Experimental and numerical investigation of wave-induced hydrodynamic interactions of a sub-floating hydrocarbon storage tank system in shallow waters

Abstract A subsystem of a large compliant floating hydrocarbon storage facility (FHSF) is established as a simplified model to validate its hydrodynamic performance. The subsystem is composed of two floating hydrocarbon storage tanks (floating tanks) placed in a large moonpool of a rigid barge frame. The barge frame is expected to serve as a breakwater as well as a protection to the floating tanks. The wave-induced responses of the subsystem with the existence of moonpool/gaps are investigated through experimental and numerical studies. The experimental studies followed a Froude scaling ratio 1:45 were conducted in an ocean basin under various wave conditions corresponding to nearshore environments. Both free surface elevations in the moonpool/gaps and the hydrodynamic responses of the three floating bodies were obtained. Besides, a numerical model based on linear potential flow theory is developed, and a dipole lid is introduced to incorporate the viscous effect on the resonant free surface motions. Comparable experimental and numerical results show that the free surface elevations in the moonpool/gaps can be reasonably predicted. Next, four different configurations of the subsystem were investigated, and different hydrodynamic coupling behaviors between the fluid resonant motions, the motions of the barge frame, and the floating tanks are revealed. It is demonstrated that the motions of the floating bodies and the resonant fluid motions in the narrow gaps are the smallest in the oblique sea. The present study provides a useful reference for the design and hydrodynamic analysis of floating multi-body systems for nearshore applications.