Vortex Patterns in a Cross Flow Past a Cylinder Near the Channel Wall at Moderate Reynolds Numbers

Abstract

Abstract: Physical experiment and direct numerical simulation are employed to study a transitional flow of viscous fluid past a spanwise circular cylinder mounted near the wall of a rectangular channel. The Reynolds number varies in the range of 60 to 480. Spiraling tornado-like motion of fluid directed from the sidewalls toward the center of the channel behind the cylinder is discovered. The evolution of this motion with the Reynolds number is outlined. Formation of large-scale vortical structures (analogue of Karman vortex street) and their turbulent breakdown in the cylinder wake are described. The behavior of the drag coefficient of the cylinder and the nearest wall with the Reynolds number is revealed.