Investigations of smoothed particle hydrodynamics method for fluid-rigid body interactions

Abstract

The aim of this project is to investigate the capability of smoothed particle hydrodynamics (SPH) method for fluid-rigid body interactions. SPH is one of the most widely used meshless methods which use particles to represent the system. The fluid is assumed either slightly compressible so weakly compressible SPH (WCSPH) is applied or truly incompressible so incompressible SPH method (ISPH) is adopted. The performance of SPH method is affected by a number of modelling parameters including the choice of kernel functions, smoothing length, total number of particles and time step size. Investigations of the effect of these parameters were conducted using one dimensional cases and the results show that smoothing length and the total number of particles can influence the accuracy significantly but other parameters are less important. In order to generate the model efficiently and maintain accuracy an appropriate boundary treatment is important. Two boundary treatments are investigated for ISPH method. Although these two boundary treatments have been used in WCSPH, they have not been used in ISPH method in the literature. They are easier to use for complicated engineering situations related to fluid structure interaction problems compared with the traditionally used ghost particles. Two approaches for solving Poisson’s equation of ISPH method are studied including the implicit solution approach and explicit solution approach. A new method is developed for multi-phase flow by combining WCSPH method and truly ISPH method to study the effect from air pressure. Within this method the compressibility of air and incompressibility of water can be retained. Based on these studies, algorithms for fluid rigid-body interaction in 2 dimensional and 3 dimensional cases have been developed to simulate the general engineering problems related to fluid rigid body interactions.

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