Experimental investigation of internal solitary wave forces on a semi-submersible

The forces on a semi-submersible induced by internal solitary waves (ISWs) have been investigated. A series of ISWs were generated by a laboratory piston-type wave maker in a density stratified two-layer fluid within a 30-meter-long wave flume. Experiments and ISW theoretical models are compared in terms of frequency-amplitude relationships and wave profiles. The forces and pitch moments on the fixed semi-submersible model were measured. Based on the experimental data, the empirical coefficients Cm and Cd are obtained as a function of KC, Reynolds number and layer depth h1/h. The force calculation was also performed based on Morison's equation and pressure integral. There is a good agreement between the calculated results and the measurements. The maximums of the forces and moments increase linearly with the amplitude becoming larger. Besides, the layer depth is found to have a close relationship with the maximum value of the horizontal forces and moments.