Numerical and Parametric investigation of Suction over a Cylinder for Reduction of Flow Unsteadiness and vortex

In this paper, flow control ability with suction over a circular cylinder has been numerically investigated in order to drag reduction and elimination of unsteadiness and the resultant vibrations. The efficiency of this flow control method is dependent to different parameters. Some of these parameters are dependent to geometry and the rest are dependent to flow characteristics. For this purpose, the geometric parameters of width and position of suction slat and also the suction flow velocity are studied in this investigation. 2D flow physics around the cylinder have been simulated in Re=3.3*104 with K - ε (RNG) turbulence model. The obtained results show the elimination of Von Karman vortices under sufficient suction. Suction causes vacuum in viscous sublayer and elimination of low momentum regions via momentum transfer from outer layers, and consequently postpone the separation. The results indicate that pressure drag is decreased, skin friction drag is increased and total drag is decreased about 55%.