Aiding mixed convection through a vertical anisotropic porous channel with oblique principal axes

In this paper, an analytical study is carried out on the mixed convection in parallel-plate vertical porous channels with an anisotropic permeability whose principal axes are oriented in a direction which is oblique to the gravity vector. The channel walls are assumed to be isothermal and the flow fully developed at the entrance is upward, so that natural convection aids the forced flow. In the formulation of the problem, use is made of the generalized Brinkman-extended Darcy model which allows the no-slip boundary condition on solid wall, to be satisfied. The flow reversal and the limiting cases of low and high porosity media for natural and forced convection are considered. The effects of varying the anisotropic permeability ratio and the orientation angle of the principal axes on the flow and the heat transfer are investigated.