Generation and sustenance mechanisms of coherent vortical structures in rotating shear turbulence of zero-mean-absolute vorticity

The vortical structures in a uniformly sheared turbulent flow in a rotating co-ordinate system are investigated theoretically based on direct numerical simulation data. New generation and sustenance mechanisms of long-lived longitudinal tubular vortical structures are discovered in a zero-mean-absolute-vorticity flow. They are born from relatively high-vorticity blobs in a random fluctuating vorticity field under the effect of the Coriolis force and grow in the form of vortex layers with their vorticity pointed to the background uniform shear vorticity. As time goes on, the vortex layers are wrapped into tubular vortices, which are intensified under a combined effect of the Coriolis force and the pressure-gradient force induced by the tubular vortices themselves.