Effect of Gravity Modulation on the Onset of Convection in a Horizontal Anisotropic Porous Layer

Abstract

A linear stability theory is used to investigate the effect of gravity modulation on the onset of convection in a homogeneous anisotropic porous layer heated from above. The Brinkman model with anisotropic permeability is considered in the current analysis. The Oberbeck‐Boussinesq approximation is employed and the corresponding governing equations are reduced to Mathieu’s equation. Floquet theory is used to find the critical Rayleigh number and the corresponding wave number as a function of modulation amplitude and frequency. It is found that the onset of convection can be advanced or delayed by adjusting amplitude and frequency depending upon the Darcy number.