Research On Real-time Fluid Simulation Based On Particle System Method

With the development of virtual reality technology and requirement of sense ofreality in virtual scenarios, realistic fluid simulation appears more and morefrequently in movies, video games and simulation systems. And in these applications,simulation of water can be the most common and attractive one. From the height fieldbased large scale water surface simulation to physics-based water simulation, fromsimulation to waves above water surface to the virtual construction of sprays andbubbles, from simply artificial interaction calculation to complicated acting forcecomputation between fluid and solid or soft bodies, the research of fluid simulationevolved continuously towards the height of more accurate, more fast and morerealistic in the past dozens of years. The work of fluid simulation can mainly bedivided into two parts–the simulation of fluid’s physical movement and the rendering.In this paper, we generally discuss the Lagrangian method of fluid physical movementsimulation and emphasize its corresponding rendering method and modeling of splasheffect in turbulent water in detail. Specifically, the following points will be discussedin this paper:(1)We discuss computational fluid dynamics based fluid simulation methods. Therelationship and differences between Eulerian viewpoint and Lagrangian viewpoint influid simulation are emphasized. Taking SPH method as a key point, we discuss theforce analysis, numerical solution of N-S formulation and the design of kernelfunctions in SPH model.(2)We introduce three commonly used fluid free surface rendering methods,which are Marching Cubes, Ray Tracing and Screen Space Splatting. An adaptivebilateral filter and an adaptive normal calculation method are proposed for the ScreenSpace Splatting process. The adaptive bilateral filter could adjust the smoothingextent adaptively according to the viewing distance, and the adaptive normalcalculation method is able to avoid numerical calculation error in the shading pass.(3)We propose a physics-based splash simulation model in fluid simulation.Cooperating with the Lagrangian method, splash particles are selected in accordancewith local densities as candidates for the breakup process, in which the distribution ofnewly generated small particles are designed based on CFD experiments. The featureof this splash model is that the whole calculation is only conducted in the renderingprocess, so that the computation efficiency will not be distinctly influenced.On the basis of the discussion in physical model of fluid simulation, we focus on the fluid free surface rendering and splash simulation in turbulent flow innovatively.To sum up, the methods presented in this paper not only can enhance the visual effectof the rendering process, but also keeps the real-time feature of the simulationmethod.