Vortex Breakdown in a Differentially Rotating Cylindrical Container

Abstract

Numerical studies are reported on the vortex breakdown in a differentially-rotating cylindrical container in which the top endwall rotates at a high angular velocity Ωt and the cylinder and bottom endwall rotate at a low angular velocity Ωsb. Critical boundaries and the location and size of the vortex breakdown bubble are quite different from the case when the top endwall rotates and the cylinder and the bottom endwall are stationary. As |Ωsb/Ωt| is increased, the breakdown bubble moves toward downstream for Ωsb/Ωt<0, whereas the bubble moves toward upstream for Ωsb/Ωt>0. The Brown and Lopez criterion is extended to a differentially-rotating container.