A2-D Smoothed Particle Hydrodynamics Study Of Flared Bow Slamming

Slamming events often occur in rough seas and have the potential to causesignificant structural damage and hull vibration even break off due to the loads andsubsequent whipping experienced by the ship. So, it is very important for shiphydrodynamics studies to predict the slamming loads accurately.However, due to the slam events having the nature of non-stationarity and the largedeformation of free surface while slamming, the accurate slamming loads are not easy toget. While, the Smoothed Particle Hydrodynamics(SPH) is one of the most powerfulmethods to deal with the problems related to violent deformation of the free surface. So,in this thesis, the SPH method was applied to simulate the slamming process of twodifferent cross-sections of the flared bow. The results of slamming loads were obtained tocompare with the experimental results and results of other methods.The main contents of this thesis are as follows:1. Simulated the initial stage of the wedge slamming process on still waterby using the one-phase, parallelized SPH code. The computed pressuredistribution and the vertical drag force on the wedge were compared with theexperimental and analytical data in literature to verify the boundary treatmentand other numerical treatment including the artificial viscosity term, densityreinitialization equation, etc. Series of symmetrical and asymmetrical stillwater impacts of hull cross-sections were simulated using the SPH methodand the results were compared with the experimental data and boundaryelement method.2. The SPH results showed that in the case of low entry speed and smallchanging rate of the curvature of hull section, the one-phase SPH methodcould obtain fair results in simulating2-D flared bow slamming on still water.However, when the entry-speed increases or the structure enteredasymmetrically with a large angle, the slamming process becamecomplicated. When the first slamming occurred, the fluid separated from theprofile rapidly. Then, the flow caused by the first slamming would impact thehull section with a big velocity. Meantime, a cavity could appear by the closing up of the free surface and the hull section. It is hard to predict thepressure in the cavity accurately with the one-phase SPH method.Nevertheless, better than the BEM method, the one-phase SPH method couldsimulate the secondary slamming phenomenon well, and predict the locationwhere the secondary slamming occurs. Hence, the SPH model developed bythe thesis could give a better understanding of bow slamming.