Real-time Simulation Algorithm Of The Motion Of A Rigid Object With Smoke

Fluid like smoke plays a pivotal role in the natural scene. Smoke simulation which based on the physics has also been a hot and difficult field in computer graphics and virtual reality research. In most of the previous studies, the real sense and the real time simulation of smoke are considered in confined space, while changing the smoke generated in real time to follow the moving object is still little involved. In the smoke dynamic tracking, we need to access position of moving object in real time. The algorithm involves the acquisition and conversion of each frame data, and the high complexity. The direction of moving objects changes randomly making smoke speed if not timely updates, to cause delays in visual and other issues, which will cause smoke to follow the movement complicated and diversely. To solve these problems, we propose a method for smoke dynamic tracking.Firstly, according to the hydrodynamics equation named N-S equation, the smoke physical model is established, through the analysis of the demand of smoke dynamic tracking, considering the influence of air resistance on movement of smoke, according to the experimental curve Nikuradse we establish the air resistance model.Secondly, the adaptive grid field is constructed, introducing the boundary box to cover the grid area, the 3D Euler gird structure is redefined. By means of the algorithm passing of the center data of the moving object and grid field, we can capture the center of the object and the adaptive grid field in real time, and they can be converted in the acceptable deviation.Third, through the analysis of the direction of movement such as rotating vector method, put the movement of the object in the direction of the smoke, we establish the force field analysis equation to update the thermal buoyancy, and solve the direction of the smoke through the influence of the thermal buoyancy factor effectively, to solve the direction of smoke tracking.Then, for solving complex problems of partial differential equations, the finite difference method is used to solve the N-S equation. We adopt Mac Cormack method to solve the advection item. In addition, considering the high efficiency of GPU parallelism, by properly handing the thread number and the gird area, the thread group is used to handle all kinds of computing, so that we can improved the real-time performance.Finally, using the Unity engine platform, combined with C# language and shader rendering, the simulation of smoke dynamic tracking is designed and implemented. Experiments show that this method can realize the smoke dynamic tracking under the complex rigid objects in real time.