Stability and experimental velocity field in Taylor—Couette flow with axial and radial flow

Abstract

The imposition of a radial or axial flow on cylindrical Couette flow alters the stability of the system and modifies the velocity field. An axial flow stabilizes cylindrical Couette flow. The supercritical flow includes a rich variety of vortical structures including helical and wavy vortices. An axial flow also results in translation of the vortices with the axial flow. A radial flow through porous cylinders stabilizes cylindrical Couette flow, whether the radial flow is inward or outward. An exception is that a small radial outward flow destabilizes the flow slightly. The radial flow results in displacing vortex centers toward the cylinder from which fluid exits the annulus. For combined axial and radial flow, the axial flow stabilizes the cylindrical Couette flow regardless of the radial flow. In addition, the radial flow stabilizes the flow compared to the situation with no radial flow. Above the supercritical transition a wide variety of flow regimes occur in the case where the inner cylinder is porous and the outer cylinder is nonporous. The velocity field for cylindrical Couette flow with axial flow and a radial inflow at the inner cylinder is altered very little for small radial flows. However, the vortices shrink in size as they translate in the annulus as fluid is lost through the inner cylinder.