Description:
<jats:p>The effect of small unsteady mass, momentum, and heat addition in a uniform (or piecewise uniform) basic flow is discussed. A general solution is given. A method for obtaining closed-form solutions, in cases where the disturbed flow is self-similar, is also presented. These solutions are applied to find the interaction between a flow, due to a piston starting impulsively from rest, and a transverse magnetic field. It is assumed that Rm « 1 and RmRh « 1, where Rm and Rh are the flow magnetic Reynolds and pressure numbers, respectively. The electrical potential is assumed to be uniform in the channel. Both a narrow (in the streamwise direction) intense magnetic field and a wide, less intense, field are treated. In the latter case it is found that the shock, generated by the motion of the piston, is decelerated by the magnetic field when the shock Mach number Ms is near 1 but is accelerated by the magnetic field when Ms is high. This behavior is due to the electromagnetic body forces dominating at Ms near 1 and the Joule heating dominating at large Ms. These numerical results also apply to the hot-gas region of a shock tube employing strong shocks.</jats:p>