Influence of the orientation of a square cylinder on the wake properties

Abstract.

An experimental investigation of flow around a square cylinder placed at various angles with respect to the approach fluid velocity is reported. The focus of the study is toward examining the sensitivity of the wake properties to the cylinder orientation and Reynolds number. Angles of incidence in the range of 0–60° and Reynolds numbers of 1340, 4990, and 9980 have been considered. Velocity measurements have been carried out using an X-wire hotwire anemometer. The Strouhal number and the drag coefficient of the cylinder have been computed from the wake measurements. Utilizing the velocity traces at distinct probe locations in the near and the far wake, statistical properties such as the RMS velocities and the spectra have been obtained. Results obtained in the present work revealed that for a cylinder with zero inclination, flow separates from the corners on the face exposed to the incoming flow. For inclinations greater than zero, the points of separation on the cylinder move downstream and the wake size increases, but the separated shear layer rolls up over a shorter distance. These factors lead to a reduced drag coefficient and a higher Strouhal number. The center-line recovery of the time-averaged velocity and the decay rates of velocity fluctuations depend on the Reynolds number. A marginal effect of the cylinder orientation is also seen.