Nonstationary spatiotemporal characteristics of internal solitary waves propagating along a convex side boundary

Abstract

The propagation of oceanic internal solitary waves (ISWs) with spatial irregularity and temporal instability is referred to as nonstationary evolution. To simplify the contraction and expansion of strait channels in the ocean into a sinusoidal geometric structure of a convex side boundary, numerical simulations with turbulent models were conducted in this study, supplemented by laboratory experiments in a stratified fluid flume, to verify the nonstationary evolution characteristics of ISWs propagating along a convex side boundary. This study reveals that when ISWs approach the convex side boundary, the wave amplitude begins to increase, and the horizontal shear increases. Upon entering the contraction segment of the side boundary, due to obstruction from the boundary, the wave shape undergoes vertical stretching and horizontal contraction, leading to a further increase in wave amplitude but a reduction in horizontal shear. The shear is the strongest when passing through the center of the convex side boundary with the smallest transect. However, the wave shape undergoes vertical contraction and horizontal stretching, resulting in decreases in both amplitude and shear compared to those at the center of the convex side boundary.