Near wake behind square cylinder of finite length on ground plane

This paper describes an experimental study on the process involved in the disappearance of arch vortices shed 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 200 mm×200 mm working section of 2000 mm length at the Reynolds number Re of 9200. The time-mean velocity and turbulence intensities were measured by a laser Doppler velocimeter. Vortex formation was observed by flow visualization in a water channel at Re=4600. Consequently, details of the flow pattern in the turbulent near wake behind a square cylinder were obtained, such as information on shedding arch vortices and horseshoe vortices. The aspect ratio for generating arch vortices seems to be higher than H/D=0.7, whereas the horseshoe vortices are generated around a square cylinder for all aspect ratios studied here.