Research On Realistic And Real-Time Simulation Of Large-Scale SPH Fluid Animation Based On Shallow Water Equations

Large-scale fluid simulation has always been the research focus of realistic and real-time fluid animation simulation.Using SPH to solve the SWE is a commonly used method in large-scale fluid simulation.However,influenced by complex scene factors like topography,architecture in large-scale scene,this method comes with problems like unstable surface phenomenon,boundary penetration under large velocity difference,poor rendering quality and low computational efficiency.This paper aims at solving the problems above,the main work includes:1.Numerical model for stable fluid simulation in large-scale complex scene.Aiming at the stability problem of fluid animation in large-scale complex scenes,we propose a stable fluid simulation numerical model based on SPH-SWE method.Firstly,we reduce the simulation domain from three-dimensional to two-dimensional surface for purpose of reducing calculation,the water depth is represented by the density of particle at the mean time.To ensure the amount of neighborhood particles is stable within a fixed range and improve the accuracy of simulation,we secondly apply a variable smoothing length to our numerical model.Then,an adaptive fluid velocity control force calculation model based on terrain difference is introduced,which corrects the velocity and position of particles by calculating the terrain difference caused by particle movement between one time step.The coordinates on terrain used for the calculation of terrain difference are dynamically chosen by the density of the particle,which helps improve the unstable fluid surface movement in large-scale complex scenes.2.A volume adaptive boundary particle method and a terrain force calculation method based on the neighbor terrain slope of fluid particle.To solve the solid-fluid interaction problem under the numerical model above,we sample the rigid bodies with volume adaptive boundary particles and introduce an artificial collision force term.For the fluid-terrain interaction problem,we propose a terrain force calculation method based on the neighbor terrain slope of fluid particle,which avoids the solution of the whole terrain gradient map and the sample points is dynamically chosen according to the density of fluid particle.The solution proposed above prevents particle penetration effectively while ensuring the fluid flows correctly.3.Real-time rendering and parallel computing scheme based on GPU acceleration.Aiming at the realism and real-time performance in large-scale complex scenes,we render the fluid surface with an improved Screen Space fluid render method,which refrains the extraction and reconstruction of fluid surface.By iterating bilateral gaussian filtering repeatedly,the fluid surface has been smoothed properly.The numerical calculation and fluid surface rendering are both deployed on the GPU for parallel execution,an interactive simulation speed of 20 f/s is achieved at 120 K particle scale.The simulation result shows that the proposed method can effectively improve the unstable fluid surface movement in large-scale complex scenes while reaching the real-time interaction level.The volumetric adaptive boundary particles,artificial collision force and terrain force term have also effectively prevented particle penetration,the density and pressure are evenly distributed during the simulation.