Experimental Study of Solitary Wave Induced Fluid Motions in a Submerged Cavity

Abstract

This paper presents an experimental investigation of solitary wave induced fluid motions in a submerged cavity. The evolution of the vortices and wave elevations were recorded for analysis. The tests were conducted in a glass-walled wave flume. A piston-typed wavemaker was installed on one end of the flume for generating desired solitary waves. A cavity of changeable size was positioned in the flume with two up-leveled acrylic panels. Three resistance-typed wave gauges were placed along the flume to record the wave profiles. The Planar Laser Induced Fluorescence (PLIF) technique was utilized to visualize and study the flow patterns as a solitary wave propagating past the cavity zone. The laser module used for the study had wavelength, output power, and projection fan angle of 532 nm (green light), 20 mW, and 100 degree, respectively. The laser excited the molecules of the fluorescent dyed fluid. As the incident wave passed by, any flow field feature would be illuminated. Each test was recorded with a video camera, and all the image frames could be further processed for comparison with the results obtained from a finite-analytic based two-dimensional (2-D) viscous flow model. This flow model solves combined stream function and vorticity equations. In terms of wave elevation and transformation of the formed vorticity, fairly good agreements are obtained between the numerical solutions and experimental observations. The results are presented and discussed.