A stochastic method is used to predict wind noise of a simplified automobile head shape. In the method, computational region is divided into two parts: One is source region, and the other is propagation region. In the source region, turbulent fluctuation velocities are synthesized with a stochastic model. In the propagation region, linearized Euler equations with source terms are solved and sound waves spread out. Compared with direct simulation method, the method has advantage of less computational cost and memory. Numerical simulations agree well with experimental data. It is shown that the method is feasible for automobile wind noise prediction, It laid a foundation for actual automobile shape wind noise prediction.

Simulation of trailing edge noise based on stochastic noise generation and radiation(SNGR)method is shown.The SNGR method combines stochastic method with computational fluid dynamics,which gives acceptable noise result with relatively low computation cost.Reynolds averaged Navier-Stokes(BANS)equations arc solved by finite volume method.Acoustic perturbation equations are Bolved by finite difference method.Numerical scheme is a dispersion-relation-preserving(DRP)scheme.Non-reflection far.field boundary eonditions are utilized.A two.dimensional flat plate and an NACA0012 airfoil are simulated and compared with reference results.It is shown that the program predicts correctly trailing edge noise.

With Lennard-Jones interaction potentials a GSS-3 molecular model is proposed to study transport properties of gas,such as coefficient of viscosity,self-diffusion and diffusion of molecules.The model is applied to unstructured direct simulation Monte Carlo method.Numerical results confirm feasibility of the model.

A compressible large eddy simulation (LES) technique based on a highly efficient and well validated finite volume,multigrid driven method is developed.The Jameson's central scheme with second and fourth order artificial dissipation is used for space discretization and dual time methodology is implemented for time marching.The subgrid scale stress tensor and the subgrid scale heat flux are simulated with Smagorinsky model.A typical simulation of isotropic turbulence decay is performed to verify the accuracy and efficiency of this method.The simulated time evolution of energy spectra and decay of the resolved turbulence kinetic energy are in good agreement with the filtered experimental CBC data.

The multigrid method is applied in the unstructured grid. The coarse mesh is obtained by the "agglomerated" method. The Jamson's finite volume method is used for the calculation of the flow. Compared with the single mesh, the unstructured multigrid algorithm can accelerate the convergence and can improve the calculation efficiency, and the CPU time is largely reduced. The two-dimensional and three-dimensional numerical examples are presented.