We describe a problem that the multifluid dynamic equations are not closed.To solve equations,they must be closed.Existing closing relations are analyzed and an adaptive closing relation method according to sound velocity is given.Numerical example shows that pressure relaxation is also important for pressure equalization in mixed cells.

By using explicit saturation and implicit concentration methods,numerical solution is presented to the polymer drive model characterizing dispersion and adsorption of polymer solution flowing through a porous medium.Saturation equation is solved by using an explicit total variation diminishing(TVD)method.To ensure the stability of concentration equation calculation,Crank-Nicolson difference format is used in spatial discretization,and variable is quasi-linear disposed in temporal discretization.The validity of the method presented is verified by comparison with analytic solutions.The calculated example indicates that dispersion causes dilution and dissipation of polymer solutions,and adsorption results in a loss,thus leading to lagging of concentration propagation.Also,the important polymer flooding mechanism- "oil block" is illustrated in the results of calculation.Under the condition of slug injection,the breakthrough time of oil enrichment zone lies between the breakthrough time of polymer concentration front and polymer concentration peak.

Based upon the horizontal displacements data in-situ in the top of concrete gravity dam, the parameter identification problem is done with the regularizing least squares method for the elastic modulus of the concrete gravite dam. The iterative format and selecting algorithm of the regularizing parameters are set up. It is also put forward to identify material physical properties according to the priori information. The practical use of the parameter identification algorithm proposed shows that this algorithm has fast convergence speed and good stability.

In this paper, we present a new interpolation formula of algebraic multigrid (AM G). The AMG algorithm with this formula can solve many problems, even very ill-conditioned problems like biharmonic equation and convection-diffusion equation with discontinuous coefficient etc. The theoretical analysis and numerical experiments demonstrate that this formula is very robust and efficient, so we have extended the application range of AMG.