Influence Of Azimuthal Magnetic Field Research Articles

Flow behind an exponential shock wave in a perfectly conducting mixture of micro size small solid particles and non-ideal gas with azimuthal magnetic field

Unsteady adiabatic and isothermal flows behind an exponential spherical or cylindrical shock wave in a perfectly conducting mixture of micro size small solid particles and non-ideal gas under the influence of azimuthal magnetic field is investigated. The moving piston drives the shock wave. The azimuthal magnetic field in the ambient medium is assumed to be varying according to exponential laws. In our study, micro size solid particles are taken to be pseudo-fluid with the supposition that the equilibrium conditions for flow are maintained in the entire flow- field region, and the heat conduction and the viscous-stress of the conducting mixture are negligible. In both the isothermal and adiabatic cases, similarity solutions are obtained by taking into consideration the magnetic field and compressibility. The effects on the shock wave propagation and on the flow variables by the ratio of the density of micro size solid particles to the initial density of the gas Ga as well as by the non-idealness parameter δ of the gas in the conducting mixture, by the mass concentration λp of micro size solid particles in the conducting mixture and by the adiabatic exponent γ are worked out in detail. A relationship between the solutions in the cases of isothermal and adiabatic flows is made. It is found that due to the thought of zero temperature gradient the flow variables fluid velocity, density and magnetic field and shock strength decrease. Also, it is important to note down that the shock wave strength enhances with an increase in Gaor due to change in geometry from cylindrical to spherical; whereas it decreases with an increase in the non-idealness parameterδ or the strength of ambient magnetic field MA−2or the adiabatic exponent γ .

Cylindrical shock wave in a self-gravitating perfect gas with azimuthal magnetic field via Lie group invariance method

In this paper, we have studied the propagation of cylindrical shock waves in a self-gravitating perfect gas under the influence of azimuthal magnetic field. The method of Lie group invariance is used to construct some special class of self-similar solutions in the presence of the azimuthal magnetic field. The different cases of solutions with a power law and exponential law shock paths are obtained with the choice of arbitrary constants appearing in the expressions for the infinitesimal generators. The similarity solution for cylindrical shock wave with power law shock path is discussed in detail. The effects of variation of Alfven-Mach number, gravitation parameter, initial density variation index and adiabatic exponent on the flow variables are analyzed graphically. It is obtained that the increase in the values of Alfven-Mach number, gravitation parameter and adiabatic exponent have decaying effect on the shock strength. Also, the shock strength increases with an increase in the values of initial density variation index. A comparison is also made between the solutions in gravitating and non-gravitating cases in the presence of magnetic field.

Similarity solutions for strong shock waves in magnetogasdynamics under a gravitational field

In the present paper, we use a Lie group of transformations to obtain a class of similarity solutions to a problem of cylindrically symmetric strong shock waves propagating through one-dimensional, unsteady, and isothermal flow of a self-gravitating ideal gas under the influence of azimuthal magnetic field. The density of the ambient medium is assumed to be non-uniform ahead of the shock. The generators of the Lie group of transformations involve arbitrary constants which yield four different cases of possible solutions. Out of all possibilities, only two cases hold similarity solutions. One is with a power law shock path, and the other one is with an exponential law shock path. We present a detailed investigation for the case of power law shock path. Numerical computations have been performed to find out the flow patterns in the flow-field behind the shock. Also, we have analyzed the effects of variation in adiabatic index, ambient density exponent, gravitational parameter, and Alfven-Mach number on the flow variables behind the shock. All computations have been done using the software package MATLAB.

Axisymmetric Natural Convection of Liquid Metal in an Annular Enclosure under the Influence of Azimuthal Magnetic Field

Natural convection of liquid metal in an annular enclosure under the influence of azimuthal static magnetic field was numerically studied. The liquid metal in the enclosure whose cross-sectional area is square was heated from an inner vertical wall and cooled from an outer vertical wall both isothermally whereas the other two horizontal walls were assumed to be adiabatic. The static azimuthal magnetic field was imposed by a long straight electric coil that was located at the central axis of the annular enclosure. The computations were carried out for the Prandtl number 0.025, the Rayleigh number 104, 5 × 105 and 107, and the Hartmann number 0–100,000 by using an in-house code. It was found that the contour map of the electric potential was similar to that of the Stokes stream function of the velocity regardless of the Hartmann number. Likewise, the contour map of the pressure was similar to the Stokes stream function of the electric current density in the case of the high Hartmann number. The average Nusselt number was decreased in proportion to the square of the Hartmann number in the high Hartmann number regime.

Electron acceleration by a chirped laser pulse in vacuum under the influence of magnetic field

A linearly polarized (LP) chirped laser pulse is employed for electron acceleration to GeV energy under the influence of azimuthal magnetic field in vacuum. LP laser pulse supports the trapping of pre-accelerated electron during laser–electron interaction in vacuum. The electron gains energy from LP laser pulse and gets accelerated in the direction of propagation of laser pulse. Additionally, the chirping increases the electron laser interaction for longer duration while the azimuthal magnetic field having pinching effect keeps the motion of electron parallel to the direction of propagation of laser pulse leads to enhance the electron acceleration. The combined effect of chirping of laser pulse and pinching of azimuthal magnetic field not only enhances the electron energy gain but also supports in retaining of gained energy by the electron for longer distances. The accelerating distance is observed to be of three times the Rayleigh length where the Rayleigh length is about 6.78 μm. We observe electron energy gain of about 1.47 GeV in the presence of azimuthal magnetic field of about 438 kG with an intense LP laser pulse of peak intensity of about 3.4 × 1021 W/cm2. Higher electron energy gain may be obtained with highly intense laser pulse.