Numerical Simulation Of Hydro-elastic Problems Based On GPU-Accelerated SPH Method

Structures interacting with free surface flows are of great interest in many engineering applications such as landing and takeoff of seaplanes and impacting of sea water to offshore structures.Numerical simulation of such problems should capture the evalution of free surface,the deformation of structures and the shape of interface correctly.Currently,researches are rarely focus on this field.To solve these problems,in this thesis,a fully meshless based Smoothed Particle Hydrodynamics(SPH)method is developed to simulate the above mentioned fluid-structure interaction problems.Additionally,to improve the efficiency of SPH method,the GPU acceleration algorithms for both fluid and structure simulation are developed.Firstly,a GPU accelerated Weakly Compressible Smoothed Particle Hydrodynamics(SPH)method for fluid simulation based on WCSPH is developed.Since the meshless and lagrangian nature of WCSPH method,it has great advantage in simulate unsteady flows with large deformation,such as free surface flows.On the other hand,the algorithm of WCSPH method is simple and easy to be parallelized on GPU.In this thesis,the non-physical pressure oscillation and particle clustering problems of WCSPH method when simulate free surface flows is overcomed by introducing density reinitialization and properly set dummy particles outside the boundary.Some typical test cases such as dam-break flows and slamming of a rigid cylinder are performed to validate the numerical method.Results show that the developed method can simulate free surface flows well,and GPU can speed up the WCSPH code obviously.Secondly,a GPU accelerated Total Lagrangian Form of Smoothed Particle Hydrodynamics(TLSPH)method is adopted.the TLSPH method can eliminate the "tensile instability" problems always occured in WCSPH method when simulate deformation of structures.The precision of TLSPH method when simulate geometrical linear and nonlinear problems is very similar to Finite Element Method(FEM)..In order to validate the precision of the TLSPH code and computational efficiency of GPU version TLSPH code,numerical simulation of typical elatic problems such as oscillating of plates and bending of beams are carried out.Results show that the algorithm and code used in this thesis works well in simulate structural deformation problems,and GPU can speed up the TLSPH code obviously.Finally,a GPU accelerated combined WCSPH and TLSPH(WC-TL SPH)method is developed to simulate hydro-elastic problems which involve free surface flows.Compared to the commonly used combined SPH and Finite Element Method(SPH-FEM),the WC-TL SPH method developed in this thesis is a fully meshless method,so the preprocessing and postprocessing of this method are more convinient and many codes developed in simulate fluid phase can be reused in solid phase.Additionally,a kind of fluid-structure interface treatment method is developed.Compared other method in literature,the method developed in this thesis is much simplier and more reliable.In order to validate the precision of the WCTL SPH code and computational efficiency of GPU version WC-TL SPH code,numerical simulation of typical hydro-elastic problems involve free surface flows such as bending of a plate under water pressure and impacting of breaking dam to elastic structures are carried out.Results show that the algorithm and code used in this thesis works well in simulate hydro-elastic problems,and GPU can speed up the WC-TL SPH code obviously.