抄録
Vortex structure and drag characteristic of a circular cylinder accelerated from a rest were investigated by drag measurement and flow visualization techniques. The circular cylinder installed in a linear-motor actuator system moves with a constant acceleration in a water tank. The drag measurement of the circular cylinder was conducted by the measurement equipment using the expansion of coil. The wake flow of a circular cylinder is visualized by using the dye. The formation and the collapse process of the twin vortex and shedding vortices were observed during accelerated motion of the circular cylinder. From the results of flow visualization, the drag was increased after the formation of twin vortex. The drag gradually increased after the collapse of twin vortex. Then the drag increased rapidly after the formation of shedding vortices.
