CHARACTERISTICS OF VORTEX SHEDDING PROCESS INDUCED BY A SOLITARY WAVE PROPAGATING OVER A SUBMERGED OBSTACLE WITH END SLOPE

摘要

The generation and evolution of shedding vortices induced by a solitary wave propagating over a submerged obstacle with sloping end were investigated experimentally. The angles of the end slope are 45, 63, 70 and 80 degree. The vortex shedding process was observed qualitatively using particle tracking photography. The velocity fields were measured quantitatively using particle image velocimetry (PIV). Base on the results of the flow visualization, the tiny vortex structure is found near the top of the slope. This is not found in the case of rectangular dike under the same water depth and wave height. On the other hand, the size of primary vortex (defined as vortex A_v) reduces with the decrease of the angle of the slope. Based on the result of circulation strength of vortex Av, the strength also decreases with the decrease of the angle of the slope. Finally, Similarity velocity profile was found in the jet-like flow along the slope in the cases of angles with 45 degree.