Turbulent near wake behind square cylinder of finite length on ground plane

This paper describes the experimental study on the process of the disappearance of the arch vortices shedding from a square cylinder of finite length, and the accompanying changes in the turbulent near wake, as a function of the aspect ratio of a square cylinder. The experiment was carried out in a circuit type wind tunnel having a 200mm × 200mm working section of 2000mm length at the Reynolds number 9200. The time-mean velocity and turbulence intensities were measured by Laser-Doppler Velocimeter. Furthermore the vortices formation was observed by flow visualization in a water channel at Re=4600. Consequently, the details of flow pattern in the turbulent near wake behind a square cylinder were obtained with the information of shedding arch vortices and horse-shoe vortices. The range of aspect ratio of shedding arch vortices seems to be more than H/D=0.7, while the horse-shoe vortices are generated around a square cylinder for all aspect ratios in this experiment.