Flood Simulation Based On Outdoor Environment

Fluid simulation and large-scale crowd behavior simulation have been the emphasis and difficulty of computer graphics, after large amounts of data analysis and study, researchers have put forward a variety of theories and algorithms. In this thesis,the fluid simulation and large scale crowd behavior simulation are combined to study the technology of large-scale crowd simulation in flood environment. We drawing on the current commonly used theoretical results, and made some improvements on the basis of previous work, To improve the validity and to reduce the computation cost as far as possible, we have carried out a large number of experiments with constantly summing up and continuous improvement. Good balance is achieved in the authenticity and computational cost.The main work of this thesis has been divided into two aspects of fluid simulation and behavior simulation, the innovation of this thesis include: In behavior modeling, we have proposed a dynamic grouping method which is close to the reality. In path planning, we have put forward a remote test algorithm to detect the collision between gents which make the collision avoidance become more natural. The specific work of this thesis includes the following contents:1. Two commonly used methods of fluid motion are described in this thesis, the Eulerian method and the Lagrange method. We have adopted the most comprehensive and the most commonly used method at present for describing the fluid motion which is the Navier-Stokes equations, then we have derived and analyzed the equation. In order to solve the N-S equation, we need discretize the fluid domain into grids. In this thesis,we choose an Eulerian discretization.2. We have adopted a fluid-solid coupling equation to calculate the velocity of fluid and solid after researching the technology of fluid-solid interaction. We need to determine whether a given boundary mesh of the fluid domain contains a solid cell before the interaction, and we also need to know the solid’s velocity for cells on the boundary. We use voxelization to do this. The voxelization is divided into an“inside-outside” voxelization and velocity voxelization in this thesis. In the process of fluid-solid coupling, we also need to set the boundary conditions, To do this, we use the free sliding boundary conditions to deal with the boundary conditions.3. After studying of crowd behaviors in real life and the previous authoritative work, we have summarized that the crowd behavior not only show individuality but also exist commonness in normal circumstances and dangerous environment. In order to model the crowd behavior, we use the Vi Crowd model and make some improvements and perfection on it. We have proposed a dynamic grouping scheme, and comprehensively considered various factors which have influence on agent speed.4. In path planning, we have used the potential field strategy. Based on the potential field scheme, we have dealt with the potential filed produced by fluid separately and proposed a remote test scheme to detect the collision, making the collision avoidance between agents become more natural.Based on these research work above, we have implemented the flood simulation system for outdoor environment, and given analysis and summary about experimental results. Finally, we pointed out the aspect which still need to be improved and made arrangements for the further work.