FLOW SEPARATION DURING SOLITARY WAVE PASSING OVER SUBMERGED OBSTACLE

This paper describes the experimental and numerical study of the vorte x formation during the passage of a solitary wave over a rectangular s tructure submerged in water. The transient patterns of the separated f low (R = 82,000) behind the black are visualized by tracing the motion of injected dye in a laboratory flume. The related numerical solution is calculated by using the stream function-vorticity formulation in a transient boundary-conformed grid system to satisfy the full nonlinea r free-surface conditions. Both experimental and numerical results ill ustrate that a large vortex is first formed at the rear of the block, accompanied by a secondary eddy below it, as the solitary wave hits th is block. Then the vortex is bulgy but decays with time, and the secon dary eddy continues to grow in both size and strength as the primary v ortex diffuses. The time development of these calculated flow patterns , including vortex shedding and vorticity transportation, agrees quite well with experimental observations.