Understanding the impact of coastal forests on the propagation of rapidly advancing onshore tsunami bores is difficult due to complexity of this phenomenon and the large amount of parameters which must be considered. The research presented in the thesis focuses on understanding the protective effect of the coastal forest on the forces generated by the tsunami and its ability to reduce the propagation and velocity of the incoming tsunami bore. Concern for this method of protecting the coast from tsunamis is based on the effectiveness of the forest and its ability to withstand the impact forces caused by both the bore and the debris carried along by it. The devastation caused by the tsunami has been investigated in recent examples such as the 2011 Tohoku Tsunami in Japan and the Indian Ocean Tsunami which occurred in 2004. This research examines the reduction of the spatial extent of the tsunami bore inundation and runup due to the presence of the coastal forest, and attempts to quantify the impact forces induced by the tsunami bores and debris impact on the structures. This research work was performed using a numerical model based on the Smoothed Particle Hydrodynamics (SPH) method which is a single-phase three-dimensional model. The simulations performed in this study were separated into three sections. The first section focused on the reduction of the extent of the tsunami inundation and the magnitude of the bore velocity by the coastal forest. This section included the analysis of the hydrodynamic forces acting on the individual trees. The second section involved the numerical modeling of some of the physical laboratory experiments performed by researchers at the University of Ottawa, in cooperation with colleagues from the Ocean, Coastal and River Engineering Lab at the National Research Council, Ottawa, in an attempt to validate the movement and impact forces of floating driftwood on a column. The final section modeled the movement and impact of floating debris traveling through a large-scale model of a coastal forest.

Heavy vehicles require tires which can withstand extreme loads while maintaining control, delivering performance and minimizing fuel consumption, particularly on soft soils. Recent advances in finite element analysis and computational efficiency have opened doors to highperformance, highly complex simulations which were not possible just a few years ago. This research aims to model two tires using non-linear finite element analysis code and validate them using static and dynamic tests, including response to steering input. Soils are modeled using both traditionally-meshed FEA techniques as well as a newer mesh-less smoothed particle hydrodynamics method. Soils are validated and the accuracy of the SPH and FEA models are compared. The tires and soils are used together to estimate the rolling resistance of the tire over various terrains. The developed soil models are sufficient to model soils behaving like clay. The SPH soil models behave closer to actual soils, providing superior penetration and shear properties. This causes the SPH soil models to exhibit rolling resistance closer to experimental data.

In this thesis, the Smoothed Particle Hydrodynamics (SPH) method is applied to elastic dynamics and fracture. More specifically, two coupling methods are presented which make use of both the Eulerian and Total Lagrangian formulations. These coupling methods are intended for problems whereby SPH particles, which constitute the domain, are required to convert from a Total Lagrangian kernel to an Eulerian kernel once a damage criterion is activated. The conservation equations are derived for the Eulerian and Total Lagrangian formulations, in a consistent manner which naturally presents the conditions required for the conservation of momentum and energy. These derivations are written such that they make no use of the symmetrical nature of the kernel function or the anti-symmetrical nature of the kernel function gradient. The conservation of momentum and energy is then enforced, along with improving the consistency of the formulations, by implementing the mixed kernel-and-gradient correction. This mixed correction can be applied to both the Eulerian and Total Lagrangian formulations without detracting from the energy and momentum preserving properties provided that the kernel gradient anti-symmetry property is not exploited. The symmetry terms, which are often found in SPH, are included in the derivation of the conservation equations. This is done both to reduce the number of calculations required and to simplify the first coupling procedure. Both coupled formulations are further expanded by highlighting how artificial viscosity can be introduced. A disadvantage of the first coupling method, this being the incompatibility with artificial stress, is also detailed. The equations of state and the plasticity and damage models used in this work are outlined. Additionally, a number of practical details concerning numerical implementation are given. These include the coupled implementations of ghost particle boundary conditions, memory storage, OpenMP implementation, and the Predict, Evaluate, Correct (PEC) form of leapfrog time integration used. Lastly, the proposed formulations and models are verified and validated. This is done by modelling progressively more complex simulations that verify individual aspects of the formulations. Either analytical or experimental results are used for validation where possible. The final simulations highlight how high velocity impacts can be modelled using the proposed coupled mixed correction Eulerian Total Lagrangian SPH method.

abstract: This document presents a new implementation of the Smoothed Particles Hydrodynamics algorithm using DirectX 11 and DirectCompute. The main goal of this document is to present to the reader an alternative solution to the largely studied and researched problem of fluid simulation. Most other solutions have been implemented using the NVIDIA CUDA framework; however, the proposed solution in this document uses the Microsoft general-purpose computing on graphics processing units API. The implementation allows for the simulation of a large number of particles in a real-time scenario. The solution presented here uses the Smoothed Particles Hydrodynamics algorithm to calculate the forces within the fluid; this algorithm provides a Lagrangian approach for discretizes the Navier-Stockes equations into a set of particles. Our solution uses the DirectCompute compute shaders to evaluate each particle using the multithreading and multi-core capabilities of the GPU increasing the overall performance. The solution then describes a method for extracting the fluid surface using the Marching Cubes method and the programmable interfaces exposed by the DirectX pipeline. Particularly, this document presents a method for using the Geometry Shader Stage to generate the triangle mesh as defined by the Marching Cubes method. The implementation results show the ability to simulate over 64K particles at a rate of 900 and 400 frames per second, not including the surface reconstruction steps and including the Marching Cubes steps respectively. / Dissertation/Thesis / M.S. Computer Science 2012

Made available in DSpace on 2018-08-24T22:53:30Z (GMT). No. of bitstreams: 1 tese_7350_1 Dissertação FINAL TOTAL.pdf: 2122640 bytes, checksum: 1f813dd895e873b49853355007e1a7ba (MD5) Previous issue date: 2013-08-19 / Neste estudo foi aplicado do método numérico, sem malhas, baseado em partículas, denominado SPH (Smoothed Particles Hydrodynamics). E um código numérico na linguagem computacional FORTRAN foi utilizado para solucionar as equações de Navier-Stokes. O clássico problema da literatura da dinâmica dos fluidos Computacional, denotado como problema da cavidade quadrada bidimensional (Shear-Driven Cavity Flow), foi estudado com a intenção de verificar o comportamento do código numérico em relação a resultados específicos já existentes do assunto. O citado problema físico das cavidades abertas é amplamente empregado como benchmark, visando a validação do método numérico utilizado no trabalho desenvolvido na pesquisa. O trabalho de análise e validação do código numérico foi dividido em três seções: a primeira lista as localizações dos centros dos vórtices principais gerados pelo escoamento na aresta superior das cavidades; a segunda plota os perfis das componentes das velocidades centrais das cavidades; e a terceira: lista os desvios absolutos dos perfis das velocidades centrais do presente trabalho, comparados com dados de outros estudos. Constata-se que o método SPH apresentou boa acurácia nas simulações realizadas, obtendo boa concordância entre os resultados das simulações dinâmicas com os dados de referências, validando-se o modelo numérico proposto, tendo melhores resultados para baixos números de Reynolds.

Understanding the impact of coastal forests on the propagation of rapidly advancing onshore tsunami bores is difficult due to complexity of this phenomenon and the large amount of parameters which must be considered. The research presented in the thesis focuses on understanding the protective effect of the coastal forest on the forces generated by the tsunami and its ability to reduce the propagation and velocity of the incoming tsunami bore. Concern for this method of protecting the coast from tsunamis is based on the effectiveness of the forest and its ability to withstand the impact forces caused by both the bore and the debris carried along by it. The devastation caused by the tsunami has been investigated in recent examples such as the 2011 Tohoku Tsunami in Japan and the Indian Ocean Tsunami which occurred in 2004. This research examines the reduction of the spatial extent of the tsunami bore inundation and runup due to the presence of the coastal forest, and attempts to quantify the impact forces induced by the tsunami bores and debris impact on the structures. This research work was performed using a numerical model based on the Smoothed Particle Hydrodynamics (SPH) method which is a single-phase three-dimensional model. The simulations performed in this study were separated into three sections. The first section focused on the reduction of the extent of the tsunami inundation and the magnitude of the bore velocity by the coastal forest. This section included the analysis of the hydrodynamic forces acting on the individual trees. The second section involved the numerical modeling of some of the physical laboratory experiments performed by researchers at the University of Ottawa, in cooperation with colleagues from the Ocean, Coastal and River Engineering Lab at the National Research Council, Ottawa, in an attempt to validate the movement and impact forces of floating driftwood on a column. The final section modeled the movement and impact of floating debris traveling through a large-scale model of a coastal forest.

No / The paper presents an incompressible Smoothed Particle Hydrodynamics (SPH) model to investigate the wave overtopping of coastal structures. The SPH method is a grid-less Lagrangian approach which is capable of tracking the large deformations of the free surface with good accuracy. The incompressible algorithm of the model is implemented by enforcing the constant particle density in the pressure projection. The SPH model is employed to reproduce a transient wave overtopping over a fixed horizontal deck and the regular/irregular waves overtopping of a sloping seawall. The computations are validated against the experimental and numerical data and a good agreement is observed. The SPH modelling is shown to provide a promising tool to predict the overtopping characteristics of different waves. The present model is expected to be of practical purpose if further improvement in the spatial resolution and CPU time can be adequately made.

The paper employs a Reynolds-averaged Navier¿Stokes (RANS) approach to investigate the time-dependent wave breaking processes. The numerical model is the smoothed particle hydrodynamic (SPH) method. It is a mesh-free particle approach which is capable of tracking the free surfaces of large deformation in an easy and accurate way. The widely used two-equation k¿¿ model is chosen as the turbulence model to couple with the incompressible SPH scheme. The numerical model is employed to reproduce cnoidal wave breaking on a slope under two different breaking conditions¿spilling and plunging. The computed free surface displacements, turbulence intensities and undertow profiles are in good agreement with the experimental data and other numerical results. According to the computations, the breaking wave characteristics are presented and discussed. It is shown that the SPH method provides a useful tool to investigate the surf zone dynamics.

Le problème de l’hydroplannage a fait l’objet de peu de travaux de simulation jusqu’à présent du fait de sa complexité : couplage fluide-structure, complexité de la structure du pneu du fait des matériaux en présence, contact avec l’asphalte, complexité de l’écoulement fluide résultant (interface extrêmement complexe,assèchement de la route, ventilation, développement éventuel de la turbulence et de cavitation). Dans ce contexte, Michelin, Centrale Nantes et NextFlowSoftware ont cherché récemment à évaluer la capacité du solveur SPH développé par ces deux derniers pour classifier des pneumatiques en fonction de la géométrie de leurs structures surfaciques, sans prendre en compte la phase gazeuse. Cela a permis de démontrer la faisabilité de telles simulations par méthode SPH, et même d’obtenir de bons résultats avec pour avantages de s’absoudre des difficultés liées au maillage. L’autre avantage conséquent d’utiliser la méthode SPH pour modéliser le fluide dans ce contexte est apparu dans sa capacité à se coupler relativement aisément à des solveurs classiques de type Eléments Finis pour le problème structurel. L’objectif du doctorat est triple, poursuivre la qualification du couplage SPH–Eléments Finis, en particulier en termes énergétiques, développer des schémas permettant d’assurer un bon compromis stabilité / précision / temps de calcul. Deuxièmement quantifier l’influence des différents phénomènes physiques en jeu pour déterminer lesquels doivent être modélisés. Enfin adapter des modélisations SPH permettant de prendre en compte simultanément les différents phénomènes influant pour réaliser des simulations du problème complet. / The aquaplaning problem has been the topic of simulation works emphasizing its complexity: fluid structure interactions, structures modelling, materials involved, contact with asphalt and the complexity of the resulting fluid flow (extremely complex interface, drying up the road, ventilation, possible development of turbulence and cavitation). As additional difficulty, the tire is a highly deformable body and fluid-structure interaction effects should be considered, leading to a challenging problem for the numerical modelling. Then Michelin, Ecole Centrale Nantes and NextFlow Software have recently tested the ability of the SPH solver developed by the two latter to classify tires based on their surface structure geometries, without considering the gas phase. In this context, the interest of SPH for modelling efficiently the aquaplaning flow has been underlined. The meshless and Lagrangian feature of SPH naturally avoid the problem of fluid/solid grid compatibility. The other significant advantage of the SPH method, in this context, appears in its ability to be relatively easily coupled to with conventional Finite Element solvers. The aim of this workis three fold. First, qualify the SPH-FE coupling strategy, especially in terms of energy and then develop schemes to ensure a good compromise among stability, accuracy and computation time. Second, quantify the influence of different involved physical phenomena to determine which should be modelled. Finally, adapt SPH models to simultaneously consider different phenomena and to performe simulations of the complete problem.

[pt] Neste trabalho, é apresentado uma abordagem para animação de águas rasas em aplicações interativas baseada em um modelo físico. Para a simulação, foi empregado o método Langrangreano conhecido como Smoothed Particle hydrodynamics (SPH). Com base no trabalho de Muller et al. (Muller et al., 2003), que utilizou SPH em computação Gráfica, e no trabalho de Rodriguez-Paz e Bonet (Rodriguez-Paz; Bonet, 2005) que propõe uma variação deste método para a simulação de águas rasas em aplicações de engenharia, propomos uma abordagem simples e eficiente para a simulação de águas rasas em jogos a influência de terrenos acidentados. / [en] In this work is present an approach to shallow-water animation on interactive applications based on a physic model. For the simulation, was employed a Lagrangian methos known as Smoothed Particle Hydrodynamics (SPH). Based on the work of muller et al. (Muller et al., 2003), which applied SPH in computer Graphics, and on the work of Rodriguez-Paz (Rodriguez-Paz; Bonet, 2005), wich proposes a variation of this method to shallow-water simulation on engineering applications, we have proposed a simple and efficient approach for shallow-water simulation on games under the influence of irregular terrains.