An Investigation Of Ship Parametric Rolling Simulation In Regular Wave Based On The CFD Method

The parametric rolling is a severe dynamic stability problem of ships,which endanger the crew's lives and our property.At present,most of the parametric roll prediction methods are based on the potential flow theory,the ideal fluid hypothesis,and part of the force linearization treatment.The viscous damping of the large amplitude roll process and the dynamic coupling effect between the rolling and the vertical motion is not easy to be simulated well.This paper studies the numerical simulation of ship roll damping and the numerical predictions of parametric roll motion using the commercial CFD solver STAR-CCM+.The numerical solution of the free decay roll motion of the hull with 6 degrees of freedom was established by using overlap grid technology.The numerical simulation results were compared with the experimental data,and the feasibility of the method was proved.The evolution of the vortices near the bilge keel from development to decay are analyzed,including vortex generation,growth,detachment,division into two and generation of new vortices,the results are similar to those of the similar experiments.Then,the causes of vortex damping are discussed with the bilge dynamic pressure analysis.Vortex damping is accompanied by bilge vortex shedding.On the basis of the study,this paper analyzes the coupling effect of the sway motion and the roll motion,which can delay the generation and fall of the vortex and reduce the vortex damping,thus indirectly promoting the rolling motion.The method of releasing and restraining hull sway motion is adopted in this paper,the effect of the heave on the response to roll motion is compared,so the above analysis is verified.Wave generation has a direct iinfluence on the numerical simulation of motions of ships in waves.In this paper,the numerical simulation of wave generation is carried out by using grid convergence test method,and the optimal wave-making scheme is summarized.Then,the method of using overlapping grid in large motion is studied.The numerical model of parameter rolling of the C11 container ship is established.Numerical simulation of the wave motion of ship under a series of working conditions is carried out,the results show that the numerical simulation results are in good agreement with the experimental results,the error is far less than that of the improved slicing method,and the effect of the parameter rolling conditions and speed on the parameter roll is verified.At last,the numerical simulation of the parameter rolling under the large wave steep is carried out.When the parameter rolling occurs under the large wave steep,the waves are often accompanied by periodic waves on the deck.The upwelling fluid moves along with the hull roll,The effect of the wave on the deck is studied quantitatively by adding the wave board in the forebody of the ship hull as the control,which can change the rolling process of the hull and increase the rolling amplitude.