Improved SPH simulation of spilled oil contained by flexible floating boom under wave-current coupling condition

A multi-phase Smoothed Particle Hydrodynamics (SPH) method is developed to model the failure process of a flexible oil boom. An algorithm is proposed based on the dynamic boundary particles (DBPs) for preventing particle disorders of multi-phase fluid particle movement around solid boundary. The improved multi-phase SPH model is firstly validated by the experimental data of a wedge falling into a two-layer oil-water fluid. Then a numerical wave-current flume is established with a piston-type active absorbing wave generator and a circulating current system. The model reliability is validated against the measured vertical profiles of velocity. Simulation of the flexible floating boom movement is implemented by introducing a Rigid Module and Flexible Connector (RMFC) multi-body system. The model is finally applied to the simulation of movement of a flexible floating boom in containing industrial gear oil under the action of combined waves and currents. Good agreements are obtained between the SPH modeling results and the experimental data in terms of the ambient wave-current field, hydrodynamic responses of the floating body and evolution process of the oil slick for the flexible boom. The hydrodynamic responses and containment performances of the flexible floating boom are also compared with those of the rigid one. It is found from both the experimental and numerical results that two vortices of the water phase exist in the front and rear of the boom skirt and the size of the front vortex decreases with increase of the current velocity while the wake vortex is reversed. It is also found that the skirt of the flexible boom has a larger magnitude of swaying and rolling than the rigid one and the maximum quantity of escaped oil of a flexible boom within one wave cycle is about 5% more than a rigid one under the present test conditions.