Convective instability in periodically heated superposed fluid-porous layer systems with asymmetric boundary conditions

When a porous layer beneath a fluid layer is heated from below, the region in which convective instability develops depends on the intrinsic properties of the coupled fluid--porous system. The present study proposes periodic heating of the superposed system, bounded by a free surface above and an impermeable surface below, to confine convective motion to a desired region and to regulate its onset without altering the system's physical properties. The amplitude of modulated heating serves as an external control parameter, governing both the onset and the region of convection in a configuration where a thin fluid layer overlies a porous layer, allowing control without modifying the system.