Numerical study of submerged body tail linearization in a strongly stratified fluid on the characteristics of generated internal waves

Abstract

Underwater motion generates internal waves in a density-stratified seawater environment. These waves can persist for several days in oceanic regions, making them detectable by synthetic aperture radar (SAR). To clarify the effect of tail linearization on the internal wave characteristics of an object, this paper builds a strongly stratified fluid flume based on the delayed detached eddy model (DDES), through which we numerically simulate the internal waves characteristics of two models, namely, a tail-planar type and a cylindrical rear spherical type. The numerical results show that the turbulent wake of the cylindrical rear spherical type diverges to both sides under the low and high Froude (Fr) number, leading to an increase in the amplitude of the generated volume effect internal wave and wake angle, but the wavelength of the volume effect internal wave is almost the same for both. Notably, at high Fr numbers, the influence of the trailing effect internal wave of the object with a linearized tail is significantly reduced. The tail-planar type of internal waves shows violent fluctuations over long distances and high-intensity violent changes in locally concentrated regions. In contrast, the internal waves of the object with tail linearization show slight fluctuations over long distances.