C233 断面積が―様な場合および縮小する場合の流路内におかれた円柱まわりの流れ

The present study deals with the flow around a circular cylinder which is located in channels with both constant and converging cross-sectional areas. The cylinder-diameter to channel-clearance ratio is of the order of unity. Experiments are performed in a water channel and a dye injection technique is used to visualize the flow. The Reynolds number ranges form 100 to 1000. The results show that there exists three-dimensional flow due to the small channel clearance. The flow patterns reveal that the flow is more stable than the two-dimensional flow around a cylinder; no traces of the Karman vortex street are detected. Some differences are also found in the flow patterns obtained for parallel and convergent walls.