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1.
The self-similar model of a shock wave, produced on account of an instantaneous release of energy in an inhomogeneous self-gravitating gaseous mass, has been discussed with the help of equations of motion and equilibrium conditions. The disturbances are headed by a shock of variable strength. The variation of velocity density, pressure, and mass have been discussed for the different values of strength of the shock. 相似文献
2.
Expressions for the variation of shock strength and its propagation in non-ideal fluids are presented by using the method developed by Whitham. The effects of the presence of rotation, rotation and magnetic field on the strength and propagation velocity of shock waves have been discussed separately. Finally, the effects of the presence of gravitation on the shock strength and on propagation velocity have been studied. 相似文献
3.
The magnetohydrodynamic model of shock waves has been discussed in an atmosphere with gravitation and radiation. The disturbance is headed by a strong shock of increasing density. The medium ahead of the shock is assumed to be inhomogeneous and at rest. Variation of magnetic field radiation flux, and other flow variables are given in tabular form. 相似文献
4.
A theoretical model of shock wave propagation in a self-gravitating radiative magneto-hydrodynamic medium has been studied. The effects of the magnetic field, radiation, and gravitation have been discussed separately. The results discussed depend upon the numerical variations of flow variables behind the shock. 相似文献
5.
Self-similar motion of a perfect gas behind a cylindrical shock wave with radiation heat flux in the presence of an azimuthal magnetic field have been discussed. The shock is assumed to be propagating in a medium at rest with non-uniform density. The conductivity of the gas is infinite and magnetic permeability is one everywhere. Also, the shock is assumed to be transparent and isothermal. 相似文献
6.
Onkar Nath 《Astrophysics and Space Science》1988,146(1):169-174
The model of self-similar shock wave produced on account of an instantaneous release of energy in a non-uniform gaseous mass, has been discussed with the equilibrium conditions. The disturbance are headed by a shock of variable strength. This model is of considerable physical interest in sonic booms, phenomena associated with laser production of plasma, high altitude nuclear detonation, supernova explosion and sudden expansion of corona into the interplanetary space. 相似文献
7.
A propagation of diverging cylindrical shock in a self-gravitating gas, having an initial density and azimuthal magnetic field distributions variable, has been studied for the two cases (i) when the shock is weak and (ii) when it is strong. Analytical relations for shock velocity and shock strength have been obtained. Lastly, the expressions for the pressure, the density and the particle velocity immediately behind the shock have been also obtained for both cases. 相似文献
8.
In the present paper, we have discussed the propagation of spherical shock waves in a radiating magnetohydrodynamic rotating interplanetary medium. The effects of force of self-gravitation have been taken into account with the assumption that at the equilibrium position the effects of rotation on the force of gravitation are negligible. The combined effects of rotation and gravitation on the variation of flow variables have been shown in tables. The particular cases of the problem have been discussed and compared by considering effects of rotation and gravitation separately. 相似文献
9.
R. C. Srivastava D. Leutloff J. P. Vishwakarma Arun Kumar 《Astrophysics and Space Science》1986,122(1):33-40
Magnetogasdynamic shock waves propagating in a medium of increasing density are discussed. The shock travels in a dense atmosphere. We have used the Runge-Kutta method to obtain a numerical solution of the problem. The distribution of flow variables behind the shock are shown by graphs. 相似文献
10.
Strong cylindrical magnetogasdynamic shock waves in rotating interplanetary medium has been studied and an analytic solution for their propagation has been obtained. Using characteristic method and considering the effect of Coriolis force, we have shown that magnetic field has significant effect on the velocity of the shock wave. 相似文献
11.
Vishnu Sharan 《Astrophysics and Space Science》1984,104(2):189-197
By use of the approximate method of Whitham (1958), the propagation of magnetogasdynamic spherical shock waves is considered for adiabatic and isothermal flows in a decreasing density medium. The effect of initial magnetic fields on the shock velocity is discussed; and a comparison made between adiabatic and isothermal cases. 相似文献
12.
A transient flow system containing several streams and shocks associated with the Bastille Day 2000 solar event was observed
by the WIND and ACE spacecraft at 1 AU. Voyager 2 (V2) at 63 AU observed this flow system after it moved through the interplanetary medium and into the distant heliosphere,
where the interstellar pickup protons strongly influence the MHD structures and flow dynamics. We discuss the Voyager 2 magnetic and plasma observations of this event. Increases in the magnetic field strength B, density N, temperature T and
speed V were observed at the front of a stream at V2, consistent with presence of a shock related to the Bastille Day shock
at 1 AU. However, the jumps occurred in a 16.9-hour data gap, so that the shock was not observed directly, and the properties
of the candidate shock cannot be determined precisely. The candidate shock was followed by a merged interaction region (MIR)
that moved past V2 for at least 10 days. The first part of this MIR contains a structure that might be a magnetic cloud. Just
ahead of the shock there was an abrupt increase in density associated with a decrease in temperature such that the solar wind
thermal pressure was constant across it. Just behind the shock there was an abrupt decrease in density associated with a net
increase in magnetic field strength. This appears to be a pressure balanced structure in which the interstellar pickup protons
make a significant contribution. 相似文献
13.
GRB 980519 is characterized by its rapidly declining optical and X-ray afterglows. Explanations of this behaviour include models invoking a dense medium environment, which makes the shock wave evolve quickly into the subrelativistic phase, a jet-like outflow, and a wind-shaped circumburst medium environment. Recently, Frail et al. found that the latter two cases are consistent with the radio afterglow of this burst. Here, by considering the transrelativistic shock hydrodynamics, we show that the dense medium model can also account for the radio light curve quite well. The potential virtue of the dense medium model for GRB 980519 is that it implies a smaller angular size of the afterglow, which is essential for interpreting the strong modulation of the radio light curve. Optical extinction arising from the dense medium is not important if the prompt optical–UV flash accompanying the γ -ray emission can destroy dust by sublimation out to an appreciable distance. Comparisons with some other radio afterglows are also discussed. 相似文献
14.
Stjepan Selak 《Astrophysics and Space Science》1973,24(2):309-321
In this paper, we study the propagation of a weak shock wave in a medium of initially constant fluid velocity, magnetic field
and thermodynamic parameters. The structure of discontinuities for such a shock in real cases will be analyzed. By examining
the change in variables inside the relaxation transition region, the length of the latter, i.e. of the disturbed region will
be obtained. In order to derive the physical model explaining the finite shock length, several assumptions have been made:
the medium has been treated as a very large layer of non-negligible viscosity and thermal conductivity. Starting from basic
MHD relations, the invariants on the shock fronts, taking into consideration the process inside the disturbed region, have
been calculated. Modified Rankine-Hugoniot equation discussing the process inside the relaxation region has been derived therefrom.
Finally, the dependence of pressure upon distance has been examined under the assumptions: the fluid is considered as polytropic.
Hence, by approximate integration of an obtained transcendental function, we get the length of relaxation region and discuss
the result obtained. 相似文献
15.
The problem of explosion along a line in a gas cloud in the presence of transverse magnetic field has been considered. Similarity solutions of the adiabatic motion of a gas behind an infinitely strong cylindrical shock wave propagating into an infinitely conducting medium at rest is obtained. Shock radius varies exponentially with time and density is inversely proportional to fourth power of shock radius just ahead of the shock front. 相似文献
16.
Similarity solutions describing the flow of a perfect gas behind a cylindrical shock wave with transverse magnetic field are investigated in an inhomogeneous medium. The total energy of the shock wave is assumed to be constant. A comparative study has been made between the results with and without magnetic field. 相似文献
17.
Using the C.C.W. method, propagation of diverging cylindrical shock wave in a self-gravitating and rotating gas under the influence of a constant axial magnetic field has been studied for two cases of weak and strong shocks. Medium ahead of the shock is supposed to be homogeneous. Analytical relations for shock velocity and shock strength along with the expressions for the pressure, density, and particle velocity just behind the shock wave have been also obtained for both cases. 相似文献
18.
In this paper propagation of spherical shock waves with radiation heat flux is considered in an exponentially increasing medium. The shock wave moves with variable velocity and the total energy of the wave is variable. For different values of radiation parameter, the numerical solution has been made and the nature of the field variables are illustrated by the tables. 相似文献
19.
The shock wave produced by a point source has been studied in a heat-conducting gas medium. The shock is assumed to be strong enough to neglect the ambient gas pressure and the similarity method is used. The distribution of flow quantities behind the shock have been obtained by the numerical integration of a system of ordinary differential equations using the boundary conditions at the shock wave. 相似文献
20.
Prasanta Chatterjee Deb Kumar Ghosh Biswajit Sahu 《Astrophysics and Space Science》2012,339(2):261-267
The nonlinear propagation of ion acoustic shock waves (IASWs) are studied in an unmagnetized plasma consisting of nonthermal
electrons, nonthermal positrons, and singly charged adiabatically hot positive ions, whose dynamics is governed by the two
dimensional nonplanar Kadomstev-Petviashvili-Burgers (KPB) equation. The shock solution of the KPB equations is obtained numerically.
The effects of several parameters and ion kinematic viscosities on the properties of ion acoustic shock waves are discussed
in planar and nonplanar geometry. It is shown that the ion acoustic shock wave propagating in cylindrical/spherical geometry
with transverse perturbation will be deformed as time goes on. Also, it is seen that the strength and the steepness of the
IASWs increases with increasing β, the nonthermal parameter. 相似文献