Convection in a porous media with inclined temperature gradient

The stability of convection in a horizontal porous layer, subjected to an inclined temperature gradient of finite magnitude, and confined between perfectly conducting planes, is investigated by means of linear stability analysis. It is shown that the instability appears in the form of stationary longitudinal rools (with axes aligned in the direction of the horizontal component of temperature gradient) superimposed on the basic ow. As the horizontal Rayleigh number increases, the critical vertical Rayleigh number also increases and there is a series of transitions to higher order modes, corresponding to multiple layer rools. i