Abstract
Time-dependent flow fields around 2:1 elliptic cylinder and 5:1 arc wing at angle of attack 45° were observed by alminum powder method. At the same time, lift and drag were measured. At the initial stage after starting, first sharp peaks in lift and drag occur and then vanish. After this, lift and drag begin to increase again and the second peaks appear. The first peaks in lift and drag occur when the potential flow is formed around the body, and the second peaks occur when a large vortex, which is separated from the leading edge, is formed on the rear of the body.
