effects of horizontal magnetic field and rotation on thermal instability of a couple-stress fluid through a porous medium: a brinkman model

a linear stability analysis is carried out to discuss the effects of horizontal magnetic field and horizontalrotation on thermal instability problem of a couple-stress fluid through a brinkman porous medium. after employing normal mode method on the dimensionless linearized perturbation equations, it is noted that for the stationary state, taylor number t a promotes stabilization, whereas medium porosity ϵ hastens the onset of convection. the medium permeability p , magnetic field q , couple-stress y and darcy-brinkman parameter da play dual role in determining the stability/instability of the system under certain restrictions. also, the sufficient conditions responsible for the non- existence of overstability are gained and the principle of exchange of stabilities holds good for a magneto-rotary system.