大尺度流体流固耦合与形变破坏的快速仿真研究

Physically based fluid animation has successfully simulate the small-scale fluid such as square-cavity, however, for large-scale fluid, it is a challenge to simultaneously describe the fluid volume and surface details with the same lattices or particles, the complex interaction between fluid and solid which may produce further deformation, crack and fracture will greatly increase the difficulties of realistic simulation..This project will focus on the modeling and quick animation of fluid-solid interaction and the phenomena of solid deformation and fracture for large-scale fluid. Firstly, a particle-lattice hybrid modeling algorithm is presented to describe the large-scale fluid volume and its surface details. The interaction and transformation between particles and mesh, and the construction of free surface, are built by the particles tracing interface with particle level set method. Secondly, the modeling of solid deformation based on FE-SPH model is proposed. By the double coupling of dynamic particles and solid cell with virtual nodes, the developing of cracks and the collision detection for multi-bodies of solids are described. Thirdly, based on the uniform element-free and particles method, the interaction rules between fluid particles on fluid surface and solid particles are built. Here a dynamic tracing strategy of these adjacent particels of fluid and solid, and the boundary condiction with mirror particles are used, Then the equation is solved by the global integral with the single operator. Fourthly, by using the nonlinear fluid-structure interaction method to perform the parallel optimization of algorithm, and the view-dependent data attempter tactics, the complex scenes of fluid-solid interaction are rendered with GPU accelerating technologies. Finally, a simulation framework is built to model the large-scale fluid and the interaction with meshless particles for the applications of fluid animation.

基于物理的流体动画在模拟方腔等小区域流体方面已经有较好的效果，但是针对大尺度流体，流体内部区域和流体表面细节无法采用统一的网格或粒子来表达，其与固体复杂交互时发生的大形变、崩裂、破碎等现象更增加了动画仿真的难度。.本项目针对大尺度流体动画中的流固耦合和固体形变破坏现象的建模和快速仿真展开研究。重点研究粒子-网格混合的大尺度流体建模方法，基于粒子水平集的界面追踪思路，进行网格与粒子的耦合转化及自由表面的构建；研究基于FE-SPH模型的固体形变建模，采用动态粒子与单元节点主-从耦合连接，进行形变裂缝的延展及多体碰撞仿真；研究基于统一无网格粒子的流固耦合，进行异质邻域粒子的交互及边界处理，实现强耦合的整体积分法求解；研究流固交互现象的快速绘制，基于非线性双渐进法进行算法的并行优化，实施面向视点的数据调度和优化策略；最后集成到一个面向大尺度流体动画的流固交互的快速仿真框架中。

基于物理的流体动画是计算机图形学领域的研究热点，目前在模拟方腔等小区域流体方面已经有较好的效果，但是针对大尺度流体，流体内部区域和流体表面细节无法采用统一的网格或粒子来表达，其与固体复杂交互时发生的大形变、崩裂、破碎等现象更增加了动画仿真的难度。本项目针对大尺度流体的流固耦合与形变破坏的快速仿真问题，在大尺度流体的建模、流固动态交互的模拟、形变破坏的高效仿真、典型流体现象加速绘制等方面进行了卓有成效的研究，提出了保细节的大尺度流体模拟、基于视频的流体重建与交互模拟、各向异性材料脆性破裂模拟、基于FE-SPH的固体形变破坏模拟、基于深度学习的碰撞交互计算、考虑热传导的流固交互仿真等新算法与方法，最后集成到一个面向大尺度流体动画的GPGPU并行处理框架,实现了泥石流、火山、凝结等典型复杂流体现象的快速真实感绘制。本项目突破了传统的基于粒子与网格的流体建模方法，构建了粒子与网格混合的流体建模技术，同时拓展了基于视频的流体重建方法，考虑固体及流固交互时能量、温度、材质等变化，逼真模拟了流固交互及固体破裂破坏，最后提出的加速处理算法保证了大尺度流体及其交互仿真的效率，相关技术可以拓展应用于各类虚拟现实、动画游戏、行业仿真等领域。