Mass or heat transfer coefficients under assisting or non-assisting natural and forced convection near a vertical wall

Abstract

The velocity superimposition and the Lighthill transformation are used to calculate heat or mass transfer coefficients for large Schmidt (Prandtl) number under combined natural and forced convection near a vertical wall at constant concentration or temperature. The resultant correlation for assisting flow is in complete agreement with the results of Ruckenstein and Rajagopalan and Churchill. However, the results for non-assisting (opposing) flow are in disagreement with the simplified result of Ruckenstein and Rajagopalan due to the occurrence of zero shear stress and flow reversal at the wall. An explicit, but more complicated, correlation in terms of the pure natural and pure forced convection is presented for the case of opposing flow.