On surface flow induced by internal waves generated by a slender body moving at low internal Froude number in a sharply stratified fluid

The studies on internal waves(IWs) generated by a moving body in a stratified fluid generally focused on wave amplitude phase characteristics in underwater space. The surface flow induced by internal waves(IWs) generated by an underwater moving body in stratified fluid is generally weak, and is rarely studied. In the present paper, the surface flow induced by body-generated IWs of a slender body(SUBOFF model) moving at F-ri = 0.547 similar to 2.189 and high Reynolds number (Re = 2.0 x 10(6) similar to 8.0 x 10(6)) in a sharply stratified fluid with finite depth is investigated numerically and experimentally. For the theoretical calculation, the Euler equations and the free surface boundary conditions are linearized, and the source-sink distribution method is used to calculate the velocity field of body-generated IWs of SUBOFF model using the potential flow theory combined with the associated eigenvalue problem on vertical velocity. Meanwhile Particle Image Velocimetry (PW) is used to measure the surface flow induced by body-generated IWs of SUBOFF model under the same conditions (object size, fluid stratification and movement parameters) at a large stratified fluid tank (25m x 3m x 1.5m) and validate the theoretical calculation method. The wave patterns, the maximum peak-to-peak velocity value of surface flow and its variation with F-ri are analyzed.