| In this paper,the potential flow theory and computational fluid dynamics were used to study the hydrodynamic performance of multi-purpose ship and multi floating offshore platform under high sea conditions.Based on the classical potential flow theory,the AQWA hydrodynamic software was used to analyze and calculate the hydrodynamic interaction of different ship distance.The results show that the amplitude of the motion response increases significantly and the new resonance frequency appears.Especially the motion response of the transport ship is more sensitive to the gap distance between the two ships.When the distance between the two ships is close,there is the resonance of the water between two ships.Based on the theory of computational fluid dynamics,this paper used FLUENT software to calculate current loads on offshore structures accurately.It analyzed the influence of different ship types,ship gap distances and current direction angles on the shielding effect of ship current loads.It was proved that the CFD method is correct and superior in the calculation of ship current loads.The results show that the ship sheltering effect is different under different current angles.The attracting force around the beam current can cause the collision of vessels and the opposite sign of moment can cause bow-to-bow or stern-to-stern collision.Using FLUENT software,the paper studied the roll damping coefficient of multi-purpose ship approaching semi-submersible ship.It was compared with the result of potential flow theory to analyze the influence of viscous flow on roll damping coefficient.It is proved that the vortex shedding phenomenon in viscous flow has an important contribution to the damping of ships,and the formation and shedding of vortex are affected by the gap distance.To solve the problem of water resonance between multi-purpose ship and multi floating offshore platform,a three-dimensional wave tank was established and its correctness was verified.Furthermore,computational fluid dynamics(CFD)simulations for the analysis of side-by-side vessels were performed.The results show that the amplitude of wave height calculated by the CFD simulations is smaller than that calculated by potential current theory.The frequency range of the resonance is wider than that of the potential flow theory.Finally,according to the wave height in the gap obtained by the CFD simulations,the damping lid method can be used to correct the AQWA results.It provides more accurate hydrodynamic results of potential flow theory and lays a technical foundation for further engineering application and berthing device design. |
