The Interaction of Thermal Vibrational and Thermal Gravitational Mechanisms of Convection Onset in a Fluid-Porous Layer

The paper reports a numerical study concerning the effect of high-frequency small-amplitude vibration on the onset of thermal convection in a fluid-porous layer in the gravitational field. It is found that vertical vibration stabilizes the thermally conductive state of the fluid heated from below. Local convection in the fluid sublayer is replaced by the large-scale one with increasing the value of oscillatory forcing. The latter convection covers the entire layer. In the case of horizontal vibration, the stabilization manifests itself at low vibrational accelerations. Their further growth reduces the stability threshold and causes an abrupt transition to a new type of convection called “interfacial” convection. It arises in the form of the rolls locating near the interface between the fluid and porous sublayers. The nature of interfacial convection is due to the thermal vibrational force alone, since it occurs in the layer heated from above where the natural thermal gravitational convection is impossible to be excited.