A numerical study of axisymmetric vortex breakdown

Abstract

In this paper we look at the axisymmetic flow of confined rotating fluid in a cylinderical container. The fluid is set in motion by the rotating bottom lid and a vortex forms along the axis of the cylinder. In some previous analytical and experimental studies it was suggested that above a critical value of the upstream swirl angle a bubble·type vortex breakdown takes place along the axis, and below that it does not. However, in our present computations, where we compute the swirl angle distribution everywhere to the flow-field, we find no evidence of strong dependence of axisymmetric vortex breakdown on upstream swirl angle, since large swirl angles are seen even in cases where there is no vortex breakdown.