New type of centrifugal instability in a thin rotating spherical layer

We numerically model the instability of viscous incompressible fluid flows caused by torsional oscillations of the inner sphere in a thin spherical layer with respect to the state of rest. We show that an increase in the frequency of torsional oscillations leads to a change in the mode of the instability, with a transition from secondary flows in the form of Taylor vortices to the structures, which were not previously observed. The revealed instability is found in the frequency range from 0.61 to 2.45 Hz or, if the wavelengths are taken relative to the layer thickness, from 0.67 to 1.33.