凹部を有する正多角形物体の流体抵抗

抄録

The objective of this study is to understand the drag coefficient of concaved solid disc. The concave body is the known as star like shape. The star like shape is the concaved from the pentagonal shape. We are focusing on the shape of concaved from the hexagon. Six types of shape of model was tested. The shape of model considered with the angle of concavity and the circumference of disc. The angle of concave was investigated as 15, 30, 45 degrees. The motion of model was free-fall in a water tank. The tank filled the water. The model motion was taken by using the high speed camera. The image analysis was carried out to investigate the velocity and acceleration of model. The drag coefficient was obtained with the force balance during the motion. The results show that the drag coefficient increase with the increase of the angle of concavity in case of constant projetction area of model. The results with the constant circumference of model show that the drag conefficient increases with the decrease of the angle of concavity of model.