Vortex dynamics of a sphere wake in proximity to a wall

• The effect of a flat plate on the wake flow characteristics of a sphere was studied.
• The vortex separation on the bottom of the sphere is suppressed.
• A jet flow under the sphere stretches to the recirculation region.
• The small-scale vortex structures concentrate on the near wake region.

Toward getting the vortex dynamics characteristics and wake structure of a sphere in proximity to a wall, the effect of a proximal flat plate on the wake of a stationary sphere is investigated via direct numerical simulation. The vortex shedding process and the significant variation of the wake structure are described in detail. The drag coefficient reduces and the wake structure of the sphere becomes complex due to the combined effect of the wake flow and the wall. A jet flow forms between the sphere and the flat plate, which suppresses the vortex separation on the bottom of the sphere. The asymmetric distributions of the coherent structures and the recirculation region behind the sphere are discussed. Besides vortex shedding patterns, the time-averaged velocity distribution, vortex dynamics, distribution regularities of turbulent kinetic energy and enstrophy are investigated.