Thermomagnetic convection in a stable circular Couette ferrofluid flow with a radial temperature gradient

Linear stability of a ferrofluid flow in a cylindrical annulus with an outward heating and an imposed magnetic field is investigated for Rayleigh-stable regimes: the sole rotation of the outer cylinder and the solid body rotation of both cylinders. The magnetic field produced by a stack of magnets located inside the inner cylinder coupled with the radial temperature gradient generates the Kelvin force whose non-conservative term acts as a thermal buoyancy with a magnetic gravity and can destabilize the flow, even in the microgravity conditions. The critical parameters of thermomagnetic convection induced by this force are determined for water-based and oil-based ferrofluids corresponding to different diffusive properties. An energy analysis is performed to evaluate the role of the different mechanisms responsible for the flow destabilization.