Dept. of Aerodynamics c-cfd Warsaw University of Technology ESPCI

First regime

In this regime the flow behind the sphere is axisymmetrical. The recirculation zone is toroidal.

Approaching to critical Reynolds number the recirculation zone puffs up on one side and at Re~210 two counter rotating vortices are formed. As clearly visible in the figure below, a defect in recirculation zone appears prior to second regime. The position of the defect is determined by holding influence.

Re 150 Re 170 Re 210
Re = 150 Re = 170 Re = 210
Recirculation zone in rear view, clearly seen defect of the recirculation zone at Re = 170.
At Re = 210 double threaded wake.