Experiments on mixing due to internal solitary waves breaking on uniform slopes

The shoaling and breaking of an internal solitary wave of depression on a u niform slope were studied experimentally. The waves were generated with as large an amplitude as possible while minimizing mixing at the generation si te, thus maximizing the amount of energy propagating onto the slope in the experiment. Various bottom slopes, fluid layer thickness ratios, and densit y ratios were investigated. The mechanism leading to breaking was examined with flow visualization and particle image velocimetry. Since the layer thi ckness ratio primarily controls the length (L-W) of the solitary wave (for a given amplitude a), it is found that the ratio of L-W and the characteris tic length of the slope L-S determines the amount of energy reflected from the slope. The mixing efficiency of the breaking event, defined as the rati o of the increase of potential energy divided by the amount of wave energy lost at the slope, peaks at a, maximum of 25% when L-W/L-S = 0.5, with a de crease in efficiency for points on either side of this peak value.