Kinematic response of submerged structures under the action of internal solitary waves

Abstract

In this study, we investigate the kinematic responses of submerged bodies under the motion of internal solitary waves (ISWs) with laboratory experiment. A two-dimensional ISW was generated in an ISW tank of 15 × 0.4 × 0.6 m dimension with a water depth of 0.5 m. The velocity field of the ISW was measured by the particle image velocimetry and the kinematic responses were recorded using a charged coupled device camera. Different conditions, such as ISW amplitude, ratio of the thickness of the upper layer to that of the lower layer, and depth and shape of the submerged structure, were considered. The results show that the amplitude of ISWs significantly affects their heave motion, and the relative distances between a model and pycnocline significantly influences the surge motion. The amplitude of the heave motion of the model was lower than that of the ISW under the corresponding conditions. The model in fluid with a thin upper layer (which easily causes strong nonlinearity) undergoes a more violent motion response. An empirical expression of the relationship between the maximum displacement of the surge motion and the velocity of the ISWs was also proposed.