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SPH固流交互中的实时固体破碎动画模拟

邵绪强1,2, 张鑫1, 杨仕和1, 金佚钟1(1.华北电力大学控制与计算机工程学院, 保定 071003;2.复杂能源系统智能计算教育部工程研究中心, 保定 071003)

摘 要
目的 针对固流交互中的固体破碎现象模拟研究较少、物理模型复杂、多求解器耦合性差、真实感与实时性难以兼顾等问题,提出一种适用于光滑粒子流体动力学(smoothed particle hydrodynamics,SPH)固流交互统一粒子框架的实时固体破碎模拟方法。方法 首先,结合断裂力学理论与统一粒子框架下固体边界粒子的空间和物理特性,构建基于物理的能量分析模型。然后,通过实时分析固体与流体之间的能量转化和自身能量平衡,将满足条件的粒子作为破碎发生的启发点。最后,采用基于几何的碎块生成方法,将启发点集作为种子点构建Voronoi图,完成碎块的生成。为确保模拟系统实时性,将模拟系统进行并行优化并加载至图形处理器(graphics processing unit,GPU)并行执行。结果 通过在不同复杂度和粒子规模的实验场景中进行模拟得到的结果表明,本文方法能够稳定地模拟固体受到流体冲击后发生的破碎现象,破碎细节真实感良好,在百万级粒子规模下能够满足实时性要求,可大规模并行执行且GPU加速效果显著,加速收益随场景规模增大而增大。结论 与现有研究相比,本文方法充分结合物理与几何方法的优点,与SPH统一粒子框架具有更高的耦合性,能够稳定地模拟固流交互中的固体破碎现象,细节符合现实世界物理规律,真实感渲染效果良好,可应用于洪涝、海啸、溃坝和泥石流等自然灾害的交互式预演、电子游戏特效等领域。
关键词
SPH fluid-solid interacted real-time solid fracture animation

Shao Xuqiang1,2, Zhang Xin1, Yang Shihe1, Jin Yizhong1(1.School of Control and Computer Engineering, North China Electric Power University, Baoding 071003, China;2.Engineering Research Center of Intelligent Computing for Complex Energy Systems, Ministry of Education, Baoding 071003, China)

Abstract
Objective Computer graphics-oriented realistic simulation of solid-fluid interaction can be as a branch of physical animation simulation technology in relevance to such domains like film and television special effects,video games,and disaster rehearsal. The fluid impact-derived fracture of solids is a common phenomenon in solid-fluid interaction. For solid simulation,current researches are mainly focused on solids-between interactions,for which it can pay much attention for solid-fluid interacted simulation of dynamics,deformation and other related phenomena. Solid fracture-related researches are required to be richer. The smoothed particle hydrodynamics(SPH)solid-fluid interaction solver is coupled and relatively poor and a large amount of coupling overhead can yield the performance of the simulation system to be decreased. For solid-fluid interacted simulation of the solid fracture phenomenon,physical models of fluid-relevant solid-fluid interaction and solid behavior are so complicated. It is required to combine the characteristics of the solid solver and the solid-fluid for real-time simulation. The characteristics of the interactive simulation system can facilitate the coupling of multiple solvers. If the solid fracture method is directly introduced,it will often prefer to a complex simulation system,a large amount of calculation,and poor coupling. To simulate solid-fluid interacted phenomenon derived from fluid impact,we develop a SPH unified particle framework-based real-time solid fracture simulation method in terms of the mixture of physics and geometry,for which it is challenged for the lack of related research,the difficulty of realism and real-time performance,and the poor coupling with the solid-fluid interaction simulation system. Method The construction of the theoretical model is based on the mechanism of fracture mechanics. First,due to the particle form of the solid and the neighborhood characteristics of the SPH method,energy limit conditions are obtained through real-time analysis of the energy transfer between the fluid particles and the solid boundary particles and the energy conversion of the solid itself. Then,the heuristic point set is used as the seed point,and the Voronoi diagram is employed as well,which can be constructed in parallel as the solid fragment generation method to quickly divide the solid volume space into subspaces for the generated solid fragmentation. To preserve its real-time performance of the simulation,the proposed method is optimized in parallel and loaded into graphics processing unit (GPU)for massive parallel acceleration. Result Multifaceted and particle scale-derived simulation results demonstrate that the fluid-affected method can simulate the fracture phenomenon of solids in terms of different fracture resistances,and the fracture details have well realism more. Real-time simulation is possible in scenes with 650 k particle count. Interactive simulation is implemented in scenes with 3 360 k particle counts. Such methods can be optimized in parallel and accelerated on the GPU,and the benefit of parallel acceleration is significant. In addition,the accelerated ratio can optimize the scale of the scene. Conclusion Our method is proposed and compared to current researches,which can fully melt the physical method into the geometric method. It has higher time efficiency while the realism can be preserved to meet the needs of real-time simulation. A better coupling can be reached between the method and the SPH unified particle framework. The simulation system can be used to simulate fluid impact-derived solid fracture. For simulation,details of fracture are cohesive to the laws of physics in the real world in related to realistic lighting rendering. Its potentials are beneficial for such simulation domains of natural disasters or video games.
Keywords

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