CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   OpenFOAM Running, Solving & CFD (http://www.cfd-online.com/Forums/openfoam-solving/)

 Lucas January 5, 2011 22:18

Convergence Problem icoFoam steady flow over an airfoil

Hi everyone,

I am trying to simulate steady flow over an airfoil and I'm having problems converging to the solution with icoFoam.

I'm using a ICEM mesh that i exported to fluent format (msh) and converted with
fluentMesh3DToFoam:

I am working with a comparation between OpenFOAM and CFX,
but i am new at OF.

The utility checkMesh set Mesh OK.

This is my case:

Thank you.

 Lucas January 6, 2011 09:49

I tried this morning some changes in the fvschemes fvsolution
I also tried to run in simpleFoam

and i got this:

Code:

``` Time = 52 Lookup gradScheme for grad(U) Lookup divScheme for div((nuEff*dev(grad(U).T()))) Lookup laplacianScheme for laplacian(nuEff,U) Lookup fluxRequired for U Lookup gradScheme for snGradCorr(U) Lookup gradScheme for snGradCorr(U) Lookup gradScheme for snGradCorr(U) Lookup divScheme for div(phi,U) Find relax for U Lookup relaxationFactor for U Lookup gradScheme for grad(p)     From function solution::solverDict(const word&)     in file matrices/solution/solution.C at line 241     Lookup solver for U smoothSolver:  Solving for Ux, Initial residual = 0.0237871, Final residual = 0.000128133, No Iterations 1 smoothSolver:  Solving for Uy, Initial residual = 0.317853, Final residual = 0.00208853, No Iterations 1 smoothSolver:  Solving for Uz, Initial residual = 8.9633e-05, Final residual = 4.39538e-07, No Iterations 1 Lookup interpolationScheme for interpolate(U) --> FOAM FATAL ERROR: Continuity error cannot be removed by adjusting the outflow. Please check the velocity boundary conditions and/or run potentialFoam to initialise the outflow. Total flux              : 3.36963e+38 Specified mass inflow  : 1.60459e+38 Specified mass outflow  : 0 Adjustable mass outflow : 4.20186e+20     From function adjustPhi(surfaceScalarField& phi, const volVectorField& U,const volScalarField& p     in file cfdTools/general/adjustPhi/adjustPhi.C at line 115. FOAM exiting```
hear is my system files:

Code:

```/*--------------------------------*- C++ -*----------------------------------*\ | =========                |                                                | | \\      /  F ield        | OpenFOAM: The Open Source CFD Toolbox          | |  \\    /  O peration    | Version:  1.7.1                                | |  \\  /    A nd          | Web:      www.OpenFOAM.com                      | |    \\/    M anipulation  |                                                | \*---------------------------------------------------------------------------*/ FoamFile {     version    2.0;     format      ascii;     class      dictionary;     location    "system";     object      controlDict; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // application    simpleFoam;  //  which solver (for documentation) startFrom      startTime;              //  firstTime, startTime, latestTime startTime      0;                      //  set > 0 to continue stopAt          endTime;                //  writeNow, endTime, nextWrite, ... endTime        600;                    //  Latest timestep allowed deltaT          1;                      //  simple counter for steadyState writeControl    adjustableRunTime;      //  or uncommon: cpuTime, clockTime writeInterval  50;                    //  time step write interval purgeWrite      0;                      //  1 recycles time steps storage                                         //  0 keeps all time steps on disk writeFormat    ascii;                  //  ascii: readable, binary: smaller writePrecision  6;                      //  precision for ascii format writeCompression uncompressed;          //  compressed for gzipped files timeFormat      general;                //  fixed, scientific or general timePrecision  6;                      //  precision for time handling runTimeModifiable yes;                  //  yes: OF reads dictionaries each                                         //  time step graphFormat    raw;                    //  raw, gnuplot, xmgr, jplot //libs()        for user libraries, p.e. user boundary conditions //functions()  for special functions```
Code:

```/*--------------------------------*- C++ -*----------------------------------*\ | =========                |                                                | | \\      /  F ield        | OpenFOAM: The Open Source CFD Toolbox          | |  \\    /  O peration    | Version:  1.7.1                                | |  \\  /    A nd          | Web:      www.OpenFOAM.com                      | |    \\/    M anipulation  |                                                | \*---------------------------------------------------------------------------*/ FoamFile {     version    2.0;     format      ascii;     class      dictionary;     location    "system";     object      fvSchemes; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // ddtSchemes {     default        steadyState; } gradSchemes {     default        Gauss linear;     grad(p)        faceLimited leastSquares 0 1;     grad(U)        Gauss linear; } divSchemes {     default        none;     div(phi,U)      Gauss upwind;     div(phi,nuTilda) Gauss linearUpwind Gauss linear;     div((nuEff*dev(grad(U).T()))) Gauss linear; } laplacianSchemes {     default        none;     laplacian(nuEff,U) Gauss linear limited 0.7;     laplacian((1|A(U)),p) Gauss linear limited 0.7;     laplacian(DnuTildaEff,nuTilda) Gauss linear corrected;     laplacian(1,p)  Gauss linear corrected; } interpolationSchemes {     default        linear;     interpolate(U)  linear; } snGradSchemes {     default        limited 0.7; } fluxRequired {     default        no;     p              ; } // ************************************************************************* //```
Code:

```/*--------------------------------*- C++ -*----------------------------------*\ | =========                |                                                | | \\      /  F ield        | OpenFOAM: The Open Source CFD Toolbox          | |  \\    /  O peration    | Version:  1.7.1                                | |  \\  /    A nd          | Web:      www.OpenFOAM.com                      | |    \\/    M anipulation  |                                                | \*---------------------------------------------------------------------------*/ FoamFile {     version    2.0;     format      ascii;     class      dictionary;     location    "system";     object      fvSolution; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // solvers {     p     {         solver          GAMG;         tolerance      1e-07;         relTol          0.001;         smoother        GaussSeidel;         nPreSweeps      1;         nPostSweeps    2;         cacheAgglomeration true;         nCellsInCoarsestLevel 500;         agglomerator    faceAreaPair;         mergeLevels    1;     }     U     {         solver          smoothSolver;         smoother        GaussSeidel;         nSweeps        2;         tolerance      1e-08;         relTol          0.01;     nSweeps        1;              // setting for smoothSolver         maxIter        100;            // limitation of iterations number     }     nuTilda     {         solver          smoothSolver;         smoother        GaussSeidel;         nSweeps        2;         tolerance      1e-08;         relTol          0.1;     } } SIMPLE {     nNonOrthogonalCorrectors 6;     convergence        1e-5;     pRefCell        0;     pRefValue      0; } relaxationFactors {     default        0;     p              0.003;     U              0.007;     nuTilda        0.007; } // ************************************************************************* //```

 tcarrigan January 6, 2011 12:08

default cellLimited leastSquares 1.0;

For the divSchemes try:
div(phi,U) Gauss linearUpwindV Gauss linear;
div(phi,nuTilda) Gauss upwind;

For pressure solver:
p GAMG tolerance 1e-8 and relTol 0

For other solvers:
PBiCG using DILU preconditioner with tolerances 1e-8 and relTol 0 rather than using smoothSolver

Try also dropping the nNonOrthogonalCorrectors down to 2, and increase the relaxation factors:
p 0.2
U 0.5
nuTilda 0.5

 Lucas January 10, 2011 15:24

thanks for your reply, but the problem was the mesh, i changed the mesh and
everything works fine.

 billynoe February 17, 2011 18:24

Quote:
 Originally Posted by Lucas (Post 289911) thanks for your reply, but the problem was the mesh, i changed the mesh and everything works fine.
what did you change in your mesh? smaller cell sizes?

 Lucas February 18, 2011 13:46

In fact i made a complete new mesh, because the last was horrible, with high number of non-orthogonal cells.

 All times are GMT -4. The time now is 00:51.