Diffusion of a passive scalar in a rotating medium with anisotropic turbulence

We investigate the influence of turbulence anisotropy and rotation on the d iffusion of a low-concentration passive scaler in a turbulent medium. Using the renormalization the diffusion tensor over the spectrum of turbulent fl uctuations, we show that enhanced horizontal mixing reduces the vertical di ffusion transport of a passive scalar. Allowance for rotation results in tw o effects? which have not been noted previously: (1)under the influence of Coriolis forces, horizontal turbulence also produces a vertical diffusion f lux. with the horizontal and vertical diffusions being of the same order of magnitude for rapidly rotating stars and (2) in the case of rapid rotation , all diffusion fluxes of a passive scalar decrease in inverse proportion t o the square root of the Coriolis number. (C) 2001 MAIK "Nauka/Interperiodi ca".