A multispecies,multispeeds lattice Boltzmann model is presented to study the mass diffusion properties.The diffusion equations are derived by the Chapman-Enskog method.The one dimensional simulations for the sinusoidal concentration distributions are compared with the theoretical results,showing good agreement.The numerical simulations for 2-D convection diffusion problems are also presented.

A new reconstruction method for the difference of primitive function derivation is developed on structure meshes.Such a scheme is based on a finite volume discretization.It achieves 3-order spatial accuracy with upwind compact difference.Numerical experiment of transonic channel flow is presented and discussed.

A method based on Bowyer Watson algorithm is used for generation of unstructured grid. The density of grid is controlled by solving Poission Equations. The Strategy of grid improves the quality of body fitting. The viscous grid is accomplished by combining the O-type in viscous zone and normal grid in other zones.

A new hybrid finite volume method for the numerical simulation of oldroyd B fluid flows is presented.As main features of this method,the technique of Chorin s pseudo compressibility is used to solve the 3-D steady incompressible continuity equation and momentum equations and the streamline upwinding approach is used to discretize the constitutive equations.The method has dealt with a sudden contractions viscoelastic flow problem for a range of Weissenberg numbers.Numerical results obtained are in good qualitative agreement with existing exprimental ones.

One kind of Generalized Finite Element Method-Taylor-Galerkin has been improved on convergences of velocity and stability.Using the improved method two dimensional transonic flow in turbomachinery is studied.Numerical results compared with that of experiment exhibit the advantages of this method.

This paper presents two schemes for solving three-dimensional Euler equations. These schemes are:(1)an efficient implicit-explicit scheme. It is used to treat the spanwise derivatives explicitly and the orther spatial derivatives implicitly, (2) an improved LU scheme for 3D flow. The two schemes are presented based on Jameson Turkel's LU decompositions and Harten's TVD concept. Numerical results indicate that these schemes are efficient and can generate good shock resolution for solving steady-state problem.

A lower-upper implicit scheme is developed for the unsteady Euler equations. The scheme requires only two sweeps through the grid and it is unconditionally stable. Each factor represents an algebraic system which is either lower block diagonal or upperblock diagonal and hence the name LU. Inversion of such systems is relatively simple and efficient. A nonlinear multigrid algorithm,full approximation storage (FAS),is combined with LU implicit scheme to produce a rapidlyconvergent algorithm for calculating steady-state solutions of the Euler equations.

A new improved Strongly Implicit Procedure is presented for solving the large sets of equations with matrix of coefficients A in fluid mechanics.This algorithm has several advantages over those now in use.First,auxiliary matrix à is symmetric and matrix A+à is positive definite and symmetric matrix when A is symmetric.This ensures the numerical stability of the iterative algorithms.Second,for an appropriate choice of iterative parameter ω,the rate of convergence of the new iterative procedure should be faster than original SIP scheme.Numerical results of two dimensional flows are given with the scheme. It is shown that the algorithm is very efficient.