Slow Dynamics in a Turbulent Von Kármán Swirling Flow

Abstract

An experimental study of a turb turbulent ulent von Ka ´rma ´n fl flow in a cylinder linder is presented. The mean flo flow is stationary up to a Reynolds ynolds number Re ! 10 104 where a bifurcation takes place. The ne new regime breaks some symmetries of the problem and becomes time dependent because of equatorial vortices mov moving ing with a precession mov movement. ement. In the ex exact act counterrotating case, a bistable regime appears and spontaneous re reversa versals ls of the azimuthal velocity elocity are re registered. gistered. A three-well potential model with additi additive ve noise reproduces this dynamic. A regime of periodic response is observ observed ed when a very weak forcing is applied.