Numerical investigation of controlling flow on a cylinder by groove

The flow over blunt bodies, such as cylinders, can be controlled by modifying the surface. One such modification involves creating holes on the surface. Depending on the location and size of the hole, the flow around blunt bodies can change. In this study, the flow attachment performance on the cylinder surface was improved using an oscillating (turbulence-generating) cavity created on the cylinder surface. Computational fluid dynamics (CFD) analyses were conducted using Reynolds-Averaged Navier-Stokes (RANS) and Detached Eddy Simulation (DES) approaches. The Reynolds number under consideration was 8000, corresponding to the shear layer regime for flow around the cylinder. RANS-based computations were performed for cavities of varying positions and sizes. As a result, it was found that the cavity located at the leading edge at 65°, with a depth of 1/8 of the cylinder diameter and a length of 1/4 of the cylinder diameter, provided the best attachment performance. Subsequently, to observe the effects of this cavity on the rear section of the cylinder more accurately, computations were carried out using the Detached Eddy Simulation approach for the cylinder with the cavity. The results examined the effects of the cavity on the cylinder, focusing on parameters such as forces acting on the cylinder, the laminar-to-turbulent transition character within the shear layer, separation angle, vortex shedding frequency, vortex formation distance (maximum turbulence point), and the centerline length of the wake region.