Abstract
Passive and active scalar fluxes in unsteady stratified turbulence are analyzed using the rapid distortion theory (RDT) with the diffusion effects of density and passive scalar. Analytical solutions of the RDT equations show that the passive scalar gives a stronger counter gradient flux than the density flux. The difference in these fluxes appear mainly appear at high wave number spectrum. However, longer time development than the previous experiments shows that the difference might be a transient one and may diminish at large times. Anyway tese all results show the importance of 'unsteady' analysis of the initial value problem in the diffusion problems in stratified turbulence.
