Warunek utraty stabilności konwekcji swobodnej w warstwie porowatej

A stability analysis of the two-dimensional natural convection in a porous layer has been performed. By means of Galerkin's method the system of two partial differential equations has been replaced by a system of six ordinary differential equations. The branch of steady-state solutions referring to primary stage of free convection has been determined. The condition for stability loss of fluid motion in porous layer induced by temperature gradient is determined by the Hopf bifurcation point for Rayleigh number equal to 30pi^2.