Characteristics of shear layer and primary vortex induced by solitary waves propagating over rectangular structures with different aspect ratios

The flow characteristics induced by a solitary wave propagating over a submerged andbottom-mounted structure were studied experimentally using time-resolved particle image velocimetry (PIV) and particle trajectory photography for flow visualization. The setup for time-resolved PIV consisted of a high-speed camera and an argon-ion laser. Image processing techniques were utilized to improve both the temporal and spatial resolutions of thePIV system. The main parameters were wave steepness (H/h = 0.16-0.38) and aspect ratios of the rectangular structures (L/D = 0.14-11.1). The vortex shedding process near the trailing edge was divided into the following phases: the formation of the separated shear layer, generation of the vortices, vortex motion, and breakdown of the vortices. The motionsof the primary vortex may differ depending on experimental parameters. By analyzing thesemotions, flow patterns were categorized into Types A, B, and C, and the conditions for these types were investigated. In the formation of the shear layer, the similarity profilewas determined by selecting the proper length and velocity scales. The relationship between characteristic scales and nondimensional experimental parameters were also investigated.