Effect of confinement on the transition from two- to three-dimensional fast-rotating turbulent flows

This work studies the effect of confinement on fastly rotating turbulent flows, leading to a dimensional transition in the presence of large-scale friction. Performing a linear stability analysis under very high rotation, the threshold between the two- and three-dimensional regime is determined. We discuss about two instability mechanisms: centrifugal and parametric. The quantification of the instability length scale is found to scale as the square root of the Rossby number. Spatial and temporal co-relation of strain rate tensor with the growth of perturbations is observed for parametric type instability. Finally, these instabilities were also studied with the oscillatory Kolmogorov flow.