HIGH ACCURATE SOLUTION OF INCOMPRESSIBLE VISCOUS FLOW WITH PRIMATIVE VARIABLE

This paper presents a higher order difference scheme for the computationof the incompressible viscous flows.The discretization of the two-dimensional incompress-ible viscous Navier-Stokes equations,in generalized curvilinear coordinates and tensor for-mulation,is based on a non-ataggered grid.The momentum equations are integrated intime using the four-stage explicit Runge-Kutta algorithm [1]and discretized in space us-ing the fourth-order accurate compact scheme[2]The pressure-Poisson equation is dis-cretized using the nine-point compact scheme.In order to satisfy the continuity constraintand ensure the smoothness of pressure field,an optimum procedure to derive a discretepressure equation is proposed [9][3]The method is applied to calculate the driven cavityflow on a stretched grid with the Reynolds numbers from 100 to 10000.The numerical re-sults are in very good agreement with the results obtained by Ghia et al [7]and includethe periodic solutions for high Reynolds numbers.     

BLOCK ITERATIVE METHODS FOR LINEAR ALGEBRAIC EQUATION AND DOMAIN DECOMPOSITION METHOD FOR INCOMPRESSIBLE VISCOUS FLOW

It was proved numerically that the Domain Decomposition Method (DDM) with one layer overlapping grids is identical to the block iterative method of linear algebra equations. The results obtained using DDM could be in reasonable aggeement with the results of full-domain simulation. With the three dimensional solver developed by the authors, the flow field in a pipe was simulated using the full-domain DDM with one layer overlapping grids and with patched grids respectively. Both of the two cases led to the convergent solution. Further research shows the superiority of the DDM with one layer overlapping grids to the DDM with patched grids. A comparison between the numerical results obtained by the authors and the experimental results given by Enayet[3] shows that the numerical results are reasonable.     

AN ALE METHOD AND DDM WITH HIGH ACCURATE COMPACT SCHEMES FOR VORTEX-INDUCED VIBRATIONS OF AN ELASTIC CIRCULAR CYLINDER

A numerical study was conducted for the vortex-induced vibrations of an elastic circular cylinder at low Reynolds numbers. An Arbitrary Lagrangian-Eulerian (ALE) method was employed to deal with the fluid-structure interaction with an H-O type of non-staggered grids incorporating the domain decomposition method(DDM), which could save the computational CPU time due to re-meshing. The computational domain was divided into nine sub-domains including one ALE sub-domain and eight Eulerian sub-domains. The convection term and dissipation term in the N-S equations were discretized using the third-order upwind compact scheme and the fourth-order central compact scheme, respectively. The motion of the cylinder was modeled by a spring-damper-mass system and solved using the Runge-Kutta method. By simulating the non-linear fluid-structure interaction, the “lock-in”,“beating” and “phase switch” phenomena were successfully captured, and the results agree with experimental data. Furthermore, the vortex structure, the unsteady lift and drag on the cylinder, and the cylinder displacement at various natural frequency of the cylinder for Re 200 were discussed in detail,by which a jump transition of the wake structure was captured.     

NUMERICAL STUDY OF FLOW PAST AN AXISYMMETRIC BODY WITH A RING WING AT VARIOUS ATTACK ANGLES

1 .　INTRODUCTIONFortraditionalbody fittedgridsystemusedtocomputetheflow pasttheaxisymmetricbody ,thesingularityonthelongitudinalaxisisalongstand ingobstacle .Rationalsolutionishardtobeachievedevenwithfinemeshesgeneratedwithinthevicinityofthelongitudinalaxis .Hence ,appro priategridsystemisreguiredtoavoidthesingulari ty .Extensivenumericalexperimentsareconductedtoobtainthedesired gridsysteminthis paper .BasedontheideaofDDM[1] ,theoriginalflowfieldofthebodyisdividedinto 8sub domainsac cor…     

NUMERICAL SIMULATION FOR 2D SHALLOW WATER EQUATIONS BY USING GODUNOV-TYPE SCHEME WITH UNSTRUCTURED MESH

1. INTRODUCTION In general, the geometry of natural water areas, such as rivers, coasts and lakes, is irregular, so that the application of mathematical models with structured mesh is quite limited and the accuracy could not be ensured especially as the m…     

2-D FLOW AND SEDIMENT SIMULATION FOR THE FLOOD REGULATION OF A RESERVOIR WITH WATER INTAKE

In this paper, the flood regulation by operating the downstream sluice gates for a reservoir with a water intake is studied. The two-dimensional depth-averaged flow equations are solved by the boundary fitted finite volume method (FVM) based on MacCormsck prediction-correction scheme. The bed deformation caused by both the bed load and incoming suspended sediment is determined in a coupled way. The model is used to simulate the practical flood regulation operation of a reservoir. The results have been compared with the physical experiment.