Some Observations on the Effect of Surface Roughness upon Diffusion

Abstract

The effect of surface roughness has been investigated experimentally and found to lead to spuriously high values of the diffusion coefficient. The magnitude of the error has been estimated as a function of Dt and the degree of roughness. The results indicate that surface roughness may contribute the major source of error in the determination of very small diffusion coefficients. The presence of an uneven source surface may also account for the anomalous tracer penetration profiles which are observed in the vicinity of the surface and, corresponding to which, anomalous values of D have been frequently reported.