The onset of convection in a bidisperse porous medium

The classical Rayleigh–Bénard theory, for the onset of convection in a horizontal layer uniformly heated from below, has been applied to a bidisperse porous medium. The linear stability analysis leads to an expression for the critical Rayleigh number as a function of a Darcy number, two volume fractions, a permeability ratio, a thermal capacity ratio, a thermal conductivity ratio, an inter-phase heat transfer parameter and an inter-phase momentum transfer parameter.