Effects of suction on flow characteristics around circular cylinders based on numerical modelling

Hydrodynamic aspects of flow field around a bluff body are of the common concerns in fluid dynamics and fluid- structure interaction and have been the subject of various experimental and numerical studies. This kind of flow is apparent in many engineering problems such as flow around the cylinders of various shapes. Considering the viscous flow features, investigating the boundary layer separation, drag forces and separation control methods become more essential. The present study mainly focuses on boundary layer modelling and also on controlling the separation of boundary layer using a uniform and continuous suction as an active boundary layer separation control technique. Numerical investigation was performed based on a finite difference scheme to solve the vorticity transport equation. Accordingly, the time dependent flow of incompressible viscous fluid around the circular cylinders was modelled. The flow regime Reynolds numbers were less than 300. The effects of suction on stabilizing flow field have also been investigated and the separation angle has been evaluated. In addition, the flow field as well as velocity field of controlled and uncontrolled flows were compared. Results show that for a laminar flow, controlling the boundary layer by suction is a very effective method to reduce the drag force and pressure drop.