THE EFFECT OF A UNIFORM VERTICAL MAGNETIC-FIELD ON THE ONSET OF OSCILLATORY MARANGONI CONVECTION IN A HORIZONTAL LAYER OF CONDUCTING FLUID

In this paper we use classical linear stability theory to undertake a detailed investigation of the effect of a uniform vertical magnetic fi eld on the onset of oscillatory thermocapillary-driven Marangoni conve ction in a horizontal layer of quiescent, electrically conducting flui d healed from below. For simplicity we restrict our attention to the s implest case of a fluid layer with a non-deformable free surface and p erfectly electrically conducting boundaries in which the onset of conv ection is always steady in the absence of the magnetic field. The pres ent numerical calculations show that the presence of the magnetic fiel d can cause the preferred mode of instability to be oscillatory rather than steady convection. Nevertheless, in all the cases investigated t he effect of the magnetic field is always to stabilise the layer relat ive to the case of no magnetic field.