Experimental investigation of elevation internal solitary wave propagation over a ridge

Abstract

The propagation of elevation internal solitary waves (ISWs) over a large triangular ridge was investigated experimentally in a stratified fluid flume. The propagation characteristics of the elevation ISWs over the ridge were measured by using the real-time wave measuring instrument and particle image velocimetry, respectively. At the front slope of the ridge, the obvious fluid accumulation appeared, the waveform was distorted and broadened, the ISW amplitude increased slightly, the phase velocity decreased suddenly, and the lower layer flow velocity increased significantly. In the region of the ridge top, counterclockwise vortex and bright spots appeared, which signified the occurrence of breaking, the shape of incident wave was transferred to the shape of table-top solitary wave. At the back slope of the ridge, the fission waves became symmetric gradually and restored to normal, the amplitude decreased significantly, and the phase velocity increased slightly. The wave energy decreased consistently during wave propagation and the whole energy loss was about 30%–35% of the incident wave. Due to the wave breaking and fission, the energy loss occurred near the ridge top was the largest and was almost the same at symmetrical positions on the front and back slopes.