The effects of buoyancy-induced pressure gradient, Prandtl number, and ratio of wall velocity to free-stream velocity on the laminar forced-convective flow and heat and mass transfer over a horizontal plane are studied analytically by the local similarity method. The transformation method coupled with the least-squares modification method is used to reduce the guessed initial values and obtain rapid convergence of the solution. Numerical results show that the local friction factor, local Nusselt number, and local Sherwood number increase with increasing buoyancy force. Movement of the plane may enhance the heat and mass transfer, but increasing the transverse mass transfer has the opposite effect on momentum and heat and mass transfer.
