A laboratory study of diffussion in stably stratified flow: Fid-Bau Portal

A laboratory study of diffussion in stably stratified flow

Chaudhry, F.H. / Meroney, R.N.

Abstract This paper investigates the usefulness of the similarity that exists between the stably stratified atmospheric boundary layer and a wind tunnel boundary layer developing over a cold plate in regard to mass diffusion phenomenon. Detailed observations of the concentration field downwind of a point source of Krypton-85 were made under different stability conditions in the wind tunnel boundary layer. The concentration characteristics obtained from diffusion experiments show excellent agreement with those observed in the atmosphere. The index $m$ , describing the power law variation of ground level concentration with distance, matches reliable field estimates. The data compares well with the predictions of Lagrangian similarity theory. It appears that the parameters evaluated in the field by Klug (1968) hold also for the wind tunnel data. A comparison of detailed observations with an available numerical solution of the three-dimensional diffusion equation suggests that the detailed diffusion patterns obtained from the wind tunnel experiments may be preferable to numerical solutions requiring arbitrary specification of lateral diffusivity.