(95e) Effect of Radius Ratio on Flow Transitions in Newtonian Taylor-Couette Flows
Taylor Couette flow has long been an interesting and challenging problem due to its rich non-linear dynamics and cascade of transitions between laminar and turbulent flows. In this study, a dozen flow state bifurcations have been mapped for a Newtonian fluid in concentric, independently rotating cylinders of radius ratio 0.912 and aspect ratio of 60.7. The resultant flow state transitions are compared to previous stability mappings obtained at various radius ratios. As a result, the effect of gap size is illuminated for various flow transitions, including transitions to axisymmetric, wavy, spiraling and/or turbulent modes. While many flow types have been previously observed, we report new sequences of bifurcations in the counter-rotating Taylor-Couette regime. Also, more emphasis is given to high Reynolds' number flows to explore loss of stability of vortex driven turbulence at a given radius ratio. Changes in stability during adiabatic increases of the inner cylinder Reynolds number were determined using flow visualization and spectral analysis. All flow states are characterized by symmetry/symmetry breaking features as well as azimuthal and axial wave numbers using a combination of flow visualization in 2D planes of radial, axial, projected azimuthal and time dimensions.