Aerodynamic characteristics of fluctuating forces on a circular cylinder

This paper presents the mechanism for the occurrence of the fluctuating force on a stationary two-dimensional circular cylinder in a smooth flow at a subcritical Reynolds number. The characteristic of the fluctuating pressures induced by the Karman vortex shedding was investigated by using the simultaneous multi-pressure measuring system. Furthermore, the fluctuation of the stagnation and separation points on the cylinder was also clarified by the instantaneous pressure distributions. The physical relationship among the fluctuations of the lift force, the stagnation and separation points was discussed in order to explain the fluctuating wind force induced by the Karman vortex shedding. It was argued that the Karman vortex shedding, which periodically oscillates the entire flow around the cylinder, dominates not only pressure fluctuations on the after body but also those on the upwind body at the separation point.