic Computing Initiative (ASCI), is Bed to simulate a blast wave experiment conducted at the University of Osaka Institute for Laser Engineering (ILE). The code was run in one and two dimensions (axis-symmetric) using a perfect gas equation of state approximation. The shock wave experiment involved irradiating a 2 micron thick piece of plastic (CH) with a high-power, short-pulse laser. The ablated material and resulting shock front from the plastic target Propagated a blast wave into ambient argon at 1.0 Torr. Evolution of the blast wave differs slightly between the cases of Spitzer-Harm conductivity on and off, and neither case matches well with experiments. Due to the high temperatures involved, a thermal wave should be expected such that the Spitzer-Harm conductivity on vase is more likely. Density an velocity profiles from experiment and numerical simulation are compared. The experiment and simulation results compare well blast wave theory
Second sound shock waves and critical velocities in liquid helium 2. Ph.D. Thesis
Turner, T. N.
1979-01-01
Large amplitude second-sound shock waves were generated and the experimental results compared to the theory of nonlinear second-sound. The structure and thickness of second-sound shock fronts are calculated and compared to experimental data. Theoretically it is shown that at T = 1.88 K, where the nonlinear wave steepening vanishes, the thickness of a very weak shock must diverge. In a region near this temperature, a finite-amplitude shock pulse evolves into an unusual double-shock configuration consisting of a front steepened, temperature raising shock followed by a temperature lowering shock. Double-shocks are experimentally verified. It is experimentally shown that very large second-sound shock waves initiate a breakdown in the superfluidity of helium 2, which is dramatically displayed as a limit to the maximum attainable shock strength. The value of the maximum shock-induced relative velocity represents a significant lower bound to the intrinsic critical velocity of helium 2.
Renal pelvic stones: choosing shock wave lithotripsy or percutaneous nephrolithotomy
Directory of Open Access Journals (Sweden)
Robert Marcovich
2003-06-01
Full Text Available Introduction of minimally invasive techniques has revolutionized the surgical management of renal calculi. Extracorporeal shock wave lithotripsy and percutaneous nephrolithotomy are now both well-established procedures. Each modality has advantages and disadvantages, and the application of each should be based on well-defined factors. These variables include stone factors such as number, size, and composition; factors related to the stone's environment, including the stone's location, spatial anatomy of the renal collecting system, presence of hydronephrosis, and other anatomic variables, such as the presence of calyceal diverticula and renal anomalies; and clinical or patient factors like morbid obesity, the presence of a solitary kidney, and renal insufficiency. The morbidity of each procedure in relation to its efficacy should be taken in to account. This article will review current knowledge and suggest an algorithm for the rational management of renal calculi with shock wave lithotripsy and percutaneous nephrolithotomy.
Extracorporeal shock wave therapy in periodontics: A new paradigm
Directory of Open Access Journals (Sweden)
Munivenkatappa Lakshmaiah Venkatesh Prabhuji
2014-01-01
Full Text Available 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 shock wave 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 shock waves in improving the treatment outcome.
Treatment of intrahepatic stones with shock wave lithotripsy
International Nuclear Information System (INIS)
Martin, L.G.; Amerson, J.R.; Ambrose, S.S.; Alspaugh, J.P.; Chuang, V.P.; Casarella, W.J.
1987-01-01
Extracorporeal shock wave lithotripsy administered with a renal lithotriptor was used for the successful removal of intrahepatic biliary stones in two patients with Oriental cholangiohepatitis. Both patients had undergone multiple surgical explorations and multiple attempts at percutaneous stone removal. Targeting of the stones was facilitated by placing the tip of an angiographic guide wire, inserted through a transhepatic catheter, adjacent to the stone. Shock waves of 16-18 keV were applied. The patients were monitored with serial vital signs, chest radiography, liver chemistry profiles, and MR imaging. No major adverse reaction was detected in either patient. Limitations to the use of lithography for intrahepatic stone removal include patient body size, target-skin disease, location of the stones, and potential injury to the lung base. The authors' preliminary experience suggests that the lithtripsy can greatly facilitate the treatment of intrahepatic stones in selected patients
Some health physics implications of extracorporeal shock wave lithotripsy
International Nuclear Information System (INIS)
Henderson, J.E.
1987-01-01
Extracorporeal Shock Wave Lithotripsy (ESWL) is a relatively new, noninvasive technique for the destruction of renal calculi (kidney stones) in vivo. X-ray localizing techniques are used to position the stone for shock wave destruction. The combination of radiographic and fluoroscopic exposure contributes significantly to patient dose. This presentation considers alternative techniques for measuring patient exposure during ESWL and details many of the problems attendant to those measurements. Factors that contribute to patient dose are described. Comparisons are made to previous interventions for renal calculi involving radiological considerations. Operator exposures are negligible for this procedure, but skin entrance exposures for patients have been found on the order of 10 R to 17 R. Attempts to quantify gonadal doses during ESWL treatment at the University of Virginia are described. A rationale for continued studies in this area is offered
Song, Yunfei; Yu, Guoyang; Jiang, Lilin; Zheng, Xianxu; Liu, Yuqiang; Yang, Yanqiang
2011-04-01
The shock wave driven by short laser pulse is used to study the damage of brittle material K9 glass. The damage morphology of K9 glass surface indicates that the material has experienced different loading modes, respectively, at the central area and the surrounding area of the shock wave. At the central area of shock wave, the wavefront is plane and has a uniform pressure distribution, the material mainly suffers a longitudinal shock pressure; but on the edge the shock wave, the wavefront is approximately spherical, besides longitudinal pressure, transverse tensile stress will emerge inside the material. In the latter case, the damage threshold of the material is much smaller than that in the case of compressing by longitudinal pressure only. According to the relationship between damage area and shock pressure, an experimental method is proposed to measure the damage threshold of materials under shock loading. The damage threshold of K9 glass under spherical shock wave is measured to be about 1.12 GPa; and the damage threshold under plane shock wave is estimated to be between 1.82 and 1.98 GPa. They are much bigger than the damage threshold under static pressure. This method could also be used to measure the damage threshold of other materials when loaded by dynamic pressure.
Extracorporeal Shock Wave Therapy for Nonunion of the Tibia
2010-03-01
the tibia treated with a reamed intramedullary interlocking nail . Clin Orrhop Relul Res. 1995; 315:56-63. 12. Wiss DA, Stetson WB. Tibial nonunion...atrophic and infected non unions . 18 24 A promising technology, extracorporeal shock wave therapy (ESWT), has been used to treat various musculoskel...nonunions has engendered innovative and alternative treat - ment approaches, including mechanical and molecular inter- ventions in the fonn of nail
On the propagation of sound waves in a stellar wind traversed by periodic strong shocks
Pijpers, F. P.
1994-01-01
It has been claimed that in stellar winds traversed by strong shocks the mechanism for driving the wind by sound wave pressure cannot operate because sound waves cannot propagate past the shocks. It is shown here that sound waves can propagate through shocks in one direction and that this is a sufficient condition for the sound wave pressure mechanism to work. A strong shock amplifies a sound wave passing through it and can drag the sound wave away from the star. It is immaterial for the soun...
Impact-driven shock waves and thermonuclear neutron generation
Energy Technology Data Exchange (ETDEWEB)
Gus' kov, S Yu; Demchenko, N N; Doskoch, I Ya; Rozanov, V B [P.N. Lebedev Physical Institute of Russian Academy of Sciences, Moscow (Russian Federation); Azechi, H; Murakami, M; Sakaiya, T; Watari, T [Institute of Laser Engineering, Osaka University, Suita, Osaka (Japan); Zmitrenko, N V, E-mail: guskov@sci.lebedev.r [Institute for Mathematical Modeling of Russian Academy of Sciences, Moscow (Russian Federation)
2009-09-15
Impact-driven shock waves, thermonuclear plasma and neutron yield were investigated. The results of 2D numerical simulations and Gekko/HIPER laser experiments on the collision of a laser-accelerated disk-projectile with a massive target, both containing (CD){sub n}-material, are discussed. A two-temperature model of the non-equilibrium plasma created by impact-driven shock waves due to the collision of a laser-accelerated planar projectile with a massive target was developed and used for analysis of the numerical and experimental results. The model defines the characteristics of shock waves and plasmas (including their lifetime) as well as neutron yields in both the colliding objects as functions of velocity, density and mass of the projectile-impactor just before collision. The neutron yield generated during the period of laser-driven acceleration of the impactor was also determined. Two effects were discovered that exert a substantial influence on the plasma parameters and neutron yield. The first of them relates to the formation of the pre-impact state of the impactor. It decreases the projectile density due to thermal expansion of its matter through a free boundary during the period of laser-driven acceleration. The other relates to the formation of impact-produced plasma. Predominant heating of the ion component of plasma leads to the existence of a non-equilibrium two-temperature plasma during the period of electron-ion relaxation.
Extracorporeal shock wave therapy for treatment of plantar fasciitis
International Nuclear Information System (INIS)
Dastgir, N.
2014-01-01
Objective: To explore the effect of extracorporeal shock wave therapy in patients with chronic plantar faciitis. Methods: The prospective study was conducted at Department of Orhopaedic, Regional Hospital, Limerick, Ireland from January to December 2004 and comprised 70 heels in 62 patients with chronic plantar fasciitis in whom conventional conservative treatment consisting of non-steroidal anti-inflammatory drugs, heel cup, orthoses and/or shoe modifications, local steroid injections had failed, and they were treated with low energy extracorporeal shock wave therapy. Patients were reviewed at 6, 12 and 24 weeks post treatment. Results: At follow-up there was significant decrease in pain on the visual analogue scale (p<0.027), with significant improvement in pain score (p<0.009) and in functional score (p<0.001). The comfortable walking distance had increased significantly and there were no reported side effects. Conclusion: Extracorporeal shock wave therapy is a new modality providing good pain relief and a satisfactory clinical outcome in patients with chronic plantar fasciitis. (author)
Stability of stagnation via an expanding accretion shock wave
Energy Technology Data Exchange (ETDEWEB)
Velikovich, A. L.; Giuliani, J. L. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States); Murakami, M. [Institute of Laser Engineering, Osaka University, Osaka 565-0871 (Japan); Taylor, B. D. [Laboratory for Computational Physics and Fluid Dynamics, Naval Research Laboratory, Washington, DC 20375 (United States); Zalesak, S. T. [Berkeley Research Associates, Beltsville, Maryland 20705 (United States); Iwamoto, Y. [Ehime University, Matsuyama, Ehime Pref. 790-8577 (Japan)
2016-05-15
Stagnation of a cold plasma streaming to the center or axis of symmetry via an expanding accretion shock wave 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 shock wave is stable, but its stability has never been studied theoretically. We present such analysis for the stagnation that does not involve a rarefaction wave behind the expanding shock 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.
Stability of stagnation via an expanding accretion shock wave
Velikovich, A. L.; Murakami, M.; Taylor, B. D.; Giuliani, J. L.; Zalesak, S. T.; Iwamoto, Y.
2016-05-01
Stagnation of a cold plasma streaming to the center or axis of symmetry via an expanding accretion shock wave 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 shock wave is stable, but its stability has never been studied theoretically. We present such analysis for the stagnation that does not involve a rarefaction wave behind the expanding shock 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.
Laser shock wave consolidation of nanodiamond powders on aluminum 319
Energy Technology Data Exchange (ETDEWEB)
Molian, Pal [Laboratory for Lasers, MEMS, and Nanotechnology, Department of Mechanical Engineering, Iowa State University, Ames, IA 50011-2161 (United States)], E-mail: molian@iastate.edu; Molian, Raathai; Nair, Rajeev [Laboratory for Lasers, MEMS, and Nanotechnology, Department of Mechanical Engineering, Iowa State University, Ames, IA 50011-2161 (United States)
2009-01-01
A novel coating approach, based on laser shock wave generation, was employed to induce compressive pressures up to 5 GPa and compact nanodiamond (ND) powders (4-8 nm) on aluminum 319 substrate. Raman scattering indicated that the coating consisted of amorphous carbon and nanocrystalline graphite with peaks at 1360 cm{sup -1} and 1600 cm{sup -1} respectively. Scanning electron microscopy revealed a wavy, non-uniform coating with an average thickness of 40 {mu}m and absence of thermal effect on the surrounding material. The phase transition from nanodiamond to other phases of carbon is responsible for the increased coating thickness. Vicker's microhardness test showed hardness in excess of 1000 kg{sub f}/mm{sup 2} (10 GPa) while nanoindentation test indicated much lower hardness in the range of 20 MPa to 2 GPa. Optical surface profilometry traces displayed slightly uneven surfaces compared to the bare aluminum with an average surface roughness (R{sub a}) in the range of 1.5-4 {mu}m depending on the shock wave pressure and type of confining medium. Ball-on-disc tribometer tests showed that the coefficient of friction and wear rate were substantially lower than the smoother, bare aluminum sample. Laser shock wave process has thus aided in the generation of a strong, wear resistant, durable carbon composite coating on aluminum 319 substrate.
Kinetic Alfven waves and electron physics. II. Oblique slow shocks
International Nuclear Information System (INIS)
Yin, L.; Winske, D.; Daughton, W.
2007-01-01
One-dimensional (1D) particle-in-cell (PIC; kinetic ions and electrons) and hybrid (kinetic ions; adiabatic and massless fluid electrons) simulations of highly oblique slow shocks (θ Bn =84 deg. and β=0.1) [Yin et al., J. Geophys. Res., 110, A09217 (2005)] have shown that the dissipation from the ions is too weak to form a shock and that kinetic electron physics is required. The PIC simulations also showed that the downstream electron temperature becomes anisotropic (T e parallel )>T e perpendicular ), as observed in slow shocks in space. The electron anisotropy results, in part, from the electron acceleration/heating by parallel electric fields of obliquely propagating kinetic Alfven waves (KAWs) excited by ion-ion streaming, which cannot be modeled accurately in hybrid simulations. In the shock ramp, spiky structures occur in density and electron parallel temperature, where the ion parallel temperature decreases due to the reduction of the ion backstreaming speed. In this paper, KAW and electron physics in oblique slow shocks are further examined under lower electron beta conditions. It is found that as the electron beta is reduced, the resonant interaction between electrons and the wave parallel electric fields shifts to the tail of the electron velocity distribution, providing more efficient parallel heating. As a consequence, for β e =0.02, the electron physics is shown to influence the formation of a θ Bn =75 deg. shock. Electron effects are further enhanced at a more oblique shock angle (θ Bn =84 deg.) when both the growth rate and the range of unstable modes on the KAW branch increase. Small-scale electron and ion phase-space vortices in the shock ramp formed by electron-KAW interactions and the reduction of the ion backstreaming speed, respectively, are observed in the simulations and confirmed in homogeneous geometries in one and two spatial dimensions in the accompanying paper [Yin et al., Phys. Plasmas 14, 062104 (2007)]. Results from this study
Jing Fu Qian
2002-01-01
Progress made in recent years on three topics that have been investigated at the Laboratory for Shock Wave and Detonation Physics Research are presented in this report. (1) A new equation of state (EOS) has been derived which can be used from a standard state to predict state variable change along an isobaric path. Good agreements between calculations for some representative metals using this new EOS and experiments have been found, covering a wide range from hundreds of MPa to hundreds of GPa and from ambient temperature to tens of thousands of GPa. (2) An empirical relation of Y/G = constant (Y is yield strength, G is shear modulus) at HT-HP has been reinvestigated and confirmed by shock wave experiment. 93W alloy was chosen as a model material. The advantage of this relation is that it is beneficial to formulate a kind of simplified constitutive equation for metallic solids under shock loading, and thus to faithfully describe the behaviours of shocked solids through hydrodynamic simulations. (3) An attempt...
Dust acoustic shock wave generation due to dust charge variation in ...
Indian Academy of Sciences (India)
pp. 1197–1201. Dust acoustic shock wave generation due to dust charge ... to generation of shock wave in the dusty plasma described as collisionless shock wave. ... Φ -(δ -1)(1+∆Qd)(1+∆Nd). ] (7) while the dust charging equation in the wave frame is d∆Qd dζ. =(1+∆Nd). µ. [ exp(Φ-z∆Qd)-exp. (-Φ σ. )( 1+ z σ +z. ∆Qd. )] σd =.
[Current status of extracorporeal shock wave lithotripsy in urinary lithiasis.
Pereira-Arias, Jose Gregorio; Gamarra-Quintanilla, Mikel; Urdaneta-Salegui, Luis Felipe; Mora-Christian, Jorge Alberto; Sánchez-Vazquez, Andrea; Astobieta-Odriozola, Ander; Ibarluzea-González, Gaspar
2017-03-01
Over the last decade, urinary lithiasis' prevalence has dramatically increased due to diet and lifestyle changes, growing 10.6% and 7.1% in men and women respectively. Extracorporeal shock wave lithotripsy has lost relevance in current practice due to endoscopic device development and unpredictability of results. Instrument miniaturization is leading to an increase of the percutaneous approach of increasingly smaller stones, while most flexible ureteroscopes durability and digitalization has allowed urologists to address larger stones. So that, decision algorithm is now impossible to define, but what is clear is that ESWL has declined worldwide. Can it disappear as a urinary lithiasis treatment modality? If we don't improve appropriate candidate selection and optimize disintegration efficiency, guidelines are going to replace the more "boring" ESWL by popular and more attractive endoscopes. Shock wave technology has evolved in the last two decades, however lithotripsy fundamental principle has not changed. ESWL has passed the test of time and centers dedicated to stone treatment should have a lithotripter in order to offer an appropriate balance in different options for different clinical situations. New developments will be focused on improvements in location (in-line navigation systems; Vision track system) and automatic ultrasound location on a robotic arm; monitoring and stone fixation, implementation of different focal sizes with new acoustic lenses, multitask working stations that allow endourological approach, coupling control (avoiding microbubbles) and low cost devices for different applications. On the other hand, optimizing outcomes by: slower pulse rates, ramping strategies and patient selection with soft stones, short stone-skin distance, low BMI and favorable collecting system anatomy, allow us to achieve better outcomes in shock wave treatments. SWL still represents a unique non invasive method of stone disease treatment with no anesthesia and low
Lengyel-Frey, D.; Macdowall, R. J.; Stone, R. G.; Hoang, S.; Pantellini, F.; Harvey, C.; Mangeney, A.; Kellogg, P.; Thiessen, J.; Canu, P.
1992-01-01
We present Ulysses URAP observations of plasma waves at seven interplanetary shocks detected between approximately 1 and 3 AU. The URAP data allows ready correlation of wave phenomena from .1 Hz to 1 MHz. Wave phenomena observed in the shock vicinity include abrupt changes in the quasi-thermal noise continuum, Langmuir wave activity, ion acoustic noise, whistler waves and low frequency electrostatic waves. We focus on the forward/reverse shock pair of May 27, 1991 to demonstrate the characteristics of the URAP data.
Second sound shock waves in rotating superfluid helium
International Nuclear Information System (INIS)
Torczynski, J.R.
1983-01-01
Second sound shock waves have been used to examine the breakdown of superfluidity in bulk He II. The maximum counterflow velocity achieved in this manner was measured at a variety of temperatures and pressures. The results are found to agree with predictions of vortex nucleation theories (Langer and Fisher, 1967) in their pressure and temperature dependences although it was shown that dissipation occurred only near the heater. A simple scaling argument is suggested, assuming breakdown occurs near the heater. A vortex dynamics model of breakdown (following the method of Turner, private communication) is developed. To examine the effect of vorticity on breakdown, second sound shocks were produced in rotating helium. Experiments were performed in which the shocks propagated either along or normal to the axis of rotation, called axial and transverse cases, respectively. In both cases the decay was seen to increase monotonically with the rotation rate. Furthermore, the decay was ongoing rather than being confined to a narrow region near the heater. However, the extraordinary dissipation in the transverse case seemed to be related primarily to the arrival of secondary waves from the heater-sidewall boundary. An explanation of this difference is put forth in terms of vortex nucleation in the bulk fluid, using ideas similar to Crocco's Theorem. In order to examine the breakdown of superfluidity away from walls in nonrotation fluid, spherically converging second shocks were produced. The temperature jumps of the waves were measured, and exact numerical solutions of the two-fluid jump conditions (Moody, 1983) were used to calculate the relative velocity in each case
Modeling the Propagation of Shock Waves in Metals
Howard, W. Michael
2005-07-01
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 ˜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 bulk modulus depends on pressure, density and temperature. The calculation of the melt temperature is based on the Lindermann law. At melt the yield strength and bulk 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 gives the correct detonation velocity and C-J pressure (P ˜ 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. We also discuss the dependence of our results upon our material model for aluminum.
The role of stress waves and cavitation in stone comminution in shock wave lithotripsy.
Zhu, Songlin; Cocks, Franklin H; Preminger, Glenn M; Zhong, Pei
2002-05-01
Using an experimental system that mimics stone fragmentation in the renal pelvis, we have investigated the role of stress waves and cavitation in stone comminution in shock-wave lithotripsy (SWL). Spherical plaster-of-Paris stone phantoms (D = 10 mm) were exposed to 25, 50, 100, 200, 300 and 500 shocks at the beam focus of a Dornier HM-3 lithotripter operated at 20 kV and a pulse repetition rate of 1 Hz. The stone phantoms were immersed either in degassed water or in castor oil to delineate the contribution of stress waves and cavitation to stone comminution. It was found that, while in degassed water there is a progressive disintegration of the stone phantoms into small pieces, the fragments produced in castor oil are fairly sizable. From 25 to 500 shocks, clinically passable fragments (stones with a primary composition of calcium oxalate monohydrate. After 200 shocks, 89% of the fragments of the kidney stones treated in degassed water became passable, but only 22% of the fragments of the kidney stones treated in castor oil were less than 2 mm in size. This apparent size limitation of the stone fragments produced primarily by stress waves (in castor oil) is likely caused by the destructive superposition of the stress waves reverberating inside the fragments, when their sizes are less than half of the compressive wavelength in the stone material. On the other hand, if a stone is only exposed to cavitation bubbles induced in SWL, the resultant fragmentation is much less effective than that produced by the combination of stress waves and cavitation. It is concluded that, although stress wave-induced fracture is important for the initial disintegration of kidney stones, cavitation is necessary to produce fine passable fragments, which are most critical for the success of clinical SWL. Stress waves and cavitation work synergistically, rather than independently, to produce effective and successful disintegration of renal calculi in SWL
Radiation exposure to patients during extracorporeal shock wave lithotripsy
International Nuclear Information System (INIS)
Van Swearingen, F.L.; McCullough, D.L.; Dyer, R.; Appel, B.
1987-01-01
Extracorporeal shock wave lithotripsy is rapidly becoming an accepted treatment of renal calculi. Since fluoroscopy is involved to image the stones it is important to know how much radiation the patient receives during this procedure. Surface radiation exposure to the patient was measured in more than 300 fluoroscopic and radiographic procedures using thermoluminescent dosimeters. Initial results showed an average skin exposure of 10.1 rad per procedure for each x-ray unit, comparing favorably with exposure rates for percutaneous nephrostolithotomy and other routine radiological procedures. Factors influencing exposure levels include stone characteristics (location, size and opacity), physician experience and number of shocks required. Suggestions are given that may result in a 50 per cent reduction of radiation exposure
Oblique shock waves in granular flows over bluff bodies
Directory of Open Access Journals (Sweden)
Gopan Nandu
2017-01-01
Full Text Available Granular flows around an object have been the focus of numerous analytical, experimental and simulation studies. The structure and nature of the oblique shock wave developed when a quasi-two dimensional flow of spherical granular particles streams past an immersed, fixed cylindrical obstacle forms the focus of this study. The binary granular mixture, consisting of particles of the same diameter but different material properties, is investigated by using a modified LIGGGHTS package as the simulation engine. Variations in the solid fraction and granular temperature within the resulting flow are studied. The Mach number is calculated and is used to distinguish between the subsonic and the supersonic regions of the bow shock.
Acceleration of galactic cosmic rays in shock waves
International Nuclear Information System (INIS)
Lagage, P.O.
1981-06-01
The old problem of the origin of cosmic rays has triggered off fresh interest owing to the discovery of a new model which enables a lot of energy to be transferred to a small number of particles on the one hand and the discovery of the coronal environment in which this transfer occurs, on the other. In this paper, interest is taken in the galactic cosmic rays and an endeavour is made to find out if the model can reveal the existence of cosmic rays over a wide energy range. The existence of an energy break, predicted by the model, was recognized fairly early but, in the literature, it varies from 30 GeV ro 10 6 GeV according to the authors. A study has been made of the two main causes of an energy break: the sphericity of the shock and the life time of the shock wave [fr
Modeling shock waves in an ideal gas: combining the Burnett approximation and Holian's conjecture.
He, Yi-Guang; Tang, Xiu-Zhang; Pu, Yi-Kang
2008-07-01
We model a shock wave in an ideal gas by combining the Burnett approximation and Holian's conjecture. We use the temperature in the direction of shock propagation rather than the average temperature in the Burnett transport coefficients. The shock wave profiles and shock thickness are compared with other theories. The results are found to agree better with the nonequilibrium molecular dynamics (NEMD) and direct simulation Monte Carlo (DSMC) data than the Burnett equations and the modified Navier-Stokes theory.
Linear shock wave therapy in the treatment of erectile dysfunction.
Pelayo-Nieto, M; Linden-Castro, E; Alias-Melgar, A; Espinosa-Pérez Grovas, D; Carreño-de la Rosa, F; Bertrand-Noriega, F; Cortez-Betancourt, R
2015-09-01
Linear Shock Wave Therapy (LSWT) is a new noninvasive therapy that uses low-intensity shock waves to induce local angiogenesis promising modality in the treatment of erectile dysfunction (ED). To evaluate the effectiveness of LSWT in men with vasculogenic erectile dysfunction (ED), in a Tertiary Care Center. Included 15 men aged 45-70 years, sexually active with mild and moderate vascular ED evaluated with the International Index of Erectile Function (IIEF). The study was conducted in three stage: screening, treatment and results. Treatment stage: 4 weekly sessions LSWT (RENOVA ®) 5000 waves (.09mJ/mm(2)). Erectile function was assessed with IIEFF-EF, SEP (Sexual Encounter Profile) and GAQ (Global Assessment Questions) at one and six months after treatment. The rate of success was 80% (12/15). Patients with mild ED (6/15) 40% and moderate ED (9/15) 60%. We found a positive association between IIEF-Basal (average 14.23 pts) and IIEF at one month and six months after therapy (19.69 pts) a difference of 5.46 pts. (P<.013). The feasibility and tolerability of this treatment, and rehabilitation potential features, make it this an attractive new treatment option for patients with ED. Copyright © 2014 AEU. Publicado por Elsevier España, S.L.U. All rights reserved.
Potential applications of low-energy shock waves in functional urology.
Wang, Hung-Jen; Cheng, Jai-Hong; Chuang, Yao-Chi
2017-08-01
A shock wave, which carries energy and can propagate through a medium, is a type of continuous transmitted sonic wave with a frequency of 16 Hz-20 MHz. It is accompanied by processes involving rapid energy transformations. The energy associated with shock waves has been harnessed and used for various applications in medical science. High-energy extracorporeal shock wave therapy is the most successful application of shock waves, and has been used to disintegrate urolithiasis for 30 years. At lower energy levels, however, shock waves have enhanced expression of vascular endothelial growth factor, endothelial nitric oxide synthase, proliferating cell nuclear antigen, chemoattractant factors and recruitment of progenitor cells; shock waves have also improved tissue regeneration. Low-energy shock wave therapy has been used clinically with musculoskeletal disorders, ischemic cardiovascular disorders and erectile dysfunction, through the mechanisms of neovascularization, anti-inflammation and tissue regeneration. Furthermore, low-energy shock waves have been proposed to temporarily increase tissue permeability and facilitate intravesical drug delivery. The present review article provides information on the basics of shock wave physics, mechanisms of action on the biological system and potential applications in functional urology. © 2017 The Japanese Urological Association.
The effectiveness of shock wave lithotripters: a case matched comparison.
Alanee, Shaheen; Ugarte, Roland; Monga, Manoj
2010-12-01
We compared the results of shock wave lithotripsy with a newer electromagnetic lithotripter to those of an electrohydraulic lithotripter using identical treatment and followup criteria. We performed a case matched comparison of 8,565 patients treated from 2003 to 2007 using the Medstone STS™ and the Modulith® SLX machines, matching for stone size, location and patient body mass index. The outcome of interest was treatment success in producing stone-free status. We report treatment characteristics, such as stone site and size, gating and final stone-free rate. Significance was considered at pModulith SLX and Medstone STS stone-free rates were equivalent (61.1% and 64.5%, respectively, p=0.0664). Matching and logistic regression results showed that differences in the stone-free rate were insignificant for all stones (p>0.7592), lower pole kidney stones (p=0.9659) and ureteral stones (p=0.6409). Medstone STS performed better than Modulith SLX only for distal ureteral stones (83.63% vs 66.67%, p=0.0154). The rate of post-lithotripsy secondary procedures was equivalent (p=0.2079). The difference was insignificant for harder stones (p=0.2988). Shock wave lithotripsy is equally effective using Medstone STS and Modulith SLX for different stone sizes and most stone sites. Shock wave lithotripsy is more successful for lower ureteral stones using the Medstone STS. To our knowledge this is the first study comparing these 2 commonly used lithotripters. Copyright © 2010 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.
NUMERICAL SIMULATION OF SHOCK WAVE REFRACTION ON INCLINED CONTACT DISCONTINUITY
Directory of Open Access Journals (Sweden)
P. V. Bulat
2016-05-01
Full Text Available We consider numerical simulation of shock wave refraction on plane contact discontinuity, separating two gases with different density. Discretization of Euler equations is based on finite volume method and WENO finite difference schemes, implemented on unstructured meshes. Integration over time is performed with the use of the third-order Runge–Kutta stepping procedure. The procedure of identification and classification of gas dynamic discontinuities based on conditions of dynamic consistency and image processing methods is applied to visualize and interpret the results of numerical calculations. The flow structure and its quantitative characteristics are defined. The results of numerical and experimental visualization (shadowgraphs, schlieren images, and interferograms are compared.
Radial extracorporeal shock wave treatment harms developing chicken embryos
Kiessling, Maren C.; Milz, Stefan; Frank, Hans-Georg; Korbel, Rüdiger; Schmitz, Christoph
2015-01-01
Radial extracorporeal shock wave treatment (rESWT) has became one of the best investigated treatment modalities for cellulite, including the abdomen as a treatment site. Notably, pregnancy is considered a contraindication for rESWT, and concerns have been raised about possible harm to the embryo when a woman treated with rESWT for cellulite is not aware of her pregnancy. Here we tested the hypothesis that rESWT may cause serious physical harm to embryos. To this end, chicken embryos were expo...
Xiang, G.; Wang, C.; Teng, H.; Jiang, Z.
2018-03-01
This study explores the three-dimensional (3D) wave configurations induced by 3D asymmetrical intersecting compression wedges in supersonic and hypersonic inviscid flows. By using the "spatial dimension reduction" approach, the problem of 3D steady shock/shock interaction is converted to that of the interaction of two moving shock waves in the characteristic two-dimensional (2D) plane. Shock polar theory is used to analyze the shock configurations in asymmetrical situations. The results show that various shock configurations exist in 3D asymmetrical shock wave interactions, including regular interaction, transitioned regular interaction, single Mach interaction, inverse single Mach interaction, transitional double Mach interaction, weak shock interaction, and weak single Mach interaction. All of the above 3D steady shock/shock interactions have their corresponding 2D moving shock/shock interaction configurations. Numerical simulations are performed by solving the 3D inviscid Euler equations with the non-oscillatory, non-free parameters, dissipative (NND) numerical scheme, and good agreement with the theoretical analysis is obtained. Furthermore, the comparison of results show that the concept of the "virtual wall" in shock dynamics theory is helpful for understanding the mechanism of two-dimensional shock/shock interactions.
Experimental Study on Colliding Shock Waves and Mach Stem Formation in Metals
Hu, Haibo; Zhang, Chongyu; Wang, Xiang; Chen, Yongtao; Tang, Tiegang; Laboratory for Shock Wave; Detonation Physics Research Team
2017-06-01
The dynamic behavior of different metals under sliding detonation loading and head-on colliding shock waves is studied by using small spot multi-channel PDV. The free surface velocity data have shown different responses of Cu, Pb and W near the colliding surface including the regular reflection and the formation of Mach stem of two colliding shock waves when shock waves comes out from inside on free surface. These experimental data can be used to give more detailed interpretation of the phenomena recorded by high speed frame photography and radiography of the high speed mass spiking in the collision region of two shock waves.
Shock Wave-Induced Damage and Poration in Eukaryotic Cell Membranes.
López-Marín, Luz M; Millán-Chiu, Blanca E; Castaño-González, Karen; Aceves, Carmen; Fernández, Francisco; Varela-Echavarría, Alfredo; Loske, Achim M
2017-02-01
Shock waves 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 shock wave-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 shock waves 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 shock wave 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 shock wave 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 shock wave parameters were needed to achieve cell membrane poration. This difference was correlated to successful gene transfection by shock waves. Our results demonstrate, for the first time, that shock waves 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 shock waves to different cells and settings.
Tandem shock waves in medicine and biology: a review of potential applications and successes
Lukes, P.; Fernández, F.; Gutiérrez-Aceves, J.; Fernández, E.; Alvarez, U. M.; Sunka, P.; Loske, A. M.
2016-01-01
Shock waves have been established as a safe and effective treatment for a wide range of diseases. Research groups worldwide are working on improving shock wave technology and developing new applications of shock waves to medicine and biology. The passage of a shock wave 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 shock waves 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 shock waves that can be delayed by tenths or hundreds of microseconds. These dual-pulse pressure pulses, which are known as tandem shock waves, 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 shock waves 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 shock waves to improve biomedical applications.
Interference heating from interactions of shock waves with turbulent boundary layers at Mach 6
Johnson, C. B.; Kaufman, L. G., II
1974-01-01
An experimental investigation of interference heating resulting from interactions of shock waves and turbulent boundary layers was conducted. Pressure and heat-transfer distributions were measured on a flat plate in the free stream and on the wall of the test section of the Langley Mach 6 high Reynolds number tunnel for Reynolds numbers ranging from 2 million to 400 million. Various incident shock strengths were obtained by varying a wedge-shock generator angle (from 10 deg to 15 deg) and by placing a spherical-shock generator at different vertical positions above the instrumented flat plate and tunnel wall. The largest heating-rate amplification factors obtained for completely turbulent boundary layers were 22.1 for the flat plate and 11.6 for the tunnel wall experiments. Maximum heating correlated with peak pressures using a power law with a 0.85 exponent. Measured pressure distributions were compared with those calculated using turbulent free-interaction pressure rise theories, and separation lengths were compared with values calculated by using different methods.
External shock waves therapy in dystonia: preliminary results.
Trompetto, C; Avanzino, L; Bove, M; Marinelli, L; Molfetta, L; Trentini, R; Abbruzzese, G
2009-04-01
Extracorporeal shock wave therapy (ESWT) has been shown to reduce hypertonia in patients with upper motor neuron syndrome without any side effect. The aim of the present study is to investigate whether ESWT could be useful also in patients with dystonia. We evaluated three patients with secondary dystonia and three patients with idiopathic writer's cramp. Placebo treatment was performed in each patient. ESWT was administered during four sessions (once weekly) to the target muscles of hand and forearm using an electromagnetic lithotripter (Modulith SLK--Storz Medical). Clinical evaluation was performed using the Unified Dystonia Rating Scale in patients with secondary dystonia and the Arm Dystonia Disability Scale in patients with writer's cramp. After treatment, the three patients with secondary dystonia showed a marked improvement which lasted at least until 1 month after the last session. In the patients with writer's cramp, the improvement after ESWT was less consistent being effective only in two subjects. There were no associated adverse effects. Extracorporeal shock wave therapy is probably an effective and safe treatment for upper limb dystonia, particularly for the secondary forms. Larger randomized studies are needed to confirm these preliminary results.
Detecting cavitation in vivo from shock-wave therapy devices
Matula, Thomas J.; Yu, Jinfei; Bailey, Michael R.
2005-04-01
Extracorporeal shock-wave 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 shock wave parameters such as amplitude and pulse repetition frequency. [Work supported by APL internal funds and NIH DK43881 and DK55674.
Radiating dispersive shock waves in non-local optical media.
El, Gennady A; Smyth, Noel F
2016-03-01
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 wave 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 shock wave (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 shock 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.
MEASUREMENTS OF SHOCK WAVE FORCE IN SHOCK TUBE WITH INDIRECT METHODS
Directory of Open Access Journals (Sweden)
Mario Dobrilović
2005-12-01
Full Text Available Tests have been conducted at the “Laboratory for testing of civil explosives, detonators, electrical detonators and pyrotechnical materials”, Department for mining and geotechnics of the Faculty of mining, geology and petroleum engineering, University of Zagreb with the purpose of designing a detonator that would unite advantages of a non-electric system and the precision in regulation of time delay in electronic initiation system. Sum of energy released by the wave force in shock tube is a pre-condition for operation of the new detonator, and measurement of wave force is the first step in determining the sum of energy. The sum of energy is measured indirectly, based on two principles: movement sensors and strain.
Incident Wave Climate at the OWC Pico Plant
DEFF Research Database (Denmark)
Le Crom, I.; Cabrera Bermejo, H.; Pecher, Arthur
2011-01-01
The aim of the study is to retrieve the incident wave information that coincides with former Pico plant operation periods. The recent implementation of a directional pressure sensor for wave measurement as well as the recovery of the data gathered by a directional wave rider buoy allowed embarkin...... on the validation of two different models by using both wave measurements: a model for wave propagation (SWAN) and an Artificial Neural Network (ANN). This paper, as a first step of a comprehensive study, leads to several recommendations to improve both methodologies in future works....
Rigid polyurethane foam as an efficient material for shock wave attenuation
Komissarov, P. V.; Borisov, A. A.; Sokolov, G. N.; Lavrov, V. V.
2016-09-01
A new method for reducing parameters of blast waves generated by explosions of HE charges on ground is presented. Most of the traditional techniques reduce the wave parameters at a certain distance from the charge, i.e. as a matter of fact the damping device interacts with a completely formed shock wave. 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 shock wave attenuation is suggested. Results of experimental shock wave investigations recorded in tests in which HE charges have been exploded with damping devices and without it are compared.
Li, Sha-dan; Wang, Qing-tang; Chen, Wei-guo
2011-05-01
The incidence of urinary lithiasis following kidney transplantation is very low, and decision-supporting data are not available. The aim of this study was to review the diagnosis and treatment of urinary lithiasis following kidney transplantation, which is of realistic significance to reduce urinary lithiasis following kidney transplantation, prolong the survival of renal allografts. The incidence, diagnosis and treatment of urinary lithiasis in ten patients following kidney transplantation were analyzed retrospectively. Seven out of these patients had stones sized approximately 0.4 - 1.1 cm, and they were treated with low-voltage, low-frequency extracorporeal shock-wave lithotripsy (ESWL). Two patients had stones sized lithiasis relapse. The diagnosis and treatment of renal allograft lithiasis are challenging. After prompt and appropriate treatment, the prognosis was satisfactory, and permanent renal functional impairment did not occur in most patients.
Radio data and computer simulations for shock waves generated by solar flares
International Nuclear Information System (INIS)
Maxwell, A.; Dryer, M.
1980-01-01
Solar radio bursts of spectral type II provide a prime diagnostic for the passage of shock waves, generated by solar flares, through the solar corona. In this investigation the authors compare radio data on the shocks with computer simulations for the propagation of fast-mode MHD shocks through the solar corona. (Auth.)
Numerical Simulation and Experiment for Underwater Shock Wave in Newly Designed Pressure Vessel
Directory of Open Access Journals (Sweden)
M Shibuta
2016-09-01
Full Text Available Modern eating habits depend in large part on the development of food processing technology. Thermal treatments are often performed in the conventional food processing, but it can cause discoloration and loss of nutrients of the food by thermal processing or treatment. On the other hand, food processing using an underwater shock wave has little influence of heat and its processing time is very short, preventing the loss of nutrients. In this research optical observation experiment and the numerical simulation were performed, in order to understand and control the behavior of the underwater shock wave in the development of the processing container using an underwater shock wave for the factory and home. In this experiment a rectangular container was used to observe the behavior of the underwater shock wave. In the experiment, the shock wave was generated by using explosive on the shock wave generation side. The shock wave, which passed through the phosphor bronze and propagated from the aluminum sidewall, was observed on the processing container side. Numerical simulation of an analogous experimental model was investigated, where LS-DYNA software was used for the numerical simulation. The comparative study of the experiment and the numerical simulation was investigated. The behavior of a precursor shock wave from the device wall was able to be clarified. This result is used for development of the device in numerical simulation.
Development of fiber optic sensors at TNO for explosion and shock wave measurements
Cheng, L.K.; Smorenburg, C.; Bree, J.L.M.J. van; Bouma, R.H.B.; Meer, B.J. van der; Prinse, W.C.; Scholtes, J.H.G.
2000-01-01
Fiber Optic sensors are found to be very suitable for explosion and shock wave measurements because they are immune to Electromagnetic Interference (EMI). In the past few years, TNO has developed a number of sensor systems for explosion and shock wave measurements in which the optical fiber is a
Fibre-optical techniques for measuring various properties of shock waves
Prinse, W.C.; Esveld, R.J. van; Oostdam, R. van; Rooijen, M. van; Bouma, R.H.B.
1999-01-01
For the past years we have developed several optical techniques to measure properties of shock waves. The fibre optic probe (FOP) is developed to measure the shock-wave velocity and/or the detonation velocity inside an explosive. The space resolution can be as small as 0.5 mm. Single fibres are used
Directory of Open Access Journals (Sweden)
P. V. Bulat
2016-03-01
Full Text Available The paper deals with current issues of the interference theory development of gas-dynamic discontinuities as applied to a problem of propulsion refinement for the air-spacecrafts, designed for hypersonic flight speeds. In the first part of the review we have presented the history of detonation study and different concepts of detonation engines, as well as air intakes designed for hypersonic flight speeds. The second part provides an overview of works on the interference theory development for gas-dynamic discontinuities. We report about classification of the gas-dynamic discontinuities, shock wave propagation, shock-wave structures and triple configurations of shock waves. We have shown that many of these processes are accompanied by a hysteresis phenomenon, there are areas of ambiguity; therefore, in the design of engines and air intakes optimal shock-wave structures should be provided and their sustainability should be ensured. Much attention has recently been given to the use of the air intakes in the shock-wave structures with the rereflection of shock waves and the interference of shock waves in the opposite directions. This review provides increased focus on it, contains references to landmark works, the last calculated and experimental results. Unfortunately, foreign surveys missed many landmark works of the Soviet and Russian researchers, as they were not published in English. At the same time, it was the Soviet school of gas dynamics that has formulated the interference theory of gas-dynamic discontinuities in its present form. To fill this gap is one of this review scopes. The review may be recommended for professionals, engineers and scientists working in the field of aerospace engineering.
Studies on Shock Attenuation in Plastic Materials and Applications in Detonation Wave Shaping
Khurana, Ritu; Gautam, P. C.; Rai, Rajwant; Kumar, Anil; Sharma, A. C.; Singh, Manjit, Dr
2012-07-01
Pressure in plastic materials attenuates due to change of impedance, phase change in the medium and plastic deformation. A lot of theoretical and experimental efforts have been devoted to the attenuation of shock wave produced by the impact of explosive driven flyer plate. However comparatively less work has been done on the attenuation of shock waves due to contact explosive detonation. Present studies deal with the attenuation of explosive driven shock waves in various plastic materials and its applications in design of Hybrid Detonation Wave Generator In present work shock attenuating properties of different polymers such as Perspex, Teflon, nylon, polypropylene and viton has been studied experimentally using rotating mirror streak camera and electrical position pins. High explosive RDX/TNT and OCTOL of diameter 75-100mm and thickness 20 to 50mm were detonated to induce shock wave in the test specimens. From experimental determined shock velocity at different locations the attenuation in shock pressure was calculated. The attenuation of shock velocity with thickness in the material indicates exponential decay according to relation US = UOexp(-ax). In few of the experiments manganin gauge of resistance 50 ohms was used to record stress time profile across shock wave. The shock attenuation data of Viton has successfully been used in the design of hybrid detonation wave generator using Octol as high explosive. While selecting a material it was ensured that the attenuated shock remains strong enough to initiate an acceptor explosive. Theoretical calculation were supported by Autodyne 2D hydro-code simulation which were validated with the experiments conducted using high speed streak photography and electrical shock arrival pins. Shock attenuation data of Perspex was used to establishing card gap test and wedge test in which test items is subjected to known pressure pulse by selecting the thickness of the plastic material.
Finite element modelling of radial shock wave therapy for chronic plantar fasciitis.
Alkhamaali, Zaied K; Crocombe, Andrew D; Solan, Matthew C; Cirovic, Srdjan
2016-01-01
Therapeutic use of high-amplitude pressure waves, or shock wave therapy (SWT), is emerging as a popular method for treating musculoskeletal disorders. However, the mechanism(s) through which this technique promotes healing are unclear. Finite element models of a shock wave source and the foot were constructed to gain a better understanding of the mechanical stimuli that SWT produces in the context of plantar fasciitis treatment. The model of the shock wave source was based on the geometry of an actual radial shock wave device, in which pressure waves are generated through the collision of two metallic objects: a projectile and an applicator. The foot model was based on the geometry reconstructed from magnetic resonance images of a volunteer and it comprised bones, cartilage, soft tissue, plantar fascia, and Achilles tendon. Dynamic simulations were conducted of a single and of two successive shock wave pulses administered to the foot. The collision between the projectile and the applicator resulted in a stress wave in the applicator. This wave was transmitted into the soft tissue in the form of compression-rarefaction pressure waves with an amplitude of the order of several MPa. The negative pressure at the plantar fascia reached values of over 1.5 MPa, which could be sufficient to generate cavitation in the tissue. The results also show that multiple shock wave pulses may have a cumulative effect in terms of strain energy accumulation in the foot.
Prediction of Shock Wave Structure in Weakly Ionized Gas Flow by Solving MGD Equation
Deng, Z. T.; Oviedo-Rojas, Ruben; Chow, Alan; Litchford, Ron J.; Cook, Stephen (Technical Monitor)
2002-01-01
This paper reports the recent research results of shockwave structure predictions using a new developed code. The modified Rankine-Hugoniot relations across a standing normal shock wave are discussed and adopted to obtain jump conditions. Coupling a electrostatic body force to the Burnett equations, the weakly ionized flow field across the shock wave was solved. Results indicated that the Modified Rankine-Hugoniot equations for shock wave are valid for a wide range of ionization fraction. However, this model breaks down with small free stream Mach number and with large ionization fraction. The jump conditions also depend on the value of free stream pressure, temperature and density. The computed shock wave structure with ionization provides results, which indicated that shock wave strength may be reduced by existence of weakly ionized gas.
Use of extracorporeal shock waves in the treatment of tendinopathy and other orthopedic diseases
Directory of Open Access Journals (Sweden)
Dushyant Nadar
2000-01-01
Full Text Available Objective: Use of extracorporeal shock waves in the treatment of tendinopathy and other orthopedic diseases. Patients and methods: 35 patients received shock wave therapy using Econolith 2000 lithotripter 19 patients had isolated lateral epicondylitis, 12 medical epicondylitis and 4 plantar fascitis. A total of 120 shock waves were given in the first sitting. Each patient received a total of three sittings with a gap of one week between each of them. Results: Based on the patients′ self-assessment, about 75% pain relief was observed in 60% of the patients. Fur-ther, in patients having isolated tendinopathies, the pain relief was better. Conclusion: The study indicated that the application of shock waves is not restricted to the fragmentation of urinary calculi. The shock waves can be effectively used for the pain relief in the common orthopedic diseases. Thus, the urologists can widen the application of lithotripters, in a cost-effective manner, to the other medical speciali-ties.
Energy Technology Data Exchange (ETDEWEB)
Kim, I.; Quevedo, H. J.; Feldman, S.; Bang, W.; Serratto, K.; McCormick, M.; Aymond, F.; Dyer, G.; Bernstein, A. C.; Ditmire, T. [Center for High Energy Density Science, Department of Physics, The University of Texas at Austin, C1510, Austin, Texas 78712 (United States)
2013-12-15
Radiative blast waves were created by irradiating a krypton cluster source from a supersonic jet with a high intensity femtosecond laser pulse. It was found that the radiation from the shock surface is absorbed in the optically thick upstream medium creating a radiative heat wave that travels supersonically ahead of the main shock. As the blast wave propagates into the heated medium, it slows and loses energy, and the radiative heat wave also slows down. When the radiative heat wave slows down to the transonic regime, a secondary shock in the ionization precursor is produced. This paper presents experimental data characterizing both the initial and secondary shocks and numerical simulations to analyze the double-shock dynamics.
Kim, I.; Quevedo, H. J.; Feldman, S.; Bang, W.; Serratto, K.; McCormick, M.; Aymond, F.; Dyer, G.; Bernstein, A. C.; Ditmire, T.
2013-12-01
Radiative blast waves were created by irradiating a krypton cluster source from a supersonic jet with a high intensity femtosecond laser pulse. It was found that the radiation from the shock surface is absorbed in the optically thick upstream medium creating a radiative heat wave that travels supersonically ahead of the main shock. As the blast wave propagates into the heated medium, it slows and loses energy, and the radiative heat wave also slows down. When the radiative heat wave slows down to the transonic regime, a secondary shock in the ionization precursor is produced. This paper presents experimental data characterizing both the initial and secondary shocks and numerical simulations to analyze the double-shock dynamics.
Relationship between plasmid size and shock wave-mediated bacterial transformation.
Campos-Guillén, Juan; Fernández, Francisco; Pastrana, Xóchitl; Loske, Achim M
2012-06-01
Bacterial transformation is a fundamental tool in molecular biology; nevertheless, there is still a lack of efficient methods for gene delivery. The use of shock waves has been proposed as an alternative. Recently, our group demonstrated that shock wave-induced transfer of deoxyribonucleic acid (DNA) into bacteria can be increased by enhancing acoustic cavitation; however, so far, little information exists about the effects of shock waves on DNA. The objective of this study was to identify the size regimes of plasmids (DNA molecules that are separate from the chromosomal DNA), which promote shock wave-induced transformation. The transformation efficiency of shock waves and the integrity of DNA were studied for six different plasmid sizes, using the parameters that led to the best results in our previous study. Copyright © 2012 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.
Observation of dust acoustic shock wave in a strongly coupled dusty plasma
International Nuclear Information System (INIS)
Sharma, Sumita K.; Boruah, A.; Nakamura, Y.; Bailung, H.
2016-01-01
Dust acoustic shock wave is observed in a strongly coupled laboratory dusty plasma. A supersonic flow of charged microparticles is allowed to perturb a stationary dust fluid to excite dust acoustic shock wave. The evolution process beginning with steepening of initial wave front and then formation of a stable shock structure is similar to the numerical results of the Korteweg-de Vries-Burgers equation. The measured Mach number of the observed shock wave agrees with the theoretical results. Reduction of shock amplitude at large distances is also observed due to the dust neutral collision and viscosity effects. The dispersion relation and the spatial damping of a linear dust acoustic wave are also measured and compared with the relevant theory.
Shock-wave dynamics under expansion of the spark channel in gas
Korytchenko, K V; Chumakov, V I
2001-01-01
The process of formation of shock waves arising at a spark discharge is considered. According to analysis of experimental statistics the results of the various about dynamics of development of the spark channel are exposed to a doubt. The definition of a concept of time of formation of a shock wave is offered and its quantitative evaluation is carried out. It has allowed to distinguish the process of formation from the process of development of a shock wave,and also to explain the fact of formation of several shock waves at a spark discharge. The offered work can be put in a basis of a technique for evaluation of the intensity of a shock wave formed at a spark discharge.
Stenting and extracorporeal shock wave lithotripsy in chronic pancreatitis
DEFF Research Database (Denmark)
Holm, M; Matzen, Peter
2003-01-01
BACKGROUND: Early observational studies of endoscopic treatment and extracorporeal shock wave lithotripsy (ESWL) reported considerable or complete relief of pain in 50%-80% of patients with chronic pancreatitis. There is no consensus on the measurement of pain, making comparison of observational...... studies difficult, and little attention has been paid to the type and amount of analgesics used by patients before and after decompressive treatment. METHODS: We performed a retrospective study of all patients with chronic pancreatitis and large-duct disease and receiving decompressing treatment between 1...... November 1994 and 31 July 1999. Primary parameters were type and amount of analgesics used. RESULTS: Forty-nine patients with chronic pancreatitis and large-duct disease received stenting of the pancreatic duct (28 patients), ESWL (6 patients) or both (15 patients). After a median follow-up of 21 months...
Approach to Residual Kidney Stone Fragments After Shock Wave Therapy
Directory of Open Access Journals (Sweden)
Tumay Ipekci
2014-04-01
Full Text Available For kidney stones up to 2 cm in diameter shock wave therapy (SDT is safely applied and kidney stones smaller than 5mm remaining in the kidney after treatment are regarded as clinically insignificant. Management of this condition is still controversial among clinicians. These stones in the kidney may continue to persist without any clinical symptoms or begin to cause clinical signs. In the event that the clinical symptoms are present, it requires detailed urological examination and treatment. The aim in the surgical treatment of urinary tract stones is completely stone clearance but in stones that are not infected, not causing urinary tract obstruction and without clinical symptoms medical treatment is also beneficial fort he prevention of growth and recurrence. In addition, surgical intervention is also possible for the residual stone fragments which become symptomatic during follow-up.
Improvements in the electromechanical conversion of energy using shock waves
International Nuclear Information System (INIS)
Landure, Yves
1971-01-01
This report concerns the electrical mechanical conversion. In this study it was obtained by the depolarization of a ferroelectric ceramic. We are particularly interested by the high electrical horse-power. Shock wave which produces depolarization is created by a gun powder. The speed of the projectile is measured and the pressures generated in the ceramic is determined graphically. The energy freed is released on a linear resistive load. We were able to prove by different parameters how to obtain the maximum electrical energy. On a resistive load of 26 ohms, it was freed 0,91 J/cm 3 in less than 0,5 μs corresponding to an electrical horse-power superior to 2 MW/cm 3 . (author) [fr
Efficacy of extracorporeal shock wave treatment in calcaneal enthesophytosis.
Cosentino, R; Falsetti, P; Manca, S; De Stefano, R; Frati, E; Frediani, B; Baldi, F; Selvi, E; Marcolongo, R
2001-11-01
To evaluate the efficacy of extracorporeal shock wave treatment (ESWT) in calcaneal enthesophytosis. 60 patients (43 women, 17 men) were examined who had talalgia associated with heel spur. A single blind randomised study was performed in which 30 patients underwent a regular treatment (group 1) and 30 a simulated one (shocks of 0 mJ/mm(2) energy were applied) (group 2). Variations in symptoms were evaluated by visual analogue scale (VAS). Variations in the dimension of enthesophytosis were evaluated by x ray examination. Variations in the grade of enthesitis were evaluated by sonography. A significant decrease of VAS was seen in group 1. Examination by x ray showed morphological modifications (reduction of the larger diameter >1 mm) of the enthesophytosis in nine (30%) patients. Sonography did not show significant changes in the grade of enthesitis just after the end of the treatment, but a significant reduction was seen after one month. In the control group no significant decrease of VAS was seen. No modification was observed by x ray examination or sonography. ESWT is safe and improves the symptoms of most patients with a painful heel, it can also structurally modify enthesophytosis, and reduce inflammatory oedema.
Shock Wave Propagation in Functionally Graded Mineralized Tissue
Nelms, Matthew; Hodo, Wayne; Livi, Ken; Browning, Alyssa; Crawford, Bryan; Rajendran, A. M.
2017-06-01
In this investigation, the effects of shock wave propagation in bone-like biomineralized tissue was investigated. The Alligator gar (Atractosteus spatula) exoskeleton is comprised of many disparate scales that provide a biological analog for potential design of flexible protective material systems. The gar scale is identified as a two-phase, (1) hydroxyapatite mineral and (2) collagen protein, biological composite with two distinct layers where a stiff, ceramic-like ganoine overlays a soft, highly ductile ganoid bone. Previous experimentations has shown significant softening under compressive loading and an asymmetrical stress-strain response for analogous mineralized tissues. The structural features, porosity, and elastic modulus were determined from high-resolution scanning electron microscopy, 3D micro-tomography, and dynamic nanoindentation experiments to develop an idealized computational model for FE simulations. The numerical analysis employed Gurson's yield criterion to determine the influence of porosity and pressure on material strength. Functional gradation of elastic moduli and certain structural features, such as the sawtooth interface, are explicitly modeled to study the plate impact shock profile for a full 3-D analysis using ABAQUS finite element software.
Shock Wave Therapy Promotes Cardiomyocyte Autophagy and Survival during Hypoxia
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Ling Du
2017-06-01
Full Text Available Background: Autophagy plays an important role in cardiovascular disease. Controversy still exists regarding the effect of autophagy on ischemic/hypoxic myocardium. Cardiac shock wave therapy (CSWT is an effective alternative treatment for refractory ischemic heart disease. Whether CSWT can regulate cardiomyocyte autophagy under hypoxic conditions is not clear. We established a myocardial hypoxia model using the H9c2 cell line and performed shock waves (SWs treatment to evaluate the effect of SW on autophagy. Methods: The H9c2 cells were incubated under hypoxic conditions, and SW treatment was then performed at energies of 0.02, 0.05, or 0.10 mJ/mm2. The cell viability and intracellular ATP level were examined. Western blot analysis was used to assess the expression of LC3B, AMPK, mTOR, Beclin-1, Sirt1, and HIF-1α. Autophagic vacuoles were visualized by monodansylcadaverine staining. Results: After the 24-hour hypoxic period, cardiomyocyte viability and ATP levels were decreased and autophagy was significantly increased in H9c2 cells. SW treatment with an energy of 0.05 mJ/mm2 significantly increased the cellular viability, ATP level, LC3B-II/I, and number of autophagic vacuoles. In addition, phosphorylated AMPK and Sirt1 were increased and phosphorylated mTOR and HIF-1α were decreased after SW treatment. Conclusion: SW treatment can potentially promote cardiomyocyte autophagy during hypoxia and protect cardiomyocyte function by regulating the AMPK/mTOR pathway.
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Sabriye Ercan
2017-09-01
Conclusions: Extracorporeal shock wave therapy lowers pain scores of plantar fasciitis patients in three weeks. Kinesiotape application in addition to extracorporeal shock wave therapy treatment does not provide additional profit.
Reintjes, Moritz; Temple, Blake
2015-05-08
We give a constructive proof that coordinate transformations exist which raise the regularity of the gravitational metric tensor from C 0,1 to C 1,1 in a neighbourhood of points of shock wave collision in general relativity. The proof applies to collisions between shock waves coming from different characteristic families, in spherically symmetric spacetimes. Our result here implies that spacetime is locally inertial and corrects an error in our earlier Proc. R. Soc. A publication, which led us to the false conclusion that such coordinate transformations, which smooth the metric to C 1,1 , cannot exist. Thus, our result implies that regularity singularities (a type of mild singularity introduced in our Proc. R. Soc. A paper) do not exist at points of interacting shock waves from different families in spherically symmetric spacetimes. Our result generalizes Israel's celebrated 1966 paper to the case of such shock wave interactions but our proof strategy differs fundamentally from that used by Israel and is an extension of the strategy outlined in our original Proc. R. Soc. A publication. Whether regularity singularities exist in more complicated shock wave solutions of the Einstein-Euler equations remains open.
The relationship between elastic constants and structure of shock waves in a zinc single crystal
Krivosheina, M. N.; Kobenko, S. V.; Tuch, E. V.
2017-12-01
The paper provides a 3D finite element simulation of shock-loaded anisotropic single crystals on the example of a Zn plate under impact using a mathematical model, which allows for anisotropy in hydrostatic stress and wave velocities in elastic and plastic ranges. The simulation results agree with experimental data, showing the absence of shock wave splitting into an elastic precursor and a plastic wave in Zn single crystals impacted in the [0001] direction. It is assumed that the absence of an elastic precursor under impact loading of a zinc single crystal along the [0001] direction is determined by the anomalously large ratio of the c/a-axes and close values of the propagation velocities of longitudinal and bulk elastic waves. It is shown that an increase in only one elastic constant along the [0001] direction results in shock wave splitting into an elastic precursor and a shock wave of "plastic" compression.
Strong Optical Shock excitation in the mismatched regime of bubble plasma-wave based LWFA
Sahai, Aakash
2017-10-01
We present investigations into the excitation of a strong optical shock through slicing of a high intensity laser pulse driving a bubble plasma wave in a regime of mis-match between the incident laser waist-size and the bubble size ( = 2√{a0} c /ωpe). In the matched regime, it is well-known that over long timescales, the laser continuously undergoes differential frequency-shifts in different bubble phases, forming an optical shock. In the mis-matched regime, rapid laser waist and resulting bubble oscillations change the location of the peak laser ponderomotive force. This changes the location and the magnitude of the peak electron density interacting with the laser pulse. A sudden increase in the electron density during a laser radial squeeze event, slices the laser envelope longitudinally near its peak amplitude, exciting a strong optical shock state. This is shown to occur much earlier in laser evolution only over a narrow range of plasma densities where the imbalance between the longitudinal & radial ponderomotive forces excites elongated bubbles, injects ultra-low emittance electron beams and sustains ultra-high peak plasma fields. We acknowledge STFC Grants ST/J002062/1 and ST/P000835/1 for the John Adams Institute of Accelerator Science.
Possible wave amplitudes in shocks in the solar corona - Predictions for Solar Probe
Moses, S. L.; Coroniti, F. V.; Greenstadt, E. W.; Tsurutani, B. T.
1991-01-01
Terrestrial shock measurements are scaled to coronal parameters to demonstrate the need for improvements for the Solar Probe instrumentation. A model of coronal shock is presented to estimate corresponding shock parameters, and a comparison is made with ISEE 3 crossings to examine terrestrial bow shock and wave activity downstream. The turbulence in the magnetosheath is scaled to predict the specific range of amplitudes and frequencies of wave regions that the Solar Probe can encounter. The high velocity of the spacecraft at perihelion constrains the potential application of present instrumentation. In order to properly characterize the coronal shocks the Solar Probe requires instrumentation that can detect shock-generated Alfven waves Doppler-shifted to frequencies of a few kHz.
Scattering of ultrasonic shock waves in suspensions of silica nanoparticles.
Baudoin, Michael; Thomas, Jean-Louis; Coulouvrat, François; Chanéac, Corinne
2011-03-01
Experiments are carried out to assess, for the first time, the validity of a generalized Burgers' equation, introduced first by Davidson [J. Acoust. Soc. Am. 54, 1331-1342 (1973)] to compute the nonlinear propagation of finite amplitude acoustical waves in suspensions of "rigid" particles. Silica nanoparticles of two sizes (33 and 69 nm) have been synthesized in a water-ethanol mixture and precisely characterized via electron microscopy. An acoustical beam of high amplitude is generated at 1 MHz inside a water tank, leading to the formation of acoustical shock waves through nonlinear steepening. The signal is then measured after propagation in a cylinder containing either a reference solution or suspensions of nanoparticles. In this way, a "nonlinear attenuation" is obtained and compared to the numerical solution of a generalized Burgers' equation adapted to the case of hydrosols. An excellent agreement (corresponding to an error on the particles size estimation of 3 nm) is achieved in the frequency range from 1 to 40 MHz. Both visco-inertial and thermal scattering are significant in the present case, whereas thermal effects can generally be neglected for most hydrosols. This is due to the value of the specific heat ratio of water-ethanol mixture which significantly differs from unity. © 2011 Acoustical Society of America
Nucleus-acoustic shock waves in white dwarfs
Jannat, S.; Mamun, A. A.
2018-04-01
The nucleus-acoustic shock waves (NASWs) propagating in a white dwarf plasma system, which contain non-relativistically or ultrarelativistically degenerate electrons, non-relativistically degenerate, viscous fluid of light nuclei, and immobile nuclei of heavy elements, have been theoretically investigated. We have used the reductive perturbation method, which is valid for small but finite-amplitude NASWs to derive the Burgers equation. The NASWs are, in fact, associated with the nucleus-acoustic (NA) waves in which the inertia is provided by the light nuclei, and restoring force is provided by the degenerate pressure of electrons. On the other hand, the stationary heavy nuclei participate only in maintaining the background charge neutrality condition at equilibrium. It is found that the viscous force acting in the fluid of light nuclei is a source of dissipation, and is responsible for the formation of NASWs. It is also observed that the basic features (polarity, amplitude, width, etc.) of the NASWs are significantly modified by the presence of heavy nuclei, and that NASWs are formed with either positive or negative potential depending on the values of the charge density of the heavy nuclei. The basic properties are also found to be significantly modified by the effects of ultrarelativistically degenerate electrons. The implications of our results in white dwarfs are briefly discussed.
Study of evaporation from He II free surface induced by thermal shock wave
International Nuclear Information System (INIS)
Murakami, M.; Maki, M.; Fujiyama, J.; Furukawa, T.
2002-01-01
Experimental study on evaporation phenomena in superfluid helium (He II, T<2.17 K) environment was carried out. We took such advantages of He II environment that a practically pure vapor-liquid system could be realized in a experimental cell because all gaseous components except helium were in frozen state and a thermal shock wave could be used as a pulsed heat source to induce evaporation. Evaporation is caused by the incidence of a second sound thermal pulse onto the He II free surface. The gas-dynamic phenomena were visualized with the laser holographic interferometer (LHI) and were measured with superconductive thermometers and pressure transducers as well as with the newly developed superconductive hot-wire anemometer. The whole gasdynamic field was seen to consist of an evaporation shock wave, a uniform flow region and a Knudsen layer. The condensation coefficient of He II is obtained from the comparison of the experimental data with the slip boundary condition at evaporating interface derived from the kinetic theory of gases. It was demonstrated that a He II environment could offer an ideal situation for experimental gas-dynamic studies, and such experimental techniques as LHI and a hot-wire fully developed in conventional fluid-dynamics were of use even in cryogenic environment
Extracorporeal shock wave therapy in orthopedics, basic research, and clinical implications
Hausdorf, Joerg; Jansson, Volkmar; Maier, Markus; Delius, Michael
2005-04-01
The molecular events following shock wave treatment of bone are widely unknown. Nevertheless patients with osteonecrosis and non unions are already treated partly successful with shock waves. Concerning the first indication, the question of the permeation of the shock wave into the bone was addressed. Therefore shockwaves were applied to porcine femoral heads and the intraosseous pressure was measured. A linear correlation of the pressure to the intraosseous distance was found. Approximately 50% of the pressure are still measurable 10 mm inside the femoral head. These findings should encourage continued shock wave research on this indication. Concerning the second indication (non union), osteoblasts were subjected to 250 or 500 shock waves at 25 kV. After 24, 48, and 72 h the levels of the bone and vascular growth factors bFGF, TGFbeta1, and VEGF were examined. After 24 h there was a significant increase in bFGF levels (p<0.05) with significant correlation (p<0.05) to the number of impulses. TGFbeta1, and VEGF showed no significant changes. This may be one piece in the cascade of new bone formation following shock wave treatment and may lead to a more specific application of shock waves in orthopedic surgery.
Incidence and pattern of brain lesions in paediatric septic shock patients.
Sanz, Debora; D'Arco, Felice; Robles, Carlos Andres; Brierley, Joe
2018-04-01
Brain injury is frequently observed during septic shock and may be primarily related to the direct effects of the septic insult on the brain or to secondary/indirect injuries (e.g. hypotension, hypoxaemia and hyperglycaemia). We sought to assess incidence and pattern of brain lesions diagnosed by neuroimaging in paediatric septic shock patients. Retrospective descriptive hospital-based study included paediatric patients with a single episode of septic shock admitted to our tertiary paediatric intensive care unit from January 2010 to December 2013. 49 of 193 septic shock patients had a neuroimaging examination [CT only 22 (45%), MRI only 14 (29%) and both 13 (27%)]. Neuroimaging was normal in 16 patients (33%) and showed acute lesions in 20 patients (40%). The most frequent findings were: cerebral infarcts/hypoxic ischaemic injury in 8 (16%) and cerebritis in 7 (14%). The incidence of acute brain lesion in our septic shock cohort was 10% (20 of 193). The diagnosis of brain dysfunction in septic shock patients relies essentially on neurological examination and neurological tests, such as electroencephalography and neuroimaging. Neuroimaging can reveal acute intracerebral structural lesions and their reversibility, helping with management and prognosis. Advances in knowledge: Ischaemic lesions and cerebritis are the most common brain anomalies complicating paediatric septic shock.
Generation and propagation of shock waves in the exhaust pipe of a 4 cycle automobile engine
Sekine, N.; Matsumura, S.; Aoki, K.; Takayama, K.
1990-07-01
An experimental investigation was made of reduction of noise generated in the exhaust pipe of a half liter 4-cycle water-cooled automobile gasoline engine. The pressure measurement along the exhaust pipe showed the nonlinear transition of compression waves discharged from the exhaust port of the engine into shock waves. In order to obtain a direct evidence of shock waves in the exhaust pipe, a flow visualization study was also conducted using a double exposure holographic interferometry. Weak shock waves of Mach number 1.09 exist in the exhaust pipe. For the purpose of collecting the data for designing optimum muffler configurations, additional shock tube experiments were carried out. The results indicates that the study of the non-linear wave interaction and propagation is important for the design of muffler.
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.
International Nuclear Information System (INIS)
Zeyer, G.
1975-01-01
In the present work results of experimental investigations on the structure of resistive MHD shock waves are reported. The anomaly of the electric conductivity possibly occurring in such shock waves is an effect which has given new insight on the interaction mechanims of a plasma. In a modified Theta-Pinch setup deuterium plasma shock waves perpendicular to the magnetic field are studied with the aid of probes and scattering of laser light to determine the internal magnetic field and electron temperature and density. (GG) [de
Sources and propagation of atmospherical acoustic shock waves
Coulouvrat, François
2012-09-01
Sources of aerial shock waves are numerous and produce acoustical signals that propagate in the atmosphere over long ranges, with a wide frequency spectrum ranging from infrasonic to audible, and with a complex human response. They can be of natural origin, like meteors, lightning or volcanoes, or human-made as for explosions, so-called "buzz-saw noise" (BSN) from aircraft engines or sonic booms. Their description, modeling and data analysis within the viewpoint of nonlinear acoustics will be the topic of the present lecture, with focus on two main points: the challenges of the source description, and the main features of nonlinear atmospheric propagation. Inter-disciplinary aspects, with links to atmospheric and geo-sciences will be outlined. Detailed description of the source is very dependent on its nature. Mobile supersonic sources can be rotating (fan blades of aircraft engines) or in translation (meteors, sonic boom). Mach numbers range from transonic to hypersonic. Detailed knowledge of geometry is critical for the processes of boom minimization and audible frequency spectrum of BSN. Sources of geophysical nature are poorly known, and various mechanisms for explaining infrasound recorded from meteors or thunderstorms have been proposed. Comparison between recorded data and modeling may be one way to discriminate between them. Moreover, the nearfield of these sources is frequently beyond the limits of acoustical approximation, or too complex for simple modeling. A proper numerical description hence requires specific matching procedures between nearfield behavior and farfield propagation. Nonlinear propagation in the atmosphere is dominated by temperature and wind stratification. Ray theory is an efficient way to analyze observations, but is invalid in various situations. Nonlinear effects are enhanced locally at caustics, or in case of grazing propagation over a rigid surface. Absorption, which controls mostly the high frequency part of the spectrum contained
International Nuclear Information System (INIS)
Williams, R.L.; Johnson, J.A. III
1993-01-01
The feasibility of using an ionizing shock wave to produce high density plasmas suitable for the propagation large amplitude relativistic plasma waves is being investigated. A 20 kv arc driven shock tube of coaxial geometry produces a hypersonic shock wave (10 p > 10 17 cm -3 ). The shock can be made to reflect off the end of the tube, collide with its wake, and thus increase the plasma density further. After reflecting, the plasma is at rest. The shock speed is measured using piezoelectric pressure probes and the ion density is measured using laser induced fluorescence (LIF) techniques on argon 488.0 nm and 422.8 nm lines. The future plans are to excite large amplitude relativistic plasma waves in this plasma by either injecting a short pulse laser (Laser Wake Field Scheme), two beating lasers (Plasma Beat Wave Scheme), or a short bunch of relativistic electrons (Plasma Wake Field Scheme). Results of recent computational and theoretical studies, as well as initial experimental measurements on the plasma using LIF, are reported. Implications for the application of high density plasmas produced in this way to such novel schemes as the plasma wave accelerator, photon accelerator, plasma wave undulator, and also plasma lens, are discussed. The effect of plasma turbulence is also discussed
Measurements on a shock wave generated by a solar flare
International Nuclear Information System (INIS)
Maxwell, A.; Dryer, M.
1982-01-01
Having reviewed data obtained on a high-velocity shock generated by a solar flare on 18 August 1979, 1400 UT and commented on some previously deduced velocities for the shock, a model, based on current computer programs to account for the overall characteristics of the shock as it propagated through the corona and the interplanetary plasma, is presented. (U.K.)
Uniqueness in inverse elastic scattering with finitely many incident waves
International Nuclear Information System (INIS)
Elschner, Johannes; Yamamoto, Masahiro
2009-01-01
We consider the third and fourth exterior boundary value problems of linear isotropic elasticity and present uniqueness results for the corresponding inverse scattering problems with polyhedral-type obstacles and a finite number of incident plane elastic waves. Our approach is based on a reflection principle for the Navier equation. (orig.)
Morphological development of coasts at very oblique wave incidence
DEFF Research Database (Denmark)
Petersen, Dorthe Pia; Deigaard, Rolf; Fredsøe, Jørgen
2003-01-01
This study focuses on one distinct feature to be found on coasts exposed to a very oblique wave incidence, namely an accumulating spit. That is a spit where no retreat of the shoreline is going on along the spit. This requires a monotonically decreasing sediment transport capacity from the updrift...
Comparison of various methods for estimating wave incident angles ...
African Journals Online (AJOL)
Five different methods were examined for their suitability in estimating the inshore wave incident angles on a nearshore zone with a complex topography. Visual observation provided preliminary estimates. Two frequency independent methods and one frequency dependent method based on current meter measurements ...
EXTRACORPOREAL SHOCK WAVE LITHOTRIPSY IN TREATMENT OF PEDIATRIC UROLITHIASIS
Directory of Open Access Journals (Sweden)
Emilija Golubovic
2006-04-01
Full Text Available The paper presents the experiences in the treatment of urinary tract calculosis in 114 children aged 6 months to 14 years by means of extracorporeal shock wave lithotripsy (ESWL.The treatment was performed at the Institute of Radiology and the Clinic for Pediatric Surgery and Orthopedics in Nis, in the period 1988-2000 on Siemens Litostar lithotriptor. The children were treated after clinical, laboratory and radiological preparation, provided that the stone was not greater than 3 cm (measured in native urinary tract graph and that it was not located in the pelvic part of the ureter. In the present study, the success in application of ESWL for treating pediatric patients was 88%. The total clearance of fragments was found in 57% of patients, whereas retention of fragments smaller than 4 mm three months after the last treatment was present in 31% of patients. ESWL treatment failed in 12% of patients since they had retained fragments greater than 4 mm.The authors recommend this method as a method of choice in the treatment of renal and urethral calculi in children.
Radial shock wave therapy in dogs with hip osteoarthritis.
Souza, Alexandre N A; Ferreira, Marcio P; Hagen, Stefano C F; Patrício, Geni C F; Matera, Julia M
2016-01-01
The study aims were to evaluate the effects of radial shock wave therapy (RSWT) in dogs with hip osteoarthritis (OA) using clinical assessment and kinetic analysis. Thirty dogs diagnosed with bilateral hip OA and 30 healthy dogs were used. In OA dogs, one limb was randomly selected for treatment with RSWT while the contralateral limb served as an untreated control. Dogs were evaluated while walking on a pressure walkway. Peak vertical force (PVF) and vertical impulse (VI) were documented; symmetry index (SI) was also calculated. Blinded clinical evaluation was performed using a visual analogue scale (VAS). Owner perception data regarding levels of physical activity were also collected. The RSWT protocol (2000 pulses, 10 Hz, 2-3.4 bars) consisted of three weekly treatment sessions (days 1, 8 and 16). Follow-up data were collected 30, 60 and 90 days after the first session. Data were compared between time points, groups and limbs pairs. At the end of the experimental period, mean PVF and VI values had increased (25.9 to 27.6%BW and 2.1 to 12.7%BW × s respectively) in treated limbs, with no significant differences in control limbs; SI values suggest improvement. Mean PVF and VI remained lower in the treated compared to the healthy group following treatment. The VAS scores suggested improvement in pain and lameness in treated dogs. Owner perception data suggested improved levels of physical activity following treatment. Outcomes of this study suggested beneficial effects of RSWT in dogs with hip osteoarthritis.
Efficient transformation of Mycosphaerella fijiensis by underwater shock waves.
Escobar-Tovar, Lina; Magaña-Ortíz, Denis; Fernández, Francisco; Guzmán-Quesada, Mauricio; Sandoval-Fernández, Jorge A; Ortíz-Vázquez, Elizabeth; Loske, Achim M; Gómez-Lim, Miguel A
2015-12-01
Black leaf streak disease, also known as black Sigatoka, causes dramatic losses in production of banana and plantains fruits. The disease is caused by the pathogenic fungus Mycosphaerella fijiensis (anamorph Pseudocercospora fijiensis; Mycosphaerellaceae). Genetic transformation of M. fijiensis would allow a better understanding of molecular basis of pathogenicity and design novel approaches to control the infection caused by this pathogen. However, transformation of this fungus has not been easy. We report here a protocol for genetic transformation of M. fijiensis employing underwater shock waves and intact conidia. The recombinant strains recovered showed genetic stability over >10 generations. The frequency of transformation obtained was between 75 and 150 times higher than the efficiency reported in the only article published on transformation of M. fijiensis using spheroplasts. This improvement allowed the use of a thousand times less cells than the amount employed before, avoiding the need for cumbersome successive batch cultures. Our protocol is simple, highly efficient, fast and reproducible and together with the available genomes of M. fijiensis and Musa acuminata, it offers new possibilities to study the diverse mechanisms of pathogenesis of the fungus. Copyright © 2015. Published by Elsevier B.V.
Generation of Two Successive Shock Waves Focusedto a Common Focal Point
Czech Academy of Sciences Publication Activity Database
Šunka, Pavel; Stelmashuk, Vitaliy; Babický, Václav; Člupek, Martin; Beneš, J.; Poučková, P.; Kašpar, J.; Bodnár, M.
2006-01-01
Roč. 34, č. 4 (2006), s. 1382-1385 ISSN 0093-3813. [International Power Modulator Conference. Washington D.C., 14.5.2006-18.5.2006] R&D Projects: GA ČR(CZ) GA202/05/0685 Institutional research plan: CEZ:AV0Z20430508 Keywords : Cavitation collpse * double shocks * focused shock waves * liver injury * secondary shocks Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.144, year: 2006
Noack, Joachim; Vogel, Alfred
1995-05-01
The shock wave emission after dielectric breakdown in water was investigated to assess potential shock wave effects in plasma mediated tissue ablation and intraocular photodisruption. Of particular interest was the dependence of shock wave pressure as a function of distance from the plasma for different laser pulse energies. We have generated plasmas in water with a Nd:YAG laser system delivering pulses of 6 ns duration. The pulses, with energies between 0.4 and 36 mJ (approximately equals 180 times threshold), were focused into a cuvette containing distilled water. The shock wave was visualized with streak photography combined with a schlieren technique. An important advantage of this technique is that the shock position as a function of time can directly be obtained from a single streak and hence a single event. Other methods (e.g. flash photography or passage time measurements between fixed locations) in contrast rely on reproducible events. Using the shock wave speed obtained from the streak images, shock wave peak pressures were calculated providing detailed information on the propagation of the shock. The shock peak pressure as a function of distance r from the optical axis was found to decrease faster than 1/r2 in regions up to distances of 100-150 micrometers . For larger distances it was found to be roughly proportional to 1/r. The scaling law for maximum shock pressure p, at a given distance was found to be proportional to the square root of the laser pulse energy E for distances of 50-200 micrometers from the optical axis.
Study of the shock wave effects to the laser transmission at the supersonic speed
Zhang, Xiang-Jin; Shen, Na; Zhang, He; Wang, Xiao-Feng
2010-05-01
Pulse infrared laser launched by the prepositional laser fuse system reaches the target first. Laser echo pulse signal then arrive the surface of photodiode laser detection receiver, and penetrates through the boundary layer - shear layer - shock wave - atmosphere - shock wave - shear layer - boundary layer under supersonic velocity, finally, focuses on the photosensitive surface. As shock wave has an effect on the prepositional laser fuse in the optical path, a great deviation has been brought between distance determining methods on static state and in the course of the actual flight. In this paper, a model of the shock wave's influence on the prepositional laser fuse's optical distance under supersonic velocity is presented. Based on a certain projectile, the optical path difference is analyzed. The optical path differences under different projectile velocities are figured out with the MATLAB software, which will provide a feasible error analysis method for the exploration of laser fuse or laser weapon under supersonic velocity.
Advances in CFD Prediction of Shock Wave Turbulent Boundary Layer Interactions
National Research Council Canada - National Science Library
Knight, Doyle; Yan, Hong; Panaras, Argyris G; Zheltovodov, Alexander
2006-01-01
... on the same topic by Knight and Degrez ("Shock Wave Boundary Layer Interactions in High Mach Number Flows - A Critical Survey of Current CFD Prediction Capabilities," AGARD Advisory Report AR-319, Volume II, December 1998...
National Aeronautics and Space Administration — Shock Wave / Turbulent Boundary Layer Flows at High Mach Numbers. This web page provides data from experiments that may be useful for the validation of turbulence...
Investigations of the Dynamic Properties of Matter Using Axis-Symmetrical Shock Waves
National Research Council Canada - National Science Library
Dudin, S
1997-01-01
.... In experiments, the shock loading of AD998 tubes was realized in two ways: by cylindrical detonation initiated by electrical explosion of wire and by impact of the stainless steel tube liner launched by the cylindrical detonation wave...
Holography and Colliding gravitational shock waves in asymptotically AdS5 spacetime.
Chesler, Paul M; Yaffe, Laurence G
2011-01-14
Using holography, we study the collision of planar shock waves in strongly coupled N=4 supersymmetric Yang-Mills theory. This requires the numerical solution of a dual gravitational initial value problem in asymptotically anti-de Sitter spacetime.
Extra corporeal lithotripsy for shock waves: Experience in the Santa Fe de Bogota Foundation
International Nuclear Information System (INIS)
Serrano, Adolfo; Gomez, Rafael
1992-01-01
Extra corporeal shock wave lithotripsy is currently the first treatment option in the majority of urinary stones. Shock-wave generation is done with different sources: electrohidraulic, electromagnetic and piezoelectric. Conduction of the waves is done through water. The patient receives shock waves being submerged in water or through a water cushion that is attached to his flank. Stone localization is done with fluoroscopy or ultrasound. Pain intensity varies depending on the lithotripter used. Stone fragmentation varies also and is directly proportional to the pain elicited. At the Fundacion Santa Fe de Bogota we use tripper Xl by oirex since June 1990. The machine has an electrohidraulic generator; uses fluoroscopic localization and shock trans-mission is done with a water cushion. We have had success in the treatment of 97% of renal calculi and in 88% of those located in the urethra; our overall success rate is 92%
A Self-similar Flow Behind a Shock Wave in a Gravitating or Non ...
Indian Academy of Sciences (India)
corona or the condensed explosives or the diaphragm containing a very high pressure driver gas, at t = 0. By sudden expansion of the stellar corona or the detonation products or the driver gas into the ambient gas, a shock wave is produced in the ambient gas, in an infinitesimal time interval t0 (say). The shocked gas is ...
Compendium of shock wave data. Section A2. Inorganic compounds. Section B. Hydrocarbons
International Nuclear Information System (INIS)
van Thiel, M.; Shaner, J.; Salinas, E.
1977-06-01
This volume lists in a concise manner the thermodynamic data in condensed media obtained by shock wave techniques. The volume should be useful both to people working in the shockwave field and to others interested primarily in thermodynamic properties at high pressure. Therefore, both dynamic variables and volumetric quantities associated with the shock wave are given. The format was selected to make the volume useful in engineering as well as scientific reserch activities. Data on the elements are contained in this volume
A Numerical Method for Blast Shock Wave Analysis of Missile Launch from Aircraft
Directory of Open Access Journals (Sweden)
Sebastian Heimbs
2015-01-01
Full Text Available An efficient empirical approach was developed to accurately represent the blast shock wave loading resulting from the launch of a missile from a military aircraft to be used in numerical analyses. Based on experimental test series of missile launches in laboratory environment and from a helicopter, equations were derived to predict the time- and position-dependent overpressure. The method was finally applied and validated in a structural analysis of a helicopter tail boom under missile launch shock wave loading.
Shock wave therapy for spastic plantar flexor muscles in hemiplegic cerebral palsy children
Hala A. Abdel Gawad; Amel E. Abdel Karim; Amira H. Mohammed
2015-01-01
Background: The spastic motor type is the most common form of cerebral palsy (CP). Spastic equines foot is the most frequent deformity in ambulated children with CP. Shock wave therapy on spastic muscles of the upper limb in stroke patients provided a significant reduction in muscle tone. Aim: The present study aimed to investigate the efficiency of shock wave therapy on spastic planter flexor muscles and its relation to the gait in spastic hemiplegic cerebral palsy children. Methods: T...
Focused tandem shock waves in water and their potential application in cancer treatment
Czech Academy of Sciences Publication Activity Database
Lukeš, Petr; Šunka, Pavel; Hoffer, Petr; Stelmashuk, Vitaliy; Poučková, P.; Zadinová, M.; Zeman, J.; Dibdiak, L.; Kolářová, H.; Tománková, K.; Binder, S.; Beneš, J.
2014-01-01
Roč. 24, č. 1 (2014), s. 51-57 ISSN 0938-1287. [International Symposium on Shock Waves/28./. Manchester, 17.07.2011-22.07.2011] R&D Projects: GA ČR GA202/09/1151 Institutional support: RVO:61389021 Keywords : focused shock waves * underwater discharge * cancer treatment Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.885, year: 2014
Can cellulite be treated with low-energy extracorporeal shock wave therapy?
Angehrn, Fiorenzo; Kuhn, Christoph; Voss, Axel
2007-01-01
Fiorenzo Angehrn1, Christoph Kuhn1, Axel Voss21Klinik Piano, Gottstattstrasse 24, Biel, Switzerland; 2SwiTech Medical AG, Kreuzlingen, SwitzerlandAbstract: The present study investigates the effects of low-energy defocused extracorporeal generated shock waves on collagen structure of cellulite afflicted skin. Cellulite measurement using high-resolution ultrasound technology was performed before and after low-energy defocused extracorporeal shock wave therapy (ESWT) in 21 female subjects. ESWT...
Czech Academy of Sciences Publication Activity Database
Sundkvist, D.; Krasnoselskikh, V.; Bale, S. D.; Schwartz, S. J.; Souček, Jan; Mozer, F.
2012-01-01
Roč. 108, č. 2 (2012), 025002/1-025002/4 ISSN 0031-9007 Institutional research plan: CEZ:AV0Z30420517 Keywords : shock waves and discontinuities * bow shock * plasma waves Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 7.943, year: 2012 http://link.aps.org/doi/10.1103/PhysRevLett.108.025002
Characteristics of coronal shock waves and solar type 2 radio bursts
Mann, G.; Classen, H.-T.
1995-01-01
In the solar corona shock waves generated by flares and/or coronal mass ejections can be observed by radio astronomical methods in terms of solar type 2 radio bursts. In dynamic radio spectra they appear as emission stripes slowly drifting from high to low frequencies. A sample of 25 solar type 2 radio bursts observed in the range of 40 - 170 MHz with a time resolution of 0.1 s by the new radiospectrograph of the Astrophvsikalisches Institut Potsdam in Tremsdorf is statistically investigated concerning their spectral features, i.e, drift rate, instantaneous bandwidth, and fundamental harmonic ratio. In-situ plasma wave measurements at interplanetary shocks provide the assumption that type 2 radio radiation is emitted in the vicinity of the transition region of shock waves. Thus, the instantaneous bandwidth of a solar type 2 radio burst would reflect the density jump across the associated shock wave. Comparing the inspection of the Rankine-Hugoniot relations of shock waves under coronal circumstances with those obtained from the observational study, solar type 2 radio bursts should be regarded to be generated by weak supercritical, quasi-parallel, fast magnetosonic shock waves in the corona.
Effects of improving current characteristics of spark discharge on underwater shock waves
Directory of Open Access Journals (Sweden)
O Higa
2016-09-01
Full Text Available We have been developing a food-processing device that uses underwater shock waves generated by spark discharges at an underwater spark gap. Underwater shock waves can be used in food processing for softening, fracturing and sterilization. These technologies are attracting attention because the food is not heated during processing, so it does not change flavour. In this study, we develop a rice-powder manufacturing system using the fracturing effect provided by underwater shock waves. Because rice grains are very hard, the process must be applied repeatedly using a momentary high pressure to fracture the grains. The fast repeated generation of shock waves should provide high pressures from low energies. Therefore, we aim to achieve higher pressures from low energies expended by the underwater gap discharge. We increase the pulse compression rate by decreasing the circuit impedance of the device and increasing the charging voltage. Using optical observations and a pressure sensor, we measure the high pressure developed by the underwater shock wave and the rise time of the discharge current. We find that we can decrease the rise time of the discharge current by 17% while maintaining the peak current, and simultaneously increase the high pressure of the underwater shock wave by 135%.
Comparison of Hydrocode Simulations with Measured Shock Wave Velocities
Energy Technology Data Exchange (ETDEWEB)
Hixson, R. S. [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Veeser, L. R. [National Security Technologies, LLC. (NSTec), Mercury, NV (United States)
2014-11-30
We have conducted detailed 1- and 2-dimensional hydrodynamics calculations to assess the quality of simulations commonly made to understand various shock processes in a sample and to design shock experiments. We began with relatively simple shock experiments, where we examined the effects of the equation of state and the viscoplastic strength models. Eventually we included spallation in copper and iron and a solid-solid phase transformation in iron to assess the quality of the damage and phase transformation simulations.
Development of a new diagnostic sensor for extra-corporeal shock-wave lithotripsy
Energy Technology Data Exchange (ETDEWEB)
Fedele, F [Medical Physics Department, Guy' s and St Thomas' NHS Trust, London, SE1 7EH (United Kingdom); Coleman, A J [Medical Physics Department, Guy' s and St Thomas' NHS Trust, London, SE1 7EH (United Kingdom); Leighton, T G [Institute of Sound and Vibration Research, University of Southampton, Southampton, SO17 1BJ (United Kingdom); White, P R [Institute of Sound and Vibration Research, University of Southampton, Southampton, SO17 1BJ (United Kingdom); Hurrell, A M [Precision Acoustics Ltd, Dorchester, DT1 1PY (United Kingdom)
2004-01-01
Extracorporeal shock-wave lithotripsy is the leading technique used in urology for the non-invasive treatment of kidney and ureteric stones. The stone is comminuted by thousands of ultrasound shocks, into fragments small enough to be naturally passed. Since the technique was introduced in the 1980 different generations of lithotripters have been developed. Nevertheless the alignment systems (x-ray, ultrasound) still have some limitations (indeed, the tighter focusing of newer lithotripter reduces the tolerance for misalignment) and there is no capability for on-line monitoring of the degree of fragmentation of the stone. There is 50% incidence of re-treatments, possibly due to these deficiencies. The objective of this research is to design a new passive acoustic sensor, exploiting the secondary acoustic emission generated during the treatment, which could be used as a diagnostic device for lithotripsy. With a passive cylindrical cavitation detector, developed by the National Physical Laboratory, it was possible to detect these emissions in a laboratory lithotripter, and it was shown that they contain information on the degree of stone fragmentation and stone location. This information could be used to perform the desired monitoring and to improve the stone targeting. In collaboration with Precision Acoustic Ltd, some clinical prototypes were developed and tested to verify the relevance of these preliminary results. Clinical results are presented.
Piezoresistive method for a laser induced shock wave detection on solids
Gonzalez-Romero, R.; Garcia-Torales, G.; Gomez Rosas, G.; Strojnik, M.
2017-08-01
A laser shock wave is a mechanical high-pressure impulse with a duration of a few nanoseconds induced by a high power laser pulse. We performed wave pressure measurements in order to build and check mathematical models. They are used for wave applications in material science, health, and defense, to list a few. Piezoresistive methods have been shown to be highly sensitive, linear, and highly appropriate for practical implementation, compared with piezoelectric methods employed in shock wave pressure measurements. In this work, we develop a novel method to obtain the sensitivity of a piezoresistive measurement system. The results shows that it is possible to use a mechanical method to measure pressure of a laser induced shock wave in nanosecond range. Experimental pressure measurements are presented.
Shock-wave lithotripsy: variance within UK practice.
Sharma, N L; Alexander, C E; Grout, E; Turney, B W
2017-04-01
The objectives of this study are to determine the current treatment policies of UK shock-wave lithotripsy centres. Fixed-site lithotripter centres in the UK were identified via the national Therapeutic Interventions for Stones of the Ureter (TISU) study (n = 25). Questionnaires were completed regarding current SWL protocols for each centre, including management of anticoagulation, use of antibiotics and analgesia, urine testing, pacemakers, and arterial aneurysms. Data were collected regarding service delivery. Responses were obtained for 21 centres. Most centres use the Storz Modulith (85.7 %). Wide variation was observed in clinical contraindications to SWL, with 47.6 % centres performing SWL in patients with an abdominal aortic aneurysm, 66.7 % performing SWL in patients with a pacemaker, and 66.7 % of centres not performing SWL in asymptomatic patients with a urine dipstick positive for nitrites and leucocytes. The management of anticoagulation pre- and post-SWL showed wide variation, with the omission of anticoagulation ranging from 0 to 10 days pre-SWL. Seventeen distinct analgesia regimens were reported and prophylactic antibiotics are routinely administered in 25.0 % of centres. Tamsulosin is prescribed to all patients in 20.0 % of centres and a further 15.0 % of centres routinely prescribe tamsulosin post-SWL of ureteric stones. The included centres undertake SWL a median of 4 days per week and treat a median of six patients per list. Emergency SWL is unavailable in 30.0 % of centres. This observational real-life study has identified a significant disparity in the delivery of SWL throughout the UK, despite high numbers of patients with renal and ureteric stones being treated with this modality. Further studies should address the key areas of controversy, including an assessment of technical training, and facilitate the development of national guidelines to ensure a high level of standardized care for SWL patients.
Laser driven shock wave experiments for equation of state studies at megabar pressures
Pant, H C; Senecha, V K; Bandyopadhyay, S; Rai, V N; Khare, P; Bhat, R K; Gupta, N K; Godwal, B K
2002-01-01
We present the results from laser driven shock wave experiments for equation of state (EOS) studies of gold metal. An Nd:YAG laser chain (2 J, 1.06 mu m wavelength, 200 ps pulse FWHM) is used to generate shocks in planar Al foils and Al + Au layered targets. The EOS of gold in the pressure range of 9-13 Mbar is obtained using the impedance matching technique. The numerical simulations performed using the one-dimensional radiation hydrodynamic code support the experimental results. The present experimental data show remarkable agreement with the existing standard EOS models and with other experimental data obtained independently using laser driven shock wave experiments.
The impact of vorticity waves on the shock dynamics in core-collapse supernovae
Huete, César; Abdikamalov, Ernazar; Radice, David
2018-04-01
Convective perturbations arising from nuclear shell burning can play an important role in propelling neutrino-driven core-collapse supernova explosions. In this work, we analyse the impact of vorticity waves on the shock dynamics, and subsequently on the post-shock flow, using the solution of the linear hydrodynamics equations. As a result of the interaction with the shock wave, vorticity waves increase their kinetic energy, and a new set of entropic and acoustic waves is deposited in the post-shock region. These perturbations interact with the neutrino-driven turbulent convection that develops in that region. Although both vorticity and acoustic waves inject non-radial motion into the gain region, the contribution of the acoustic waves is found to be negligibly small in comparison to that of the vorticity waves. On the other hand, entropy waves become buoyant and trigger more convection. Using the concept of critical neutrino luminosity, we assess the impact of these modes on the explosion conditions. While the direct injection of non-radial motion reduces the critical neutrino luminosity by ˜ 12 per cent for typical problem parameters, the buoyancy-driven convection triggered by entropy waves reduces the critical luminosity by ˜ 17-24 per cent, which approximately agrees with the results of three-dimensional neutrino-hydrodynamics simulations. Finally, we discuss the limits of validity of the assumptions employed.
STEREO Observations of Waves in the Ramp Regions of Interplanetary Shocks
Cohen, Z.; Breneman, A. W.; Cattell, C. A.; Davis, L.; Grul, P.; Kersten, K.; Wilson, L. B., III
2017-12-01
Determining the role of plasma waves in providing energy dissipation at shock waves is of long-standing interest. Interplanetary (IP) shocks serve as a large database of low Mach number shocks. We examine electric field waveforms captured by the Time Domain Sampler (TDS) on the STEREO spacecraft during the ramps of IP shocks, with emphasis on captures lasting 2.1 seconds. Previous work has used captures of shorter duration (66 and 131 ms on STEREO, and 17 ms on WIND), which allowed for observation of waves with maximum (minimum) frequencies of 125 kHz (15 Hz), 62.5 kHz (8 Hz), and 60 kHz (59 Hz), respectively. The maximum frequencies are comparable to 2-8 times the plasma frequency in the solar wind, enabling observation of Langmuir waves, ion acoustic, and some whistler-mode waves. The 2 second captures resolve lower frequencies ( few Hz), which allows us to analyze packet structure of the whistler-mode waves and some ion acoustic waves. The longer capture time also improves the resolvability of simultaneous wave modes and of waves with frequencies on the order of 10s of Hz. Langmuir waves, however, cannot be identified at this sampling rate, since the plasma frequency is usually higher than 3.9 kHz. IP shocks are identified from multiple databases (Helsinki heliospheric shock database at http://ipshocks.fi, and the STEREO level 3 shock database at ftp://stereoftp.nascom.nasa.gov/pub/ins_data/impact/level3/). Our analysis focuses on TDS captures in shock ramp regions, with ramp durations determined from magnetic field data taken at 8 Hz. Software is used to identify multiple wave modes in any given capture and classify waves as Langmuir, ion acoustic, whistler, lower hybrid, electron cyclotron drift instability, or electrostatic solitary waves. Relevant frequencies are determined from density and magnetic field data collected in situ. Preliminary results suggest that large amplitude (≥ 5 mV/m) ion acoustic waves are most prevalent in the ramp, in agreement with
Shock formation in small-data solutions to 3D quasilinear wave equations
Speck, Jared
2016-01-01
In 1848 James Challis showed that smooth solutions to the compressible Euler equations can become multivalued, thus signifying the onset of a shock singularity. Today it is known that, for many hyperbolic systems, such singularities often develop. However, most shock-formation results have been proved only in one spatial dimension. Serge Alinhac's groundbreaking work on wave equations in the late 1990s was the first to treat more than one spatial dimension. In 2007, for the compressible Euler equations in vorticity-free regions, Demetrios Christodoulou remarkably sharpened Alinhac's results and gave a complete description of shock formation. In this monograph, Christodoulou's framework is extended to two classes of wave equations in three spatial dimensions. It is shown that if the nonlinear terms fail to satisfy the null condition, then for small data, shocks are the only possible singularities that can develop. Moreover, the author exhibits an open set of small data whose solutions form a shock, and he prov...
Molecular dynamics of shock waves in one-dimensional chains. II. Thermalization
International Nuclear Information System (INIS)
Straub, G.K.; Holian, B.L.; Petschek, R.G.
1979-01-01
The thermalization behavior behind a shock front in one-dimensional chains has been studied in a series of molecular-dynamics computer experiments. We have found that a shock wave generated in a chain initially at finite temperature has essentially the same characteristics as in a chain initially at zero temperature. We also find that the final velocity distribution function for particles behind the shock front is not the Maxwell-Boltzmann distribution for an equilibrium system of classical particles. For times long after the shock has passed, we propose a nonequilibrium velocity distribution which is based upon behavior in the harmonic and hard-rod limits and agrees with our numerical results. Temperature profiles for both harmonic and anharmonic chains are found to exhibit a long-time tail that decays inversely with time. Finally, we have run a computer experiment to generate what qualitatively resembles solitons in Toda chains by means of shock waves
Discrete Element Simulation of Elastoplastic Shock Wave Propagation in Spherical Particles
Directory of Open Access Journals (Sweden)
M. Shoaib
2011-01-01
Full Text Available Elastoplastic shock wave propagation in a one-dimensional assembly of spherical metal particles is presented by extending well-established quasistatic compaction models. The compaction process is modeled by a discrete element method while using elastic and plastic loading, elastic unloading, and adhesion at contacts with typical dynamic loading parameters. Of particular interest is to study the development of the elastoplastic shock wave, its propagation, and reflection during entire loading process. Simulation results yield information on contact behavior, velocity, and deformation of particles during dynamic loading. Effects of shock wave propagation on loading parameters are also discussed. The elastoplastic shock propagation in granular material has many practical applications including the high-velocity compaction of particulate material.
Analytical solution of the problem of a shock wave in the collapsing gas in Lagrangian coordinates
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.
Effect of a transverse plasma jet on a shock wave induced by a ramp
Directory of Open Access Journals (Sweden)
Hongyu WANG
2017-12-01
Full Text Available We conducted experiments in a wind tunnel with Mach number 2 to explore the evolution of a transverse plasma jet and its modification effect on a shock wave induced by a ramp with an angle of 24Â°. The transverse plasma jet was created by arc discharge in a small cylindrical cavity with a 2â¯mm diameter orifice. Three group tests with different actuator arrangements in the spanwise or streamwise direction upstream from the ramp were respectively studied to compare their disturbances to the shock wave. As shown by a time-resolved schlieren system, an unsteady motion of the shock wave by actuation was found: the shock wave was significantly modified by the plasma jet with an upstream motion and a reduced angle. Compared to spanwise actuation, a more intensive impact was obtained with two or three streamwise actuators working together. From shock wave structures, the control effect of the plasma jet on the shock motion based on a thermal effect, a potential cause of shock modification, was discussed. Furthermore, we performed a numerical simulation by using the Improved Delayed Detached Eddy Simulation (IDDES method to simulate the evolution of the transverse plasma jet plume produced by two streamwise actuators. The results show that flow structures are similar to those identified in schlieren images. Two streamwise vortices were recognized, which indicates that the higher jet plume is the result of the overlap of two streamwise jets. Keywords: Flow control, Improved delayed detached eddy simulation (IDDES method, Plasma synthetic jet, Shock wave/boundary layer interaction, Time resolved schlieren system
Dust acoustic shock wave generation due to dust charge variation in ...
Indian Academy of Sciences (India)
Burger equation. Results of the numerical investigation of the propagation of large-amplitude dust acoustic stationary shock wave are presented here using the complete set of non-linear dust fluid equations coupled with the dust charging equation and Poisson equation. The DA waves are of compressional type showing ...
Generation and Micro-scale Effects of Electrostatic Waves in an Oblique Shock
Goodrich, K.; Ergun, R.; Schwartz, S. J.; Newman, D.; Johlander, A.; Argall, M. R.; Wilder, F. D.; Torbert, R. B.; Khotyaintsev, Y. V.; Lindqvist, P. A.; Strangeway, R. J.; Russell, C. T.; Giles, B. L.; Gershman, D. J.; Burch, J. L.
2017-12-01
We present an analysis of large amplitude (>100 mV/m), high frequency (≤1 kHz), electrostatic waves observed by MMS during an oblique bow shock crossing event. The observed waves primarily consist of electrostatic solitary waves (ESWs) and oblique ion plasma waves (IPWs). ESWs typically include nonlinear structures such as double layers, ion phase-space holes, and electron phase-space holes. Oblique IPWs are observed to be similar to ion acoustic waves, but can propagate up to 70° from the ambient magnetic field direction. Both wave-modes, particularly IPWs, are observed to have very short wavelengths ( 100 m) and are highly localized. While such wave-modes have been previously observed in the terrestrial bow shock, instrumental constraints have limited detailed insight into their generation and their effect on their plasma shock environment. Analysis of this oblique shock event shows evidence that ESWs and oblique IPWs can be generated through field-aligned currents associated with magnetic turbulence and through a counterstreaming ion instability respectively. We also present evidence that this wave activity can facilitate momentum exchange between ion populations, resulting in deceleration of incoming solar wind, and localized electron heating.
Dust acoustic shock wave generation due to dust charge variation in ...
Indian Academy of Sciences (India)
Keywords. Non-adiabatic charge variation; shock wave. Abstract. In a dusty plasma, the non-adiabaticity of the charge variation on a dust grain surface results in an anomalous dissipation. Analytical investigation shows that this results in a small but ﬁnite amplitude dust acoustic (DA) wave propagation which is described by ...
Shock wave polarizations and optical metrics in the Born and the Born–Infeld electrodynamics
Energy Technology Data Exchange (ETDEWEB)
Minz, Christoph, E-mail: christoph.minz@alumni.tu-berlin.de [Institute of Theoretical Physics, Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin (Germany); Borzeszkowski, Horst-Heino von, E-mail: borzeszk@mailbox.tu-berlin.de [Institute of Theoretical Physics, Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin (Germany); Chrobok, Thoralf, E-mail: tchrobok@mailbox.tu-berlin.de [Institute of Theoretical Physics, Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin (Germany); Schellstede, Gerold, E-mail: schellst@physik.fu-berlin.de [ZARM (Center of Applied Space Technology and Microgravity), Universität Bremen, Am Fallturm, D-28359 Bremen (Germany)
2016-01-15
We analyze the behavior of shock waves in nonlinear theories of electrodynamics. For this, by use of generalized Hadamard step functions of increasing order, the electromagnetic potential is developed in a series expansion near the shock wave front. This brings about a corresponding expansion of the respective electromagnetic field equations which allows for deriving relations that determine the jump coefficients in the expansion series of the potential. We compute the components of a suitable gauge-normalized version of the jump coefficients given for a prescribed tetrad compatible with the shock front foliation. The solution of the first-order jump relations shows that, in contrast to linear Maxwell’s electrodynamics, in general the propagation of shock waves in nonlinear theories is governed by optical metrics and polarization conditions describing the propagation of two differently polarized waves (leading to a possible appearance of birefringence). In detail, shock waves are analyzed in the Born and Born–Infeld theories verifying that the Born–Infeld model exhibits no birefringence and the Born model does. The obtained results are compared to those ones found in literature. New results for the polarization of the two different waves are derived for Born-type electrodynamics.
Study on storage and measurement system of shock-wave pressure
International Nuclear Information System (INIS)
Fan Zehui; Tian Zhong; Tang Jian; Yang Jian; Wei Xiangwen; Wang Lihua
1998-12-01
The principle, systematic structure of the storage and measurement system of shock-wave pressure and the calibration and application measurement of the system are introduced. The measured results show that the measuring system can be used as a substitute of the traditional pressure measurement system and used for storage and measurement of pressure wave shape of the shock-wave resulted from explosion. It has the following advantages: free of lead-wire, resistant against bad conditions, anti-interference, high reliability, easy calibration and simple measurement procedure, easy to carry, direct communication with micro-computer
Charging-delay induced dust acoustic collisionless shock wave: Roles of negative ions
International Nuclear Information System (INIS)
Ghosh, Samiran; Bharuthram, R.; Khan, Manoranjan; Gupta, M. R.
2006-01-01
The effects of charging-delay and negative ions on nonlinear dust acoustic waves are investigated. It has been found that the charging-delay induced anomalous dissipation causes generation of dust acoustic collisionless shock waves in an electronegative dusty plasma. The small but finite amplitude wave is governed by a Korteweg-de Vries Burger equation in which the Burger term arises due to the charging-delay. Numerical investigations reveal that the charging-delay induced dissipation and shock strength decreases (increases) with the increase of negative ion concentration (temperature)
Numerical Investigation of Rockburst Effect of Shock Wave on Underground Roadway
Directory of Open Access Journals (Sweden)
Cai-Ping Lu
2015-01-01
Full Text Available Using UDEC discrete element numerical simulation software and a cosine wave as vibration source, the whole process of rockburst failure and the propagation and attenuation characteristics of shock wave in coal-rock medium were investigated in detail based on the geological and mining conditions of 1111(1 working face at Zhuji coal mine. Simultaneously, by changing the thickness and strength of immediate roof overlying the mining coal seam, the whole process of rockburst failure of roadway and the attenuation properties of shock wave were understood clearly. The presented conclusions can provide some important references to prevent and control rockburst hazards triggered by shock wave interferences in deep coal mines.
Kang, Gwansuk; Huh, Jung Sik; Choi, Min Joo
2017-07-01
Extracorporeal shock wave therapy employs intense shock waves that produce cavitation bubbles understood to play an important role in therapeutic effects. This study considers shock-wave-induced cavitation bubbles, expected to be closely associated with treated therapeutic regions. A simple optical method was devised to visualize the cavitation bubbles under micropulse LED light illumination and to capture an afterimage of the bubbles for their entire lifetime from formation to collapse. The optical images of the cavitation bubbles produced by a clinical shock wave therapeutic device were shown to preserve the characteristics of the focusing shock wave field. The similarity of the characteristics may enable the cavitation cloud image to provide the intensity and location of shock wave irradiation for the clinical quality assurance of therapeutic devices. Further research that includes the dynamic effects in the static images of cavitation bubbles is suggested.
International Nuclear Information System (INIS)
Max, C.E.; Zachary, A.; Arons, J.
1988-01-01
We have performed computer simulations to investigate whether sizeable electron density fluctuations might be produced in the process of cosmic-ray acceleration at supernova remnant shock waves. The hypothesis is the following: Cosmic-ray acceleration via a Fermi I mechanism leads to large-amplitude Alfven waves upstream of a supernova remnant shock wave. If the Alfven waves reach a large enough amplitude, they can drive sound waves in the interstellar medium. The fluctuations in the electron density due to these sound waves will then contribute to the observed interstellar scintillation. Our simulations suggest that this mechanism may be a plausible one. Issues remaining to be addressed include the resulting filling factor, and the integrated strength C 2 /sub n/ to be expected for the turbulence
Application of extracorporeal shock wave on bone: preliminary report.
Ikeda, K; Tomita, K; Takayama, K
1999-11-01
We have studied the effect of extracorporeal shock waves (ESW) on bone. ESW emitted by the new powerful generator provides three to six times greater energy than a common lithotriptor. Because the ESW causes fracture of rabbit femurs and induces new bone formation, we have called this treatment as ESWIB (ESW-induced bone formation). The purpose of this study is to confirm the effect of ESWIB on a canine model, which is more similar to clinical cases, and to apply ESWIB on nonunion of clinical cases. In our basic research, ESWIB was applied on six canine femurs as follows: group I with 100, 500, 1,000 shots and group II with 100, 500, 1,000 shots. A femur was extracted immediately after ESWIB in group I and 2 months after ESWIB in group II. Blood tests, including blood cell counts and blood chemistry studies, were performed before and after ESWIB in group II. In our clinical research, we applied ESWIB to six patients of delayed or nonunion of the fracture. The sites of the ESWIB application were three tibiae, one radius, one femur, and one humerus. Average age of the patients, the period from the previous surgery, and the period until fusion was achieved were 38.6 years, 14.0 months, and 4.3 months, respectively. In our basic research, group I, 500 or more shots caused periosteum detachment. In addition, small fractures of the inner surface of the cortex were observed. However, gross fracture with displacement was not observed. In group II, 500 or more shots caused callus formation beneath the detached periosteum. Subcutaneous hemorrhage was seen in all dogs, and the degree of bleeding was directly proportional to the number of the shots. The blood was absorbed within a week. The level of serum creatine kinase was significantly high 2 days after ESWIB, but it recovered in a week. In our clinical research, four of the patients achieved union without any complications except mild subcutaneous bleeding. We predict that ESWIB will be one of the tactics for treatment of
Dandekar, Dattatraya P.
1998-12-01
This article reports a set of experiments designed to measure change in the refractive index of transparent material under both planar shock and release wave propagations. Information about both mechanical and optical properties of transparent material were obtained simultaneously through the measurement of particle velocity at or near the impact surface and the free surface velocity. Data thus obtained is used to determine shock and release wave velocities and the Hugoniot elastic limit (HEL) of the material. Shock wave velocity in soda lime glass remains unchanged at 5.83±0.04 km/s, i.e., equal to the measured ultrasonic longitudinal wave velocity, when it is shock compressed to less than or equal to 4.3 GPa. The value of shock wave velocity begins to decline when the impact stress in the glass exceeds this value. The release wave velocity, however, remains equal to the measured ultrasonic longitudinal wave velocity to only 3 GPa, it begins to decline at higher stresses. The variation in the refractive index of the glass shows a cusp at 3.04-3.14 GPa. Additionally, up to and including the impact stress of 3.14 GPa, the refractive index after shock compression and release is within 1% of its ambient value, but at higher stresses it differs by larger percentage points. The HEL of the glass is determined to be 3.10±0.06 GPa although it lacks the classic well defined cusp in all the recorded wave profiles of soda lime glass.
Numerical study of heterogeneous mean temperature and shock wave in a resonator
Energy Technology Data Exchange (ETDEWEB)
Yano, Takeru [Department of Mechanical Engineering, Osaka University, Suita 565-0871 (Japan)
2015-10-28
When a frequency of gas oscillation in an acoustic resonator is sufficiently close to one of resonant frequencies of the resonator, the amplitude of gas oscillation becomes large and hence the nonlinear effect manifests itself. Then, if the dissipation effects due to viscosity and thermal conductivity of the gas are sufficiently small, the gas oscillation may evolve into the acoustic shock wave, in the so-called consonant resonators. At the shock front, the kinetic energy of gas oscillation is converted into heat by the dissipation process inside the shock layer, and therefore the temperature of the gas in the resonator rises. Since the acoustic shock wave travels in the resonator repeatedly over and over again, the temperature rise becomes noticeable in due course of time even if the shock wave is weak. We numerically study the gas oscillation with shock wave in a resonator of square cross section by solving the initial and boundary value problem of the system of three-dimensional Navier-Stokes equations with a finite difference method. In this case, the heat conduction across the boundary layer on the wall of resonator causes a spatially heterogeneous distribution of mean (time-averaged) gas temperature.
Passive shock wave/boundary layer control of wing at transonic speeds
Directory of Open Access Journals (Sweden)
Ling Zhou
2017-11-01
Full Text Available At supercritical conditions a porous strip (or slot strip placed beneath a shock wave can reduce the drag by a weaker lambda shock system, and increase the buffet boundary, even may increase the lift. Passive shock wave/boundary layer control (PSBC for drag reduction was conducted by SC(2-0714 supercritical wing, with emphases on parameter of porous/slot and bump, such as porous distribution, hole diameter, cavity depth, porous direction and so on. A sequential quadratic programming (SQP optimization method coupled with adjoint method was adopted to achieve the optimized shape and position of the bumps. Computational fluid dynamics (CFD, force test and oil test with half model all indicate that PSBC with porous, slot and bump generally reduce the drag by weaker lambda shock at supercritical conditions. According to wind tunnel test results for angle of attack of 2° at Mach number M=0.8, the porous configuration with 6.21% porosity results in a drag reduction of 0.0002 and lift–drag ratio increase of 0.2, the small bump configuration results in a drag reduction of 0.0007 and lift–drag ratio increase of 0.3. Bump normally reduce drag at design point with shock wave position being accurately computed. If bump diverges from the position of shock wave, drag will not be easily reduced.
Trajkovik, Slobodan; Lutovac, Suzana; Ravilik, Marija; Doneva, Nikolinka
2013-01-01
The blast effect problem of shock waves is growing in the area surrounding blasting activities. In addition to damage shock waves may cause on buildings and mining site facilities, they also impact badly human force there, namely the environment. Lately considerable research in the world has been dedicated to the examination and numeric modelling of this phenomenon. Specific standards have been established defining the blast effect margin level of shock waves on facilities and human force th...
Energy Technology Data Exchange (ETDEWEB)
Fröhlich, Markus G., E-mail: FroehlichM@missouri.edu, E-mail: ThompsonDon@missouri.edu; Sewell, Thomas D., E-mail: SewellT@missouri.edu; Thompson, Donald L., E-mail: FroehlichM@missouri.edu, E-mail: ThompsonDon@missouri.edu [Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri 65211-7600 (United States)
2014-01-14
The mechanical and structural responses of hydroxyl-terminated cis-1,4-polybutadiene melts to shock waves were investigated by means of all-atom non-reactive molecular dynamics simulations. The simulations were performed using the OPLS-AA force field but with the standard 12-6 Lennard-Jones potential replaced by the Buckingham exponential-6 potential to better represent the interactions at high compression. Monodisperse systems containing 64, 128, and 256 backbone carbon atoms were studied. Supported shock waves were generated by impacting the samples onto stationary pistons at impact velocities of 1.0, 1.5, 2.0, and 2.5 km s{sup −1}, yielding shock pressures between approximately 2.8 GPa and 12.5 GPa. Single-molecule structural properties (squared radii of gyration, asphericity parameters, and orientational order parameters) and mechanical properties (density, shock pressure, shock temperature, and shear stress) were analyzed using a geometric binning scheme to obtain spatio-temporal resolution in the reference frame centered on the shock front. Our results indicate that while shear stress behind the shock front is relieved on a ∼0.5 ps time scale, a shock-induced transition to a glass-like state occurs with a concomitant increase of structural relaxation times by several orders of magnitude.
Experiment and analysis of shock waves radiated from pulse laser focusing in a gelatin gel
Nakamura, Nobuyuki; Ando, Keita
2017-11-01
A fundamental understanding of shock and bubble dynamics in human tissues is essential to laser application for medical purposes. Here, we experimentally study the dynamics of shock waves in viscoelastic media. A nanosecond laser pulse of wavelength at 532 nm and of energy up to 2.66 +/- 0.09 mJ was focused through a microscope objective lens (10 x, NA = 0.30) into a gel of gelatin concentration at 3 and 10 wt%; a shock wave and a bubble can be generated, respectively, by rapid expansion of the laser-induced plasma and local heat deposition after the plasma recombines. The shock propagation and the bubble growth were recorded by a ultra-high-speed camera at 100 Mfps. The shock evolution was determined by image analysis of the recording and the shock pressure in the near field was computed according to the Rankine-Hugoniot relation. The far-field pressure was measured by a hydrophone. In the poster, we will present the decay rate of the shock pressure in the near and far fields and examine viscous effects on the shock dynamics. The Research Grant of Keio Leading-edge Laboratory of Science & Technology.
Extracorporeal shock wave lithotripsy in children: Results and short-term complications.
da Cunha Lima, João Paulo; Duarte, Ricardo Jordão; Cristofani, Lílian Maria; Srougi, Miguel
2007-08-01
The introduction of extracorporeal shock wave lithotripsy represented an important evolution in urinary tract lithiasis management. The aim of this study is to describe the results of extracorporeal shock wave lithotripsy for the treatment of urinary tract lithiasis in children, focusing on the index of elimination of the calculi and the complications occurring during the procedure and during the following three months. From September 1991 to July 2002, 135 children between one and 12 years, suffering from urinary tract lithiasis underwent extracorporeal shock wave lithotripsy. A retrospective analysis of these patients was carried out. One hundred and ninety-five calculi ranging in size from 5.0 mm to 20.0 mm were treated, out of which 147 were found in the kidneys and 48 in the ureter. Urinary tract dilation was presented by 30% of the children at the time of the procedure. After extracorporeal shock wave lithotripsy 75.8% of the calculi were eliminated: 64.1% were stone-free and 11.7% had pain. In children, extracorporeal shock wave lithotripsy proved to be able to eliminate 75.8% of the treated calculi and 83.7% of the patients presented a complete or partial response. Complications were observed in 23.7% of patients, and pain was the most frequent symptom.
On the Effects of Viscosity on the Shock Waves for a Hydrodynamical Case—Part I: Basic Mechanism
Directory of Open Access Journals (Sweden)
Huseyin Cavus
2013-01-01
Full Text Available The interaction of shock waves with viscosity is one of the central problems in the supersonic regime of compressible fluid flow. In this work, numerical solutions of unmagnetised fluid equations, with the viscous stress tensor, are investigated for a one-dimensional shock wave. In the algorithm developed the viscous stress terms are expressed in terms of the relevant Reynolds number. The algorithm concentrated on the compression rate, the entropy change, pressures, and Mach number ratios across the shock wave. The behaviour of solutions is obtained for the Reynolds and Mach numbers defining the medium and shock wave in the supersonic limits.
Directory of Open Access Journals (Sweden)
Chun Wai Chan
2017-10-01
Full Text Available Low-intensity extracorporeal shock wave therapy is a new treatment in treating vasculogenic erectile dysfunction. We report a case of low-intensity extracorporeal shock wave therapy used for treating radiation-induced erectile dysfunction. A 66-year-old gentleman with dyslipidemia and smoking presented with radiation-induced erectile dysfunction. Six sessions of low-intensity extracorporeal shock wave therapy were administered. Pre-treatment IIEF- 5 score was 10 and post-treatment IIEF-5 score at one month was 19. Low-intensity extracorporeal shock wave therapy has the potential to treat radiation-induced erectile dysfunction.
Nonplanar electrostatic shock waves in an opposite polarity dust ...
Indian Academy of Sciences (India)
M Amina
2017-05-30
May 30, 2017 ... The coexistence of positively and negatively charged dust grains has been observed in the Earth's mesosphere [11,12] as well as in cometary tails and comae [6]. The propagation of various types of nonlinear waves in dusty plasmas, viz., dust-acoustic (DA) waves [13], dust-ion-acoustic (DIA) waves [14,15] ...
Energy Technology Data Exchange (ETDEWEB)
Loske, A.M.; Fernandez, F. [Centro de Fisica Aplicada y Tecnologia Avanzada, UNAM, Queretaro, Qro. (Mexico); Gutierrez, J. [Univ. de Guadalajara, Nuevo Hospital Civil, Guadalajara, Jalisco (Mexico)
2005-07-01
The non-invasive disintegration of kidney stones using shock waves, referred to as extracorporal shock wave lithotripsy, has been successful for more than twenty years in treating patients having renal and ureteral stones. Two modified shock wave generators are described in this article. The novel systems produce two similar shock waves (tandem shock waves) generated with a short time delay. The second shock wave arrives during collapse of the bubbles generated in the neighborhood of the stone due to the first shock wave. This may increase cavitation bubble collapse and could enhance cavitation-induced damage to kidney stones during shock wave lithotripsy. In vitro comparison of standard systems with the new designs showed that fragmentation efficiency of artificial kidney stones was significantly enhanced using tandem shock waves. (orig.)
Russell, C. T.; Strangeway, R. J.; Schwartz, S. J.
2017-12-01
The Magnetospheric Multiscale (MMS) spacecraft, with their state-of-the-art plasma and field instruments onboard, allow us to investigate electromagnetic waves at the bow shock and their association with small-scale disturbances in the shocked plasmas. Understanding these waves could improve our knowledge on the heating of electrons and ions across the shock ramp and the energy dissipation of supercritical shocks. We have found broad-band and narrow band waves across the shock ramp and slightly downstream. The broad-band waves propagate obliquely to the magnetic field direction and have frequencies up to the electron cyclotron frequency, while the narrow-band waves have frequencies of a few hundred Hertz, durations under a second, and are right-handed circularly polarized and propagate along the magnetic field lines. Both wave types are likely to be whistler mode with different generation mechanisms. When the solar wind pressure changes, MMS occasionally observed a pair of bow shocks when the magnetosphere was compressed and then expanded. We compare the wave observations under these two situations to understand their roles in the shock ramp as well as the upstream and downstream plasmas.
Criterion for vortex breakdown on shock wave and streamwise vortex interactions.
Hiejima, Toshihiko
2014-05-01
The interactions between supersonic streamwise vortices and oblique shock waves are theoretically and numerically investigated by three-dimensional (3D) Navier-Stokes equations. Based on the two inequalities, a criterion for shock-induced breakdown of the streamwise vortex is proposed. The simple breakdown condition depends on the Mach number, the swirl number, the velocity deficit, and the shock angle. According to the proposed criterion, the breakdown region expands as the Mach number increases. In numerical simulations, vortex breakdown appeared under conditions of multiple pressure increases and the helicity disappeared behind the oblique shock wave along the line of the vortex center. The numerical results are consistent with the predicted breakdown condition at Mach numbers 2.0 and 3.0. This study also found that the axial velocity deficit is important for classifying the breakdown configuration.
Dust Ion-Acoustic Shock Waves in a Multicomponent Magnetorotating Plasma
Kaur, Barjinder; Saini, N. S.
2018-02-01
The nonlinear properties of dust ion-acoustic (DIA) shock waves in a magnetorotating plasma consisting of inertial ions, nonextensive electrons and positrons, and immobile negatively charged dust are examined. The effects of dust charge fluctuations are not included in the present investigation, but the ion kinematic viscosity (collisions) is a source of dissipation, leading to the formation of stable shock structures. The Zakharov-Kuznetsov-Burgers (ZKB) equation is derived using the reductive perturbation technique, and from its solution the effects of different physical parameters, i.e. nonextensivity of electrons and positrons, kinematic viscosity, rotational frequency, and positron and dust concentrations, on the characteristics of shock waves are examined. It is observed that physical parameters play a very crucial role in the formation of DIA shocks. This study could be useful in understanding the electrostatic excitations in dusty plasmas in space (e.g. interstellar medium).
Constrained reaction volume approach for studying chemical kinetics behind reflected shock waves
Hanson, Ronald K.
2013-09-01
We report a constrained-reaction-volume strategy for conducting kinetics experiments behind reflected shock waves, achieved in the present work by staged filling in a shock tube. Using hydrogen-oxygen ignition experiments as an example, we demonstrate that this strategy eliminates the possibility of non-localized (remote) ignition in shock tubes. Furthermore, we show that this same strategy can also effectively eliminate or minimize pressure changes due to combustion heat release, thereby enabling quantitative modeling of the kinetics throughout the combustion event using a simple assumption of specified pressure and enthalpy. We measure temperature and OH radical time-histories during ethylene-oxygen combustion behind reflected shock waves in a constrained reaction volume and verify that the results can be accurately modeled using a detailed mechanism and a specified pressure and enthalpy constraint. © 2013 The Combustion Institute.
Li, L.; Li, J.; Teo, C. J.; Chang, P. H.; Khoo, B. C.
2018-03-01
The study of deflagration-to-detonation transition (DDT) in bent tubes is important with many potential applications including fuel pipeline and mine tunnel designs for explosion prevention and detonation engines for propulsion. The aim of this study is to exploit low-speed incident shock waves for DDT using an S-shaped geometry and investigate its effectiveness as a DDT enhancement device. Experiments were conducted in a valveless detonation chamber using ethylene-air mixture at room temperature and pressure (303 K, 1 bar). High-speed Schlieren photography was employed to keep track of the wave dynamic evolution. Results showed that waves with velocity as low as 500 m/s can experience a successful DDT process through this S-shaped geometry. To better understand the mechanism, clear images of local explosion processes were captured in either the first curved section or the second curved section depending on the inlet wave velocity, thus proving that this S-shaped tube can act as a two-stage device for DDT. Owing to the curved wall structure, the passing wave was observed to undergo a continuous compression phase which could ignite the local unburnt mixture and finally lead to a local explosion and a detonation transition. Additionally, the phenomenon of shock-vortex interaction near the wave diffraction region was also found to play an important role in the whole process. It was recorded that this interaction could not only result in local head-on reflection of the reflected wave on the wall that could ignite the local mixture, and it could also contribute to the recoupling of the shock-flame complex when a detonation wave is successfully formed in the first curved section.
The Formation of Massive Molecular Filaments and Massive Stars Triggered by a MHD Shock Wave
Inoue, Tsuyoshi; Hennebelle, Patrick; Fukui, Yasuo; Matsumoto, Tomoaki; Iwasaki, Kazunari; Inutsuka, Shu-ichiro
2017-01-01
Recent observations suggest that intensive molecular cloud collision can trigger massive star/cluster formation. The most important physical process caused by the collision is a shock compression. In this paper, the influence of a shock wave on the evolution of a molecular cloud is studied numerically by using isothermal magnetohydrodynamics (MHD) simulations with the effect of self-gravity. Adaptive-mesh-refinement and sink particle techniques are used to follow long-time evolution of the sh...
Observation of Self-Cavitating Envelope Dispersive Shock Waves in Yttrium Iron Garnet Thin Films
Janantha, P. A. Praveen; Sprenger, Patrick; Hoefer, Mark A.; Wu, Mingzhong
2017-07-01
The formation and properties of envelope dispersive shock wave (DSW) excitations from repulsive nonlinear waves in a magnetic film are studied. Experiments involve the excitation of a spin wave step pulse in a low-loss magnetic Y3Fe5O12 thin film strip, in which the spin wave amplitude increases rapidly, realizing the canonical Riemann problem of shock theory. Under certain conditions, the envelope of the spin wave pulse evolves into a DSW that consists of an expanding train of nonlinear oscillations with amplitudes increasing from front to back, terminated by a black soliton. The onset of DSW self-cavitation, indicated by a point of zero power and a concomitant 180° phase jump, is observed for sufficiently large steps, indicative of the bidirectional dispersive hydrodynamic nature of the DSW. The experimental observations are interpreted with theory and simulations of the nonlinear Schrödinger equation.
A new mathematical approach for shock-wave solution in a dusty plasma
Energy Technology Data Exchange (ETDEWEB)
Das, G.C.; Dwivedi, C.B. [Plasma Physics Division, Institute of Advanced Study in Science and Technology, Khanapara, Guwahati-781022, Assam (India); Talukdar, M. [Computer Science Division, Institute of Advanced Study in Science and Technology, Khanapara, Guwahati-781022, Assam (India); Sarma, J. [Department of Mathematics, R. G. Baruah College, Guwahati-781025, Assam (India)
1997-12-01
The problem of nonlinear Burger equation in a plasma contaminated with heavy dust grains has been revisited. As discussed earlier [C. B. Dwivedi and B. P. Pandey, Phys. Plasmas {bold 2}, 9 (1995)], the Burger equation originates due to dust charge fluctuation dynamics. A new alternate mathematical approach based on a simple traveling wave formalism has been applied to find out the solution of the derived Burger equation, and the method recovers the known shock-wave solution. This technique, although having its own limitation, predicts successfully the salient features of the weak shock-wave structure in a dusty plasma with dust charge fluctuation dynamics. It is emphasized that this approach of the traveling wave formalism is being applied for the first time to solve the nonlinear wave equation in plasmas. {copyright} {ital 1997 American Institute of Physics.}
Whistler waves, core ion heating, and nonstationarity in oblique collisionless shocks
International Nuclear Information System (INIS)
Scholer, Manfred; Burgess, David
2007-01-01
One-dimensional full particle simulations of supercritical collisionless shocks with an ion and electron beta of 0.1 (particle to magnetic field pressure) over a wide Alfven Mach number range and range of shock normal-magnetic field angles between Θ Bn =60 deg. and Θ Bn =80 deg. are presented. The whistler critical Mach number M w , below which a linear phase-standing whistler can exist, is proportional to the square root of the ion-to-electron mass ratio and to cos Θ Bn . In small mass ratio simulations of oblique shocks, M w can be artificially small and close to the first critical Mach number M c , above which the process of ion reflection is needed in order to achieve shock dissipation. We use in the simulations the physical ion-to-electron mass ratio so that M c and M w are well separated. This also allows excitation of the modified two-stream instability (MTSI) between incoming ions and electrons. We find that in oblique but close to perpendicular (Θ Bn ≥80 deg.) shocks, upstream whistler waves do occur, but reformation is due to accumulation of reflected-gyrating ions at the upstream edge of the foot. In less oblique shocks above the whistler critical Mach number, the whistler amplitude in the foot upstream of the ramp grows, leading to vortices of the incoming ions and the reflected ions in velocity phase space, and eventually to phase mixing. The shock re-forms at the upstream edge of the whistler wave train, which is particularly evident in very high Mach number shocks where the scale of the foot is large compared with the whistler wave train. After reformation, the region with phase-mixed incoming and reflected ions constitutes a hot core downstream of the shock ramp. In this whistler induced reformation process, the MTSI results mainly in heating of the incoming ions in the foot
Hydrogen film cooling with incident and swept-shock interactions in a Mach 6.4 nitrogen free stream
Olsen, George C.; Nowak, Robert J.
1995-01-01
The effectiveness of slot film cooling of a flat plate in a Mach 6.4 flow with and without incident and swept oblique shock interactions was experimentally investigated. Hydrogen was the primary coolant gas, although some tests were conducted using helium as the coolant. Tests were conducted in the Calspan 48-Inch Shock Tunnel with a nitrogen flow field to preclude combustion of the hydrogen coolant gas. A two-dimensional highly instrumented model developed in a previous test series was used. Parameters investigated included coolant mass flow rate, coolant gas, local free-stream Reynolds number, incident oblique shock strength, and a swept oblique shock. Both gases were highly effective coolants in undisturbed flow; however, both incident and swept shocks degraded that effectiveness.
Fourth American Physical Society Topical Conference on Shock Waves in Condensed Matter
Shock Waves in Condensed Matter
1986-01-01
The Fourth American Physical Society Topical Conference on Shock Waves in Condensed Matter was held in Spokane, Washington, July 22-25, 1985. Two hundred and fifty scientists and engineers representing thirteen countries registered at the conference. The countries represented included the United States of America, Australia, Canada, The People's Repub lic of China, France, India, Israel, Japan, Republic of China (Taiwan), United Kingdom, U. S. S. R, Switzerland and West Germany. One hundred and sixty-two technical papers, cov ering recent developments in shock wave and high pressure physics, were presented. All of the abstracts have been published in the September 1985 issue of the Bulletin of the American Physical Society. The topical conferences, held every two years since 1979, have become the principal forum for shock wave studies in condensed materials. Both formal and informal technical discussions regarding recent developments conveyed a sense of excitement. Consistent with the past conferences, th...
Current evidence of extracorporeal shock wave therapy in chronic Achilles tendinopathy.
Gerdesmeyer, Ludger; Mittermayr, Rainer; Fuerst, Martin; Al Muderis, Munjed; Thiele, Richard; Saxena, Amol; Gollwitzer, Hans
2015-12-01
Chronic Achilles tendinopathy has been described as the most common overuse injury in sports medicine. Several treatment modalities such as activity modification, heel lifts, arch supports, stretching exercises, nonsteroidal anti-inflammatories, and eccentric loading are known as standard treatment mostly without proven evidence. After failed conservative therapy, invasive treatment may be considered. Extracorporeal shock wave therapy (ESWT) has been successfully used in soft-tissue pathologies like lateral epicondylitis, plantar fasciitis, tendinopathy of the shoulder and also in bone and skin disorders. Conclusive evidence recommending ESWT as a treatment for Achilles tendinopathy is still lacking. In plantar fasciitis as well as in calcific shoulder tendinopathy shock wave therapy is recently the best evaluated treatment option. This article analysis the evidence based literature of ESWT in chronic Achilles tendinopathy. Recently published data have shown the efficacy of focused and radial extracorporeal shock wave therapy. Copyright © 2015 IJS Publishing Group Limited. All rights reserved.
International Nuclear Information System (INIS)
Maevskii, K. K.; Kinelovskii, S. A.
2015-01-01
The numerical results of modeling of shock wave loading of mixtures with the SiO 2 component are presented. The TEC (thermodynamic equilibrium component) model is employed to describe the behavior of solid and porous multicomponent mixtures and alloys under shock wave loading. State equations of a Mie–Grüneisen type are used to describe the behavior of condensed phases, taking into account the temperature dependence of the Grüneisen coefficient, gas in pores is one of the components of the environment. The model is based on the assumption that all components of the mixture under shock-wave loading are in thermodynamic equilibrium. The calculation results are compared with the experimental data derived by various authors. The behavior of the mixture containing components with a phase transition under high dynamic loads is described
Propagating Structure Of A Microwave Driven Shock wave Inside A Tube
International Nuclear Information System (INIS)
Shimada, Yutaka; Shibata, Teppei; Yamaguchi, Toshikazu; Komurasaki, Kimiya; Oda, Yasuhisa; Kajiwara, Ken; Takahashi, Koji; Kasugai, Atsushi; Sakamoto, Keishi; Arakawa, Yoshihiro
2010-01-01
The thrust generation process of a microwave rocket is similar to a pulse detonation engine, and understanding the interactions between microwave plasma and shock waves is important. Shadowgraph images of the microwave plasma generated in a tube under atmospheric air were taken. The observed plasma and shock wave were propagating one-dimensionally at constant velocity inside the tube. In order to understand the flow field inside the rocket, one-dimensional CFD analysis was conducted. With the change of microwave power density, the structure of the flow field was classified into two regimes: Microwave Supported Combustion (MSC), and Microwave Supported Detonation (MSD). The structure of the MSD was different from the structure of a chemical detonation, which implied the existence of a preheating in front of the shock wave. Furthermore, the flight performance was estimated by calculating the momentum coupling coefficient. It was confirmed that the efficiency was nearly constant in the MSD regime, with the increase of microwave power density.
International Nuclear Information System (INIS)
Yakubovich, Alexander V.; Surdutovich, Eugene; Solov’yov, Andrey V.
2012-01-01
We report on the results of full-atom molecular dynamics simulations of the heat spike in the water medium caused by the propagation of the heavy ion in the vicinity of its Bragg peak. High rate of energy transfer from an ion to the molecules of surrounding water environment leads to the rapid increase of the temperature of the molecules in the vicinity of ions trajectory. As a result of an abrupt increase of the temperature we observe the formation of the nanoscale shock wave propagating through the medium. We investigate the thermomechanical damage caused by the shock wave to the nucleosome located in the vicinity of heavy ion trajectory. We observe the substantial deformation of the DNA secondary structure. We show that the produced shock wave can lead to the thermomechanical breakage of the DNA backbone covalent bonds and present estimates for the number of such strand brakes per one cell nucleus.
State equations and stability of shock wave fronts in homogeneous and heterogeneous metallic medium
International Nuclear Information System (INIS)
Romain, Jean-Pierre
1977-01-01
This research thesis in physical sciences reports a theoretical and experimental study of some mechanical and thermodynamic aspects related to a shock wave propagation in homogeneous and heterogeneous metallic media: state equations, stability and instability of shock wave fronts. In the first part, the author reports the study of the Grueneisen coefficient for some metallic elements with known static and dynamic compression properties. The second part reports the experimental investigation of dynamic compressibility of some materials (lamellar Al-Cu compounds). The front shock wave propagation has been visualised, and experimental Hugoniot curves are compared with those deduced from a developed numeric model and other models. The bismuth Hugoniot curve is also determined, and the author compares the existence and nature of phase transitions obtained by static and dynamic compression
Streaked optical pyrometer system for laser-driven shock-wave experiments on OMEGA.
Miller, J E; Boehly, T R; Melchior, A; Meyerhofer, D D; Celliers, P M; Eggert, J H; Hicks, D G; Sorce, C M; Oertel, J A; Emmel, P M
2007-03-01
The temperature of laser-driven shock waves is of interest to inertial confinement fusion and high-energy-density physics. We report on a streaked optical pyrometer that measures the self-emission of laser-driven shocks simultaneously with a velocity interferometer system for any reflector (VISAR). Together these diagnostics are used to obtain the temporally and spatially resolved temperatures of approximately megabar shocks driven by the OMEGA laser. We provide a brief description of the diagnostic and how it is used with VISAR. Key spectral calibration results are discussed and important characteristics of the recording system are presented.
Formation and damping of a shock wave induced by laser in a metallic target
International Nuclear Information System (INIS)
Cottet, F.
1981-01-01
In the first part of this work, a numerical simulation of the formation and of the damping of the shock wave induced in a solid target by a laser impulse is developed. It allows to interpret the experimental obtained in the second part of the study. Two series of experiments have been realized. An iron target metallographic study is intended to verify if laser shocks produce effects comparable with conventional shocks, particularly a deformation by albite twinning the existence of which is related to the shock amplitude and its evolution during the propagation in the target. Macles observation become a possible mean to estimate the value of the induced pressures. Another experiment series has been realized to determine more directly the shock parameters. Piezoelectric cermets have been used to detect a shock-wave passage and to measure the time taken to go through targets of variable thickness. The numerical solution allows, afterwards, to deduce the maximum pressure of the induced shock. The most part of the tests have been done on copper targets, the behaviour of which is well known in a large pressure domain. Some tests have been realized on aluminium and iron targets [fr
A study on early microstructural changes in the rabbit kidney induced by shock waves
International Nuclear Information System (INIS)
Cha, Kyung Soo; Shim, Hyung Jin; Kim, Kun Sang; Song, In Sup; Lee, Yong Chul; Song, Kei Yong
1993-01-01
Many reports have been published on the tissue damage of a shock wave with respect to histopathological changes in light microscopy and various imaging modalities. However, the studies on the electron microscopic findings and cause of renal functional change such as parenchymal obstructive pattern following extracorporeal shock wave lithotripsy (ESWL) have not been elucidated. In order to evaluate the microstructural changes after shock wave exposure, gross, light microscopic and transmission electron microscopic findings were analyzed with rabbit kidneys. Preliminary study (n=2) was performed to determine the dosage intensity of shock waves to inflict damage, using a EDAP LT 01 piezoelectric extracorporeal shock wave lithotriptor. A shock wave of various intensities were given to the left kidneys of 3 different groups of rabbits. Storage of value of 100, 50, 25 at rate of 20/sec under 87% power were given to group I (n=4), group II (n=4), and group III (n=3) respectively. The right kidneys were preserved as the control group. The rabbits were killed 6-12 hour later. In gross, there were a few subcapsular hemorrhage foci and mild congestion of corticomedullary junction without a large hematoma formation. No significant differences were noted between each group. Light microscopic findings were mainly hydropic changes in the proximal convoluted tubules and congestion without significant necrotic changes. The observed pathologic changes in the transmission electron microscopy were vacuolization of cytoplasm with swelling of epithelial cells especially porximal convoluted tubules. There were also tubular obstruction due to swelling and desquamation of epithelial cells into tubular lumen. The structural changes of intracellular organelles were not found at storage values of 25 and 50. But dilatation and structural alterations of endoplasmic reticulums were noted at value of 100 with cell membrane rupture. The findings of this study suggest that tubular obstructions with
A Discontinuous Galerkin Method for Two-Dimensional Shock Wave Modeling
Directory of Open Access Journals (Sweden)
W. Lai
2011-01-01
Full Text Available A numerical scheme based on discontinuous Galerkin method is proposed for the two-dimensional shallow water flows. The scheme is applied to model flows with shock waves. The form of shallow water equations that can eliminate numerical imbalance between flux term and source term and simplify computation is adopted here. The HLL approximate Riemann solver is employed to calculate the mass and momentum flux. A slope limiting procedure that is suitable for incompressible two-dimensional flows is presented. A simple method is adapted for flow over initially dry bed. A new formulation is introduced for modeling the net pressure force and gravity terms in discontinuous Galerkin method. To validate the scheme, numerical tests are performed to model steady and unsteady shock waves. Applications include circular dam break with shock, shock waves in channel contraction, and dam break in channel with 45∘ bend. Numerical results show that the scheme is accurate and efficient to model two-dimensional shallow water flows with shock waves.
A fast estimation of shock wave pressure based on trend identification
Yao, Zhenjian; Wang, Zhongyu; Wang, Chenchen; Lv, Jing
2018-04-01
In this paper, a fast method based on trend identification is proposed to accurately estimate the shock wave pressure in a dynamic measurement. Firstly, the collected output signal of the pressure sensor is reconstructed by discrete cosine transform (DCT) to reduce the computational complexity for the subsequent steps. Secondly, the empirical mode decomposition (EMD) is applied to decompose the reconstructed signal into several components with different frequency-bands, and the last few low-frequency components are chosen to recover the trend of the reconstructed signal. In the meantime, the optimal component number is determined based on the correlation coefficient and the normalized Euclidean distance between the trend and the reconstructed signal. Thirdly, with the areas under the gradient curve of the trend signal, the stable interval that produces the minimum can be easily identified. As a result, the stable value of the output signal is achieved in this interval. Finally, the shock wave pressure can be estimated according to the stable value of the output signal and the sensitivity of the sensor in the dynamic measurement. A series of shock wave pressure measurements are carried out with a shock tube system to validate the performance of this method. The experimental results show that the proposed method works well in shock wave pressure estimation. Furthermore, comparative experiments also demonstrate the superiority of the proposed method over the existing approaches in both estimation accuracy and computational efficiency.
Experimental and numerical investigations of shock wave propagation through a bifurcation
Marty, A.; Daniel, E.; Massoni, J.; Biamino, L.; Houas, L.; Leriche, D.; Jourdan, G.
2018-02-01
The propagation of a planar shock wave through a split channel is both experimentally and numerically studied. Experiments were conducted in a square cross-sectional shock tube having a main channel which splits into two symmetric secondary channels, for three different shock wave Mach numbers ranging from about 1.1 to 1.7. High-speed schlieren visualizations were used along with pressure measurements to analyze the main physical mechanisms that govern shock wave diffraction. It is shown that the flow behind the transmitted shock wave through the bifurcation resulted in a highly two-dimensional unsteady and non-uniform flow accompanied with significant pressure loss. In parallel, numerical simulations based on the solution of the Euler equations with a second-order Godunov scheme confirmed the experimental results with good agreement. Finally, a parametric study was carried out using numerical analysis where the angular displacement of the two channels that define the bifurcation was changed from 90° , 45° , 20° , and 0° . We found that the angular displacement does not significantly affect the overpressure experience in either of the two channels and that the area of the expansion region is the important variable affecting overpressure, the effect being, in the present case, a decrease of almost one half.
On the efficiency of Gore-Tex layer for brain protection from shock wave damage in cranioplasty
Saito, T.; Voinovich, P. A.; Nakagawa, A.; Hosseini, S. H. R.; Takayama, K.; Hirano, T.
2004-11-01
The effectiveness of a Gore-Tex layer for protecting soft tissue from damage in shock wave therapy is investigated analytically, numerically and experimentally. Analytical considerations based on the fundamentals of wave dynamics and two-dimensional numerical simulations based on the elastodynamic equations are carried out for underwater shock wave propagation and interaction with Gore-Tex membrane models of different complexity. The results clearly demonstrate that considerable attenuation of shock waves with Gore-Tex is due to the air trapped inside the membrane. The experimental results confirm that a Gore-Tex sheet placed in the liquid reduces the transmitted shock wave peak overpressure significantly, by up to two orders of magnitude. Another experimental series reveals what kind of damage in the rat brain tissue can be caused by shock waves of different intensity.
Cosmic Rays Accelerated at Cosmological Shock Waves Renyi Ma1 ...
Indian Academy of Sciences (India)
Abstract. Based on hydrodynamic numerical simulations and diffusive shock acceleration model, we calculated the ratio of cosmic ray (CR) to thermal energy. We found that the CR fraction can be less than ∼ 0.1 in the intracluster medium, while it would be of order unity in the warm-hot intergalactic medium. Key words.
Shock wave structure in an ideal dissociating gas
Liu, K. H.
1975-01-01
Composition changes within the shock layer due to chemical reactions are considered. The Lighthill ideal dissociating gas model was used in an effort to describe the oxygen type molecule. First, the two limiting cases, when the chemical reaction rates are very slow and very fast in comparison to local convective rates, are investigated. Then, the problem is solved for arbitrary chemical reaction rates.
Experimental investigation of a collisionless shock wave in a longitudinal magnetic field
International Nuclear Information System (INIS)
El-Khalafawy, T.A.; El-Nicklawy, M.; Beshara, A.B.; Abo-Ellil, M.S.
1978-01-01
The results of the experimental investigations of the parameters and the structure of a shock wave propagating along a static magnetic field are discussed. It is also shown that the wave observed experimentally represents a ''switch-on'' shock and its front structure is determined by the mechanism of the energy collisionless dissipation. In case of small Alfvene-Mach numbers I 3 smaller than the conductivity caused by Coulombs' collisions. The paper describes briefly the installation and also the probe methods of measuring the main plasma parameters, (the electron temperature Tsub(e) and the density nsub(e))
High-energy effective action from scattering of QCD shock waves
Energy Technology Data Exchange (ETDEWEB)
Ian Balitsky
2005-07-01
At high energies, the relevant degrees of freedom are Wilson lines - infinite gauge links ordered along straight lines collinear to the velocities of colliding particles. The effective action for these Wilson lines is determined by the scattering of QCD shock waves. I develop the symmetric expansion of the effective action in powers of strength of one of the shock waves and calculate the leading term of the series. The corresponding first-order effective action, symmetric with respect to projectile and target, includes both up and down fan diagrams and pomeron loops.
Can cellulite be treated with low-energy extracorporeal shock wave therapy?
Angehrn, Fiorenzo; Kuhn, Christoph; Voss, Axel
2007-01-01
The present study investigates the effects of low-energy defocused extracorporeal generated shock waves on collagen structure of cellulite afflicted skin. Cellulite measurement using high-resolution ultrasound technology was performed before and after low-energy defocused extracorporeal shock wave therapy (ESWT) in 21 female subjects. ESWT was applied onto the skin at the lateral thigh twice a week for a period of six weeks. Results provide evidence that low-energy defocused ESWT caused remodeling of the collagen within the dermis of the tested region. Improving device-parameters and therapy regimes will be essential for future development of a scientific based approach to cellulite treatment. PMID:18225463
Vorozhtsov, S. A.; Kudryashova, O. B.; Lerner, M. I.; Vorozhtsov, A. B.; Khrustalyov, A. P.; Pervikov, A. V.
2017-11-01
The authors consider and evaluate the physical parameters and regularities of the process of consolidation of Fe-Cu, Cu-Nb, Ag-Ni, Fe-Pb nanoparticles when creating composite materials by means of shock wave compaction. As a result of theoretical consideration of explosive compaction process, researchers established and discussed the physical process conditions, established a number of threshold pressure values corresponding to different target indicators of the state of the compact. The time of shock wave impact on powders for powder consolidation was estimated.
International Nuclear Information System (INIS)
Eibl, J.; Ockert, J.
1994-01-01
Especially the need to design safe reactor containments, but also the necessity to protect facilities and human beings against impacts induced secondarily by explosions and detonations, demand simulations and design calculations of concrete under shock wave loading. The necessary computer codes are available, but the relevant constitutive laws for concrete with volumetric pressures up to more than 10000 MPa are lacking. Therefore shock wave tests have been carried out to develop such constitutive laws by loading concrete slabs with contact explosions. By the use of hot-molded carbon composition resistors shock waves propagating through the slab were measured. Pressures up to 13900 MPa were registered. Additionally shock wave velocities were determined from the different arrival times of the wave at the gages. By these two measured values and the conservation equations of mass and momentum the needed p-V relationship, the so called Hugoniot-Curve, was established up to 13900 MPa. Using the theory of Mie-Grueneisen and the so called P-α model the Hugoniot-Curve was extended to the equation of state for concrete. In a first step the deviatoric part of the constitutive law was attached from own static experiments considering the existing knowledge of strain rate effects since relevant dynamic tests under extreme loads are not available. With this constitutive law the analysis of the experiments then was backward verified in detail. (orig.) [de
Han, Ruoyu; Zhou, Haibin; Wu, Jiawei; Qiu, Aici; Ding, Weidong; Zhang, Yongmin
2017-09-01
An experimental study of pressure waves generated by an exploding copper wire in a water medium is performed. We examined the effects of energy deposited at different stages on the characteristics of the resulting shock waves. In the experiments, a microsecond time-scale pulsed current source was used to explode a 300-μm-diameter, 4-cm-long copper wire with initial stored energies ranging from 500 to 2700 J. Our experimental results indicated that the peak pressure (4.5-8.1 MPa) and energy (49-287 J) of the shock waves did not follow a simple relationship with any electrical parameters, such as peak voltage or deposited energy. Conversely, the impulse had a quasi-linear relationship with the parameter Π. We also found that the peak pressure was mainly influenced by the energy deposited before separation of the shock wave front and the discharge plasma channel (DPC). The decay time constant of the pressure waveform was affected by the energy injection after the separation. These phenomena clearly demonstrated that the deposited energy influenced the expansion of the DPC and affected the shock wave characteristics.
SHOCKFIND - an algorithm to identify magnetohydrodynamic shock waves in turbulent clouds
Lehmann, Andrew; Federrath, Christoph; Wardle, Mark
2016-11-01
The formation of stars occurs in the dense molecular cloud phase of the interstellar medium. Observations and numerical simulations of molecular clouds have shown that supersonic magnetized turbulence plays a key role for the formation of stars. Simulations have also shown that a large fraction of the turbulent energy dissipates in shock waves. The three families of MHD shocks - fast, intermediate and slow - distinctly compress and heat up the molecular gas, and so provide an important probe of the physical conditions within a turbulent cloud. Here, we introduce the publicly available algorithm, SHOCKFIND, to extract and characterize the mixture of shock families in MHD turbulence. The algorithm is applied to a three-dimensional simulation of a magnetized turbulent molecular cloud, and we find that both fast and slow MHD shocks are present in the simulation. We give the first prediction of the mixture of turbulence-driven MHD shock families in this molecular cloud, and present their distinct distributions of sonic and Alfvénic Mach numbers. Using subgrid one-dimensional models of MHD shocks we estimate that ˜0.03 per cent of the volume of a typical molecular cloud in the Milky Way will be shock heated above 50 K, at any time during the lifetime of the cloud. We discuss the impact of this shock heating on the dynamical evolution of molecular clouds.
Influence of shock waves from plasma actuators on transonic and supersonic airflow
Mursenkova, I. V.; Znamenskaya, I. A.; Lutsky, A. E.
2018-03-01
This paper presents experimental and numerical investigations of high-current sliding surface discharges of nanosecond duration and their effect on high-speed flow as plasma actuators in a shock tube. This study deals with the effectiveness of a sliding surface discharge at low and medium air pressure. Results cover the electrical characteristics of the discharge and optical visualization of the discharge and high-speed post-discharge flow. A sliding surface discharge is first studied in quiescent air conditions and then in high-speed flow, being initiated in the boundary layer at a transverse flow velocity of 50-950 m s-1 behind a flat shock wave in air of density 0.04-0.45 kg m-3. The discharge is powered by a pulse voltage of 25-30 kV and the electric current is ~0.5 kA. Shadow imaging and particle image velocimetry (PIV) are used to measure the flow field parameters after the pulse surface discharge. Shadow imaging reveals shock waves originating from the channels of the discharge configurations. PIV is used to measure the velocity field resulting from the discharge in quiescent air and to determine the homogeneity of energy release along the sliding discharge channel. Semicylindrical shock waves from the channels of the sliding discharge have an initial velocity of more than 600 m s-1. The shock-wave configuration floats in the flow along the streamlined surface. Numerical simulation based on the equations of hydrodynamics matched with the experiment showed that 25%-50% of the discharge energy is instantly transformed into heat energy in a high-speed airflow, leading to the formation of shock waves. This energy is comparable to the flow enthalpy and can result in significant modification of the boundary layer and the entire flow.
Polymorphic transition of tin under shock wave compression: Experimental results
Directory of Open Access Journals (Sweden)
Sinatti F.
2012-08-01
Full Text Available In this work, the β-bct polymorphic transition in tin is investigated by means of plate impact experiments. The Sn target surface is observed in a partially released state obtained thanks to a transparent lithium fluoride (LiF anvil. We report both measurements of interface velocity and temperature obtained using Photon Doppler Velocimetry and IR optical pyrometer on shock-loaded tin from 8 to 16 GPa. We show that the Mabire Model EOS associated to the SCG plasticity model provides an overall good estimate of the velocity profiles. However, depnding on the shock amplitude, its prediction of the temperature profile may be less satisfactory, hence underlining the need for future improvements in terms of phase transition kinetics description.
Predictions of lithium interactions with earth's bow shock in the presence of wave activity
Decker, R. B.; Lui, A. T. Y.; Vlahos, L.
1984-01-01
The results of a test-particle simulation studying the movement of a lithium tracer ion injected upstream of the bow shock are reported. Wave activity consists of parallel and antiparallel propagating Alfven waves characterized by a frequency power spectrum within a frequency or range of amplitudes defined separately in the upstream and downstream regions. The results show that even a moderate level of wave activity can substantially change the results obtained in the absence of waves. Among the effects observed are: (1) increased ion transmission; (2) both the average energy gain and spread about the average are increased for transmitted and reflected particles; (3) the average final pitch angle for transmitted particles tends to 90 deg, and the spread of reflected particles is reduced; and (4) the spatial dispersion of the ions on the bow shock after a single encounter is increased.
CARBON, HELIUM, AND PROTON KINETIC TEMPERATURES IN A CYGNUS LOOP SHOCK WAVE
International Nuclear Information System (INIS)
Raymond, John C.; Edgar, Richard J.; Ghavamian, Parviz; Blair, William P.
2015-01-01
Observations of SN 1006 have shown that ions and electrons in the plasma behind fast supernova remnant shock waves are far from equilibrium, with the electron temperature much lower than the proton temperature and ion temperatures approximately proportional to ion mass. In the ∼360 km s −1 shock waves of the Cygnus Loop, on the other hand, electron and ion temperatures are roughly equal, and there is evidence that the oxygen kinetic temperature is not far from the proton temperature. In this paper, we report observations of the He ii λ1640 line and the C iv λ1550 doublet in a 360 km s −1 shock in the Cygnus Loop. While the best-fit kinetic temperatures are somewhat higher than the proton temperature, the temperatures of He and C are consistent with the proton temperature and the upper limits are 0.5 and 0.3 times the mass-proportional temperatures, implying efficient thermal equilibration in this collisionless shock. The equilibration of helium and hydrogen affects the conversion between proton temperatures determined from Hα line profiles and shock speeds, and the efficient equilibration found here reduces the shock speed estimates and the distance estimate to the Cygnus Loop of Medina et al. to about 800 pc
Characterizing shock waves in hydrogel using high speed imaging and a fiber-optic probe hydrophone
Anderson, Phillip A.; Betney, M. R.; Doyle, H. W.; Tully, B.; Ventikos, Y.; Hawker, N. A.; Roy, Ronald A.
2017-05-01
The impact of a stainless steel disk-shaped projectile launched by a single-stage light gas gun is used to generate planar shock waves with amplitudes on the order of 102MPa in a hydrogel target material. These shock waves are characterized using ultra-high-speed imaging as well as a fiber-optic probe hydrophone. Although the hydrogel equation of state (EOS) is unknown, the combination of these measurements with conservation of mass and momentum allows us to calculate pressure. It is also shown that although the hydrogel behaves similarly to water, the use of a water EOS underpredicts pressure amplitudes in the hydrogel by ˜10 % at the shock front. Further, the water EOS predicts pressures approximately 2% higher than those determined by conservation laws for a given value of the shock velocity. Shot to shot repeatability is controlled to within 10%, with the shock speed and pressure increasing as a function of the velocity of the projectile at impact. Thus the projectile velocity may be used as an adequate predictor of shock conditions in future work with a restricted suite of diagnostics.
Nonstandard Analysis and Shock Wave Jump Conditions in a One-Dimensional Compressible Gas
Energy Technology Data Exchange (ETDEWEB)
Roy S. Baty, F. Farassat, John A. Hargreaves
2007-05-25
Nonstandard analysis is a relatively new area of mathematics in which infinitesimal numbers can be defined and manipulated rigorously like real numbers. This report presents a fairly comprehensive tutorial on nonstandard analysis for physicists and engineers with many examples applicable to generalized functions. To demonstrate the power of the subject, the problem of shock wave jump conditions is studied for a one-dimensional compressible gas. It is assumed that the shock thickness occurs on an infinitesimal interval and the jump functions in the thermodynamic and fluid dynamic parameters occur smoothly across this interval. To use conservations laws, smooth pre-distributions of the Dirac delta measure are applied whose supports are contained within the shock thickness. Furthermore, smooth pre-distributions of the Heaviside function are applied which vary from zero to one across the shock wave. It is shown that if the equations of motion are expressed in nonconservative form then the relationships between the jump functions for the flow parameters may be found unambiguously. The analysis yields the classical Rankine-Hugoniot jump conditions for an inviscid shock wave. Moreover, non-monotonic entropy jump conditions are obtained for both inviscid and viscous flows. The report shows that products of generalized functions may be defined consistently using nonstandard analysis; however, physically meaningful products of generalized functions must be determined from the physics of the problem and not the mathematical form of the governing equations.
Studies of Shock Wave Interaction with a Curtain of Massive Particles
Lingampally, Sumanth Reddy; Wayne, Patrick; Cooper, Sean; Izard, Ricardo Gonzalez; Jacobs, Gustaaf; Vorobieff, Peter
2017-11-01
Interaction of a shock wave with planar and perturbed curtain of massive particles is studied experimentally. To form the curtain, solid soda lime particles (30-50 micron diameter) are dropped from a hopper fitted with mesh sieves and vibrated with a motor. The curtain forms when the particles move through a rectangular slot in the top of the test section of the shock tube used in experiment. The curtain can be either planar or perturbed in the horizontal plane (parallel to the shock direction) based on the shape of the slot. This setup generates a particle curtain with a volume fraction varying between 2 and 8 percent along its vertical height. A laser illuminates the curtain in vertical and horizontal planes. When the diaphragm separating the driver and the driven section is ruptured, shock waves with Mach numbers ranging from 1 to 2, depending on the pressure, propagate down the driven section and into test section. The phenomena following the shock wave impingement on the particle curtain are captured using an Apogee Alta U42 camera. This work is supported by the National Science Foundation Grant 1603915/1603326.
A Time-Domain Method for Separating Incident and Reflected Irregular Waves
DEFF Research Database (Denmark)
Frigaard, Peter; Brorsen, Michael
of the model test. Goda and Suzuki (1976) presented a frequency method for estimation of irregular incident and reflected waves in random waves. Mansard and Funke (1980) improved this method uaing a least squares technique. In the following, a time-domain method for seperating the incident waves...
Dynamics of cylindrical converging shock waves interacting with aerodynamic obstacle arrays
International Nuclear Information System (INIS)
Vignati, F.; Guardone, A.
2015-01-01
Cylindrical converging shock waves interacting with an array of aerodynamic obstacles are investigated numerically for diverse shock 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 shock focus point (r LE )/(r LE ref ) are 1, 2, and 2.5, where r LE ref =7 is the dimensionless reference distance from the origin. Considered impinging shock Mach numbers M 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 LE =7,M s =2.7) was proposed by Kjellander et al. [“Thermal radiation from a converging shock implosion,” Phys. Fluids 22, 046102 (2010)]. Numerical results compare fairly well to available one-dimensional models for shock propagation and to available experimental results in the reference configuration. Local reflection types are in good agreement with the classical criteria for planar shock waves. The main shock reshaping patterns are identified and their dependence on the shock strength and obstacle configuration is exposed. In particular, different shock patterns are observed after the leading edge reflection, which results in polygonal shock wave 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 LE ref . In terms of compression efficiency at the origin, the 16-obstacle configuration is found to perform slightly better than the reference 8-obstacle configuration—with an efficiency increase of about 2%-3%, which is well within the model accuracy—thus confirming the goodness of the obstacle arrangement proposed by Kjellander and collaborators
Experimental study of the Richtmyer-Meshkov instability induced by a Mach 3 shock wave
International Nuclear Information System (INIS)
BP Puranik; JG Oakley; MH Anderson; R Bonaazza
2003-01-01
OAK-B135 An experimental investigation of a shock-induced interfacial instability (Richtmyer-Meshkov instability) is undertaken in an effort to study temporal evolution of interfacial perturbations in the late stages of development. The experiments are performed in a vertical shock tube with a square cross-section. A membraneless interface is prepared by retracting a sinusoidally shaped metal plate initially separating carbon dioxide from air, with both gases initially at atmospheric pressure. With carbon dioxide above the plate, the Rayleigh-Taylor instability commences as the plate is retracted and the amplitude of the initial sinusoidal perturbation imposed on the interface begins to grow. The interface is accelerated by a strong shock wave (M=3.08) while its shape is still sinusoidal and before the Kelvin-Helmhotz instability distorts it into the well known mushroom-like structures; its initial amplitude to wavelength ratio is large enough that the interface evolution enters its nonlinear stage very shortly after shock acceleration. The pre-shock evolution of the interface due to the Rayleigh-Taylor instability and the post-shock evolution of the interface due to the Richtmyer-Meshkov instability are visualized using planar Mie scattering. The pre-shock evolution of the interface is carried out in an independent set of experiments. The initial conditions for the Richtmyer-Meshkov experiment are determined from the pre-shock Rayleigh-Taylor growth. One image of the post-shock interface is obtained per experiment and image sequences, showing the post-shock evolution of the interface, are constructed from several experiments. The growth rate of the perturbation amplitude is measured and compared with two recent analytical models of the Richtmyer-Meshkov instability
Heat-flow equation motivated by the ideal-gas shock wave.
Holian, Brad Lee; Mareschal, Michel
2010-08-01
We present an equation for the heat-flux vector that goes beyond Fourier's Law of heat conduction, in order to model shockwave propagation in gases. Our approach is motivated by the observation of a disequilibrium among the three components of temperature, namely, the difference between the temperature component in the direction of a planar shock wave, versus those in the transverse directions. This difference is most prominent near the shock front. We test our heat-flow equation for the case of strong shock waves in the ideal gas, which has been studied in the past and compared to Navier-Stokes solutions. The new heat-flow treatment improves the agreement with nonequilibrium molecular-dynamics simulations of hard spheres under strong shockwave conditions.
Heat-flow equation motivated by the ideal-gas shock wave
Holian, Brad Lee; Mareschal, Michel
2010-08-01
We present an equation for the heat-flux vector that goes beyond Fourier’s Law of heat conduction, in order to model shockwave propagation in gases. Our approach is motivated by the observation of a disequilibrium among the three components of temperature, namely, the difference between the temperature component in the direction of a planar shock wave, versus those in the transverse directions. This difference is most prominent near the shock front. We test our heat-flow equation for the case of strong shock waves in the ideal gas, which has been studied in the past and compared to Navier-Stokes solutions. The new heat-flow treatment improves the agreement with nonequilibrium molecular-dynamics simulations of hard spheres under strong shockwave conditions.
Propagation of interplanetary shock waves by observations of type II solar radio bursts on IMP-6
International Nuclear Information System (INIS)
Chertok, I.M.; Fomichev, V.V.
1976-01-01
A new interpretation of the low frequency type II solar radio bursts of 30 June 1971, and 7-8 August 1972 observed with IMP-6 satellite (Malitson, H.H., Fainberg, J. and Stone, R.G., 1973, Astrophys. Lett., vol. 14, 111; Astrophys. J., vol. 183, L35) is suggested. The analysis is carried out for two models of the electron density distribution in the interplanetary medium taking into account that N approximately 3.5 cm -3 at a distance of 1 a.u. It is assumed that the frequency of the radio emission corresponds to the average electron density behind the shock front which exceeds the undisturbed electron density by the factor of 3. The radio data indicate essential deceleration of the shock waves during propagation from the Sun up to 1 a.u. The characteristics of the shock waves obtained from the type II bursts agree with the results of the in situ observations. (author)
Limits of shock wave ignition of hydrogen–oxygen mixture in the presence of particles
Efremov, V. P.; Obruchkova, L. R.; Ivanov, M. F.; Kiverin, A. D.
2018-01-01
It is a well known fact that the cloud of non-reacting particles in the flow weakens or even suppresses the detonation. Contrary to this phenomenon there are experimental data showing that the presence of solid particles in the combustible mixtures shorten significantly the ignition delay time. In other words particles could promote the initiation of detonation. This paper analyzes numerically the phenomenon of detonation initiation behind the shock wave in the combustible mixture containing only one solid particle. Numerical results demonstrate a significant degree of lowering of ignition limits. Namely, it is shown that it becomes possible to ignite the gaseous mixture much earlier due to the shock wave interaction with solid particle surface. It is found that ignition arises in subsonic region located between the particle and the bow shock front.
The effect of suppressors and muzzle brakes on shock wave strength
Phan, K. C.; Stollery, J. L.
Experimental simulations of a gun blast were performed in the course of an optimization study of shock-wave suppressor and muzzle-brake geometry. A single-spark schlieren system was used to photograph the shock waves emerging from a 32-mm shock tube. The suppressor systems tested with respect to the overpressure level included a perforated tube enclosed in an expansion chamber, a cup-and-box suppressor, and noise-absorbent materials inside a suppressor; high suppression efficiency was observed for the first two. Recoil simulation tests, performed with plain and pyramidal baffles, disk, and cylinder, show that the blast level is generally higher for a more efective muzzle brake. An optimum distance from the muzzle to the brake is suggested to be in the region of one caliber.
Laser driven shock wave experiments for equation of state studies at megabar pressures
International Nuclear Information System (INIS)
Pant, H C; Shukla, M; Senecha, V K; Bandyopadhyay, S; Rai, V N; Khare, P; Bhat, R K; Gupta, N K; Godwal, B K
2002-01-01
We present the results from laser driven shock wave experiments for equation of state (EOS) studies of gold metal. An Nd:YAG laser chain (2 J, 1.06 μm wavelength, 200 ps pulse FWHM) is used to generate shocks in planar Al foils and Al + Au layered targets. The EOS of gold in the pressure range of 9-13 Mbar is obtained using the impedance matching technique. The numerical simulations performed using the one-dimensional radiation hydrodynamic code support the experimental results. The present experimental data show remarkable agreement with the existing standard EOS models and with other experimental data obtained independently using laser driven shock wave experiments
1987-02-01
The eruption of the Krakatoa volcano in the magnetopause cavity contains the famous Van Allen radia- 1883 in Indonesia is estimated to have had an... Krakatoa . The airborne ash caused "a shock-wave phenomena in space, one of the most interesting is year without a summer" in 1816 and 12.000 people were
Experimental Study on Peak Pressure of Shock Waves in Quasi-Shallow Water
Directory of Open Access Journals (Sweden)
Zhenxiong Wang
2015-01-01
Full Text Available Based on the similarity laws of the explosion, this research develops similarity requirements of the small-scale experiments of underwater explosions and establishes a regression model for peak pressure of underwater shock waves under experimental condition. Small-scale experiments are carried out with two types of media at the bottom of the water and for different water depths. The peak pressure of underwater shock waves at different measuring points is acquired. A formula consistent with the similarity law of explosions is obtained and an analysis of the regression precision of the formula confirms its accuracy. Significance experiment indicates that the influence of distance between measuring points and charge on peak pressure of underwater shock wave is the greatest and that of water depth is the least within the range of geometric parameters. An analysis of data from experiments with different media at the bottom of the water reveals an influence on the peak pressure, as the peak pressure of a shock wave in a body of water with a bottom soft mud and rocks is about 1.33 times that of the case where the bottom material is only soft mud.
Effects of radial extracorporeal shock wave therapy on hand spasticity in poststroke patient
Gjerakaroska Savevska, C; Nikolikj Dimitrova, E; Gocevska, M
2016-01-01
Background: Hand spasticity after a stroke greatly increases the difficulties of the daily living activities and limits the effectiveness of rehabilitation. Radial extracorporeal shock wave therapy (RESWT) has been suggested as an alternative treatment for spasticity reduction. We demonstrate the effectiveness of RESWT regarding hand spasticity in a stroke patient.
Effect of air jet vortex generators on a shock wave boundary layer interaction
Souverein, L.J.; Debiève, J.F.
2010-01-01
The effect of upstream injection by means of continuous air jet vortex generators (AJVGs) on a shock wave turbulent boundary layer interaction is experimentally investigated. The baseline interaction is of the impinging type, with a flow deflection angle of 9.5degrees and a Mach number Me = 2.3.
Shock Waves Oscillations in the Interaction of Supersonic Flows with the Head of the Aircraft
Bulat, Pavel V.; Volkov, Konstantin N.
2016-01-01
In this article we reviewed the shock wave oscillation that occurs when supersonic flows interact with conic, blunt or flat nose of aircraft, taking into account the aerospike attached to it. The main attention was paid to the problem of numerical modeling of such oscillation, flow regime classification, and cases where aerospike attachment can…
High density nuclear Mach shock waves in relativistic nucleus-nucleus collisions
International Nuclear Information System (INIS)
Stocker, H.; Hofmann, J.; Scheid, W.; Greiner, W.
1976-01-01
The occurrence of high density nuclear Mach shock waves in relativistic nucleus-nucleus collisions and related phenomena, as density isomers, highly isobaric and hot nuclear matter, pionization and granulation of dense matter, compressibility and soundwaves in nuclear matter, are discussed
Tandem shock waves in medicine and biology: a review of potential applications and successes
Czech Academy of Sciences Publication Activity Database
Lukeš, Petr; Fernández, F.; Gutiérrez-Aceves, J.; Fernández, E.; Alvarez, U.M.; Šunka, Pavel; Loske, A.M.
2016-01-01
Roč. 26, č. 1 (2016), s. 1-23 ISSN 0938-1287 Institutional support: RVO:61389021 Keywords : Tandem shock waves * Acoustic cavitation * Clinical applications * Bactericidal effect * Genetic transformation * Cancer treatment Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.107, year: 2016 http://link.springer.com/ article /10.1007%2Fs00193-015-0577-0
Kijvikai, Kittinut; Haleblian, George E.; Preminger, Glenn M.; de la Rosettet, Jean
2007-01-01
Purpose: The goal of treating ureteral calculi is to achieve complete stone clearance with minimal patient morbidity. Shock wave lithotripsy and ureteroscopy have become standards of care for ureteral calculi. However, the optimal choice of treatment depends on various factors, including stone size,
Lunar cycle may have an effect on Shock Wave Lithotripsy related ...
African Journals Online (AJOL)
Objectives: We tried to investigate the effects of lunar phase on Shock Wave Lithotripsy (SWL) related pain. In addition, correlation of various clinical parameters with the pain perception during SWL procedure, were also investigated. Methods: A total of 378 patients who underwent first SWL sessions for renal or ureteral ...
Role of extracorporeal shock wave lithotripsy in hepato-biliary-pancreatic surgery
R.L. van der Hul (René); P.W. Plaisier; O.T. Terpstra (Onno); H.A. Bruining (Hajo)
1993-01-01
textabstractSince the early 1980s extracorporeal shock wave lithotripsy (ESWL) has partially replaced major operative procedures in various fields of surgery. In the interest of the patient, it is important to determine the exact role of ESWL in surgery. Comparing our own prospectively followed
Flow features that arise due to the interaction of a plane shock wave with concave profiles
CSIR Research Space (South Africa)
MacLucas, David A
2012-10-01
Full Text Available The focus of the author's thesis was the aerodynamic flow field that develops as a result of the interaction of a moving plane shock wave with concave profiles. In this presentation, he discusses some of the interesting flow phenomena that arise...
Spallation reactions in shock waves at supernova explosions and related problems
Energy Technology Data Exchange (ETDEWEB)
Ustinova, G. K., E-mail: ustinova@dubna.net.ru [RAS, V.I. Vernadsky Institute of Geochemistry and Analytical Chemistry (Russian Federation)
2013-05-15
The isotopic anomalies of some extinct radionuclides testify to the outburst of a nearby supernova just before the collapse of the protosolar nebula, and to the fact that the supernova was Sn Ia, i.e. the carbon-detonation supernova. A key role of spallation reactions in the formation of isotopic anomalies in the primordial matter of the Solar System is revealed. It is conditioned by the diffusive acceleration of particles in the explosive shock waves, which leads to the amplification of rigidity of the energy spectrum of particles and its enrichment with heavier ions. The quantitative calculations of such isotopic anomalies of many elements are presented. It is well-grounded that the anomalous Xe-HL in meteoritic nanodiamonds was formed simultaneously with nanodiamonds themselves during the shock wave propagation at the Sn Ia explosion. The possible effects of shock wave fractionation of noble gases in the atmosphere of planets are considered. The origin of light elements Li, Be and B in spallation reactions, predicted by Fowler in the middle of the last century, is argued. All the investigated isotopic anomalies give the evidence for the extremely high magnetohydrodynamics (MHD) conditions at the initial stage of free expansion of the explosive shock wave from Sn Ia, which can be essential in solution of the problem of origin of cosmic rays. The specific iron-enriched matter of Sn Ia and its MHD-separation in turbulent processes must be taking into account in the models of origin of the Solar System.
Tandem shock waves in medicine and biology: a review of potential applications and successes
Czech Academy of Sciences Publication Activity Database
Lukeš, Petr; Fernández, F.; Gutiérrez-Aceves, J.; Fernández, E.; Alvarez, U.M.; Šunka, Pavel; Loske, A.M.
2016-01-01
Roč. 26, č. 1 (2016), s. 1-23 ISSN 0938-1287 Institutional support: RVO:61389021 Keywords : Tandem shock waves * Acoustic cavitation * Clinical applications * Bactericidal effect * Genetic transformation * Cancer treatment Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.107, year: 2016 http://link.springer.com/article/10.1007%2Fs00193-015-0577-0
International Nuclear Information System (INIS)
Lee, Won Hong; Yang, Seon Wook; Uhm, Joon Yong; Cho, Cheong Chan; Ryu, Meung Sun; Kim, Keon Chung
2002-01-01
The pain of chronic pancreatitis associated intraductal stones is related to increased intraductal pressure. Decom-pression of the pancreatic duct along with extraction of stones are the goals of a combined endoscopic-extracorporeal shock wave lithotripsy approach. The aim of this study is to define radiographic prognostic criteria for better complete free rate of pancreatic head and body ductal stones for extracorporeal shock wave lithotripsy. Fifty-nine patients with chronic pancreatitis were treated by extracorporeal shock wave lithotripsy for endoscopically unretrievable stones. The stones on endoscopic retrograde pancreatograms were classified into four characteristics including number, size of longest diameter, density compared with vertebral body, and shape. Complete stone free were obtained in 45 of 59 (76.3%). Pancreatic ductal stones with radiographic characteristics including higher density than vertebral body, square shape, and rim calcified stones were hindrance factors for extracorporeal shock wave lithotripsy. We propose that patients with rim calcified stone of our three hindrance factors should be treated by other technique
A Self-similar Flow Behind a Shock Wave in a Gravitating or Non ...
Indian Academy of Sciences (India)
The propagation of a spherical shock wave in an ideal gas with heat conduction and radiation heat-flux, and with or without self-gravitational effects, is investigated. The initial density of the gas is assumed to obey a power law. The heat conduction is expressed in terms of Fourier's law and the radiation is considered to be of ...
Summary of work on shock wave feature extraction in 3-D datasets
Hesselink, Lambertus (Principal Investigator)
1996-01-01
A method for extracting and visualizing shock waves from three dimensional data-sets is discussed. Issues concerning computation time, robustness to numerical perturbations, and noise introduction are considered and compared with other methods. Finally, results using this method are discussed.
Theoretical investigation of nonequilibrium processes in shock wave in bubbly liquid
Bityurin, V. A.; Velikodnyi, V. Yu.; Bykov, A. A.
The effects related to a translational nonequilibrium at the shock wave front in a bubbly liquid flow with volume gas contents within 0.3 a parts per thousand currency sign phi a parts per thousand currency sign 0.98 have been theoretically studied. Analytical expressions for the longitudinal and
Equation of state for potassium in shock waves at high pressures
Khishchenko, K. V.
2018-01-01
A simple caloric equation-of-state model, which relates the pressure with density and internal energy, is applied for potassium in the bcc-solid and liquid phases. Thermodynamic characteristics along the principal Hugoniot are calculated for the metal and compared with available data from shock-wave experiments at high pressures.
TUMOR-GROWTH DELAY BY LASER-GENERATED SHOCK-WAVES
de Reijke, T. M.; Schamhart, D. H.; Kurth, K. H.; Löwik, C. W.; Donkers, L. H.; Sterenborg, H. J.
1994-01-01
The antiproliferative effect of laser-generated shock waves (L-SW) was investigated on a human renal cell carcinoma, RC-8, grown subcutaneously in the nu/nu mouse. The RC-8 is characterized by the syndrome of humoral hypercalcemia of malignancy (HHM) associated with profound cachexia, increase of
Measuring the flexoelectric coefficient of bulk barium titanate from a shock wave experiment
Hu, Taotao; Deng, Qian; Liang, Xu; Shen, Shengping
2017-08-01
In this paper, a phenomenon of polarization introduced by shock waves is experimentally studied. Although this phenomenon has been reported previously in the community of physics, this is the first time to link it to flexoelectricity, the coupling between electric polarization and strain gradients in dielectrics. As the shock waves propagate in a dielectric material, electric polarization is thought to be induced by the strain gradient at the shock front. First, we control the first-order hydrogen gas gun to impact and generate shock waves in unpolarized bulk barium titanate (BT) samples. Then, a high-precision oscilloscope is used to measure the voltage generated by the flexoelectric effect. Based on experimental results, strain elastic wave theory, and flexoelectric theory, a longitudinal flexoelectric coefficient of the bulk BT sample is calculated to be μ 11 = 17.33 × 10 - 6 C/m, which is in accord with the published transverse flexoelectric coefficient. This method effectively suppresses the majority of drawbacks in the quasi-static and low frequency dynamic techniques and provides more reliable results of flexoelectric behaviors.
Chen, Wen; Maurel, Olivier; La Borderie, Christian; Reess, Thierry; De Ferron, Antoine; Matallah, Mohammed; Pijaudier-Cabot, Gilles; Jacques, Antoine; Rey-Bethbeder, Frank
2014-05-01
The objective of this study is to simulate the propagation of the shock wave in water due to an explosion. The study is part of a global research program on the development of an alternative stimulation technique to conventional hydraulic fracturing in tight gas reservoirs aimed at inducing a distributed state of microcracking of rocks instead of localized fracture. We consider the possibility of increasing the permeability of rocks with dynamic blasts. The blast is a shock wave generated in water by pulsed arc electrohydraulic discharges. The amplitude of these shock waves is prescribed by the electrohydraulic discharges which generate high pressures of several kilobars within microseconds. A simplified method has been used to simulate the injected electrical energy as augmentation of enthalpy in water locally. The finite element code EUROPLEXUS is used to perform fluid fast dynamic computation. The predicted pressure is consistent with the experimental results. In addition, shock wave propagation characteristics predicted with simulation can be valuable reference for design of underwater structural elements and engineering of underwater explosion.
Schropp, Andreas
2013-06-01
The emergence of x-ray sources of the fourth generation, so called x-ray free-electron lasers (XFELs), comes along with completely new research opportunities in various scientific fields. During the last year we developed an x-ray microscope based on beryllium compound refractive lenses (Be-CRLs), which is especially optimized for the XFEL environment and provides focusing capabilities down to 100nm and even below. Based on magnified x-ray phase contrast imaging, this new setup enables us to pursue high-resolution x-ray imaging experiments with single XFEL-pulses. In a first experiment, carried out at the Matter in Extreme Conditions (MEC) endstation of the LCLS, the performance of the instrument was investigated by direct imaging of shock waves in different materials. The shock wave was induced by an intense 150 ps optical laser pulse. The evolution of the shock wave was then monitored with the XFEL-beam. In this contribution we report on first analysis results of phase contrast imaging of shock waves in matter. In collaboration with Brice Arnold, Eric Galtier, Hae Ja Lee, Bob Nagler, Jerome Hastings, SLAC National Accelerator Laboratory, 2575 Sand Hill Rd., Menlo Park, CA 94025, USA; Damian Hicks, Yuan Ping, Gilbert Collins, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551, USA; and Robert Hoppe, Vivienne Meier, Jens Patommel, Frank Seiboth, Christian Schroer, Institute of Structural Physics, Technische Universität Dresden, D-01062 Dresden, Germany.
Shape of shock wave produced by a concentrated impact on a surface
International Nuclear Information System (INIS)
Nutt, G.; Klein, L.
1981-01-01
An approximate similarity solution, derived by Raizer, of a concentrated impact (or intense explosion) at the boundary of a semi-infinite volume of a perfect gas is used to determine the propagation velocity of the shock front as a function of its position. This velocity function is then used to obtain the shape of the propagating shock wave. It is shown that dish-shaped shock fronts are formed when the movement of the gas at the surface is into the gas region and that cup-shaped shock fronts are formed when the movement is out of the gas region. Comparison of these results with the shapes of explosions and meteorite craters are discussed
Two-dimensional numerical investigation of a normal shock wave boundary layer interaction
Turlin, Miranda P.
Shock wave boundary layer interactions (SWBLIs) occur when a shock wave meets a boundary layer. This study aims to isolate the interaction through numerical investigation of a normal SWBLI and build knowledge of the computational fluid dynamics software, Wind-US 3.0. The test geometry, based on the experimental work of Bruce et al [16], contains a two-dimensional duct split into upper and lower channels by a shock holding plate. The boundary conditions were based on experimental conditions, and include: an inlet Mach number of 1.6; inlet total pressure and temperature of 62.5 psi and 522 degrees R, respectively; and viscous walls on all physical surfaces. Downstream boundary conditions are varied in attempts to produce a correct shock structure throughout the domain. This study uses two-dimensional structured grids containing approximately 832,000 elements. Wind-US solves the Reynolds-Averaged Navier-Stokes equations using Roe's second-order upwind-biased flux-difference splitting algorithm with a total variation diminishing (TVD) limiting parameter. The turbulence model selected for this study was the Menter SST k-o model. Attempts to produce the correct shock structure have included varying the downstream boundary conditions, changing the number of cycles and associated Courant-Friedrichs-Lewy, TVD, and grid sequencing parameters. This study used several tutorial files available through the NPARC Alliance to establish the analysis settings needed to produce a shock wave in the lower channel. This enables progress to be made on the next step of this project which is to simulate and analyze the interaction of a normal SWBLI in two dimensions. Results illustrate the correct combination of boundary conditions necessary to generate a shock in the expected location. In addition, an appropriate zonal configuration has been determined to eliminate the horizontal zone interfaces which can cause non-physical behavior in those locations.
Time-resolved shock compression of porous rutile: Wave dispersion in porous solids
Energy Technology Data Exchange (ETDEWEB)
Anderson, M.U.; Graham, R.A.; Holman, G.T.
1993-08-01
Rutile (TiO{sub 2}) samples at 60% of solid density have been shock-loaded from 0.21 to 6.1 GPa with sample thickness of 4 mm and studied with the PVDF piezoelectric polymer stress-rate gauge. The technique uses a copper capsule to contain the sample which has PVDF gauge packages in direct contact with front and rear surfaces. A precise measure is made of the compressive stress wave velocity through the sample, as well as the input and propagated shock stress. Initial density is known from sample preparation, and the amount of shock-compression is calculated from the measurement of shock velocity and input stress. Shock states and re-shock states are measured. Observed data are consistent with previously published high pressure data. It is observed that rutile has a ``crush strength`` near 6 GPa. Propagated stress-pulse rise times vary from 234 to 916 nsec. Propagated stress-pulse rise times of shock-compressed HMX, 2Al + Fe{sub 2}O{sub 3}, 3Ni + Al, and 5Ti + 3Si are presented.
Modulation theory, dispersive shock waves and Gerald Beresford Whitham
Minzoni, A. A.; Smyth, Noel F.
2016-10-01
Gerald Beresford (GB) Whitham, FRS, (13th December, 1927-26th January, 2014) was one of the leading applied mathematicians of the twentieth century whose work over forty years had a profound, formative impact on research on wave motion across a broad range of areas. Many of the ideas and techniques he developed have now become the standard tools used to analyse and understand wave motion, as the papers of this special issue of Physica D testify. Many of the techniques pioneered by GB Whitham have spread beyond wave propagation into other applied mathematics areas, such as reaction-diffusion, and even into theoretical physics and pure mathematics, in which Whitham modulation theory is an active area of research. GB Whitham's classic textbook Linear and Nonlinear Waves, published in 1974, is still the standard reference for the applied mathematics of wave motion. In honour of his scientific achievements, GB Whitham was elected a Fellow of the American Academy of Arts and Sciences in 1959 and a Fellow of the Royal Society in 1965. He was awarded the Norbert Wiener Prize for Applied Mathematics in 1980.
Comparison of shock wave rise time prediction techniques
Raspet, Richard; Bass, Henry E.
1990-01-01
Two techniques for predicting sonic-boom rise times are described, and the values of the rise time (defined as the time required for the shock front to go from 10 percent to 90 percent of the maximum overpressure) predicted when using the two approaches are compared. The results are applied to the prediction of the rise time from two hypothetical supersonic transport aircraft. In both cases, the rise time predicted at the ground was much greater than that predicted for a conventional SST.
Delta Shock Wave for the Suliciu Relaxation System
Directory of Open Access Journals (Sweden)
Richard De la cruz
2014-01-01
Full Text Available We study the one-dimensional Riemann problem for a hyperbolic system of three conservation laws of Temple class. This system is a simplification of a recently proposed system of five conservations laws by Bouchut and Boyaval that model viscoelastic fluids. An important issue is that the considered 3×3 system is such that every characteristic field is linearly degenerate. We show an explicit solution for the Cauchy problem with initial data in L∞. We also study the Riemann problem for this system. Under suitable generalized Rankine-Hugoniot relation and entropy condition, both existence and uniqueness of particular delta-shock type solutions are established.
Elastic precursor wave decay in shock-compressed aluminum over a wide range of temperature
Austin, Ryan A.
2018-01-01
The effect of temperature on the dynamic flow behavior of aluminum is considered in the context of precursor wave decay measurements and simulations. In this regard, a dislocation-based model of high-rate metal plasticity is brought into agreement with previous measurements of evolving wave profiles at 300 to 933 K, wherein the amplification of the precursor structure with temperature arises naturally from the dislocation mechanics treatment. The model suggests that the kinetics of inelastic flow and stress relaxation are governed primarily by phonon scattering and radiative damping (sound wave emission from dislocation cores), both of which intensify with temperature. The manifestation of these drag effects is linked to low dislocation density ahead of the precursor wave and the high mobility of dislocations in the face-centered cubic lattice. Simulations performed using other typical models of shock wave plasticity do not reproduce the observed temperature-dependence of elastic/plastic wave structure.
Laser Ion Acceleration from Shock Wave Generated Targets
Helle, Michael; Gordon, Daniel; Kaganovich, Dmitri; Ting, Antonio
2012-10-01
Efficient acceleration of ions by means of high power laser radiation requires electron plasma densities at or in excess of the critical density. Traditionally, this has been achieved using solid targets. More recently, laser facilities at Brookhaven National Laboratory and the University of California in Los Angeles have achieved acceleration using Terawatt CO2 interacting with gas jets. Gas targets are advantageous in that they are relatively simple and can be operated at high repetition rates; however, they typically operate at densities far below those required for optical wavelengths, where most of the world's terawatt lasers operate. To get around this and other issues, a new type of target, a ``gas foil,'' has been developed at the Naval Research Laboratory. The target is created by igniting an optically driven hydrodynamic shock into the flow of a gas jet in vacuum. Experiments have shown that a laser-ignited shock is capable of producing 4 times ambient. These results have been incorporated into 3D PIC simulations. Results for a relatively compact and inexpensive 20 TW laser yielded protons with energies in excess of 5 MeV. Simulations as well as preliminary experimental results will be discus
NUMERICAL SIMULATION OF SHOCK WAVE DIFFRACTION OVER RIGHT ANGLE ON UNSTRUCTURED MESHES
Directory of Open Access Journals (Sweden)
P. V. Bulat
2016-03-01
Full Text Available Subject of Research. Numerical simulation results and investigation of shock wave diffraction of differentintensity on the flat right angleare presented. Method. The numerical model is based on the solution of unsteadyEuler equations for inviscid compressible gas. The finite volume method and explicit WENO-type difference scheme of the third-order of accuracyare used. Convective fluxesare calculated independently for each direction with the approximate Riemann solver(HLLC method. Time integration is performed with the Runge-Kutta method of the third order. Main Results. Flow structure and flowquantitative characteristicshave beendetermined. To visualize and interpret the results of numerical calculations theprocedure of identification and classification of gas-dynamic discontinuities has beenappliedbased on the use of dynamic compatibility conditions and methods of digital image processing. The results of calculations have beenpresented in the form of numerical shadow pictures, schlieren images and interferograms, and compared with the optical observations. Significantly better agreement with the experimental data has beendemonstrated as compared toconventionalnumerical methods. Application of numerical methods of high order accuracy has yielded a numerical solution which is free from non-physicaloscillations on the shock waves with minimal smearingoverdifference cells. Practical Relevance. The study of shock-wave phenomena is of interest for the solution of problems related to the impact of shock waves on the design elements, the operation of pulsed gas-dynamic devices, the use of shock waves in technological processes. Supersonic flows around angle configurations lead to interference and diffraction phenomena complicated by flow separation. These effects make complexthe calculation of such phenomena using conventional numericalmethods. The problem ofthe results interpretation is not less complicated one,as well, in particular, identification
Ganjehi, Lili; Marchiano, Régis; Coulouvrat, François; Thomas, Jean-Louis
2008-07-01
The influence of the planetary boundary layer on the sonic boom received at the ground level is known since the 1960s to be of major importance. Sonic boom propagation in a turbulent medium is characterized by an increase of the mean rise time and a huge variability. An experiment is conducted at a 1:100,000 scale in water to investigate ultrasonic shock wave interaction with a single heterogeneity. The experiment shows a very good scaling with sonic boom, concerning the size of the heterogeneities, the wave amplitude, and the rise time of the incident wave. The wave front folding associated with local focusing, and its link to the increase of the rise time, are evidenced by the experiment. The observed amplification of the peak pressure (by a factor up to 2), and increase of the rise time (by up to about one magnitude order), are in qualitative agreement with sonic boom observations. A nonlinear parabolic model is compared favorably to the experiment on axis, though the paraxial approximation turns out less precise off axis. Simulations are finally used to discriminate between nonlinear and linear propagations, showing nonlinearities affect mostly the higher harmonics that are in the audible range for sonic booms.
International Nuclear Information System (INIS)
Ohsawa, Yukiharu.
1984-12-01
A 2-1/2 dimensional fully relativistic, fully electromagnetic particle code is used to study a time evolution of nonlinear magnetosonic pulse propagating in the direction perpendicular to a magnetic field. The pulse is excited by an instantaneous piston acceleration, and evolves totally self-consistently. Large amplitude pulse traps some ions and accelerates them parallel to the wave front. They are detrapped when their velocities become of the order of the sum of the ExB drift velocity and the wave phase velocity, where E is the electric field in the direction of wave propagation. The pulse develops into a quasi-shock wave in a collisionless plasma by a dissipation due to the resonant ion acceleration. Simple nonlinear wave theory for a cold plasma well describes the shock properties observed in the simulation except for the effects of resonant ions. In particular, magnitude of an electric potential across the shock region is derived analytically and is found to be in good agreement with our simulations. The potential jump is proportional to B 2 , and hence the ExB drift velocity of the trapped ions is proportional to B. (author)
Experimental Research about Shock Wave in a 1+1/2 Counter-Rotating Turbine
Directory of Open Access Journals (Sweden)
Li Chao
2018-01-01
Full Text Available To investigate the internal distribution regularities of shock wave structure in 1+1/2 counter-rotating turbine, numerical simulation and experimental research about the shock wave structure were conducted by using the schlieren apparatus under different working conditions.From the point of the unsteady results, the unsteady effect has few influence on the flow field of high pressure guide vane, but the wake of the high pressure guide leaves periodically sweeps through the front edge of the high pressure blade and there presents strong unsteady effect on flow field of high pressure rotor. Because of periodic influence of external wake and shock wave, the unsteadiness of flow in low pressure rotor is still strong but not that drastic compared to the high pressure rotor. 50% height section of the blade of the three types of blades are extracted respectively to make plane cascades which are conducted blowing experiments in supersonic wind tunnel. The final photograph were analyzed by comparing with the CFD results. Results show that with the increase of expansion ratio, the wave structures in blade channel move toward the exit and the caudal interference between the outer tail wave and is strengthened gradually.
A Shock-Refracted Acoustic Wave Model for the Prediction of Screech Amplitude in Supersonic Jets
Kandula, Max
2007-01-01
A physical model is proposed for the estimation of the screech amplitude in underexpanded supersonic jets. The model is based on the hypothesis that the interaction of a plane acoustic wave with stationary shock waves provides amplification of the transmitted acoustic wave upon traversing the shock. Powell's discrete source model for screech incorporating a stationary array of acoustic monopoles is extended to accommodate variable source strength. The proposed model reveals that the acoustic sources are of increasing strength with downstream distance. It is shown that the screech amplitude increases with the fuiiy expanded jet Mach number. Comparisons of predicted screech amplitude with available test data show satisfactory agreement. The effect of variable source strength on directivity of the fundamental (first harmonic, lowest frequency mode) and the second harmonic (overtone) is found to be unimportant with regard to the principal lobe (main or major lobe) of considerable relative strength, and is appreciable only in the secondary or minor lobes (of relatively weaker strength
Shock Wave Reflection Behavior in Double-Layer Meteoroid Bumper Systems
Nahme, H.; Stilp, A. J.; Weber, K.
1997-07-01
For laminated meteor bumpers it has been found that the impedance mismatch and the order of the layers strongly influences the crater hole size, the shapes and velocities of debris clouds as well as the number and size of fragments. It is shown that the shock wave transfer is affected by the shock impedance mismatch at the interface of the layers. For the Ti-W target the higher pressure changes, caused by loading and unloading waves, over a relatively longer time seem to be responsible for the higher degree of fragmentation compared to the W-Ti target. Evidence for this is given by VISAR measurements. Planar impact experiments with aluminum discs on Ti-W and the reversed W-Ti target have been performed in the velocity range 500-1000 m/s. The velocity-time diagrams show different wave propagations inside the target components, dependent on the layer sequence.
Characteristics and measurement of supersonic projectile shock waves by a 32-microphone ring array
Chang, Ho; Wu, Yan-Chyuan; Tsung, Tsing-Tshih
2011-08-01
This paper discusses about the characteristics of supersonic projectile shock wave in muzzle region during firing of high explosive anti-tank (HEAT) and high explosive (HE) projectiles. HEAT projectiles are fired horizontally at a muzzle velocity of Mach 3.5 from a medium caliber tank gun equipped with a newly designed multi-perforated muzzle brake, whereas HE projectiles are fired at elevation angles at a muzzle velocity of Mach 2 from a large caliber howitzer equipped with a newly designed double-baffle muzzle brake. In the near field, pressure signatures of the N-wave generated from projectiles are measured by 32-microphone ring array wrapped by cotton sheath. Records measured by the microphone array are used to demonstrate several key characteristics of the shock wave of supersonic projectile. All measurements made in this study can be a significant reference for developing guns, tanks, or the chassis of fighting vehicles.
Khokhlova, Tatiana D; Canney, Michael S; Khokhlova, Vera A; Sapozhnikov, Oleg A; Crum, Lawrence A; Bailey, Michael R
2011-11-01
In high intensity focused ultrasound (HIFU) applications, tissue may be thermally necrosed by heating, emulsified by cavitation, or, as was recently discovered, emulsified using repetitive millisecond boiling caused by shock wave heating. Here, this last approach was further investigated. Experiments were performed in transparent gels and ex vivo bovine heart tissue using 1, 2, and 3 MHz focused transducers and different pulsing schemes in which the pressure, duty factor, and pulse duration were varied. A previously developed derating procedure to determine in situ shock amplitudes and the time-to-boil was refined. Treatments were monitored using B-mode ultrasound. Both inertial cavitation and boiling were observed during exposures, but emulsification occurred only when shocks and boiling were present. Emulsified lesions without thermal denaturation were produced with shock amplitudes sufficient to induce boiling in less than 20 ms, duty factors of less than 0.02, and pulse lengths shorter than 30 ms. Higher duty factors or longer pulses produced varying degrees of thermal denaturation combined with mechanical emulsification. Larger lesions were obtained using lower ultrasound frequencies. The results show that shock wave heating and millisecond boiling is an effective and reliable way to emulsify tissue while monitoring the treatment with ultrasound.
Numerical study of shock waves in non-ideal magnetogasdynamics (MHD
Directory of Open Access Journals (Sweden)
Addepalli Ramu
2016-01-01
Full Text Available One-dimensional unsteady adiabatic flow of strong converging shock waves in cylindrical or spherical symmetry in MHD, which is propagating into plasma, is analyzed. The plasma is assumed to be non-ideal gas whose equation of state is of Mie–Gruneisen type. Suitable transformations reduce the governing equations into ordinary differential equations of Poincare type. In the present work, McQueen and Royce equations of state (EOS have been considered with suitable material constants and the spherical and cylindrical cases are worked out in detail to investigate the behavior and the influence on the shock wave propagation by energy input and β(ρ/ρ0, the measure of shock strength. The similarity solution is valid for adiabatic flow as long as the counter pressure is neglected. The numerical technique applied in this paper provides a global solution to the implosion problem for the flow variables, the similarity exponent α for different Gruneisen parameters. It is shown that increasing β(ρ/ρ0 does not automatically decelerate the shock front but the velocity and pressure behind the shock front increases quickly in the presence of the magnetic field and decreases slowly and become constant. This becomes true whether the piston is accelerated, is moving at constant speed or is decelerated. These results are presented through the illustrative graphs and tables. The magnetic field effects on the flow variables through a medium and total energy under the influence of strong magnetic field are also presented.
Test of a new heat-flow equation for dense-fluid shock waves
Holian, Brad Lee; Mareschal, Michel; Ravelo, Ramon
2010-09-01
Using a recently proposed equation for the heat-flux vector that goes beyond Fourier's Law of heat conduction, we model shockwave propagation in the dense Lennard-Jones fluid. Disequilibrium among the three components of temperature, namely, the difference between the kinetic temperature in the direction of a planar shock wave and those in the transverse directions, particularly in the region near the shock front, gives rise to a new transport (equilibration) mechanism not seen in usual one-dimensional heat-flow situations. The modification of the heat-flow equation was tested earlier for the case of strong shock waves in the ideal gas, which had been studied in the past and compared to Navier-Stokes-Fourier solutions. Now, the Lennard-Jones fluid, whose equation of state and transport properties have been determined from independent calculations, allows us to study the case where potential, as well as kinetic contributions are important. The new heat-flow treatment improves the agreement with nonequilibrium molecular-dynamics simulations under strong shock wave conditions, compared to Navier-Stokes.
Shock wave plasticity in Mo at 293K and 1673K
International Nuclear Information System (INIS)
Tonks, D.L.
1996-01-01
The shock wave plasticity of Mo is extracted from two VISAR wave profiles; of about 110 kbar strength at 293 K and of about 120 kbar strength at 1673 K. The Wallace weak shock analysis is used to obtain the plastic strain and deviatoric stress, and the normal stress and volumetric strain, through the shock rise from the velocity profile data. The Wallace analysis uses the steady wave assumption for the plastic portion of the shock rise, a plausible evolution for the precursor portion, a thermoelastic model, and the mechanical equations of motion. Comparison of the high and low temperature results is of interest in assessing the mechanisms of plastic flow. In the results, the (von Mises equivalent) peak deviatoric stresses are 12.8 kbar and 20.3 kbar, for the hot and cold Mo, respectively, while the peak plastic strain rate of the hot Mo is about 2.6 times that of the cold Mo. These values rule out thermal activation. In addition, they are not consistent with a simple phonon viscosity linear in the temperature. Additional effects are needed to explain the results, e.g. evolution of the mobile dislocation density. copyright 1996 American Institute of Physics
Shock wave science and technology reference library. Vol. 4. Heterogeneous detonation
Energy Technology Data Exchange (ETDEWEB)
Zhang, Fan (ed.) [Defence Research and Development Canada, Suffield, AB (Canada)
2009-07-01
This book, as a volume of the Shock Wave Science and Technology Reference Library, is primarily concerned with detonation waves or compression shock waves in reactive heterogeneous media, including mixtures of solid, liquid and gas phases. The topics involve a variety of energy release and control processes in such media - a contemporary research field that has found wide applications in propulsion and power, hazard prevention as well as military engineering. The six extensive chapters contained in this volume are: - Spray Detonation (SB Murray and PA Thibault) - Detonation of Gas-Particle Flow (F Zhang) - Slurry Detonation (DL Frost and F Zhang) - Detonation of Metalized Composite Explosives (MF Gogulya and MA Brazhnikov) - Shock-Induced Solid-Solid Reactions and Detonations (YA Gordopolov, SS Batsanov, and VS Trofimov) - Shock Ignition of Particles (SM Frolov and AV Fedorov). Each chapter is self-contained and can be read independently of the others, though, they are thematically interrelated. They offer a timely reference, for graduate students as well as professional scientists and engineers, by laying out the foundations and discussing the latest developments including yet unresolved challenging problems. (orig.)
Test of a new heat-flow equation for dense-fluid shock waves.
Holian, Brad Lee; Mareschal, Michel; Ravelo, Ramon
2010-09-21
Using a recently proposed equation for the heat-flux vector that goes beyond Fourier's Law of heat conduction, we model shockwave propagation in the dense Lennard-Jones fluid. Disequilibrium among the three components of temperature, namely, the difference between the kinetic temperature in the direction of a planar shock wave and those in the transverse directions, particularly in the region near the shock front, gives rise to a new transport (equilibration) mechanism not seen in usual one-dimensional heat-flow situations. The modification of the heat-flow equation was tested earlier for the case of strong shock waves in the ideal gas, which had been studied in the past and compared to Navier-Stokes-Fourier solutions. Now, the Lennard-Jones fluid, whose equation of state and transport properties have been determined from independent calculations, allows us to study the case where potential, as well as kinetic contributions are important. The new heat-flow treatment improves the agreement with nonequilibrium molecular-dynamics simulations under strong shock wave conditions, compared to Navier-Stokes.
Shock bifurcation and emergence of diffusive solitons in a nonlinear wave equation with relaxation
Energy Technology Data Exchange (ETDEWEB)
Christov, Ivan; Jordan, P M [Code 7181, Naval Research Laboratory, Stennis Space Center, MS 39529-5004 (United States)], E-mail: pjordan@nrlssc.navy.mil
2008-04-15
A hyperbolic generalization of Burgers' equation, which includes relaxation, is examined using analytical and numerical tools. By means of singular surface theory, the evolution of initial discontinuities (i.e. shocks) is fully classified. In addition, the parameter space is explored and the bifurcation experienced by the shock amplitude is identified. Then, by means of numerical simulations based on a Godunov-type scheme, we confirm the theoretical findings and explore the solution structure of a signaling-type initial-boundary-value problem with discontinuous boundary data. In particular, we show that diffusive solitons (or Taylor shocks) can emerge in the solution, behind the wavefront. We also show that, for certain parameter values, a shock wave becomes an acceleration wave in infinite time, an unexpected result that is the exact opposite of the well-known phenomenon of finite-time acceleration wave blow-up. Finally, the 'red light turning green' problem is re-examined.
Gas-grain energy transfer in solar nebula shock waves: Implications for the origin of chondrules
Hood, L. L.; Horanyi, M.
1993-01-01
Meteoritic chondrules provide evidence for the occurrence of rapid transient heating events in the protoplanetary nebula. Astronomical evidence suggests that gas dynamic shock waves are likely to be excited in protostellar accretion disks by processes such as protosolar mass ejections, nonaxisymmetric structures in an evolving disk, and impact on the nebula surface of infalling 'clumps' of circumstellar gas. Previous detailed calculations of gas-grain energy and momentum transfer have supported the possibility that such shock waves could have melted pre-existing chondrule-sized grains. The main requirement for grains to reach melting temperatures in shock waves with plausibly low Mach numbers is that grains existed in dust-rich zones (optical depth greater than 1) where radiative cooling of a given grain can be nearly balanced by radiation from surrounding grains. Localized dust-rich zones also provide a means of explaining the apparent small spatial scale of heating events. For example, the scale size of at least some optically thick dust-rich zones must have been relatively small (less than 10 kilometers) to be consistent with petrologic evidence for accretion of hot material onto cold chondrules. The implied number density of mm-sized grains for these zones would be greater than 30 m(exp -3). In this paper, we make several improvements of our earlier calculations to include radiation self-consistently in the shock jump conditions, and we include heating of grains due to radiation from the shocked gas. In addition, we estimate the importance of momentum feedback of dust concentrations onto the shocked gas which would tend to reduce the efficiency of gas dynamic heating of grains in the center of the dust cloud.
International Nuclear Information System (INIS)
Hollenbach, D.; McKee, C.F.
1980-01-01
The postshock destruction of molecules is examined, including the processes of (i) collisions with neutral hydrogen atoms and molecules, (ii) electronic collisions, and (iii) neutral chemical reactions with atoms, particularly atomic hydrogen. Using conservative estimates of collisional dissociation rates from individual vibrational states, we find that process (i) leads to the destruction of molecular hydrogen behind shocks with speeds v/sub s/> or approx. =25 km s -1 if the preshock molecular gas has hydrogen nucleus densities of n 0 > or approx. =10 4 cm -3 . At lower densities (n 0 approx. =10 2 cm -3 ), destruction occurs for v/sub s/> or approx. =50 km s -1 and process (ii) dominates. Dissociation of molecules such as CO, H 2 O, and O 2 follows the destruction of H 2 , as the resultant hydrogen atoms chemically dissociate the metal atoms from their bonds (process iii) in the hot postshock gas. These results demonstrate that many of the observed high-speed interstellar molecules, if shock accelerated, must have dissociated and reformed in the postshock gas
Shock drift electron acceleration and generation of waves
Czech Academy of Sciences Publication Activity Database
Karlický, Marian; Vandas, Marek
2007-01-01
Roč. 55, č. 15 (2007), s. 2336-2339 ISSN 0032-0633 R&D Projects: GA AV ČR 1QS300120506; GA AV ČR IAA300030701; GA ČR GA205/04/0358; GA ČR GA205/06/0875 Institutional research plan: CEZ:AV0Z10030501 Keywords : electrons beam * electromagnetic waves * solar radio bursts Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 1.842, year: 2007
Influence of crack opening and incident wave angle on second harmonic generation of Lamb waves
Yang, Yi; Ng, Ching-Tai; Kotousov, Andrei
2018-05-01
Techniques utilising second harmonic generation (SHG) have proven their great potential in detecting contact-type damage. However, the gap between the practical applications and laboratory studies is still quite large. The current work is aimed to bridge this gap by investigating the effects of the applied load and incident wave angle on the detectability of fatigue cracks at various lengths. Both effects are critical for practical implementations of these techniques. The present experimental study supported by three-dimensional (3D) finite element (FE) modelling has demonstrated that the applied load, which changes the crack opening and, subsequently, the contact nonlinearity, significantly affects the amplitude of the second harmonic generated by the fundamental symmetric mode (S0) of Lamb wave. This amplitude is also dependent on the length of the fatigue crack as well as the incident wave angle. The experimental and FE results correlate well, so the modelling approach can be implemented for practical design of damage monitoring systems as well as for the evaluation of the severity of the fatigue cracks.
The Coronal Analysis of SHocks and Waves (CASHeW) framework
Kozarev, Kamen A.; Davey, Alisdair; Kendrick, Alexander; Hammer, Michael; Keith, Celeste
2017-11-01
Coronal bright fronts (CBF) are large-scale wavelike disturbances in the solar corona, related to solar eruptions. They are observed (mostly in extreme ultraviolet (EUV) light) as transient bright fronts of finite width, propagating away from the eruption source location. Recent studies of individual solar eruptive events have used EUV observations of CBFs and metric radio type II burst observations to show the intimate connection between waves in the low corona and coronal mass ejection (CME)-driven shocks. EUV imaging with the atmospheric imaging assembly instrument on the solar dynamics observatory has proven particularly useful for detecting large-scale short-lived CBFs, which, combined with radio and in situ observations, holds great promise for early CME-driven shock characterization capability. This characterization can further be automated, and related to models of particle acceleration to produce estimates of particle fluxes in the corona and in the near Earth environment early in events. We present a framework for the coronal analysis of shocks and waves (CASHeW). It combines analysis of NASA Heliophysics System Observatory data products and relevant data-driven models, into an automated system for the characterization of off-limb coronal waves and shocks and the evaluation of their capability to accelerate solar energetic particles (SEPs). The system utilizes EUV observations and models written in the interactive data language. In addition, it leverages analysis tools from the SolarSoft package of libraries, as well as third party libraries. We have tested the CASHeW framework on a representative list of coronal bright front events. Here we present its features, as well as initial results. With this framework, we hope to contribute to the overall understanding of coronal shock waves, their importance for energetic particle acceleration, as well as to the better ability to forecast SEP events fluxes.
Phisical and chemical transformation of rocks and ores in spherical shock waves
Kozlov, E. A.; Anfilogov, V. N.; Zugin, Y. N.; Belogub, E. V.; Brichko, S. N.
2003-04-01
The method of creation of the spherical converging waves in shut system is worked out. A spheric sample of rock is placed into a steel container. The shock wave is produced by layer explosive, which is placed on the surface of a steel container. The experiments are realized in the shut condition and the result of the shock action is preserved in the sample. Graphitic qurartzite, graphic granit and sulfide ore were exposed of the shock wave action. The pressure and temperature in the spheric sample is the function of radius. We have following results of the shock wave action from periphery to center. The graphitic quartzite: 24 - 11 mm - big fractures in quartz grains; 11- 8 mm - planar fractures in quartz grains (P = 7.5 Gpa); 8 - 7 mm (P = 14 - 22 Gpa) amorphous areas in quartz, little crystals of coesite; 7 -5.8 mm-diaplectic and partial meltihg zone; 5.8 - 1.4 mm - isotropic glass. There is no transformation of graphite to diamond. The graphic granit: 24- 13 mm - unchanged granit; 13 - 10 mm - quartz has block structure; 10-8 mm - grains of fielspar become isotropic, quartz has planar separate forms; 8 -4.5 mm - clean transparent rose diaplectic glass; 4,5 - 0 mm clean granulated glass. The sample of the sulphide ore consists of pyrite, chalcopyrite and quartz. The results of the shock action on sulphilde ore: 24 -12 mm - big fractures in the sulphide ore; 12 -8 mm - relicts of the primary sulphides with rims and veinlets of the new sulphides (mainly chalcopyrite), which were crystalizated from melt; 8 -0 mm- porous material consists of bornite, chalcopyrite, pyrrotite, pyrite and little quantity of silicate glass.
Density profile in shock wave fronts of partially ionized xenon plasmas
Reinholz, H; Morozov, I; Mintsev, V; Zaparoghets, Y; Fortov, V; Wierling, A
2003-01-01
Results for the reflection coefficient of shock-compressed dense xenon plasmas at pressures of 1.6-20 GPa and temperatures around 30 000 K are interpreted. In addition to former experiments using laser beams with lambda = 1.06 mu m, measurements at lambda = 0.694 mu m have been performed recently. Reflectivities typical for metallic systems are found at high densities. Besides free carriers, the theoretical description also takes into account the influence of the neutral component of the plasma on the reflectivity. A consistent description of the measured reflectivities is achieved only if a finite width of the shock wave front is considered.
Modeling shock waves in an ideal gas: Going beyond the Navier-Stokes level
International Nuclear Information System (INIS)
Holian, B.L.; Patterson, C.W.; Mareschal, M.; Salomons, E.
1993-01-01
We model a shock wave in an ideal gas by solving a modified version of the compressible Navier-Stokes equations of hydrodynamics, where, following an earlier conjecture by Holian [Phys. Rev. A 37, 2562 (1988)], we use the temperature in the direction of shock propagation T xx , rather than the average temperature T=(T xx +T yy +T zz )/3, in the evaluation of the linear transport coefficients. The results are found to agree much better with the molecular-dynamics simulations of Salomons and Mareschal [Phys. Rev. Lett. 69, 269 (1992)] than standard Navier-Stokes theory
Turbulent properties of axisymmetric shock-wave/boundary-layer interaction flows
Brown, J. L.; Kussoy, M. I.; Coakley, T. J.
1986-01-01
A combined experimental and computational investigation of an axisymmetric turbulent shock-wave boundary-layer interaction flow is presented. Experimental measurements include both mean and fluctuating data obtained by LDV techniques and identify large scale unsteady motions associated with shock induced separation. Computations using the compressible Navier-Stokes equations, and a two-equation turbulence model are in relatively good agreement with experimental measurements. It is found that the large scale unsteady motions do not appear to have a critical impact on the ability to compute the mean properties of the flows investigated in this paper.
Dynamics of shock wave propagation and interphase process in liquid-vapor medium
Energy Technology Data Exchange (ETDEWEB)
Pokusaev, B.G. [Moscow State Academy of Chemical Mechanical Engineering (Russian Federation); Pribaturin, N.A. [Institute of Thermophysics, Siberian Branch of Russian Academy of Sciences, Novosibirsk (Russian Federation)
1995-09-01
This paper considers the experimental results and physical effects on the pressure wave dynamics of a vapour-liquid two-phase medium of bubble and slug structure. The role of destruction and collapse of bubbles and slugs, phase transition (condensation and evaporation) on pressure wave dynamics is also studied. The general mechanisms of the wave formation, behavior and instability of a vapour-liquid structure under pressure waves, basic peculiarities of the interface heat transfer are obtained. In the experiments it has been shown that for the bubble medium the shock wave can be transformed into the powerful pressure pulse with an amplitude greater then the amplitude of the initial pressure wave. For the slug medium a characteristic structure of the amplificated wave is {open_quotes}comb{close_quotes} - like wave. It has been shown that the wave amplification caused by generation of secondary waves in a medium caused by destruction and collapse of bubbles and slugs. The obtained results can be useful at transient and emergency operational regimes of nuclear reactors, fuel tank, pipelines with two-phase flows and for development of safety models for chemical industry.
Euler-Lagrange Simulations of Shock Wave-Particle Cloud Interaction
Koneru, Rahul; Rollin, Bertrand; Ouellet, Frederick; Park, Chanyoung; Balachandar, S.
2017-11-01
Numerical experiments of shock interacting with an evolving and fixed cloud of particles are performed. In these simulations we use Eulerian-Lagrangian approach along with state-of-the-art point-particle force and heat transfer models. As validation, we use Sandia Multiphase Shock Tube experiments and particle-resolved simulations. The particle curtain upon interaction with the shock wave is expected to experience Kelvin-Helmholtz (KH) and Richtmyer-Meshkov (RM) instabilities. In the simulations evolving the particle cloud, the initial volume fraction profile matches with that of Sandia Multiphase Shock Tube experiments, and the shock Mach number is limited to M =1.66. Measurements of particle dispersion are made at different initial volume fractions. A detailed analysis of the influence of initial conditions on the evolution of the particle cloudis presented. The early time behavior of the models is studied in the fixed bed simulations at varying volume fractions and shock Mach numbers.The mean gas quantities are measured in the context of 1-way and 2-way coupled simulations. 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.
Focused tandem shock waves in water and their potential application in cancer treatment
Lukes, P.; Sunka, P.; Hoffer, P.; Stelmashuk, V.; Pouckova, P.; Zadinova, M.; Zeman, J.; Dibdiak, L.; Kolarova, H.; Tomankova, K.; Binder, S.; Benes, J.
2014-01-01
The generator of two focused successive (tandem) shock waves (FTSW) in water produced by underwater multichannel electrical discharges at two composite electrodes, with a time delay between the first and second shock waves of 10 s, was developed. It produces, at the focus, a strong shock wave with a peak positive pressure of up to 80 MPa, followed by a tensile wave with a peak negative pressure of up to MPa, thus generating at the focus a large amount of cavitation. Biological effects of FTSW were demonstrated in vitro on hemolysis of erythrocytes and cell viability of human acute lymphoblastic leukemia cells as well as on tumor growth delay ex vivo and in vivo experiments performed with B16 melanoma, T-lymphoma, and R5-28 sarcoma cell lines. It was demonstrated in vivo that FTSW can enhance antitumor effects of chemotherapeutic drugs, such as cisplatin, most likely due to increased permeability of the membrane of cancer cells induced by FTSW. Synergetic cytotoxicity of FTSW with sonosensitive porphyrin-based drug Photosan on tumor growth was observed, possibly due to the cavitation-induced sonodynamic effect of FTSW.
Asymmetric Shock Wave Generation in a Microwave Rocket Using a Magnetic Field
Takahashi, Masayuki
2017-10-01
A plasma pattern is reproduced by coupling simulations between a particle-in- cell with Monte Carlo collisions model and a finite-difference time-domain simulation for an electromagnetic wave propagation when an external magnetic field is applied to the breakdown volume inside a microwave-rocket nozzle. The propagation speed and energy-absorption rate of the plasma are estimated based on the breakdown simulation, and these are utilized to reproduce shock wave propagation, which provides impulsive thrust for the microwave rocket. The shock wave propagation is numerically reproduced by solving the compressible Euler equation with an energy source of the microwave heating. The shock wave is asymmetrically generated inside the nozzle when the electron cyclotron resonance region has a lateral offset, which generates lateral and angular impulses for postural control of the vehicle. It is possible to develop an integrated device to maintain beaming ight of the microwave rocket, achieving both axial thrust improvement and postural control, by controlling the spatial distribution of the external magnetic field.
Optimum hypersonic airfoil with power law shock waves
International Nuclear Information System (INIS)
Wagner, B.A.
1990-01-01
In the present paper the flow field over a class of two-dimensional lifting surfaces is examined from the viewpoint of inviscid, hypersonic small-disturbance theory (HSDT). It is well known that a flow field in which the shock shape S(x) is similar to the body shape F(x) is only possible for F(x) = x k and the freestream Mach number M ∞ = ∞. This self-similar flow has been studied for several decades as it represents one of the few existing exact solutions of the equations of HSDT. Detailed discussions are found for example in papers by Cole, Mirels, Chernyi and Gersten and Nicolai but they are limited to convex body shapes, that is, k ≤ 1. The only study of concave body shapes was attempted by Sullivan where only special cases were considered. The method used here shows that similarity also exists for concave shapes and a complete solution of the flow field for any k > 2/3 is given. The effect of varying k on C L 3/2 /C D is then determined and an optimum shape is found. Furthermore, a wider class of lifting surfaces is constructed using the streamlines of the basic flow field and analysed with respect to the effect on C L 3/2 /C D . 9 refs., 3 figs
Converging xenon shock waves driven by megagauss magnetic fields
International Nuclear Information System (INIS)
Shearer, J.W.; Steinberg, D.J.
1986-07-01
We attempted to implode a conducting metal linear at high velocity, and our failure to do so led to switching, or rapidly transferring the field from pushing an aluminum conductor to snow-plowing a half-atmosphere of xenon gas. We successfully initiated convergent xenon gas shocks with the use of a magnetohydrodynamic switch and coaxial high-explosive, flux-compression generators. Principal diagnostics used to study the imploding xenon gas were 133 Xe radioactive tracers, continuous x-ray absorption, and neutron output. We compressed the xenon gas about five to sixfold at a velocity of 10 cm/μs at a radius of 4 cm. The snowplow efficiency was good; going from 13- to 4-cm radius, we lost only about 20% of the mass. The temperature of the imploded sheath was determined by mixing deuterium with the xenon and measuring the neutron output. Using reasonable assumptions about the amount, density, and uniformity of the compressed gas, we estimate that we reached temperatures as high as 155 eV. Energy-loss mechanisms that we encountered included wall ablation and Taylor instabilities of the back surface
Self-exchange of oxygen behind reflected shock waves
International Nuclear Information System (INIS)
Bopp, A.F.; Kern, R.D.; Niki, T.; Stack, G.M.
1979-01-01
The rate of isotopic exchange of equimolar mixtures of 32 O 2 + 36 O 2 dilute in Ne-1% Ar was studied over the temperature range 2625 to 3700 K. the reacting gas was analyzed from the reflected shock zone at 20-μs intervals with a time-of-flight mass spectrometer. Each experimental product profile obtained was compared to the corresponding computer-simulated profile calculation from an atomic mechanism by using previously published rate constants. It was observed that the growth of the exchange product exceeded that predicted by the atomic mechanism at the lower temperatures of this study. However, these differences diminished as the temperature increased. Static analysis of the gas mixtures investigated revealed that H 2 or D 2 if present were at a level of less than 2.5 ppM. Computer simulation of product profiles demonstrated that this impurity level was insufficient to affect the observed rate of product formation. It is proposed that contributions from molecular channels are operative at the lower temperatures while atomic pathways dominate at the higher temperatures
Generation of Shock-Wave Disturbances at Plasma-Vapor Bubble Oscillation
Kuznetsova, N. S.; Yudin, A. S.; Voitenko, N. V.
2015-11-01
The complex physical and mathematical model describing all steps of plasma-vapor bubble evolution in the system of the water-ground condensed media is presented. Discharge circuit operation, discharge plasma channel expansion, its transformation into the vapor-plasma bubble and its pulsation, pressure wave generation and propagation of the mechanical stress waves in the ground are self-consistently considered in the model. The model allows investigation of the basic laws of stored energy transformation into the discharge plasma channel, next to the plasma-vapor bubble and transformation of this energy to the energy of pressure wave compressing the surrounding ground. Power characteristics of wave disturbances generated by gas-vapor bubble oscillation in liquid depending on the circuit parameters are analyzed for the prediction of the ground boundary displacement. The dynamics of the shock-wave propagation in water-ground condensed media depending on the rate of the plasma channel energy release is investigated. Simulation of the shock-wave phenomena at a plasma-vapor bubble oscillation in condensed media consecutively describes the physical processes underlying technology for producing piles by electro-discharge stuffing. The quantitative model verified by physical experimental tests will allow optimization of pulse generator parameters and electrode system construction of high-voltage equipment.
Harmonic Wave Generated by Contact Acoustic Nonlinearity in Obliquely Incident Ultrasonic Wave
Energy Technology Data Exchange (ETDEWEB)
Yun, Dong Seok; Choi, Sung Ho; Kim, Chung Seok; Jhang, Kyung Young [Hangyang University, Seoul (Korea, Republic of)
2012-08-15
The objective of this study is to image the harmonic wave generated by contact acoustic nonlinearity in obliquely incident ultrasonic wave for early detection of closed cracks. A closed crack has been simulated by contacting two aluminum block specimens producing solid-solid contact interfaces and then acoustic nonlinearity has been imaged with contact pressure. Sampling phased array(SPA) and synthetic aperture focusing technique(SAFT) are used for imaging techniques. The amplitude of the fundamental frequency decreased with applying pressure. But, the amplitude of second harmonic increased with pressure and was a maximum amplitude at the simulation point of closed crack. Then, the amplitude of second harmonic decreased. As a result, harmonic imaging of contact acoustic nonlinearity is possible and it is expected to be apply for early detection of initial cracks.
Propagation of exponential shock wave in an axisymmetric rotating non-ideal dusty gas
Nath, G.
2016-09-01
One-dimensional unsteady isothermal and adiabatic flow behind a strong exponential shock wave propagating in a rotational axisymmetric mixture of non-ideal gas and small solid particles, which has variable azimuthal and axial fluid velocities, is analyzed. The shock wave is driven out by a piston moving with time according to exponential law. The azimuthal and axial components of the fluid velocity in the ambient medium are assumed to be varying and obeying exponential laws. In the present work, small solid particles are considered as pseudo-fluid with the assumption that the equilibrium flow-conditions are maintained in the flow-field, and the viscous-stress and heat conduction of the mixture are negligible. Solutions are obtained in both the cases, when the flow between the shock and the piston is isothermal or adiabatic by taking into account the components of vorticity vector and compressibility. It is found that the assumption of zero temperature gradient brings a profound change in the density, axial component of vorticity vector and compressibility distributions as compared to that of the adiabatic case. To investigate the behavior of the flow variables and the influence on the shock wave propagation by the parameter of non-idealness of the gas overline{b} in the mixture as well as by the mass concentration of solid particles in the mixture Kp and by the ratio of the density of solid particles to the initial density of the gas G1 are worked out in detail. It is interesting to note that the shock strength increases with an increase in G1 ; whereas it decreases with an increase in overline{b} . Also, a comparison between the solutions in the cases of isothermal and adiabatic flows is made.
International Nuclear Information System (INIS)
Shooshtari, S.H. Rajaee; Shahsavand, A.
2017-01-01
Natural gases provide around a quarter of energy consumptions around the globe. Supersonic separators (3S) play multifaceted role in natural gas industry processing, especially for water and hydrocarbon dew point corrections. These states of the art devices have minimum energy requirement and favorable process economy compared to conventional facilities. Their relatively large pressure drops may limit their application in some situations. To maximize the energy recovery of the dew point correction facility, the pressure loss across the 3S unit should be minimized. The optimal structure of 3s unit (including shock wave location and diffuser angle) is selected using simultaneous combination of normal shock occurrence and condensation in the presence of nucleation and growth processes. The condense-free gas enters the non-isentropic normal shock wave. The simulation results indicate that the normal shock location, pressure recovery coefficient and onset position strongly vary up to a certain diffuser angle (β = 8°) with the maximum pressure recovery of 0.88 which leads to minimum potential energy loss. Computational fluid dynamic simulations show that separation of boundary layer does not happen for the computed optimal value of β and it is essentially constant when the inlet gas temperatures and pressures vary over a relatively broad range. - Highlights: • Supersonic separators have found numerous applications in oil and gas industries. • Maximum pressure recovery is crucial for such units to maximize energy efficiency. • Simultaneous condensation and shock wave occurrence are studied for the first time. • Diverging nozzle angle of 8° can provide maximum pressure recovery of 0.88. • The optimal diffuser angle remains constant over a broad range of inlet conditions.
Generation of coincedent EMIC and whistler mode waves by an ICME-shock.
Halford, A. J.; Mann, I. R.
2016-12-01
Radiation belt dynamics are controlled by the competition of multiple acceleration and loss mechanisms. Electromagnetic ion cyclotron (EMIC), chorus, and hiss waves have all been implicated as potential loss mechanisms of radiation belt electrons. Chorus waves are also proposed as a mechanism for accelerating the lower energy source population to MeV energies. Understanding the relative importance of these waves as well as where and under what conditions they are generated is vital to predicting radiation belt dynamics. Although the size of the solar wind compression on 9 Jan. 2014 event discussed here was modest, it gave us an opportunity to clearly observe how a magnetospheric compression can lead to the generation of EMIC, chorus, and hiss waves. The ICME generated shock encountered the Earth's magnetosphere at 20:11 UT on 9 Jan. 2014, and the Van Allen Probes observe the coincident excitation of EMIC and Chorus waves outside the plasmasphere, and hiss waves inside the plasmasphere. As the shock encountered the magnetosphere, an electric field impulse was observed to generate an increase in temperature anisotropy for both ions and electrons. This increased temperature anisotropy led to increased wave growth on both the ion and electron cyclotron branches. The simultaneous generation of multiple wave types may lead to significant impacts on the acceleration and loss of radiation belt electrons, especially during geomagnetic compressions observed during storms and substorms, as well as during quiet time sudden impulse events. For example, the excitation of both EMIC and chorus waves at the same place and time, may complicate studies seeking a causal connection between specific individual plasma wave bursts and observations of particle loss to the atmosphere. During this relatively small event, BARREL had three payloads in conjunction with the Van Allen Probes, two of the payloads inferred electron precipitation within the energy range typically associated with
Measuring oblique incidence sound absorption using a local plane wave assumption
Kuipers, E.R.; Wijnant, Ysbrand H.; de Boer, Andries
2014-01-01
In this paper a method for the measurement of the oblique incidence sound absorption coefficient is presented. It is based on a local field assumption, in which the acoustic field is locally approximated by one incident- and one specularly reflected plane wave. The amplitudes of these waves can be
Influence of plasma shock wave on the morphology of laser drilling in different environments
Zhai, Zhaoyang; Wang, Wenjun; Mei, Xuesong; Wang, Kedian; Yang, Huizhu
2017-05-01
Nanosecond pulse laser was used to study nickel-based alloy drilling and compare processing results of microholes in air environment and water environment. Through analysis and comparison, it's found that environmental medium had obvious influence on morphology of laser drilling. High-speed camera was used to shoot plasma morphology during laser drilling process, theoretical formula was used to calculate boundary dimension of plasma and shock wave velocity, and finally parameters were substituted into computational fluid dynamics simulation software to obtain solutions. Obtained analysis results could intuitively explain different morphological features and forming reasons between laser drilling in air environment and water environment in the experiment from angle of plasma shock waves. By comparing simulation results and experimental results, it could help to get an understanding of formation mechanism of microhole morphology, thus providing basis for further improving process optimization of laser drilling quality.
The effects of gas explosion shock wave load on the containment building
International Nuclear Information System (INIS)
Varpasuo, P.
1981-01-01
The analysis for shock wave for the containment building with height of 69 meters and with diameter of 48 meters surrounded by a cylinder of 77 meters diameter and 33 meters height was carried out. The nature of the shock wave load was quite complicated and the determining the arrival times and pulse forms for different parts of the containment was laborious. The 3-D shell element model for half containment building with 4300 degrees of freedom was used in the analyses and the analysis was carried out with STARDYNE program. The displacement and stress states were determined in four time points during the transient, whose length was taken to be four times the impulse-effective part of the load history of 0.8 sec. The maximum displacement was reached in the apex of the containment cupola and was about 1.0 centimeter. (orig./HP)
Shock wave, fluid instability and implosion studies with a kinetic particle approach
Sagert, Irina; Even, Wesley P.; Strother, Terrance T.
2016-10-01
Many problems in laboratory plasma physics are subject to flows that move between the continuum and the kinetic regime. The correct description of these flows is crucial in order to capture their impact on the system's dynamical evolution. Examples are capsule implosions in inertial confinement fusion (ICF). Although their dynamics is predominantly shaped by shock waves and fluid instabilities, non-equilibrium flows in form of deuterium/tritium ions have been shown to play a significant role. We present recent studies with our Monte Carlo kinetic particle code that is designed to capture continuum and kinetic flows in large physical systems with possible applications in ICF studies. Discussed results will include standard shock wave and fluid instability tests and simulations that are adapted towards future ICF studies with comparisons to hydrodynamic simulations. This work used the Wolf TriLAB Capacity Cluster at LANL. I.S. acknowledges support through a Director's fellowship (20150741PRD3) from Los Alamos National Laboratory.
Experimental study of numerical methods for the solution of gas dynamics problems with shock waves
Godunov, S. K.; Klyuchinskiy, D. V.; Safronov, A. V.; Fortova, S. V.; Shepelev, V. V.
2018-01-01
The work is devoted to some important questions that come with the solution of gas dynamics equations using standard Godunov scheme with the corrections of A V Safronov. The numerical solution is succeeded by intrinsic differential realization of energy conservation law. It has been found experimentally that in all computational cells the entropy nondecreasing is provided. The fact makes it possible to model the entropy rising on shock waves. Besides the experiments described in the paper gives the intrinsic explanation of the reasons for the appearance of the zones with decreased accuracy order in the results. The influence of the computational grid parameters (Courant number) on the plots of grid structures of shock waves is also studied.
Effects of trapped electrons on electromagnetic fields in an oblique shock wave
International Nuclear Information System (INIS)
Toida, Mieko; Shikii, Kenta
2009-01-01
A magnetosonic shock wave propagating obliquely to an external magnetic field can trap electrons and accelerate them to ultrarelativistic energies. The effect of trapped electrons on electromagnetic fields in a shock wave is studied by theory and particle simulations. The expressions for field strengths are analytically obtained, including the number of trapped electrons n t as a factor. It is shown that as n t increases, the magnitude of F increases, where F is the integral of the parallel electric field, E || =(E·B)/B, along B. Theoretical analysis also suggests that the increase in F causes the electrons to be trapped deeper and accelerated to higher kinetic energies. These theoretical predictions are verified with relativistic electromagnetic particle simulations.
Pressure transducer used for measuring close-in shock waves of nuclear explosions in the atmosphere
International Nuclear Information System (INIS)
Lin, J.; Zhou, Z.
1985-01-01
This paper introduces a variable reluctance pressure transducer. It has been successfully used for the measurement of close-in shock waves of nuclear explosions in the atmosphere. This transducer's highest pressure range is 100kg/cm 2 and its response rise time for all ranges is lms. It uses a specially made oil-filled pressure which allows the transducer to be able to realize underground installation. In this way, it can endure the intense nuclear radiation of nuclear explosions without losing its fast speed response characteristics. This transducer has undergone a series of environmental tests and dynamic standardizations. Therefore, it was used to measure the complete waveform of shock wave overpressure in areas near the fire ball of nuclear explosions. This paper lists the test data of a group of nuclear explosion tests
Using second-sound shock waves to probe the intrinsic critical velocity of liquid helium II
Turner, T. N.
1983-01-01
A critical velocity truly intrinsic to liquid helium II is experimentally sought in the bulk fluid far from the apparatus walls. Termed the 'fundamental critical velocity,' it necessarily is caused by mutual interactions which operate between the two fluid components and which are activated at large relative velocities. It is argued that flow induced by second-sound shock waves provides the ideal means by which to activate and isolate the fundamental critical velocity from other extraneous fluid-wall interactions. Experimentally it is found that large-amplitude second-sound shock waves initiate a breakdown in the superfluidity of helium II, which is dramatically manifested as a limit to the maximum attainable shock strength. This breakdown is shown to be caused by a fundamental critical velocity. Secondary effects include boiling for ambient pressures near the saturated vapor pressure or the formation of helium I boundary layers at higher ambient pressures. When compared to the intrinsic critical velocity discovered in highly restricted geometries, the shock-induced critical velocity displays a similar temperature dependence and is the same order of magnitude.
Numerical computation of the Shock Tube Problem by means of wave digital principles
Directory of Open Access Journals (Sweden)
A. Mengel
2006-01-01
Full Text Available Partial differential equations can be solved numerically by means of wave digital principles. The great advantage of this method is the simultaneous achievement of high robustness, massive parallelism full localness and high accuracy. Among others this method will be applied in order to solve the Euler-equations according to one dimension in space. Especially the so called Shock Tube Problem will be examined. The analytical solution of this problem contains two discontinuities, namely a shock and a contact discontinuity. These result in oscillations which are due to numerical integration methods of higher order. Also solutions of the Wave Digital Method contain these oscillations, contrary to what had been observed of Yuhui Zhu (2000. This behaviour is also known as Gibbs Phenomena. The Navier-Stokes-equations, which are from a physical point of view more exactly, additionally take viscosity terms into account. This leads to smooth solutions near shocks. It will be shown that this approach leads to the suppression of the oscillations near the shock. Furthermore it will be shown that quite good results for the computation of velocity and pressure can be obtained.
Interactions of Delta Shock Waves for Zero-Pressure Gas Dynamics with Energy Conservation Law
Directory of Open Access Journals (Sweden)
Wei Cai
2016-01-01
Full Text Available We study the interactions of delta shock waves and vacuum states for the system of conservation laws of mass, momentum, and energy in zero-pressure gas dynamics. The Riemann problems with initial data of three piecewise constant states are solved case by case, and four different configurations of Riemann solutions are constructed. Furthermore, the numerical simulations completely coinciding with theoretical analysis are shown.
Iqbal, Nadeem; Assad, Salman; Rahat Aleman Bhatti, Joshua; Hasan, Aisha; Shabbir, Muhammad Usman; Akhter, Saeed
2016-01-01
Objective To retrospectively evaluate the effectiveness of extracorporeal shock wave lithotripsy (ESWL) for urolithiasis and compare the results between children and adults. Materials and methods From January 2011 to January 2015 (four years), ESWL was performed in 104 children and 300 adults for urolithiasis. MODULITH? SLX-F2 lithotripter (Storz Medical AG, T?gerwilen, Switzerland) equipment was used for ESWL. The stone-free rates, the number of ESWL sessions required, complication rates and...
Effect of electron-ion equilibration on optical emission from a shock wave
International Nuclear Information System (INIS)
Chiu, G.; Ng, A.; Forsman, A.
1997-01-01
Optical emission from a shock wave emerging from a free surface is studied using numerical simulations taking into account the effect of temperature equilibration between electrons and ions. The results show significant variations depending on the equilibration rate. They also illustrate how measurements of the absolute intensity, relative spectral intensities, and temporal history of such emission can provide a new and important means for determining electron-ion equilibration rate in dense matter. copyright 1997 The American Physical Society
Blast Shock Wave Mitigation Using the Hydraulic Energy Redirection and Release Technology
Chen, Yun; Huang, Wei; Constantini, Shlomi
2012-01-01
A hydraulic energy redirection and release technology has been developed for mitigating the effects of blast shock waves on protected objects. The technology employs a liquid-filled plastic tubing as a blast overpressure transformer to transfer kinetic energy of blast shock waves into hydraulic energy in the plastic tubings. The hydraulic energy is redirected through the plastic tubings to the openings at the lower ends, and then is quickly released with the liquid flowing out through the openings. The samples of the specifically designed body armor in which the liquid-filled plastic tubings were installed vertically as the outer layer of the body armor were tested. The blast test results demonstrated that blast overpressure behind the body armor samples was remarkably reduced by 97% in 0.2 msec after the liquid flowed out of its appropriate volume through the openings. The results also suggested that a volumetric liquid surge might be created when kinetic energy of blast shock wave was transferred into hydraulic energy to cause a rapid physical movement or displacement of the liquid. The volumetric liquid surge has a strong destructive power, and can cause a noncontact, remote injury in humans (such as blast-induced traumatic brain injury and post-traumatic stress disorder) if it is created in cardiovascular system. The hydraulic energy redirection and release technology can successfully mitigate blast shock waves from the outer surface of the body armor. It should be further explored as an innovative approach to effectively protect against blast threats to civilian and military personnel. PMID:22745740
Czech Academy of Sciences Publication Activity Database
Stelmashuk, Vitaliy; Hoffer, Petr
2012-01-01
Roč. 40, č. 7 (2012), s. 1907-1912 ISSN 0093-3813 Institutional research plan: CEZ:AV0Z20430508 Keywords : Corona * impedance matching * shock waves Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.868, year: 2012 http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=&arnumber=6205646&contentType=Journals+%26+Magazines&queryText%3Dstelmashuk
Perirenal Hematomas Induced by Extracorporeal Shock Wave Lithotripsy (ESWL). Therapeutic Management
Labanaris, Apostolos P.; Kühn, Reinhard; Schott, Günter E.; Zugor, Vahudin
2007-01-01
Extracorporeal shock wave lithotripsy (ESWL) is nowadays accepted as the treatment of choice for the majority of patients with renal or proximal ureteral calculi. Although, a relatively noninvasive modality with low morbidity, minor or major complications can be noted. A relative severe complication for the patient and confusing for the treating physician is the perirenal hematoma. With review the literature and an example of perirenal hematoma induced by ESWL in a patient treated in our depa...
Supersonic flow with shock waves. Monte-Carlo calculations for low density plasma. I
International Nuclear Information System (INIS)
Almenara, E.; Hidalgo, M.; Saviron, J. M.
1980-01-01
This Report gives preliminary information about a Monte Carlo procedure to simulate supersonic flow past a body of a low density plasma in the transition regime. A computer program has been written for a UNIVAC 1108 machine to account for a plasma composed by neutral molecules and positive and negative ions. Different and rather general body geometries can be analyzed. Special attention is played to tho detached shock waves growth In front of the body. (Author) 30 refs
Effectiveness of shock wave therapy as an alternative to the rotator cuff injury treatment
Roberto Joaquín Del Gordo-D´Amato; Guillermo Orlando Trout-Guardiola; José Acuña-Pinilla
2016-01-01
Rotator cuff injuries are reason for consultation frequent in elderly patients. Most of the time there are no background traumatic acute generating progressive limitations in activities of daily living (ADLS). The objective of this study is to show results in tendonitis of the rotator cuff, in patients treated with extracorporeal shock wave therapy (ESWT). It is a prospective descriptive observational study which presents clinical and functional outcomes in patients with described lesion, tre...
Shahat, Ahmed; Elderwy, Ahmad; Safwat, Ahmed S; Abdelkawi, Islam F; Reda, Ahmed; Abdelsalam, Yasser; Sayed, Mohamed; Hammouda, Hisham
2016-04-01
We assessed the effect of tamsulosin as an adjunctive therapy after shock wave lithotripsy for pediatric single renal pelvic stones. A total of 120 children with a unilateral single renal pelvic stone were included in a prospective randomized, controlled study. All children were randomized to 2 equal groups. Group 1 received tamsulosin (0.01 mg/kg once daily) as adjunctive therapy after shock wave lithotripsy in addition to paracetamol while group 2 received paracetamol only. Stone clearance was defined as no renal stone fragments or fragments less than 3 mm and no pelvicalyceal system dilatation. Our study included 69 boys and 51 girls with a median age of 3.5 years and a median stone size of 1.2 cm. There was no statistically significant difference between groups 1 and 2 in stone or patient criteria. Of the children 99 (82.5%) achieved stone clearance after the first session, including 50 in group 1 and 49 in group 2. All children in each group were cleared of stones after the second session. The overall complication rate was 14.2%. There was no statistically significant difference between single session stone clearance rates (p = 0.81) and complications rates (p = 0.432) in either group. On multivariate analysis using logistic regression smaller stone size (p = 0.016) and radiopaque stones (p = 0.019) were the only predictors of stone clearance at a single shock wave lithotripsy session. Tamsulosin therapy did not affect stone clearance (p = 0.649). Tamsulosin does not seem to improve renal stone clearance. Smaller and radiopaque renal stones have more chance of clearance after shock wave lithotripsy for pediatric single renal pelvic stones. Copyright © 2016 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.
Shock-wave profile formation in a gas with allowance for relaxation effects
Lipnitskii, Yu. M.; Panasenko, A. V.
2009-11-01
An important distinctive feature of gaseous media that possess relaxation properties is a delay in the heat transfer, which must be taken into account in the description of processes in these media. Numerical solution of the Navier-Stokes equations shows that the classical distribution of parameters in a shock wave described by the well-known analytical solution of Becker [1] can be unacceptable if the medium possesses relaxation properties manifested on a nanosecond time scale.
Blast shock wave mitigation using the hydraulic energy redirection and release technology.
Directory of Open Access Journals (Sweden)
Yun Chen
Full Text Available A hydraulic energy redirection and release technology has been developed for mitigating the effects of blast shock waves on protected objects. The technology employs a liquid-filled plastic tubing as a blast overpressure transformer to transfer kinetic energy of blast shock waves into hydraulic energy in the plastic tubings. The hydraulic energy is redirected through the plastic tubings to the openings at the lower ends, and then is quickly released with the liquid flowing out through the openings. The samples of the specifically designed body armor in which the liquid-filled plastic tubings were installed vertically as the outer layer of the body armor were tested. The blast test results demonstrated that blast overpressure behind the body armor samples was remarkably reduced by 97% in 0.2 msec after the liquid flowed out of its appropriate volume through the openings. The results also suggested that a volumetric liquid surge might be created when kinetic energy of blast shock wave was transferred into hydraulic energy to cause a rapid physical movement or displacement of the liquid. The volumetric liquid surge has a strong destructive power, and can cause a noncontact, remote injury in humans (such as blast-induced traumatic brain injury and post-traumatic stress disorder if it is created in cardiovascular system. The hydraulic energy redirection and release technology can successfully mitigate blast shock waves from the outer surface of the body armor. It should be further explored as an innovative approach to effectively protect against blast threats to civilian and military personnel.
Impact of extracorporeal shock wave therapy in the treatment of chronic lateral epicondylitis
Deroanne, Adrien; Deroanne, Didier; Florkin, Marc; Kaux, Jean-François
2012-01-01
Background and aim: radial shock wave therapy (RSWT) is a relatively new way to treat chronic tendinopathies, such as lateral epicondylitis. However, very few studies have been realized on this subject, and the results are very divergent. We aimed to observe the impact of this technique on chronic lateral elbow pain. Method: fifteen subjects who had a lateral epicondylitis for at least 3 months were included in the study. Two groups were formed: experimental (10 subjects) who received 6 s...
Study on possible explosive reactions of sodium nitrate-bitumen mixtures initiated by a shock wave
International Nuclear Information System (INIS)
Savornin, J.; Vasseur, C.
1986-01-01
Potential hazards of the mixture sodium nitrate-bitumen obtained by embedding in bitumen liquid radioactive effluents concentrated by evaporation are studied in case of accidental shock wave. A theoretical evaluation based on thermodynamical data show a low probability, nevertheless different from zero. No explosion occurred in tests realized in severe conditions. In conclusion there is no risk of detonation of large quantity of bitumen-nitrates stored in 200-liter drum in radioactive waste storage [fr
Blast shock wave mitigation using the hydraulic energy redirection and release technology.
Chen, Yun; Huang, Wei; Constantini, Shlomi
2012-01-01
A hydraulic energy redirection and release technology has been developed for mitigating the effects of blast shock waves on protected objects. The technology employs a liquid-filled plastic tubing as a blast overpressure transformer to transfer kinetic energy of blast shock waves into hydraulic energy in the plastic tubings. The hydraulic energy is redirected through the plastic tubings to the openings at the lower ends, and then is quickly released with the liquid flowing out through the openings. The samples of the specifically designed body armor in which the liquid-filled plastic tubings were installed vertically as the outer layer of the body armor were tested. The blast test results demonstrated that blast overpressure behind the body armor samples was remarkably reduced by 97% in 0.2 msec after the liquid flowed out of its appropriate volume through the openings. The results also suggested that a volumetric liquid surge might be created when kinetic energy of blast shock wave was transferred into hydraulic energy to cause a rapid physical movement or displacement of the liquid. The volumetric liquid surge has a strong destructive power, and can cause a noncontact, remote injury in humans (such as blast-induced traumatic brain injury and post-traumatic stress disorder) if it is created in cardiovascular system. The hydraulic energy redirection and release technology can successfully mitigate blast shock waves from the outer surface of the body armor. It should be further explored as an innovative approach to effectively protect against blast threats to civilian and military personnel.
Suppression of transverse instabilities of dark solitons and their dispersive shock waves
Armaroli, Andrea
2009-11-03
We investigate the impact of nonlocality, owing to diffusive behavior, on transverse instabilities of a dark stripe propagating in a defocusing cubic medium. The nonlocal response turns out to have a strongly stabilizing effect both in the case of a single soliton input and in the regime where dispersive shock waves develop (multisoliton regime). Such conclusions are supported by the linear stability analysis and numerical simulation of the propagation. © 2009 The American Physical Society.
Supersonic flow with shock waves. Monte-Carlo calculations for low density plasma. Part. 1
International Nuclear Information System (INIS)
Almenara, E.; Hidalgo, M.; Saviron, J.M.
1980-01-01
A preliminary information about a Monte Carlo procedure to simulate supersonic flow past a body of a low density plasma in the transition regime is gived. A computer program has been written for a Univac 1108 machine to account for a plasma composed by neutral molecules and positive and negative ions. Different and rather general body geometries can be analyzed. Special attention is payed to the detached shock waves growth in front of the body. (author)
Observation of strong oscillations of areal mass in an unsupported shock wave.
Aglitskiy, Y; Karasik, M; Velikovich, A L; Serlin, V; Weaver, J; Kessler, T J; Schmitt, A J; Obenschain, S P; Metzler, N; Oh, J
2012-08-24
An experimental study of hydrodynamic perturbation evolution in a strong unsupported shock wave, which is immediately followed by an expansion wave, is reported. A planar solid plastic target rippled on the front side is irradiated with a 350-450 ps long laser pulse. The perturbation evolution in the target is observed using face-on monochromatic x-ray radiography during and for up to 4 ns after the laser pulse. The theoretically predicted large oscillations of the areal mass in the target are observed for the first time. Multiple phase reversals of the areal mass modulation are detected.
An Approximate Analytical Model of Shock Waves from Underground Nuclear Explosions
1990-12-01
of the official yields. 14, SUBJECT TERMS 15 NUMBER OF PAGES iilr’sh41old JI Vs B/lIT1 rt t , lirodvinam it methiods, ’-hock waves, 74 1111(1 rl ~I...shock wave methods, to appear in Explosion Source Pheno neiolgy, S. R. Taylor, P. G. Richards, and H. J. Patton , eds., American Geophysical Union...Fig. A6 62 DISTR I TON ,1 1ST Proo. ’i ifl as Ahrcns Dr. T.J. BennettSe-inotogical Lab, 252-21 S-CUBF.D Division of Geological & Planetary Sciences A
Postural change-dependent T-wave oversensing resulting in the administration of inappropriate shocks
Directory of Open Access Journals (Sweden)
Yukoh Hirai
2012-10-01
Full Text Available A 68-year-old man with dilated cardiomyopathy (left ventricular ejection fraction, 15% and nonsustained ventricular tachycardia received an implantable cardioverter defibrillator. Even though his cardiac status had greatly improved 2 years later after β-blocker therapy, he experienced 2 episodes of sudden shock when he was squatting in a bathroom without any preceding symptoms. His serum electrolyte and plasma glucose levels were normal. Interrogation of the device revealed that the shock was caused by sinus tachycardia and T-wave oversensing. A number of episodes of nonsustained ventricular tachycardia due to T-wave oversensing was also recorded. Follow-up interrogation of the device with the patient in the supine position could not reproduce the T-wave oversensing. We were able to elicit T-wave oversensing only after reproduction of the patient's clinical situation using isoproterenol and postural changes (i.e., sinus tachycardia and squatting. This case suggests that sudden increases in nonsustained ventricular tachycardia events may be caused by T-wave oversensing, and postural changes should be taken into consideration in such situations.
Predictability of the individual clinical outcome of extracorporeal shock wave therapy for cellulite
Directory of Open Access Journals (Sweden)
Schlaudraff KU
2014-05-01
Full Text Available Kai-Uwe Schlaudraff,1 Maren C Kiessling,2 Nikolaus BM Császár,2 Christoph Schmitz21Concept Clinic, Geneva, Switzerland; 2Department of Anatomy II, Ludwig-Maximilians-University of Munich, Munich, GermanyBackground: Extracorporeal shock wave therapy has been successfully introduced for the treatment of cellulite in recent years. However, it is still unknown whether the individual clinical outcome of cellulite treatment with extracorporeal shock wave therapy can be predicted by the patient's individual cellulite grade at baseline, individual patient age, body mass index (BMI, weight, and/or height.Methods: Fourteen Caucasian females with cellulite were enrolled in a prospective, single-center, randomized, open-label Phase II study. The mean (± standard error of the mean cellulite grade at baseline was 2.5±0.09 and mean BMI was 22.8±1.17. All patients were treated with radial extracorporeal shock waves using the Swiss DolorClast® device (Electro Medical Systems, S.A., Nyon, Switzerland. Patients were treated unilaterally with 2 weekly treatments for 4 weeks on a randomly selected side (left or right, totaling eight treatments on the selected side. Treatment was performed at 3.5–4.0 bar, with 15,000 impulses per session applied at 15 Hz. Impulses were homogeneously distributed over the posterior thigh and buttock area (resulting in 7,500 impulses per area. Treatment success was evaluated after the last treatment and 4 weeks later by clinical examination, photographic documentation, contact thermography, and patient satisfaction questionnaires.Results: The mean cellulite grade improved from 2.5±0.09 at baseline to 1.57±0.18 after the last treatment (ie, mean δ-1 was 0.93 cellulite grades and 1.68±0.16 at follow-up (ie, mean δ-2 was 0.82 cellulite grades. Compared with baseline, no patient's condition worsened, the treatment was well tolerated, and no unwanted side effects were observed. No statistically significant (ie, P<0
Ge, Ni-Na; Wei, Yong-Kai; Ji, Guang-Fu; Chen, Xiang-Rong; Zhao, Feng; Wei, Dong-Qing
2012-11-26
We have performed quantum-based multiscale simulations to study the initial chemical processes of condensed-phase octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) under shock wave loading. A self-consistent charge density-functional tight-binding (SCC-DFTB) method was employed. The results show that the initial decomposition of shocked HMX is triggered by the N-NO(2) bond breaking under the low velocity impact (8 km/s). As the shock velocity increases (11 km/s), the homolytic cleavage of the N-NO(2) bond is suppressed under high pressure, the C-H bond dissociation becomes the primary pathway for HMX decomposition in its early stages. It is accompanied by a five-membered ring formation and hydrogen transfer from the CH(2) group to the -NO(2) group. Our simulations suggest that the initial chemical processes of shocked HMX are dependent on the impact velocity, which gain new insights into the initial decomposition mechanism of HMX upon shock loading at the atomistic level, and have important implications for understanding and development of energetic materials.
In Vitro Assessment of Three Clinical Lithotripters Employing Different Shock Wave Generators.
Faragher, Stuart Roy; Cleveland, Robin O; Kumar, Sunil; Wiseman, Oliver J; Turney, Benjamin W
2016-05-01
To test the hypothesis that shock wave lithotripsy machines vary in their ability to fragment standardized artificial urinary calculi. An in vitro test configuration was used to fragment synthetic U-30 Gypsum (U.S. Gypsum, Chicago, IL) stones (mean length 7.1 ± 0.2 mm, mean diameter 6.5 ± 0.07 mm, mean mass 299 ± 16 mg) using the Sonolith i-sys (EDAP TMS, Vaulx-en-Velin, France), Modulith SLX F2 (Storz Medical AG, Tägerwilen, Switzerland), and Piezolith 3000 (Richard Wolf GmbH, Knittlingen, Germany) lithotripters. Gypsum stones were placed at the nominal focus and treated with 250, 500, or 1000 shocks. The residual mass following passage through a 2-mm wire mesh was measured and compared using ANOVA and the Tukey-Kramer HSD test. There was no statistically significant difference between the Modulith SLX F2 and Piezolith 3000 lithotripters for 250 and 1000 shock treatments (p = 0.34 and 0.31, respectively). The Piezolith 3000 demonstrated the most favorable stone mass reduction for 500 shock treatments (187.4 ± 45.2 mg). The Sonolith i-sys was found to be significantly less effective than the other lithotripters for all shockwave conditions. Furthermore, performance of the Sonolith i-sys decreased beyond a threshold generator electrode age of 6000 shocks. This in vitro study found considerable variability in the ability of lithotripters to fragment synthetic urinary calculi. Synthetic stones were employed to provide a repeatable means of assessing variability in fragmentation efficiency of lithotripters. The Modulith SLX F2 and Piezolith 3000 are broadly equal and resulted in greater fragmentation efficiencies than the Sonolith i-sys. The performance of the Sonolith i-sys deteriorates at 6000 shocks, before the specified lifetime of 20,000 shocks.
Instrumentation techniques for monitoring shock and detonation waves
Dick, R. D.; Parrish, R. L.
1985-09-01
CORRTEX (Continuous Reflectometry for Radius Versus Time Experiments), SLIFER (Shorted Location Indication by Frequency of Electrical Resonance), and pin probes were used to monitor several conditions of blasting such as the detonation velocity of the explosive, the functioning of the stemming column confining the explosive, and rock mass motion. CORRTEX is a passive device that employs time-domain reflectometry to interrogate the two-way transit time of a coaxial cable. SLIFER is an active device that monitors the changing frequency resulting from a change in length of a coaxial cable forming an element of an oscillator circuit. Pin probes in this application consist of RG-174 coaxial cables, each with an open circuit, placed at several known locations within the material. Each cable is connected to a pulse-forming network and a voltage source. When the cables are shorted by the advancing wave, time-distance data are produced from which a velocity can be computed. Each technique, installation of the gauge, examples of the signals, and interpretation of the records are described.
Muller, Milos; Garen, Walter; Koch, Sandra; Marsik, Frantisek; Neu, Walter; Saburov, Eduado
2004-04-01
Temporal evolution of laser generated cavitation bubbles and shock waves were studied. Q-switched Nd-Yag laser pulses at 1064 nm are focused into the liquid. An Imager 3 CCD camera with multi exposure mode allows recording of 10 images with minimal exposure delay of 100 ns and minimal exposure time of 100 ns. Illumination is provided by xenon flash lamp for single exposure (shock wave recording) and by halogen lamp for multi exposure mode (bubble recording). Distilled water and a retrograde fluid, isooctane, have been under investigation to identify the differences in the cavitation process and shock wave propagation. The calculation of the shock wave velocities in water and isooctane are based on image recording at constant exposure time of 100 ns and using laser differential interferometry. Strong differences of bubble oscillation were observed in water and isooctane. Gilmore's model is used for numerical simulation of bubble dynamics.
National Aeronautics and Space Administration — Large amplitude, unsteady heating loads and steep flow gradients produced in regions of shock-wave/turbulent boundary-layer interaction (SWTBLI) pose a serious and...
National Aeronautics and Space Administration — Large amplitude, unsteady heating loads and steep flow gradients produced in regions of shock-wave/turbulent boundary-layer interaction (SWTBLI) pose a serious and...
Luh, Jer-Junn; Huang, Wan-Ting; Lin, Kwan-Hwa; Huang, Yi-You; Kuo, Po-Ling; Chen, Wen-Shiang
2018-01-01
Cavitation plays a substantial role in the clinical effects of extracorporeal shock wave therapy (ESWT). It is also generally accepted as a major mechanism in sonophoresis. To identify the enhancing effect of extracorporeal shock wave-mediated transdermal drug delivery, 24 Wistar rats were randomly assigned to four groups: (i) topical application of a eutectic mixture of local anesthetics (EMLA); (ii) 1-MHz ultrasound; (iii) ESWT pre-treatment combined with EMLA application; (iv) ESWT concurrent with EMLA application on rat tails. The degree of anesthesia was assessed using the amplitude and latency of sensory nerve action potentials within 5 min after a 60-min EMLA application. The results indicated that ESWT pre-treatment and concurrent ESWT accelerated the anesthetic effects of the EMLA cream on the tail nerve (p < 0.05). This finding might indicate that shock wave-mediated transdermal drug delivery is possible during the ESWT period. Copyright © 2018 World Federation for Ultrasound in Medicine and Biology. Published by Elsevier Inc. All rights reserved.
Progression of crack formation in artificial kidney stones subject to shock waves
Van Cauwelaert, Javier; Cleveland, Robin
2002-11-01
We used micro computed tomography (CT) imaging to follow the progressive development of cracks in artificial kidney stones. The artificial stones were made from U30 cement with a cylindrical shape (6.5 mm diameter and 7.5 mm long). The stones were held within a polypropylene vial in one of three different orientations: vertical, horizontal, and angled at 45 deg. The stones were treated with an electromagnetic lithotripter using between 50 and 150 shock waves. The initiation and growth of cracks was observed using microCT. We found that crack formation in the U30 stones was influenced by the orientation of the stone with respect to the shock wave (SW) propagation direction. Vertical stones developed a spall-like crack near the distal surface; horizontal stones had little internal damage for the number of shock waves applied; and angled stones were damaged primarily in the vicinity of the leading corner. The position of the cracks were in qualitative agreement with the numerical solutions of the pressure field inside the stones. The elastic properties of the U30 stones are being measured which will alow a quantitative analysis of crack growth to be performed and compared to the experimental data. [Work supported by the Whitaker Foundation.
Effect of shock wave therapy on ankle plantar flexors spasticity in stroke patients.
Sawan, Salah; Abd-Allah, Foad; Hegazy, Montasser M; Farrag, Mohammad A; El-Den, Nancy Hosney Sharf
2017-01-01
Large number of patients with first-ever stroke developed spasticity. Spasticity can reduce the range of motion, hinder voluntary movements, provoke pain, and result in impairment of functional activities of daily living. Demonstrate the effect of shock wave therapy on ankle plantar flexors spasticity in stroke patients. We included forty ischemic stroke patients divided into 2 groups; group I were subjected to the selected physical therapy program and shock wave therapy whereas group II received the selected physical therapy program as well as placebo shock wave for six weeks. Both groups were subjected to pre- and post-treatment assessment by H/M ratio, dorsiflexion active range of motion, and time of ten-meters walking. Baseline characteristics showed no significant difference between the two groups regarding the grades of spasticity. Whereas After treatment, there were a highly significant difference between both groups regarding the grades of spasticity according to the 3 parameters, H/M ratio, dorsiflexion active range of motion, and time of ten-meters walking test (P values; therapy is effective in controlling spasticity, increase dorsiflexion active range of motion of ankle and improving ten- meters walking test in stroke patients.
Influence of water conductivity on shock waves generated by underwater electrical wire explosion
Liu, Ben; Wang, Deguo; Guo, Yanbao
2018-01-01
The new application of electrical explosion of wire (EEW) used in petroleum industry is to enhance oil recovery (EOR). Because of the complex environment underground, the effect of underground water conductivity on EEW should be considered. This work describes the effect of water conductivities on discharge current, voltage and shock waves. It was found that the effect of water conductivity contains two parts. One is the shunt effect of saline water, which can be considered as a parallel load with the copper wire between the electrodes connected to the discharge circuit. The peak pressure of shock waves are gradually decrease with the increase of water conductivity. The other is the current loss through saline water directly to the ground ends without flowing through the electrodes. The shunt effect is the main factor affecting the wire discharge process. As the charging voltage increased, the energy loss caused by these two parts are all reduced. These indicate that increasing the charging voltage to a certain value will increase the energy efficiency to generate a more powerful shock waves in conductive water.
A Review of Computational Methods in Materials Science: Examples from Shock-Wave and Polymer Physics
Steinhauser, Martin O.; Hiermaier, Stefan
2009-01-01
This review discusses several computational methods used on different length and time scales for the simulation of material behavior. First, the importance of physical modeling and its relation to computer simulation on multiscales is discussed. Then, computational methods used on different scales are shortly reviewed, before we focus on the molecular dynamics (MD) method. Here we survey in a tutorial-like fashion some key issues including several MD optimization techniques. Thereafter, computational examples for the capabilities of numerical simulations in materials research are discussed. We focus on recent results of shock wave simulations of a solid which are based on two different modeling approaches and we discuss their respective assets and drawbacks with a view to their application on multiscales. Then, the prospects of computer simulations on the molecular length scale using coarse-grained MD methods are covered by means of examples pertaining to complex topological polymer structures including star-polymers, biomacromolecules such as polyelectrolytes and polymers with intrinsic stiffness. This review ends by highlighting new emerging interdisciplinary applications of computational methods in the field of medical engineering where the application of concepts of polymer physics and of shock waves to biological systems holds a lot of promise for improving medical applications such as extracorporeal shock wave lithotripsy or tumor treatment. PMID:20054467
Directory of Open Access Journals (Sweden)
Akhtar Sobia
2003-01-01
Full Text Available Abstract Background To determine factors influencing the clearance of fragments after extra-corporeal shock wave lithotripsy (ESWL for lower pole calyceal (LPC stones. Methods In the period between July 1998 and Oct 2001, 100 patients with isolated lower polar calyceal calculi ≤ 20 mm, in patients aged ≥ 14 years, were included in the study. Intravenous urograms (IVU were reviewed to define the LPC anatomy (width of the infundibulum and pelvicalyceal angle. Study end points i.e. stone free status; number of shock waves used and number of sessions were correlated with variables like LPC anatomy, body mass index and stone size. Results At three months follow up the clearance for stone size ≤ 10 mm, 11–15 mm and 16–20 mm were 95, 96 and 90% respectively. Patients with acute LPC (90° had stone clearance of 94 and 100% respectively. For the infundibular width of 4 mm, it was 100%. For body mass index (BMI less than and > 30 kg/m2, the stone clearance was 92 and 95% respectively. Conclusions There is a trend towards more ESWL sessions and shock wave requirement in patients with acute pelvi-calyceal angle and narrow infundibulum but it is not statistically significant. Size (≤ 20 mm and BMI has no relation with stone clearance. With modern lithotripter, stones up to 20 mm could primarily be treated by ESWL, irrespective of an un-favorable lower polar calyceal anatomy and body habitus.
Extracorporeal shock waves lithotripsy of urinary organs in patients with one kidney
Directory of Open Access Journals (Sweden)
Zogović Jezdimir
2002-01-01
Full Text Available Extracorporeal Shock Waves Lithotripsy (ESWL is a method of choice in the treatment of lithiasis. Surgical treatment is reduced to minimum, which in our case means 1-2%. Contraindications for using this method are: blood coagulation disorders, manifest tuberculosis, pregnancy, over obesity. Thanks to appropriate indications and technique which is used in an adequate way as well as to various endurological manipulations, removal of a stone by this method is safe, trauma is minimised, which is very important for patients with one kidney. During the last three years, usually in hospital conditions, 57 patients were treated in this way. Removal of a stone was performed by Extracorporeal Shock Waves Lithotripsy as mono therapy in 30 (53% patients; Extracorporeal Shock Waves Lithotripsy by using Double-J catheter in 16 (28% patients; Extracorporeal Lithotripsy with urine derivation by percutaneous nephrostome in 11 (19% patients. Endurological methods were used in 27 patients. Disintegration of stone was performed in the proper way. Full success was reached. Two patients had incrustation of ureteral catheter which had to be removed by surgery. In two other patients with inferior function of one kidney, after brief obstruction, hemodialisis was performed. Our results confirm that this method is nonaggressive, tech nically perfect for disintegration of urineorgans stone on all levels followed by small complications which are often solved by endoscopie manipulations.
Soliton shock wave fronts and self-similar discontinuities in dispersion hydrodynamics
International Nuclear Information System (INIS)
Gurevich, A.V.; Meshcherkin, A.P.
1987-01-01
Nonlinear flows in nondissipative dispersion hydrodynamics are examined. It is demonstrated that in order to describe such flows it is necessary to incorporate a new concept: a special discontinuity called a ''self-similar'' discontinuity consisting of a nondissipative shock wave and a powerful slow wave discontinuity in regular hydrodynamics. The ''self similar discontinuity'' expands linearly over time. It is demonstrated that this concept may be introduced in a solution to Euler equations. The boundary conditions of the ''self similar discontinuity'' that allow closure of Euler equations for dispersion hydrodynamics are formulated, i.e., those that replace the shock adiabatic curve of standard dissipative hydrodynamics. The structure of the soliton front and of the trailing edge of the shock wave is investigated. A classification and complete solution are given to the problem of the decay of random initial discontinuities in the hydrodynamics of highly nonisothermic plasma. A solution is derived to the problem of the decay of initial discontinuities in the hydrodynamics of magnetized plasma. It is demonstrated that in this plasma, a feature of current density arises at the point of soliton inversion
Extracorporeal shock wave therapy for calcific tendinitis at unusual sites around the hip.
Oh, Kwang-Jun; Yoon, Jung-Ro; Shin, David Sung-Joon; Yang, Jae-Hyuk
2010-10-11
Extracorporeal shock wave therapy has been considered to be an effective treatment for various pathogenic orthopedic conditions. However, it is not generally recognized in treatment for calcific tendinitis around the hip region. This article presents 2 cases of calcific tendinitis at the hip, located in the pectineus muscle and the rectus femoris muscle, where successful treatment was achieved using extracorporeal shock wave therapy. In 1 case, a 60-year-old woman presented with pain in her right thigh of 1 month's duration that had become severe in intensity for 1 week. Physical examination revealed marked localized tenderness over the posterolateral aspect of the right thigh when positioned in flexion, abduction, and external rotation. Anteroposterior and frog-leg lateral radiographs revealed nodular-shaped calcium deposits at the posterolateral aspect of the proximal thigh. T1- and T2-weighted magnetic resonance imaging of the hip joint revealed a 2.7×1.3-cm, low-signal density area near the femoral insertion of pectineus and gluteus maximus muscle with inflammatory infiltration in the surrounding soft tissue. Treatment was started in the form of extracorporeal shock wave therapy, doses of which were administered in 3 sessions with an interval of 7 days. Radiographs of the affected thigh taken 4 weeks after therapy showed disintegration of the calcium deposits. Copyright 2010, SLACK Incorporated.
Complexity-action duality of the shock wave geometry in a massive gravity theory
Miao, Yan-Gang; Zhao, Long
2018-01-01
On the holographic complexity dual to the bulk action, we investigate the action growth for a shock wave geometry in a massive gravity theory within the Wheeler-DeWitt (WDW) patch at the late time limit. For a global shock wave, the graviton mass does not affect the action growth in the bulk, i.e., the complexity on the boundary, showing that the action growth (complexity) is the same for both the Einstein gravity and the massive gravity. Nevertheless, for a local shock wave that depends on transverse coordinates, the action growth (complexity) caused by the boundary disturbance (perturbation) is proportional to the butterfly velocity for the two gravity theories, but the butterfly velocity of the massive gravity theory is smaller than that of the Einstein gravity theory, indicating that the action growth (complexity) of the massive gravity is depressed by the graviton mass. In addition, we extend the black hole thermodynamics of the massive gravity and obtain the right Smarr formula.
Can cellulite be treated with low-energy extracorporeal shock wave therapy?
Directory of Open Access Journals (Sweden)
Fiorenzo Angehrn
2008-01-01
Full Text Available Fiorenzo Angehrn1, Christoph Kuhn1, Axel Voss21Klinik Piano, Gottstattstrasse 24, Biel, Switzerland; 2SwiTech Medical AG, Kreuzlingen, SwitzerlandAbstract: The present study investigates the effects of low-energy defocused extracorporeal generated shock waves on collagen structure of cellulite afflicted skin. Cellulite measurement using high-resolution ultrasound technology was performed before and after low-energy defocused extracorporeal shock wave therapy (ESWT in 21 female subjects. ESWT was applied onto the skin at the lateral thigh twice a week for a period of six weeks. Results provide evidence that low-energy defocused ESWT caused remodeling of the collagen within the dermis of the tested region. Improving device-parameters and therapy regimes will be essential for future development of a scientific based approach to cellulite treatment.Keywords: cellulite (gynoid lipodystrophy, collagen structure of dermis, collagenometry high-resolution ultrasound of skin, low-energy defocused extracorporeal shock wave therapy (ESWT, septa of subcutaneous connective tissue
Extracorporeal shock wave therapy relieved pain in patients with coccydynia: a report of two cases.
Marwan, Yousef; Husain, Wael; Alhajii, Waleed; Mogawer, Magdy
2014-01-01
Extracorporeal shock wave therapy (ECSWT) has been used widely for musculoskeletal conditions; however, no reports are available about its use for coccydynia. Study the effect of ECSWT in relieving pain of coccydynia. Case report. Extracorporeal shock wave therapy was used for two male patients, Patients 1 and 2, who failed to respond completely to other conservative management of coccydynia. Numerical pain scale (NPS) and visual analogue scale (VAS) were used to assess the pain. Consent to publish the data was obtained from both the patients. Before starting ECSWT, Patient 1 reported a pain intensity of 6/10 and 5.1/10 on NPS and VAS, respectively, whereas the intensity of pain in Patient 2 was 7/10 and 6.9/10 on NPS and VAS, respectively. Four weeks after ECSWT, Patient 1 reported complete relief of pain on NPS and VAS, whereas Patient 2 reported a pain intensity of 1/10 and 0.8/10 on NPS and VAS, respectively. The same intensity of pain was reported by both patients after 12 months of follow-up. Extracorporeal shock wave therapy relieved pain of coccydynia in our patients. Copyright © 2014 Elsevier Inc. All rights reserved.
Development of an Omnidirectional-Capable Electromagnetic Shock Wave Generator for Lipolysis
Directory of Open Access Journals (Sweden)
Ming Hau Chang
2017-01-01
Full Text Available Traditional methods for adipose tissue removal have progressed from invasive methods such as liposuction to more modern methods of noninvasive lipolysis. This research entails the development and evaluation of an omnidirectional-capable flat-coil electromagnetic shock wave generator (EMSWG for lipolysis. The developed EMSWG has the advantage of omnidirectional-capable operation. This capability increases the eventual clinical usability by adding three designed supports to the aluminum disk of the EMSWG to allow omnidirectional operation. The focal pressures of the developed EMSWG for different operating voltages were measured, and its corresponding energy intensities were calculated. The developed EMSWG was mounted in a downward orientation for lipolysis and evaluated as proof of concept. In vitro tests on porcine fatty tissues have been carried out. It is found that at a 6 kV operating voltage with 1500 shock wave exposures, a 2 cm thick subcutaneous hypodermis of porcine fatty tissue can be ruptured, resulting in a damaged area of 1.39 mm2. At a 6.5 kV operating voltage with 2000 shock wave exposures, the damaged area is increased to about 5.20 mm2, which can be enlarged by changing the focal point location, resulting in significant lipolysis for use in clinical applications.
International Nuclear Information System (INIS)
Guo Bin
2009-01-01
Based on the electromagnetic theory and by using an analytical technique-the transfer matrix method, the obliquely incident electromagnetic waves propagating in one-dimension plasma photonic crystals is studied. The dispersion relations for both the P-polarization waves and S-polarization waves, depending on the plasma density, plasma thickness and period, are discussed. (basic plasma phenomena)
International Nuclear Information System (INIS)
Van Kessel, C.G.M.; Sachsenmaier, P.; Sigel, R.
1975-01-01
Shock waves driven by laser ablation in plane transparent plexiglass and solid hydrogen targets have been observed with streak and framing techniques using a high speed image converter camera, and a dye laser as a light source. The framing pictures have been made by mode locking the dye laser and using a wide streak slit. In both materials a growing hemispherical shock wave is observed with the maximum velocity at the onset of laser radiation. (author)
Qi, Baochang; Yu, Tiecheng; Wang, Chengxue; Wang, Tiejun; Yao, Jihang; Zhang, Xiaomeng; Deng, Pengfei; Xia, Yongning; Junger, Wolfgang G; Sun, Dahui
2016-10-03
Osteosarcoma is the most prevalent primary malignant bone tumor, but treatment is difficult and prognosis remains poor. Recently, large-dose chemotherapy has been shown to improve outcome but this approach can cause many side effects. Minimizing the dose of chemotherapeutic drugs and optimizing their curative effects is a current goal in the management of osteosarcoma patients. In our study, trypan blue dye exclusion assay was performed to investigate the optimal conditions for the sensitization of osteosarcoma U2OS cells. Cellular uptake of the fluorophores Lucifer Yellow CH dilithium salt and Calcein was measured by qualitative and quantitative methods. Human MTX ELISA Kit and MTT assay were used to assess the outcome for osteosarcoma U2OS cells in the present of shock wave and methotrexate. To explore the mechanism, P2X7 receptor in U2OS cells was detected by immunofluorescence and the extracellular ATP levels was detected by ATP assay kit. All data were analyzed using SPSS17.0 statistical software. Comparisons were made with t test between two groups. Treatment of human osteosarcoma U2OS cells with up to 450 shock wave pulses at 7 kV or up to 200 shock wave pulses at 14 kV had little effect on cell viability. However, this shock wave treatment significantly promoted the uptake of Calcein and Lucifer Yellow CH by osteosarcoma U2OS cells. Importantly, shock wave treatment also significantly enhanced the uptake of the chemotherapy drug methotrexate and increased the rate of methotrexate-induced apoptosis. We found that shock wave treatment increased the extracellular concentration of ATP and that KN62, an inhibitor of P2X7 receptor reduced the capacity methotrexate-induced apoptosis. Our results suggest that shock wave treatment promotes methotrexate-induced apoptosis by altering cell membrane permeability in a P2X7 receptor-dependent manner. Shock wave treatment may thus represent a possible adjuvant therapy for osteosarcoma.
Collapse and fragmentation of molecular cloud cores. 2: Collapse induced by stellar shock waves
Boss, Alan P.
1995-01-01
The standard scenario for low-mass star formation involves 'inside-out' collapse of a dense molecular cloud core following loss of magnetic field support through ambipolar diffusion. However, isotopic anomalies in presolar grains and meteoritical inclusions imply that the collapse of the presolar cloud may have been triggered by a stellar shock wave. This paper explores 'outside-in' collapse, that is, protostellar collapse initiated directly by the compression of quiescent dense cloud cores impacted by relatively slow stellar shock waves. A second-order accurate, gravitational hydrodynamics code has been used to study both the spherically symmetrical and three-dimensional evolution of initially centrally condensed, isothermal, self-gravitating, solar-mass cloud cores that are struck by stellar shock waves with velocities up to 25 km/s and postshock temperatures of 10 to 10,000 K. The models show that such mild shock waves do not completely shred and destroy the cloud, and that the dynamical ram pressure can compress the cloud to the verge of self-gravitational collapse. However, compression caused by a high postshock temperature is a considerably more effective means of inducing collapse. Shock-induced collapse produces high initial mass accretion rates (greater than 10(exp -4) solar mass/yr in a solar-mass cloud) that decline rapidly to much lower values, depending on the presence (approximately 10(exp -6) solar mass/yr) or absence (approximately 10(exp -8) to 10(exp -7) solar mass/yr) of an infinite reservoir of mass. Stellar mass accretion rates approximately 10(exp -7) solar mass/yr have been previously inferred from the luminosities of T Tauri stars; balanced mass accretion (stellar rate = envelope rate) at approximately 10(exp -7) solar mass/yr could then be possible if accretion occurs from a finite mass reservoir. Fluid tracers are used to determine what fraction of the stellar shock material is incorporated into the resulting protostellar object and disk
Skolarikos, Andreas; Mitsogiannis, Heraklis; Deliveliotis, Charalambos
2010-03-01
To clarify the current indications, factors influencing outcome and methods to predict and improve the results of shock wave lithotripsy for the treatment of renal and upper ureteral calculi. English literature on the Medline and MeSH databases was reviewed. Key words used for search included shock wave lithotripsy, calculi, stones, renal, kidney, ureter, efficacy, prediction, improvement and guidelines. Shock wave lithotripsy still has certain indications for renal and upper ureteral stones. Major impact on outcome has the stone size, with a diameter of less than 20 mm being the cutoff point. Shock wave monotherapy should not be used for larger stones and should be combined with other treatment modalities such as percutaneous nephrolithotomy or ureteroscopy. Other factors influencing outcome include stone number, composition and location, existence of congenital abnormalities, obesity and bleeding diathesis. Nomograms, artificial neural networks and computed tomography are useful adjuncts in predicting the outcome. Potential methods of improvement are the decrease of shock wave rate, the progressive increase in lithotripter output, the use of two simultaneous or sequential pulses and the use of expulsive and chemolytic treatment. Shock wave lithotripsy continues to be a significant part in the urologists armamentarium for the treatment of renal and upper ureteral stones.
Mendez-Probst, C E; Vanjecek, M; Razvi, H; Cadieux, P A
2010-12-01
In vitro shock wave lithotripsy (SWL) research is typically performed utilizing wet coupling lithotriptors with a mesh basket model. This model does not take into account shock wave energy attenuation through tissue. Models using dry coupling lithotriptors rely on immersion chambers and face similar limitations. Ordnance gelatin (OG) displays strength and viscous properties similar to human tissue and is therefore widely used for ballistic tissue injury research. We present our initial experience using an OG tissue simulating scaffold for dry coupling SWL research. Using 10% OG prepared in a disc-shaped mold (five stone wells/gel), we tested the model using a Modulith SLX-F2 lithotriptor and artificial stone phantoms. Following a test of concept run on an empty gel mold and a material integrity check for leakage, we shocked 60 stones (30 narrow focus [NF], 30 wide focus [WF]) in human pooled urine. Half were shocked using gels containing open-ended wells with the remainder closed-ended wells. Fragmentation coefficients (FC) were calculated across both foci and gel models. All gels successfully completed 5,000 shocks (1,000/well) without loss of gel integrity or fluid leakage. The mean FC using open-ended wells was 77.9 ± 7.6% NF and 74.4 ± 4.8% WF, and for closed wells 75.9 ± 8.0% NF and 67.1 ± 3.5% WF. The total model cost including the preparation of gels and begostones was assessed at approximately $1 per stone (Canadian). Ordnance gel serves as an excellent surrogate tissue shockwave scaffold providing an easily manufactured, reproducible and inexpensive model for dry coupling SWL research.
MOLECULAR LINE EMISSION FROM MULTIFLUID SHOCK WAVES. I. NUMERICAL METHODS AND BENCHMARK TESTS
International Nuclear Information System (INIS)
Ciolek, Glenn E.; Roberge, Wayne G.
2013-01-01
We describe a numerical scheme for studying time-dependent, multifluid, magnetohydrodynamic shock waves in weakly ionized interstellar clouds and cores. Shocks are modeled as propagating perpendicular to the magnetic field and consist of a neutral molecular fluid plus a fluid of ions and electrons. The scheme is based on operator splitting, wherein time integration of the governing equations is split into separate parts. In one part, independent homogeneous Riemann problems for the two fluids are solved using Godunov's method. In the other, equations containing the source terms for transfer of mass, momentum, and energy between the fluids are integrated using standard numerical techniques. We show that, for the frequent case where the thermal pressures of the ions and electrons are << magnetic pressure, the Riemann problems for the neutral and ion-electron fluids have a similar mathematical structure which facilitates numerical coding. Implementation of the scheme is discussed and several benchmark tests confirming its accuracy are presented, including (1) MHD wave packets ranging over orders of magnitude in length- and timescales, (2) early evolution of multifluid shocks caused by two colliding clouds, and (3) a multifluid shock with mass transfer between the fluids by cosmic-ray ionization and ion-electron recombination, demonstrating the effect of ion mass loading on magnetic precursors of MHD shocks. An exact solution to an MHD Riemann problem forming the basis for an approximate numerical solver used in the homogeneous part of our scheme is presented, along with derivations of the analytic benchmark solutions and tests showing the convergence of the numerical algorithm.
Molecular Line Emission from Multifluid Shock Waves. I. Numerical Methods and Benchmark Tests
Ciolek, Glenn E.; Roberge, Wayne G.
2013-05-01
We describe a numerical scheme for studying time-dependent, multifluid, magnetohydrodynamic shock waves in weakly ionized interstellar clouds and cores. Shocks are modeled as propagating perpendicular to the magnetic field and consist of a neutral molecular fluid plus a fluid of ions and electrons. The scheme is based on operator splitting, wherein time integration of the governing equations is split into separate parts. In one part, independent homogeneous Riemann problems for the two fluids are solved using Godunov's method. In the other, equations containing the source terms for transfer of mass, momentum, and energy between the fluids are integrated using standard numerical techniques. We show that, for the frequent case where the thermal pressures of the ions and electrons are Lt magnetic pressure, the Riemann problems for the neutral and ion-electron fluids have a similar mathematical structure which facilitates numerical coding. Implementation of the scheme is discussed and several benchmark tests confirming its accuracy are presented, including (1) MHD wave packets ranging over orders of magnitude in length- and timescales, (2) early evolution of multifluid shocks caused by two colliding clouds, and (3) a multifluid shock with mass transfer between the fluids by cosmic-ray ionization and ion-electron recombination, demonstrating the effect of ion mass loading on magnetic precursors of MHD shocks. An exact solution to an MHD Riemann problem forming the basis for an approximate numerical solver used in the homogeneous part of our scheme is presented, along with derivations of the analytic benchmark solutions and tests showing the convergence of the numerical algorithm.
Shock-wave-like structures induced by an exothermic neutralization reaction in miscible fluids.
Bratsun, Dmitry; Mizev, Alexey; Mosheva, Elena; Kostarev, Konstantin
2017-11-01
We report shock-wave-like structures that are strikingly different from previously observed fingering instabilities, which occur in a two-layer system of miscible fluids reacting by a second-order reaction A+B→S in a vertical Hele-Shaw cell. While the traditional analysis expects the occurrence of a diffusion-controlled convection, we show both experimentally and theoretically that the exothermic neutralization reaction can also trigger a wave with a perfectly planar front and nearly discontinuous change in density across the front. This wave propagates fast compared with the characteristic diffusion times and separates the motionless fluid and the area with anomalously intense convective mixing. We explain its mechanism and introduce a new dimensionless parameter, which allows to predict the appearance of such a pattern in other systems. Moreover, we show that our governing equations, taken in the inviscid limit, are formally analogous to well-known shallow-water equations and adiabatic gas flow equations. Based on this analogy, we define the critical velocity for the onset of the shock wave which is found to be in the perfect agreement with the experiments.
Dynamic capability of irradiated fuel bay to resist shock waves due to flask drop
International Nuclear Information System (INIS)
Ishac, M.F.; Tang, J.G.K.
1983-01-01
The transfer of irradiated fuel in the storage bays is accomplished by the use of very heavy flasks made of thick stainless steel and depleted uranium composite walls. The flask is transported by overhead crane. During its travel over the bay, it is postulated that the flask may be dropped accidentally into the storage bay water, inducing shock wave pressures on the concrete bay walls. In the event of such an accident, it has been found that very high hydrodynamic pressure waves would be generated. The magnitudes of these shock waves have to be assessed by hydraulic model tests. The purpose of this paper is to describe a methodology to develop mathematical models for an Irradiated Fuel Bay Structure, to compute its dynamic response due to pressure wave effects, and to evaluate the capability of the walls to withstand such hydrodynamic pressures. The procedure is demonstrated by a dynamic analysis of Irradiated Fuel Bay finite element model using the NASTRAN Computer Code. The natural frequencies of the first 20 modes were extracted, and the peak pressure time histories were applied as forcing functions acting at the nodes of the structural bay wall taking into consideration the spatial variation of the force amplitude at different node location. The time history dynamic response of the Irradiated Fuel Bay walls was computed by the modal analysis including the first 20 modes of vibration. (orig./GL)
Andrushchenko, V. A.; Murashkin, I. V.; Shevelev, Yu. D.
2016-06-01
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 shock waves 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 reflected shocks waves on them—are investigated. The tendency of the external wave 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 waves are manifested more clearly in this caseTwo variants with different altitude of the explosions above the surface are calculated.
International Nuclear Information System (INIS)
Dragila, R.; Vukovic, S.
1988-01-01
The properties of surfave waves that are associated with a boundary between a rare plasma and a dense magnetoactive plasma and that propagate along a dc magnetic field are investigated. It is shown that the presence of the magnetic field introduces symmetry in terms of the polarization of the incident electromagnetic wave that excites the surface waves. A surface wave excited by an incident p-polarized (s-polarized) electromagnetic wave leaks in the form of an s-polarized (p-polarized) electromagnetic wave. The rate of rotation of polarization is independent of the polarization of the incident wave. Because a surface wave can leak in the form of an s-polarized electromagnetic wave, it can also be pumped by such a wave, and conditions were found for excitation of a surface wave by an s-polarized incident electromagnetic wave
2016-12-01
To estimate the incidence density, point prevalence and outcome of severe sepsis and septic shock in German intensive care units (ICUs). In a prospective, multicentre, longitudinal observational study, all patients already on the ICU at 0:00 on 4 November 2013 and all patients admitted to a participating ICU between 0:00 on 4 November 2013 and 2359 hours on 1 December 2013 were included. The patients were followed up for the occurrence of severe sepsis or septic shock (SEPSIS-1 definitions) during their ICU stay. A total of 11,883 patients from 133 ICUs at 95 German hospitals were included in the study, of whom 1503 (12.6 %) were diagnosed with severe sepsis or septic shock. In 860 cases (57.2 %) the infections were of nosocomial origin. The point prevalence was 17.9 % (95 % CI 16.3-19.7).The calculated incidence rate of severe sepsis or septic shock was 11.64 (95 % CI 10.51-12.86) per 1000 ICU days. ICU mortality in patients with severe sepsis/septic shock was 34.3 %, compared with 6 % in those without sepsis. Total hospital mortality of patients with severe sepsis or septic shock was 40.4 %. Classification of the septic shock patients using the new SEPSIS-3 definitions showed higher ICU and hospital mortality (44.3 and 50.9 %). Severe sepsis and septic shock continue to be a frequent syndrome associated with high hospital mortality. Nosocomial infections play a major role in the development of sepsis. This study presents a pragmatic, affordable and feasible method for the surveillance of sepsis epidemiology. Implementation of the new SEPSIS-3 definitions may have a major effect on future epidemiological data.
Directory of Open Access Journals (Sweden)
Xiankai Meng
2017-01-01
Full Text Available The laser shock wave (LSW generated by the interaction between a laser and a material has been widely used in laser manufacturing, such as laser shock peening and laser shock forming. However, due to the high strain rate, the propagation of LSW in materials, especially LSW at elevated temperatures, is difficult to study through experimental methods. A molecular dynamics simulation was used in this study to investigate the propagation of LSW in an Al-Cu alloy. The Hugoniot relations of LSW were obtained at different temperatures and the effects of elevated temperatures on shock velocity and shock pressure were analyzed. Then the elastic and plastic wave of the LSW was researched. Finally, the evolution of dislocations induced by LSW and its mechanism under elevated temperatures was explored. The results indicate that the shock velocity and shock pressure induced by LSW both decrease with the increasing temperatures. Moreover, the velocity of elastic wave and plastic wave both decrease with the increasing treatment temperature, while their difference decreases as the temperature increases. Moreover, the dislocation atoms increases with the increasing temperatures before 2 ps, while it decreases with the increasing temperatures after 2 ps. The reason for the results is related to the formation and evolution of extended dislocations.
Feng, Aixin; Cao, Yupeng; Wang, Heng; Zhang, Zhengang
2018-01-01
In order to reveal the quantitative control of the residual stress on the surface of metal materials, the relevant theoretical and experimental studies were carried out to investigate the dynamic response of metal thin plates and the formation mechanism of residual stress induced by laser shock wave. In this paper, the latest research trends on the surface residual stress of laser shock processing technology were elaborated. The main progress of laser shock wave propagation mechanism and dynamic response, laser shock, and surface residual stress were discussed. It is pointed out that the multi-scale characterization of laser and material, surface residual stress and microstructure change is a new hotspot in laser shock strengthening technology.
Lipatov, A. S.; Sibeck, D. G.
2016-01-01
We use a new hybrid kinetic model to simulate the response of ring current, outer radiation belt, and plasmaspheric particle populations to impulsive interplanetary shocks. Since particle distributions attending the interplanetary shock waves and in the ring current and radiation belts are non-Maxwellian, waveparticle interactions play a crucial role in energy transport within the inner magnetosphere. Finite gyroradius effects become important in mass loading the shock waves with the background plasma in the presence of higher energy ring current and radiation belt ions and electrons. Initial results show that shocks cause strong deformations in the global structure of the ring current, radiation belt, and plasmasphere. The ion velocity distribution functions at the shock front, in the ring current, and in the radiation belt help us determine energy transport through the Earth's inner magnetosphere.