Boundary Layer Effect on a Square Cylinder by Changing Chamfer Dimensions

Abstract

In this research the upstream and downstream of a square cylinder with finite height was studied having different chamfer dimensions. Particle Image Velocimetry (PIV) is used for this research (which is a non-intrusive technique) in a closed loop water channel with variable tunnel speed varying from 10 cm/s to 50 cm/s having turbulent intensity less than 7%. The study focused on the flow behavior with change in chamfer dimensions of the cylinder both downstream and upstream and formation of vortices such as horseshoe vortex, Von-Karman vortices etc. Four cylinders were used having chamfer dimension C/d = 0, 0.1, 0.2, 0.3 where (C is chamfer dimension and d is cylinder diameter) and cylinder diameter of 14mm. Aspect ratio (AR) for all cylinders was kept 3 and Reynolds number (Red) was kept at 1400 based on cylinder diameter. The cylinder was placed at 1600 mm from the leading edge to get a boundary layer height of δ/h = 0.5. It was found that chamfer dimension significantly influences the characteristics of flow around the wall mounted cylinder. The increase in chamfer dimension decreased the wake region thus improving flow. Also, by the introduction of chamfer the downflow and specifically upwash flow increased significantly thus effecting the vortex structures downstream. Moreover, horseshoe vortex at the junction of cylinder and wall also reduced in size and strength by the introduction of the chamfer dimension respectively