Experimental investigation on shoaling characteristics of internal solitary wave over a gentle slope

The propagation of ocean internal waves along continental shelves can impose greatly on the mixing of marine sediments, and its non-stationary characteristics on time-space has augmented the uncertainty of threating threatening the safety of marine engineering structures and submerged vehicles. Laboratory experiments on the shoaling, breaking and splitting of the internal solitary wave over a gentle slope, similar to the topography in the northeast of the South China Sea, were conducted in a stratified fluid tank. The qualitative and quantitative measurements on the evolving characteristics of internal solitary waves were carried out by use of the dye-tracing technique and the multi-channel conductivity-probe arrays respectively. The result has shown that due to the shoaling effect the internal solitary waves of large amplitude are restrained; however, but the waves of small amplitude are magnified, and its propagation velocity is decreased. Furthermore, the shoaling effect can bring about the strong shear flow of instability and finally it makes internal solitary wavesbroken . The breaking wave will generate the fission from one large amplitude wave into several small amplitude waves with the same polarity. By means of the Mile's stability theory, the instable unstable happening-location of the internal solitary wave over the gentle slope can be described through the Richardson number, which of experimental results consistent well with the theoretical analyses analysis. It is significant that the regular characteristics of propagation are understood for those internal solitary waves of large amplitude over the continental shelf in the northeast of the South China Sea.