Turbulence Effect on Flow Around Circular Cylinder

Abstract

Free‐stream turbulence has significant effects on the flow around a circular cylinder. Wind tunnel experiments were conducted on a smooth circular cylinder to investigate the effect of free‐stream turbulence, particularly small‐scale turbulence, on the flow past the cylinder. Tests were carried out in smooth flow and in a rod‐generated turbulent flow. The results showed that increase in free‐stream turbulence promotes early transition from laminar to turbulent boundary layer flow and a delay in flow separation. These changes resulted in a modification of the mean pressure distribution and a reduction in drag. It is suggested that only the small‐scale turbulence, of an appropriate length, near the stagnation line of the cylinder is required to produce these effects of free‐stream turbulence.