Real-time Fluid Interactive Simulation Algorithm

Recently physically based computer animation is always a hot topic in computer graphics, especially in the special effects industry for films and games. Physically based modeling is used to build precise movement model for objects using computer through exploring physical nature of natural phenomena in the real world, and then simulate object's movement more realistically. However, the complexity of the physical computation often leads to serious performance degradation, so it is necessary to investigate on the acceleration techniques. This paper aims to solve the problem by seeking for a tradeoff between the realistic effects and real time performance, to meet the needs from computer games.Physically based models have been popular in computer graphics community. The most significant contributions have been presented, which produce such perceivably realistic animations: Euler method, Lagrange method, Smoothed Particle Hydrodynamics, and etc.. We also make a connection to the simulation of other continua, such as fluid, crowd flow for completeness.This paper focuses on the study in two aspects:1. We proposed an approach based on Smoothed Particle Hydrodynamics to simulate fluids with free surfaces, while surface tension was modeled by using a Van der Waals equation of state with a combination of short-range repulsive and longer-range attractive interactions between fluid particles, finally designed a GPU-based particle splatting algorithm for rendering. This approach completely avoids the temporal discretization artifacts, which results in the interactive high quality rendering effects. In contrast to traditional Lagrangian approaches, this method uses the simplified surface tension model with fast rendering algorithm, reduces the complexity of the simulation and efficiently advances the run-time speed. Furthermore, the purpose of this study is to present a novel method for simulating middle- and small-scale details of incompressible viscous fluids and solid coupling. To animate the fluid model, the Smoothed Particle Hydrodynamics (SPH) method models the flow as a particle system in middle-scale, and based on it, the research focuses on the interaction between water and solid surface, especially the effects of absorption and adhesion. The absorption is simulated by absorption equations, and the adhesion is simulated by a linear spring and dashpot model, which can simulate the adhesive force. The proposed method works here to realistically animate the water gradually penetrating into the solid object, as well as some movements of runoff and flashing water. This new method thus improves existing fluid simulations, making them capable of generating new kinds of multi-scale interactions which have not realized in the present researches. Experimental results demonstrate that our method is satisfactory and is efficient enough to meet the demands of realistic and real time in computer game.2. Focused on the algorithm of the real-time crowd animation in large-scale and simulated the real-time dynamic scenario. Researched in the key techniques of real-time crowd animation, especially on how to enhance the effect of real-time simulation and rendering speed in very large-scale. This algorithm uses the global dynamic potential field to drive the crowd to move. Meanwhile, this model considers the factors of people's density, velocity, topography, and discomfort field. Our approach unifies global path planning and local collision avoidance into a single optimization framework. Our formulation is designed for groups with common goals, where each person's feature is different in the group. The system is implemented in the 2D environment. Moreover, we regard some intelligent behaviors of the crowd, such as collision avoidance, traffic simulation, topographical moving, and fire avoidance simulations, etc..