Tornado-like vortices behind a cylinder in a channel at moderate Reynolds numbers

Abstract

Abstract Experiments and direct numerical simulation were employed to study the near wake of a circular cylinder in a cross flow in a rectangular channel. The gap between the cylinder and the channel wall was varied. Moderate Reynolds numbers were considered. The analysis of experimental results in combination with numerical simulation revealed the common patterns in the vortical structure of flow behind the cylinder, namely the tornado-like vortices formed in the region where the cylinder was attached to the sidewalls of the channel. The effect of the cylinder location on the onset of Karman vortex street was estimated. The formation mechanism of tornado-like vortices was described.