The Effect of Negative Spanwise Rotation on Dean Vortices

A finite-volume numerical analysis is performed to examine effect of spanwise rotation on Dean vortices. The specific problem considered is fully developed flow in a square channel with streamwise curvature and spanwise rotation in a negative sense, i.e., the Coriolis force counteracts the centrifugal force. The rotation of the channel is found to have a significant effect on the flow structure in general, and the Dean vortices in particular. The nonlinear interaction of the Coriolis instability and the centrifugal instability results in several new flow structures, including one with coexistence of Ekman, Dean, and corner vortices, one with coexistence of Ekman and corner vortices, one with one-pair vortices and an agostrophic, virtually inviscid core, and one with Coriolis vortices on the inner convex wall. These are in agreement with the experimental findings.