Utility snappyHexMesh refines background mesh in direction to the surface model. The set-up is read from system/snappyHexMeshDict:

castellatedMesh true;
snap            true;
addLayers       false;


// Geometry. Definition of all surfaces. All surfaces are of class
// searchableSurface.
// Surfaces are used
// - to specify refinement for any mesh cell intersecting it
// - to specify refinement for any mesh cell inside/outside/near
// - to 'snap' the mesh boundary to the surface
geometry
{
    RotorAMI1.stl { type triSurfaceMesh; name RotorAMI1; }
    RotorAMI2.stl { type triSurfaceMesh; name RotorAMI2; }
    RotorBlade.stl { type triSurfaceMesh; name RotorBlade; }
    RotorShroud.stl { type triSurfaceMesh; name RotorShroud; }
    RotorHub.stl { type triSurfaceMesh; name RotorHub; }
    RotorOut.stl { type triSurfaceMesh; name RotorOut; }

    RotorMXP_00.stl { type triSurfaceMesh; name RotorMXP00; }
    RotorMXP_01.stl { type triSurfaceMesh; name RotorMXP01; }
    RotorMXP_02.stl { type triSurfaceMesh; name RotorMXP02; }
    RotorMXP_03.stl { type triSurfaceMesh; name RotorMXP03; }
    RotorMXP_04.stl { type triSurfaceMesh; name RotorMXP04; }
    RotorMXP_05.stl { type triSurfaceMesh; name RotorMXP05; }
    RotorMXP_06.stl { type triSurfaceMesh; name RotorMXP06; }
    RotorMXP_07.stl { type triSurfaceMesh; name RotorMXP07; }
    RotorMXP_08.stl { type triSurfaceMesh; name RotorMXP08; }
    RotorMXP_09.stl { type triSurfaceMesh; name RotorMXP09; }
    RotorMXP_10.stl { type triSurfaceMesh; name RotorMXP10; }
    RotorMXP_11.stl { type triSurfaceMesh; name RotorMXP11; }
    RotorMXP_12.stl { type triSurfaceMesh; name RotorMXP12; }
    RotorMXP_13.stl { type triSurfaceMesh; name RotorMXP13; }
    RotorMXP_14.stl { type triSurfaceMesh; name RotorMXP14; }
    RotorMXP_15.stl { type triSurfaceMesh; name RotorMXP15; }
    RotorMXP_16.stl { type triSurfaceMesh; name RotorMXP16; }
    RotorMXP_17.stl { type triSurfaceMesh; name RotorMXP17; }
    RotorMXP_18.stl { type triSurfaceMesh; name RotorMXP18; }
    RotorMXP_19.stl { type triSurfaceMesh; name RotorMXP19; }
    RotorMXP_20.stl { type triSurfaceMesh; name RotorMXP20; }
    RotorMXP_21.stl { type triSurfaceMesh; name RotorMXP21; }
    RotorMXP_22.stl { type triSurfaceMesh; name RotorMXP22; }
    RotorMXP_23.stl { type triSurfaceMesh; name RotorMXP23; }
    RotorMXP_24.stl { type triSurfaceMesh; name RotorMXP24; }
    RotorMXP_25.stl { type triSurfaceMesh; name RotorMXP25; }
    RotorMXP_26.stl { type triSurfaceMesh; name RotorMXP26; }
    RotorMXP_27.stl { type triSurfaceMesh; name RotorMXP27; }
    RotorMXP_28.stl { type triSurfaceMesh; name RotorMXP28; }
    RotorMXP_29.stl { type triSurfaceMesh; name RotorMXP29; }
    RotorMXP_30.stl { type triSurfaceMesh; name RotorMXP30; }
    RotorMXP_31.stl { type triSurfaceMesh; name RotorMXP31; }
    RotorMXP_32.stl { type triSurfaceMesh; name RotorMXP32; }
    RotorMXP_33.stl { type triSurfaceMesh; name RotorMXP33; }
    RotorMXP_34.stl { type triSurfaceMesh; name RotorMXP34; }
    RotorMXP_35.stl { type triSurfaceMesh; name RotorMXP35; }
};



// Settings for the castellatedMesh generation.
castellatedMeshControls
{

    // Refinement parameters
    // ~~~~~~~~~~~~~~~~~~~~~

    // If local number of cells is >= maxLocalCells on any processor
    // switches from from refinement followed by balancing
    // (current method) to (weighted) balancing before refinement.
    maxLocalCells 1000000;

    // Overall cell limit (approximately). Refinement will stop immediately
    // upon reaching this number so a refinement level might not complete.
    // Note that this is the number of cells before removing the part which
    // is not 'visible' from the keepPoint. The final number of cells might
    // actually be a lot less.
    maxGlobalCells 10000000;

    // The surface refinement loop might spend lots of iterations refining just a
    // few cells. This setting will cause refinement to stop if <= minimumRefine // are selected for refinement. Note: it will at least do one iteration // (unless the number of cells to refine is 0) minRefinementCells 0; // Allow a certain level of imbalance during refining // (since balancing is quite expensive) // Expressed as fraction of perfect balance (= overall number of cells / // nProcs). 0=balance always. maxLoadUnbalance 0.10; // Number of buffer layers between different levels. // 1 means normal 2:1 refinement restriction, larger means slower // refinement. nCellsBetweenLevels 2; // Explicit feature edge refinement // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ // Specifies a level for any cell intersected by its edges. // This is a featureEdgeMesh, read from constant/triSurface for now. features ( { file "RotorBlade.eMesh"; level 0; } { file "RotorAMI1.eMesh"; level 0; } { file "RotorAMI2.eMesh"; level 0; } ); // Surface based refinement // ~~~~~~~~~~~~~~~~~~~~~~~~ // Specifies two levels for every surface. The first is the minimum level, // every cell intersecting a surface gets refined up to the minimum level. // The second level is the maximum level. Cells that 'see' multiple // intersections where the intersections make an // angle > resolveFeatureAngle get refined up to the maximum level.

    refinementSurfaces
    {
        "(RotorShroud|RotorHub)"
        {
            level (3 3);
        }
        "RotorOut"
        {
            level (1 3);
        }
        "RotorBlade"
        {
            level (3 4);
        }
        "RotorAMI.*"
        {
            level (3 3);
        }
        "RotorMXP.*"
        {
            level (4 4);
        }
    }

    // Resolve sharp angles
    resolveFeatureAngle 30;

Create the mesh running snappyHexMesh utility:

 snappyHexMesh

In order to reduce bandwidth and to speed up computation on the generated rotor mesh, it is convenient to use renumberMesh utility using following command:

 renumberMesh -latestTime

When finished, check the mesh running checkMesh and view the mesh in paraview:

 checkMesh
 paraFoam