[flowwwww]

Hello everyone.
I am working in a rectangular duct geometry. At the inlet, the duct has rectangular holes where the fluid pass through.
Captura de pantalla de 2019-12-02 15-21-09.png


I am stuggling with the mesh at the rectangular holes area. The rectangular figure get lost when i snap the mesh so i obtain a bad mesh there.
Here i attach the results of the castellated mesh and the snaped mesh.

Captura de pantalla de 2019-12-02 15-20-06.png CASTELLATED MESH
Captura de pantalla de 2019-12-02 15-20-31.png SNAP MESH




My snappyHexMeshDict is the following.

castellatedMesh true;
snap            true;
addLayers       false;



geometry
{
    walls.stl
    {
        type triSurfaceMesh;
        name walls;
    }

    inlet.stl
    {
        type triSurfaceMesh;
        name inlet;
    }


castellatedMeshControls
{
    maxLocalCells 100000;
    maxGlobalCells 2000000;
    minRefinementCells 10;
    maxLoadUnbalance 0.10;
    nCellsBetweenLevels 3;
    features
    (

        {
            file "walls.eMesh";
            level 3;
        }
    refinementSurfaces
    {
        walls
        {
            level (3 3);
            patchInfo
            {
                type wall;
                inGroups (walls);
            }
        }
        inlet
        {
            level (3 3);
            patchInfo
            {
                type patch;
                inGroups (inlet);
            }
       }
    resolveFeatureAngle 30;
    locationInMesh (4.0 2.0 0.5);
    allowFreeStandingZoneFaces true;


snapControls
{
    nSmoothPatch 10;
    tolerance 1.0;
    nSolveIter 100;
    nRelaxIter 10;

    // Feature snapping
        nFeatureSnapIter 35;
        implicitFeatureSnap false;
        explicitFeatureSnap true;
        multiRegionFeatureSnap false;
}


meshQualityControls
{
    maxNonOrtho 90;
    maxBoundarySkewness 20;
    maxInternalSkewness 4;
    maxConcave 80;
    minVol -1e30;
    minTetQuality 1e-30;
    minArea -1;
    minTwist 0.02;
    minDeterminant 0.001;
    minFaceWeight 0.02;
    minVolRatio 0.01;
    minTriangleTwist -1;

    // Advanced
    nSmoothScale 4;
    errorReduction 0.75;
}


// Advanced
debug 0;
mergeTolerance 1e-6;