Improvement In Efficient And Real-Time Smoke Simulation Based On Navier-Stokes Equation

The simulation of the natural phenomena is an important exploration field of computer graphics. It is a challenging research topic especially for such as smoke, clouds, fire, water and other irregular objects. With the rapid development of the related technology, the smoke simulated by computer is widely applied to special effects, video games, advertising and other areas. It can greatly enhance the realistic effect of the virtual scene. Based on a careful analysis of domestic and international experiments on smoke stimulation, this thesis chiefly focuses on the real-time and the realism of the smoke simulation. This study provides an in-depth examination and discussion with the emphasis of following aspects.Firstly, the real-time of the physically-based smoke simulation is not effective because of the complication in solving the Navier-Stokes equations. The nondimensional processing method is introduced to solve the Navier-Stokes equations. By analyzing physically-based equations with the dimensional analysis method, the correct relationship between various factors which affects the fluid flow is established as well as similar principles of the fluid flow. This study utilizes the nondimensional processing method to make the physical quantities in the Navier-Stokes equations nondimensional and to normalize the equations'form in order to simplify the Navier-Stokes equations'format and to reduce the time costs. Meanwhile, we use the GPU to accelerate the calculation and improve the real-time of the smoke simulation.Secondly, the real-time of the physically-based smoke simulation is not realistic and effective due to the complication in solving the Navier-Stokes equations. The point-based method is proposed to solve the advection item and the pressure item of the Navier-Stokes equations. We compute a Voronoi diagram to perform the pressure projection and to avoid the numerical dissipation used by the regular grids. The point-based method is proposed to solve the advection item of the Navier-Stokes equations in order to track thin features of the smoke and avoid the numerical dissipation associated with the semi-Lagrangian scheme, ultimately, improve the visual effect and meet the requirement of the real-time of the smoke simulation.Finally, by implementing VC++, OpenGL and Cg, a real-time smoke simulation system is designed and realized to validate the effectiveness of the methods proposed. Experimental results show that more realistic visual effects are obtained to meet the requirement for the realism and the real time of the smoke simulation.