A special case of spatial averaging of the diffusion coefficient

Steady-state mass transfer through a heterogeneous layer formed by coordinate planes of an orthogonal coordinate system is considered under the assumption that the boundary conditions at both layer boundaries are independent of coordinates. It is established that, if the coordinate dependence of the diffusion coefficient is described by the product of functions depending on different coordinates, then the surfaces of equal concentration (isohalines) coincide with the coordinate planes. It is shown that, in this case, the diffusion problem has an exact solution and the averaging of the diffusion coefficient is performed by elementary methods.Translated from Teoreticheskie Osnovy Khimicheskoi Tekhnologii, Vol. 39, No. 1, 2005, pp. 101–105.Original Russian Text Copyright © 2005 by Babenko.