Stability and stationary convection induced by gravity and centrifugal forces in a rotating porous layer distant from the axis of rotation

The stability and onset of stationary convection in a rotating fluid saturated porous layer placed at an arbitrary positive distance from the rotation axis and subject to gravity and centrifugal body forces is investigated analytically. The stability of a basic gravity driven convection is analyzed. The marginal stability criterion is established in terms of critical centrifugal Rayleigh numbers and a critical wave number. The results show that apart from providing a non-motionless basic state and dictating the direction of the wave number, the gravity plays a relatively passive role, without affecting the stability results. Furthermore, it is demonstrated that the neutral curves for combined centrifugal and gravity convection in the stationary case are identical to the case when the gravity effects are neglected. The results also provide a simple stability map for a wide range of values of the parameter controlling the offset distance from the axis of rotation.