Parameter Dependence of Switching between Supercritical and Subcritical Turbulent Transitions in Inner-Cylinder Rotating Taylor-Couette-Poiseuille flow

We performed direct numerical simulations to investigate the dependence of the flow state transition processes on the inner cylinder azimuthal rotation and axial pressure gradient drive in high-radius-ratio Taylor-Couette-Poiseuille flows. The Taylor-Couette flow with only inner cylinder rotation is a supercritical transition that is complicated stepwise from the Taylor vortex to the wavy Taylor vortex, and to the modulated wavy Taylor vortex. With the increasing axial pressure gradient, the straight/wavy Taylor vortices were gradually weakened, leading to a complete laminar flow, followed by the onset of localized turbulence in a stripe pattern that is a characteristic to the subcritical transition. When based on the modulated wavy Taylor vortex, neither laminarization nor local turbulent structure occurred when subjected to axial flow, and the flow gradually changed to turbulence as in a supercritical transition. These results suggested that laminarization phenomenon does not occur when the inner cylinder rotation is faster than a certain value.