Incompressible Conducting Flow in an Applied Magnetic Field at Large Interaction Parameters

Abstract

It has long been known that the effect of a suitable magnetic field on an electrically conducting fluid controls the growth of a boundary layer. This is a recognized tool even on an industrial scale for handling highly conductive materials like liquid metals and semiconducting melts. But it is to be noted that fluids of low electrical conductivity like seawater also permit electromagnetic flow control. A considerable amount of research has been devoted to the control of flow separation as separation of flow is considered an undesirablefeature.Besidesthecontrolexercisedbyelectromagneticforces,therearetechniques like suction,blowing,and wall movement for the control of separation. A renewed interestintheuseofelectromagnetic forcestocontroltheflowofelectrolytes aroseinthe 90s. For an incompressible viscous and electrically conducting fluid flowing over a semi-infinite flat plate in the presence of a normal magnetic field, Rossow [24] has shown that the resulting boundary-layer thickness is constant far from the leading edge, whereas without the magnetic field, the thickness increases as the square root of this distance from the leading edge of the plate. The effect of such a magnetic field in a region of rising pressure would be to diminish the latter’s effect so that in cases where separation occurs, the position of the separation point is delayed; indeed if the field is sufficiently strong, separation is completely inhibited. These conclusions are confirmed experimentally by Tsinober et al. [30] who reported a downstream shift of the separation point at