Flow structure in semi-circular cavity

This paper describes the complicated flow associated with the three-dimensional surface mounted semi-circular cavities. The experiment was carried out in three types of wind tunnels and a water channel. The effect of the aspect ratio (cavity length to width : L/W=1-8) of the cavity has been investigated in terms of the surface pressure distribution and the velocity profiles in the flow inside the cavity. The flow pattern inside the cavity was observed by the flow visualization. The three-dimensionality of the primary vortex in the cavities has been estimated from location of the center along the span of the cavity. Consequently it was found that ( i ) the large periodic variation with several peaks appears in the pressure distribution near the downstream edge because of the existence of the cell structure, ( ii ) the similarity of the pressure distribution exists in each cell structure independent of aspect ratio L/W, (iii) the cell number and cell span increases as the aspect ratio L/W increases, and (iv) the cell structure formation is due to the distortion of the primary vortex.