探討粒子法在動態波擊模擬實驗的實用性

The Applicability of Particle Method in Dynamic Slamning Simulation of Ship Hull

本文主要在探討粒子法中的光滑粒子流體動力學法（SPH）在模擬二維船殼底部遭受波擊時的實用性，由於SPH為利用無網格離散與拉格朗日描述變形，因此可以輕易得到每個流體質點在瞬時狀態下的位置、壓力、以及速度。相較於目前主要分析波擊現象所使用的有限元素法與有限體積法。SPH可以直接求得流體與固體的邊界以及自由液面的形狀。另外SPH在處理移動邊界時，也不需要remesh以避免網格扭曲。本文使用SPH方法分析二維water impact中波擊壓力的變他、以及部分船體落下撞擊平靜水面時的波擊力結果，並與傳統有限體積法的模擬結果，以及實驗研究數據進行對照。結果顯示SPH在面對動態波擊問題時具有可靠性、效率與自由度高等優點。 In this paper, the applicability of smoothed particle hydrodynamics method (SPH) for ship hull slamming load problems is tested. The SPH method is based on the Lagrangian formulation and particle discretization. Therefore, it can be easily applied to problems involves surface wave, fluid-structure interaction (FSI) and wave breaking phenomenon. Comparing with the most popular methods for fluid analysis, such as Finite Element Method (FEM) and Finite Volume Method (FVM), the SPH method can directly trace the motion of the water and structure motion and calculate position, pressure and velocity, etc. When modeling moving boundaries such as the falling ship hull, the SPH does not require re-meshing to update the new interface, while the general mesh based approach need a new mesh that conform the moving boundary/interface. Several numerical analyses are performed to show that the SPH method offers reliable results when compared to FVM and experiment in the two-dimensional water impact and ship entry problem. The result also shows that SPH has wide applicability for large deformation of surface wave slamming problems.