THE EFFECT OF A FINITE PROPAGATION VELOCITY ON TURBULENT MASS TRANSFER NEAR A RIGID INTERFACE†

Because or the close coupling between the mean and fluctuating fields, the turbulent flux of a passive additive will exhibit a relaxation phenomenon over a space-time domain which affects the mean field. For fully developed turbulent flow near a rigid interface at large Schmidt numbers, the theory developed here yields The memory length l11 (x1) and the turbulent diffusivity D11(x1) are related to the velocity space-time correlation and the molecular diffusion coefficient. The existence of a finite propagation velocity up(=D11/l11) causes a retardation of the turbulent flux and a decrease in the mean mass transfer coefficient compared with the case up=∞ The Stanton numbers predicted for up<∞ are in better agreement with experimental data than previous calculations which assumed l11=0.