Experimental Study of Mass Diffusion in a Turbulent Boundary Layer in Neutral and Unstable Stratified Flow.

An experimental study of mass dispersion in a stratified turbulent boundary layer over a smooth flat plate is described, in which the concentration distribution of a tracer gas fed into the flow from a point source at the plate was measured. From the results obtained, the characteristics of the dispersed gas trail are expressed in terms of the aerodynamic and thermal boundary layer data, and hence the effect of thermal layering due to heating of the plate on mass diffusion is determined. The results are expressed nondimensionally and are compared with data estimated by various theories and the results of measurement in the atmosphere.