Abstract
The critical phenomenon of wake structure occurs at 30 degrees of the rear slant angle of Ahmed's bluff body. Originally, such the characteristic phenomenon was pointed out by L.J. Janssen and W.H. Hucho in 1975. In 1984 S.R. Ahmed was conducted systematic measurement by changing the slant angle of the rectangular bluff body, namely Ahmed's body, to find the critical phenomena. After that, in 2001, D.B. Sims-Williams found that Ahmed's body had the vortex structure which had specific frequency. However, the reason why the phenomenon was occurred at the angle has not been clarified yet. Then this study is performed to analyze the fluctuation of the wake structure by observing the frequency due to the typical vortex shedding with the hot-wire anemometer and dynamic PIV system. As a result, the behavior of the vortex shedding which has specific frequency was confirmed.
