For the uncoupled and coupled cases, the behavior of the isotherms and streamlines was different; so the decoupling of two modes of heat transfer for A = 8, 12 and 16 and inclination angles range of 15◦ λ 35◦ is not possible; different thermal plumes and a multi-cell flow streamlines were observed in both cases. For the uncoupled case, the increase of the aspect ratio and/or the increase of the Rayleigh number reduce the buoyancy forces, so the multi-cell pattern disappears. But for the coupled case, buoyancy forces raise and the multi-cell patterns were observed in most cases.