The asymptotic form of the laminar boundary-layer mass-transfer rate for large interfacial velocities

The convective diffusion of matter from a stationary object to a moving fluid stream is distinct from pure heat transfer because of the appearance of a finite interfacial velocity at the solid surface. This velocity is related to the rate of mass transfer by a dimensionless groupBin such a way that for −1 <B< 0 the transfer is from the bulk to the surface while for 0 <B< ∞ the transfer is from the surface to the main stream. In this paper, asymptotic solutions to the two-dimensional laminar boundary-layer equations are developed for the caseB[Gt ] 1, and for rather general systems. It is shown that in most instances the asymptotic expressions for the rate of mass transfer become accurate whenB> 3 and that the transition region between the pure heat-transfer analogy (B∼ 0) and theB[Gt ] 1 asymptote may be described by a simple graphical interpolation. These results may easily be extended to three-dimensional surfaces of revolution by the usual co-ordinate transformations of boundary-layer theory.