Experimental study on the wake characteristics of the circular cylinder with the V-groove surface

Abstract

In order to understand the wake characteristics for the circular cylinder with the V-groove surface, the Particle Image Velocimetry (PIV) and Proper Orthogonal Decomposition (POD) technology are used to measure and analyze the flow field velocity and the flow characteristic of the wake flow of the circular cylinder with the V-groove surface. This study focuses on the length of the velocity gradient, the Reynolds stress, the turbulent kinetic energy, the vortex shedding process, and the velocity fluctuating characteristics of flow field with POD technology. Compared with the smooth cylinder, the velocity gradient of the circular cylinder with the V-groove surface are larger. The peak values of Reynolds stress of the circular cylinders with the V-groove surface (the peak values are 0.33, 0.28 and 0.24) is lower than that of the smooth cylinder (0.39), and the peak values of turbulent kinetic energy are also lower. The recirculation region of the circular cylinders with the V-groove surface is larger, the length of the recirculation region are increased by 5.9%, 13.0% and 16.1% respectively, and it implies the suppression of vortex by the V-groove structure. Otherwise, the correlation of POD mode coefficients is disturbed for the circular cylinders with the V-groove surface, further proving that the effect of V-groove structure on vortex shedding.