共查询到20条相似文献，搜索用时 15 毫秒
1.
The effect of the disturbance behind a strong plane shock wave propagating in a medium with exponentially varying density in the presence of magnetic field is investigated. The similarity solution is used to find the two interaction terms at all points of the flow. A method has been developed to determine the similarity exponent in magnetogasdynamics. 相似文献
2.
In this paper, similarity solutions for the propagation of strong-plane shock waves in optically-thin grey atmospheres are obtained in the presence of a magnetic field. Density and magnetic field are constant in the undisturbed gaseous medium in front of the shock. Planck's diffusion approximation has been taken into account in this problem and a comparative study has been made between the results of ordinary gasdynamics and magnetogasdynamics. 相似文献
3.
J. B. Singh 《Astrophysics and Space Science》1988,150(1):43-52
Using a well-known similarity method, different aspects of cylindrical shock waves in magnetogasdynamics are investigated. Weak and strong shocks have been discussed in strong magnetic field. Combined effects of both the components of magnetic field on flow variables are studied. 相似文献
4.
Mithilesh Singh 《Astrophysics and Space Science》2013,343(2):615-619
In present paper, I have studied second-kind self-similar solutions of converging cylindrical shock wave in non-ideal magnetogasdynamics. Two trial functions suggested by Singh et al. and the shooting method of Landau–Stanyukovich are used to determine the similarity exponent α for different values of specific heat ratio γ and the parameter k, where k∈(0,1] and internal volume $\tilde{b}$ in non-ideal magnetogasdynamics. 相似文献
5.
A self-similar solution to the problem of the implosion of a cylindrical shock wave in the presence of a magnetic field has been investigated. A strong shock wave in a cylindrically-symmetric flow travels to the axis of symmetry through a gas of uniform initial density 0 and zero-pressure. A comparative study has been made between the results obtained in ordinary gasdynamics and magnetogasdynamics with transverse and axial components of the magnetic field. The value of similarity exponent has been assigned from that found in the paper of Whitham (1958). 相似文献
6.
An exact similarity solution for a spherical magnetogasdynamic shock is obtained in the case when radiation energy, radiation pressure and radiative heat flux are important. The total energy of the shock wave increase with time. We have shown that due to the magnetic field the flow variables are considerably changed. Also, due to increases in radiation pressure number the radiation flux is increased. 相似文献
7.
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
8.
The point-source, spherical magnetogasdynamics shock wave moving into a constant density -law gas is considered in the limit of infinite shock strength, from the point of view of the Richtmyer-Von Neumann viscosity technique. Numerical solutions of this problem has been obtained in viscous and non-viscous regions. A similarity solution of this problem is shown to exist. We have shown that field variables change rapidly when the magnetic field is imposed in both the viscous and the non-viscous regions.Supported by CSIR, New DeIhi under the grant No. 7157/287/81-DMR-I. 相似文献
9.
A similarity solution for the flow variables behind a radiation-driven magnetohydrodynamic shock wave has been obtained. Owing to absorption of radiation incident on the shock layer, it is assumed that the total energy contained behind the shock surface is increasing. The ambient medium in which shock wave moves is non-uniform and it is optically thin so that there is no interaction with the incident radiation. A comparison has been made between the results with and without the magnetic field when the density and azimuthal magnetic field distributions are variable.While this paper was in press, Professor Verma passed away on 4 April 1985, without being able to read its proofs. 相似文献
10.
The quasisimilar theory is used to investigate the solution of the blast wave problem with generalized geometries in a non-ideal
gas satisfying the equation of state of the Van der Waals type. Here it is assumed that the distribution of normalized velocity,
pressure and density are nearly similar in the narrow range of the shock strength. A comparison between approximate analytical
solution and numerical solution of the problem is presented for the cylindrical geometry. The numerical solutions are presented
for the generalized geometry in a non-ideal gas. It is also assessed as to how the non-idealness of the gas affects the behavior
of the flow parameters. 相似文献
11.
The propagation of magnetogasdynamic cylindrical shock waves in an exponentially increasing medium including the effects of the azimuthal magnetic field, is investigated. The shock wave moves with variable velocity and the total energy of the wave is variable. It is shown that the magnetic field has its significant effect on the pressure flow velocity and the inner expanding vacuum region. 相似文献
12.
J. Daskalakis N. Kafoussias A. Lewkowicz E. W. Williams 《Astrophysics and Space Science》1989,151(2):217-226
A similarity analysis for the free and forced convection hydromagnetic flow over a horizontal semi-infinite flat plate through a non-homogeneous porous medium is presented, taking into account the hydrostatic pressure variation normal to the flat plate. The similarity solution of the problem under consideration is obtained under certain valid simplifying assumptions when, (i) the plate temperature is inversely proportional to the square root of the distance from the leading edge, (ii) the intensity of the applied magnetic field, normal to the plate, changes with the inverse square root of the distance from the leading edge, and (iii) the permeability of the porous medium, occupying a semi-infinite region of the space bounded by the flat plate, is proportional to the distance measured in the direction of the flow. A numerical solution of the resulting system of ordinary differential equations of motion and energy is obtained, depending on the Prandtl number Pr, the magnetic parameterM
n
,the bouyancy parameter , and the permeability parameterP
m
.The variations of the fundamental quantities of the problem are shown graphically followed by a quantitative discussion. 相似文献
13.
In this paper propagation of magnetogasdynamic spherical shock waves is considered in an exponentially increasing medium. The shock wave moves with variable velocity and the total energy of the wave is variable. It is shown that the magnetic field changes the flow velocity, density and pressure. 相似文献
14.
The problem of shock wave propagation in a heat-conducting and self-gravitating medium has been studied. The shock is strong enough so that the ambient gas pressure can be neglected. The variation of velocity, density, temperature, and mass distributions behind the shock have been obtained from a numerical solution of similarity equations involved. 相似文献
15.
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
16.
Similarity solutions describing the flow of a perfect gas behind a spherical and cylindrical shock wave in a magnetic field with radiation heat flux have been investigated. The total energy of the expanding wave has been assumed to remain constant. The solutions, however, are only applicable to a gaseous medium where the undisturbed pressure falls as the inverse square of the distance from the line of explosion. 相似文献
17.
We investigate the formation and evolution of isothermal collapse nonuniformity for rotating magnetic interstellar clouds. The initial and boundary conditions correspond to the statement of the problem of homogeneous cloud contraction from a pressure equilibrium with the external medium. The initial uniform magnetic field is collinear with the angular velocity. Fast and slow magnetosonic rarefaction waves are shown to be formed and propagate from the boundary of the cloud toward its center in the early collapse stages. The front of the fast rarefaction wave divides the gas mass into two parts. The density, angular velocity, and magnetic field remain uniform in the inner region and have nonuniform profiles in the outer region. The rarefaction wave front surface can take both prolate and oblate shapes along the rotation axis, depending on the relationship between the initial angular velocity and magnetic field. We derive a criterion that separates the two regimes of rarefaction wave dynamics with the dominant role of electromagnetic and centrifugal forces. Based on analytical estimations and numerical calculations, we discuss possible scenarios for the evolution of collapse nonuniformity for rotating magnetic interstellar clouds. 相似文献
18.
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
19.
B. C. Low 《Solar physics》1980,67(1):57-77
A method is prescribed for generating exact solutions of magnetostatic equilibrium describing a cylindrically symmetric magnetic flux tube oriented vertically in a stratified medium. Given the geometric shape of the field lines, compact formulae are presented for the direct calculation of all the possible distributions of pressure, density, temperature and magnetic field strength compatible with these field lines under the condition of static equlibrium. The plasma satisfies the ideal gas law and gravity is uniform in space. A particular solution is obtained by this method for a medium sized sunspot whose magnetic field obeys the similarity law of Schlüter and Temesváry (1958). With this solution, it is possible for the first time to illustrate explicitly the confinement of the magnetic field of the cool sunspot by the hotter external plasma in an exact relationship involving both magnetic pressure and field tension as well as the support of the weight of the plasma by pressure gradients. It is found that the cool region of the sunspot is not likely to extend much more than a few density scale heights below the photosphere. The sunspot field approaches being potential in the neighbourhood of the photosphere so that the Lorentz force exerting on the photosphere is less than what the magnetic pressure would suggest. This accounts for how the sunspot field can be confined in the photosphere where its magnetic pressure is often observed to even exceed the normal photospheric pressure. The energy mechanism operating in the sunspot and the question of mechanical stability are not treated in this paper.Normally at Lau Kuei Huat (Singapore) Private Limited, 55 Shipyard Road, Singapore 22, Singapore. 相似文献
20.
In this paper we have obtained a similarity solution for a spherical magneto-gas dynamic shock wave in a self-gravitating system. It is observed that the total energy of the shock wave is not a constant, but it decreases with time. A remarkable change in radiation flux is also being observed here because of the presence of the magnetic field while there is no change in density, velocity and pressure. 相似文献