INHIBITION OF TURBULENT CASCADE BY SWEEP

The effects of large-scale sweeping velocity on the turbulent, cascade to small scales are examined for two problems: the advection of a pas sive scaler by a multivariate-Gaussian velocity field and incompressib le Alfven-wave turbulence. In both cases, the sweeping produces anisot ropy and reduces the strength of cascade. If the direction of the swee p velocity varies with time, a balance is reached between this anisotr opy and isotropizing effects associated with the change of direction.