벽면에 근접한 정사각주의 와류 박리에 관한 실험적 연구

The experiments are studied on the now past a square cylinder placed near a wall at Re = 18,000. Contrary to the free-standing square cylinder, the square cylinder near a wall exhibits different now characteristics due to a wall boundary layer. The formation of Karman vortex streets is interrupted when the gap height comes to a critical value and the mechanism of this phenomenon is the main concern of this paper. From spectral analysis, the critical gap height and Strouhal number distributions were investigated for various gap heights. In addition, we studied the effect of boundary layer thickness on vortex shedding. The careful measurement in gap now reveals that two distinct now characteristics exist and the gap now determines the process of periodic vortex shedding. The surface flow visualization shows that the location of separation line on the wall is strongly correlated with the Strouhal number and vortex shedding process.