Optimization Research On The Simulation Of Smoke In The Fluctuating Wind Field

The simulation of natural phenomena such as smoke, has been one of the most challenging research areas in computer graphics. The smoke image generated by traditional particle system and the texture mapping is poor and can hardly meet the requirements of high authenticity. As extensive research in fluid dynamics has been done, physically based method has been widely used to simulate smoke. It analyses the inherent physical characteristics of the smoke, and establishes an accurate physical model to obtain the realistic smoke. We adopt the physical method to simulate the smoke, and focus on our researches on the real-time and the reality of the simulation.Firstly, in order to improve the real-time quality, we use non-viscous incompressible Navier-Stokes equations to establish the physical model of the smoke, solve physical equations by the finite difference method and GPU acceleration, discrete the computational domain, and simplify the basic physics equations to reduce the computational time. In addition, we adopt MacCormack method to solve the advection item of the Navier-Stokes equation, so as to reduce the solving steps of traditional methods, improve the computational speed and ensure the solving processes are unconditional stable.Secondly, for the purpose of improving the authentic performance, we introduce the role of wind field, so that the shape and movement of the smoke will be more realistic and natural. We use optimized Karman spectrum to establish cross-spectral density matrix of the wind field, then introduce Proper Orthogonal Decomposition(POD) technique for solving the matrix, and then calculate the fluctuating wind velocity in the frequency domain space by the Fast Fourier Transform(FFT). Finally, the wind fields are considered as the outside forces to be added into the physical equations of the smoke, so the interaction of the fluctuating wind and the smoke is realized.Thirdly, the gravity, thermal buoyancy and vorticity confinement force, which greatly affect the smoke's movement, are added into the smoke field, to improve the details and the reality of the smoke's movement. Moreover, we also consider that the smoke's density and temperature changes with the velocity field, to ensure the smoke's gravity and buoyancy are calculated accurately.Finally, in order to verify our improved smoke simulation algorithms, we use the VC++ language and Open Graphics Library to design the real-time smoke simulation system. Experiment results show: our algorithms can run in real-time and the smoke effects are of great reality and nature in the turbulent wind environment.