Experimental and numerical investigation of the free surface and internal wave characteristics induced by the movement of a 2D cylindrical submerged body in a stratified two-layer fluid

This study conducted a two-dimensional analysis of the propagation characteristics of free surface waves and internal waves generated by a horizontally moving circular cylinder in a two-layer fluid domain. The characteristics of the baroclinic and barotropic modes of flow in the rear region of the cylinder were analyzed under subcritical and supercritical conditions by comparing the experimental and potential flow-based numerical results. The depression depth of the surface waves was affected by the towing speed of the submerged body, whereas the depth of the upper fluid layer affected the internal waves. The quantitative changes in the characteristics of the baroclinic and barotropic modes of the internal waves under the critical condition of the internal wave mode were identified. The experiments were carried out in a two-dimensional submerged body towing tank. The two-dimensional numerical towing tank technique was good at representing the flow features due to pressure changes caused by the movement of the submerged body but had limitations in representing the complex flow in the rear region of the cylinder caused by fluid viscosity. This study provides the basic information for understanding the flow characteristics caused by the movement of submerged bodies in stratified fluid layers, ultimately leading to the development of underwater body detection and monitoring technologies through more precise experimental conditions and numerical simulation techniques.