Electron-beam measurements of shock-wave thickness.
Electron beam measurement of shock wave thickness used to determine limits of validity of Navier- Stokes equations
SHOCK WAVE PROFILE↗
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Prediction of Shock Wave Structure in Weakly Ionized Gas Flow by Solving MGD Equation
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.
Deng, Z. T.↗
Nucleosynthesis in Supernova Shock Waves
Thermonuclear reactions occurring in supernova shock wave propagating through stellar envelope
THERMONUCLEAR REACTION↗
On the observation of a flare-generated shock wave at 9.7 AU by Pioneer 10
An apparent solar-flare-generated shock wave detected by Pioneer-10 at 9.7 AU on April 9, 1976 is discussed. The shock wave may be correlated with a radio emission burst from Jupiter not associated with Io (March 30). The fact that solar flares observed on March 20 were at the central meridian with respect to Jupiter and Pioneer-10 and the fact that solar activity was very low before March 20 contribute to the argument that a shock wave had propagated to the region of the spacecraft.
Dryer, M.↗
Pre-plasma effect on energy transfer from laser beam to shock wave generated in solid target
Efficiency of the laser radiation energy transport into the shock wave generated in layered planar targets (consisting of massive Cu over coated by thin CH layer) was investigated. The targets were irradiated using two laser pulses. The 1ω pulse with the energy of ∼50 J produced a pre-plasma, imitating the corona of the pre-compressed inertial confinement fusion target. The second main pulse used the 1ω or 3ω laser harmonics with the energy of ∼200 J. The influence of the pre-plasma on parameters of the shock wave was determined from the crater volume measurements and from the electron density distribution measured by 3-frame interferometry. The experimental results show that the energy transport by fast electrons provides a definite contribution to the dynamics of the ablative process, to the shock wave generation, and to the ablation pressure in dependence on the target irradiation conditions. The strong influence of the pre-plasma on the investigated process was observed in the 1ω case. Theoretical analysis supports the explanation of experimental results.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Two dimensional electrostatic shock waves in relativistic electron positron ion plasmas
Ion-acoustic shock waves (IASWs) are studied in an unmagnetized plasma consisting of electrons, positrons and hot ions. In this regard, Kadomtsev-Petviashvili-Burgers (KPB) equation is derived using the small amplitude perturbation expansion method. The dependence of the IASWs on various plasma parameters is numerically investigated. It is observed that ratio of ion to electron temperature, kinematic viscosity, positron concentration, and the relativistic ion streaming velocity affect the structure of the IASW. Limiting case of the KPB equation is also discussed. Stability of KPB equation is also presented. The present investigation may have relevance in the study of electrostatic shock waves in relativistic electron-positron-ion plasmas.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Aero-thermal numerical characterization of blunt fin-induced shock wave–boundary layer interaction and its control through leading-edge cooling injection
This study represents a novel evaluation of active flow control to alleviate the aerothermal penalties created by the blunt fin-induced shock wave–boundary layer interaction. The manuscript analyzes the effect of flow injection on a blunt fin-induced shock wave–boundary layer interaction via computational fluid dynamics simulations with various degrees of resolution. The impact on the mean flow topology and wall variables was investigated utilizing Reynolds-averaged Navier–Stokes simulations. Detached-eddy simulations revealed the low-frequency shock motion, shock wave–boundary layer, and horseshoe vortex interaction. The test article was exposed to two different incoming boundary layer thicknesses; the thicker boundary layer led to the appearance of larger turbulent scales. The Detached-eddy simulations revealed the time history of the shock wave–boundary layer interaction, focusing on the inception and development of the recirculated flow regions. Ultimately, spectral proper orthogonal decomposition was employed to identify the structures associated with the low-frequency shock motion caused by the shock wave–boundary layer interaction.
Lozano, Francisco (ORCID:0000000277871125)↗
Three-dimensional shock-wave/boundary-layer interactions with bleed through a circular hole
Computations were performed to study three-dimensional (3-D), shock-wave/boundary-layer interactions on a flat plate in which fluid in the boundary layer was bled through a circular hole into a plenum to control shock-wave induced separation. Results are presented which show the details of the 3-D flowfield about the bleed hole and how bleed-hole placement relative to shock-wave impingement affect upstream, spanwise, and downstream influence lengths. This study revealed an underlying mechanisms by which bleed holes can affect shock-wave/boundary-layer interactions. This investigation is based on the ensemble-averaged, "full-compressible" Navier-Stokes equations closed by the Baldwin-Lomax turbulence model. Solutions to these equations were obtained by an implicit finite-volume method based on the partially-split, two-factored algorithm of Steger.
Rimlinger, M. J.↗
The structure of strong shock waves in the krook collision model
Shock wave profile computation using krook collision model equation in iteration scheme starting from navier-stokes solution
KROOK EQUATION↗
Application of shock wave data to earth and planetary science
It is pointed out that shock wave data for: (1) low temperature condensable gases H2 and He, (2) H2O, CH4, NH3, CO, CO2, and N2 ices, and (3) silicates, metals, oxides and sulfides have many applications in geophysics and planetary science. The present paper is concerned with such applications. The composition of planetary interiors is discussed, taking into account the division of the major constituent of the planets in three groups on the basis of 'cosmic abundance' arguments, the H-He mixtures in the case of Jupiter and Saturn, shock wave data for hydrogen, and constraints on the internal structure of Uranus and Neptune. Attention is also given to the earth's mantle, shock wave data for mantle materials, the earth's core, impacts on planetary surfaces, elastic wave velocities as a function of pressure along the Hugoniot of iron, and reactions which yield the CO2 bearing atmospheres for Venus, earth, and Mars.
Ahrens, T. J.↗
Interplanetary shock waves and the structure of solar wind disturbances
Observations and theoretical models of interplanetary shock waves are reviewed, with emphasis on the large-scale characteristics of the associated solar wind disturbances and on the relationship of these disturbances to solar activity. The sum of observational knowledge indicates that shock waves propagate through the solar wind along a broad, roughly spherical front, ahead of plasma and magnetic field ejected from solar flares. Typically, the shock front reaches 1 AU about two days after its flare origin, and is of intermediate strength. Not all large flares produce observable interplanetary shock waves; the best indicator of shock production appears to be the generation of both type 2 and type 4 radio bursts by a flare. Theoretical models of shock propagation in the solar wind can account for the typically observed shock strength, transit time, and shape.
Hundhausen, A. J.↗
On the stability and structure of shock waves in interplanetary space
Structure of interplanetary shock waves formed by interaction of geomagnetic field and solar wind - earth bow shock
SHOCK WAVE INTERACTION↗
Synchrotron based X-ray radiography of convergent shock waves driven by underwater electrical explosion of a cylindrical wire array
We present x-ray radiography images showing the propagation of shock waves generated by electrical explosion of a cylindrical arrangement of wires in water driven by pulsed power. In previous experiments [S. N. Bland et al., Phys. Plasmas 24, 082702 (2017)] the merger of shock waves from adjacent wires has produced a highly symmetrical, cylindrical shock wave converging on the axis, where it is expected to produce a high density, strongly coupled plasma ideal for warm dense matter research. However, diagnostic limitations have meant that much of the dynamics of the system have been inferred from the position of the front of the cylindrical shock and timing/spectra of light emitted from the axis. Here we present synchrotron-based radiography of such experiments – providing direct quantitative measurements on the formation of the convergent shock wave, the increased density of water on axis caused by its arrival, and its ‘bounce’ after arrival on axis. The obtained images are compared with twodimensional hydrodynamic simulations which reproduce the observed dynamics with a satisfactory agreement in density values.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
The effects of shock waves on meteorites Final report
Shock wave effects on iron and iron-nickel alloys in meteorites analyzed by phase diagrams and residual effects due to shock loading
De Carli, P. S.↗
Physical mechanisms for turbulent dissipation in collisionless shock waves
Dissipation processes in collisionless shock waves are discussed in terms of simple physical models. Two cases are considered: one is concerned with quasi-parallel shocks and the other deals with quasi-perpendicular shocks. In the former case it is explained why the magnetic field profile of a parallel shock usually appears turbulent. The dominant instability responsible for collisionless dissipation processes is discussed. The situation is quite different in a quasi-perpendicular shock in which cross-field currents are believed to be responsible for the collisionless dissipation. Important instabilities are reviewed and discussed. A brief comparison of the theory with recent observations will also be given.
Wu, C. S.↗
Visualization of Shock Wave Driven by Millimeter Wave Plasma in a Parabolic Thruster
By focusing a high-power millimeter wave beam generated by a 170 GHz gyrotron, a breakdown occurred and a shock wave was driven by plasma heated by following microwave energy. The shock wave and the plasma around a focal point of a parabolic thruster were visualized by a shadowgraph method, and a transition of structures between the shock wave and the plasma was observed. There was a threshold local power density to make the transition, and the propagation velocity at the transition was around 800 m/s.
42 ENGINEERING↗
Shock waves in the solar system.
Review of the role of gasdynamic processes involving shock waves in the transfer of solar material and energy to the earth and elsewhere in the solar system. The role of shock waves in maintaining the high temperature of the solar corona and in establishing the steady-state solar wind is discussed. An approximate hydromagnetic theory is developed to explain the flow of a supersonic solar wind past planets and the moon. Data concerning the passage of interplanetary shock waves and the ability of a solar flare to produce such a wave are reviewed, and some terrestrial consequences of solar activity are cited.
Spreiter, J. R.↗
Experimental study of shock-wave reflection from a thermally accommodating wall.
Shock-tube experiments have been conducted to study the nonequilibrium gas-surface interaction which occurs when a thick shock wave in argon reflects from a coplanar, heat-conducting wall. Fast-response instrumentation was used to monitor variations in temperature and normal stress on the surface of the shock-tube end wall during and immediately following reflection of the incident shock wave. The laboratory observations are compared with computer predictions obtained by Deiwert using the direct-simulation Monte Carlo method, and excellent agreement is obtained when a suitable average thermal accommodation coefficient is chosen for the wall surface.
Hanson, R. K.↗