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Smoothed Particle Hydrodynamics (SPH) is a computational technique for the numerical simulation of the equations of fluid dynamics without the use of an underlying numerical mesh. Although originally developed for use in astrophysical gas dynamics, SPH has recently been applied to many other areas of numerical fluid dynamics and materials modelling, several of which have particular relevance to defense problems of interest to the DSTO. In this report we review the basics of the method and then describe a simple two-dimensional SPH code for the simulation of incompressible fluid flow. The code is then applied to simple problems such as a dam break, the sloshing of water and wave breaking over ships. These examples illustrate both the capabilities of the technique and the relative ease with which the method can treat problems which have previously been considered difficult to solve using traditional methods such as finite difference, finite volume or finite element grid based methods. Further applications of the method are then reviewed, concentrating in particular on the utility of the technique in solid mechanics modelling, and then current applications of SPH within Maritime Platforms Division are described.
This is the first-ever book on smoothed particle hydrodynamics (SPH) and its variations, covering the theoretical background, numerical techniques, code implementation issues, and many novel and interesting applications. It contains many appealing and practical examples, including free surface flows, high explosive detonation and explosion, underwater explosion and water mitigation of explosive shocks, high velocity impact and penetration, and multiple scale simulations coupled with the molecular dynamics method. An SPH source code is provided and coupling of SPH and molecular dynamics is discussed for multiscale simulation, making this a friendly book for readers and SPH users.
During the study of geophysical flows, some software packages (such as TITAN2D, GeoClaw) have been developed to simulate the behavior of geophysical flows of lava, avalanche, and mudslide. While these packages have led a better understanding of geophysical flows, there are some impediments which limit the widespread acceptance of these packages in practice. For example, some of the current programs (e.g. TITAN2D) are based on the depth average model and such a methodology can be computationally challenging when dealing with boundary conditions. With the development of computational fluid mechanics, a mesh free method called Smoothed Particle Hydrodynamics (SPH) has been introduced by Gingold and Monaghan. Because of the limitation of classical SPH, Reformulated Smoothed Particle Hydrodynamics (RSPH) has been derived from convolution integral of the original hydrodynamics equations. Such a framework uses a Riemann Solver to determine the force acting on each fluid particle and is recently recognized to be more efficient and accurate for tracking particle movements, making it possible to capture the behavior of fluids under strong shock. This dissertation focuses on implementation of RSPH for simulation of large scale of geophysical flows. The 1-D and 2-D cases were first discussed to confirm the advantage of using Riemann Solver, followed by the development of a formula to determine where to use Riemann Solver. For the cases without boundary conditions, a Von Neumann stability analysis was conducted to assess the stability and benefit of RSPH in comparison with standard SPH. For the cases with boundary conditions, the GKSO theory (a theory given by Gustaffson, Kreiss, Sundstrom and Osher) was used to analyze the stability of SPH. The framework of RSPH for use in materials with plastic viscosity was also developed together with a discussion of its stability under different boundary conditions. At last, stability of the SPH with corrected derivative and weight smoothing was addressed. This work provides building blocks for further implementation of RSPH technique in engineering fluid mechanics.
As a branch of CFD, Meshless method called 'Smoothed Particle Hydrodynamics' (SPH) has the advantage to deal with complicated free surface flows and some other attractive features. In this thesis, a robust, accurate and efficient SPH code was developed to simulate the 3D nonlinear free surface flows. MPI (message passing interface) was adopted for parallelization. Approximate solid ghost particles were proposed to simulate general 3D geometry on solid boundaries. Local pressure evaluation method was used to calculate response loads on structure and to simulate fully coupling motion between solid and liquid. Some other techniques were developed and adopted in our code in order to construct a more accurate and stable simulation. For verification and validation of SPH method, one-phase and two-phase dam break and wedge entry were tested with discussion of solid boundary, pressure evaluation method and variable smoothed length. Subsequently, the method was used to study 2D and 3D sloshing and flooding problems. Comparisons were carried out between experimental and other numerical results. The features of the phenomenon for instance in terms of wave height, structural loads and large deformation of free surface were analyzed and discussed. Key words: SPH (Smoothed Particle Hydrodynamics), three dimension, nonlinear, free surface, sloshing, flooding.