Generation of zonal flows in nonuniform rotating astrophysical fluids

Abstract

The generation of large scale zonal flows by flute-like wave modes in nonuniform rotating self-gravitating fluids is considered. In the geostrophic approximation, viz. when the mode frequencies are much smaller than the Coriolis frequency, the coupled mode equations are obtained by using the continuity, momentum and Poisson equations. The equations are then Fourier analyzed to obtain a nonlinear dispersion relation, which exhibits the parametric excitation of zonal flows by the nonlinear force of the flute-like wave modes. Nonlinearly excited zonal flows undergo further cascading and constitute a new turbulent state. They also contribute to the formation of large scale structures in astrophysical fluids.