Hydrodynamic performances and wakes induced by a generic submarine operating near the free surface in continuously stratified fluid.

The wake of a submarine is a crucial element that greatly affects its stealth and hydrodynamic performance. To investigate the propagation and evolution characteristics of submarine wakes in a stratified fluid, particularly under free surface conditions, a numerical method to simulate the linearly stratified environment was developed. A thermocline model based on Boussinesq assumption was introduced to match the continuously stratified fluid. The volume of fluid (VOF) method was utilized to capture free surface waves, while a fully structured grid and the SST k - ω turbulence model were combined to solve the complex flow of submarines. Grid independence study in homogenous flow near the free surface was initially conducted. Furthermore, the hydrodynamic performance, wake evolution characteristics, free surface signatures as well as decay of velocity under different stratification levels were analyzed. Results demonstrated that the numerical method employed was efficient in simulating stratified flows. Moreover, it showed that density stratification had a significant impact on the hydrodynamics and wake characteristics of a submarine, especially under strong density stratification circumstances. [ABSTRACT FROM AUTHOR]