基于稳定性SPH-SWE数值模型的真实感流体动画实时模拟  

Real-time simulation of realistic fluid animation based on stable SPH-SWE numerical model

作　　者：邵绪强[1] 梅鹏 陈文新 Shao Xu-Qiang;Mei Peng;Chen Wen-Xin(School of Control and Computer Engineering,North China Electric Power University(BaoDing),Baoding 071003,China)

机构地区：[1]华北电力大学控制与计算机工程学院,保定071003

出　　处：《物理学报》2021年第23期254-265,共12页Acta Physica Sinica

基　　金：河北省自然科学基金(批准号:F2020502014);中央高校基本科研业务费(批准号:2021MS095);国家自然科学基金(批准号:61502168)资助的课题.

摘　　要：流体动画模拟的真实感与实时性一直是流体模拟研究中的热点.针对在复杂地形场景中不稳定的流体表面运动现象,本文提出一种基于地形差异的自适应流体速度控制力,建立了稳定性光滑粒子流体动力学方法以求解浅水方程数值模型.首先,将模拟域从三维降至二维表面来降低计算量,通过粒子的密度大小表示其水深高度值;其次,采用变长光滑搜索半径,确保搜索邻域内的粒子数目稳定在固定范围内,提高模拟精度;最后引入一种基于地形差异的自适应流体速度控制力,根据粒子密度大小的实时变化来确定计算速度控制力的地形研究范围,通过插值计算粒子运动前后时间步所处地形位置的差异来修正粒子的速度和位置.本文使用屏幕空间流体渲染方法对流体表面进行绘制,避免了表面网格的提取与重建,流体的运动数值计算和渲染均被加载到GPU上并行化执行,实验结果表明在达到实时交互级别的同时,本文方法有效地改善了在复杂地形场景中流体表面的不稳定运动现象,同时流体模拟过程中密度与压强的分布均匀.The reality and real-time performance have always been the research hot-point of fluid simulation.Aiming at the unstable fluid surface motion in the scenes with complex terrain,in this paper,we propose an adaptive fluid velocity control force calculation model based on terrain difference,and a stable SPH numerical model for solving the shallow water equations is established.In this proposed numerical model,firstly we reduce the simulation domain from three-dimensional space to two-dimensional surface for reducing calculation quantity,and the water depth is represented by the density of particles at the meantime.Secondly,to ensure that the number of neighborhood particles is stable within a fixed range and to improve the accuracy of simulation,we apply a variable smoothing length to our numerical model.Then,an adaptive fluid velocity control force calculation model is introduced based on terrain difference,in which the velocity and position of particles are corrected by calculating the terrain difference caused by particle movement between each time step.The coordinates on terrain used for the calculation of terrain difference are dynamically chosen by the density of the particles.To improve the real-time performance of simulation,a screen space fluid rendering method is used to refrain the extraction and reconstruction of fluid surface.The numerical calculation and fluid surface rendering both load on the GPU for parallel execution.The simulation result shows that the proposed method can effectively improve the unstable fluid surface movement in scenes with complex terrain while reaching a real-time interaction level.The density and pressure are evenly distributed during the simulation.

关 键 词：光滑粒子动力学 浅水方程 并行计算 复杂地形 

分 类 号：TP391.41[自动化与计算机技术—计算机应用技术]