CFD Online Logo CFD Online URL
Home > Forums > OpenFOAM Running, Solving & CFD

moveDynamicMesh - bad cells after motion

Register Blogs Members List Search Today's Posts Mark Forums Read

LinkBack Thread Tools Display Modes
Old   December 8, 2014, 07:46
Default moveDynamicMesh - bad cells after motion
Petr Furmanek
Join Date: Jan 2012
Location: Prague, Czech Republic
Posts: 60
Rep Power: 5
petr.f. is on a distinguished road
Nice Monday afternoon to all!

Recently I've run into a problem with moveDynamicMesh. I'd like to perform a simple flutter analysis with openfoam. I'm using the standard NACA 0012 profile, which is attached to en elastic axis EA (i.e. in 2D it is a point located on the profiles chord) and can oscillate around this axis and vibrate in vertical direction.
In order to place the profile into right initial position (e.g. Alpha_init = 3, h_init = -0.01m) I'm using moveDynamicMesh solver and mesh created with GridPro. With this mesh I can perform steady simulations without any problem (the only error checkMesh reports are highAspectRatio cells, which is normal. However, if I add prescribed motion it always ends with many bad cells (no matter what time-step or tolerance parameters I use)

Checking geometry...
    Overall domain bounding box (-2.69997 -3 0) (1.5 3 0.015)
    Mesh (non-empty, non-wedge) directions (1 1 0)
    Mesh (non-empty) directions (1 1 0)
    All edges aligned with or perpendicular to non-empty directions.
    Boundary openness (-1.83973e-18 1.14303e-19 7.89943e-15) OK.
 ***High aspect ratio cells found, Max aspect ratio: 1265.93, number of cells 6
  <<Writing 6 cells with high aspect ratio to set highAspectRatioCells
    Minimum face area = 3.73703e-09. Maximum face area = 0.00237795.  Face area magnitudes OK.
 ***Zero or negative cell volume detected.  Minimum negative volume: -2.45686e-09, Number of negative volume cells: 5
  <<Writing 5 zero volume cells to set zeroVolumeCells
    Mesh non-orthogonality Max: 179.673 average: 7.00679
   *Number of severely non-orthogonal (> 70 degrees) faces: 83.
 ***Number of non-orthogonality errors: 9.
  <<Writing 92 non-orthogonal faces to set nonOrthoFaces
 ***Error in face pyramids: 28 faces are incorrectly oriented.
  <<Writing 24 faces with incorrect orientation to set wrongOrientedFaces
    Max skewness = 0.92386 OK.
    Coupled point location match (average 0) OK.

Failed 4 mesh checks.
Problematic cells are located on and behind the trailing edge. The motion itself is prescribed in a standard way using the pointDisplacement file in 0 directory

         type            fixedValue;
         value           uniform (0 0 0);
        type            angularOscillatingDisplacement;
        axis            (0 0 1);
        origin          (0.12 0 0.0075);
        angle0          0;
        amplitude       -0.05235987755983; //rad
        omega           3.14159; //rad/s
        value           uniform (0 0 0);

        type empty;

dynamicMeshDict in the constant directory

dynamicFvMesh      dynamicMotionSolverFvMesh;

motionSolverLibs ("");

solver displacementLaplacian;
// solver velocityComponentLaplacian z;

    diffusivity quadratic inverseDistance 1(wing);
and this solver for point motion in the fvSolution

        solver          GAMG;
        tolerance       1e-5;
        relTol          0.0;
        smoother        DICGaussSeidel;
        cacheAgglomeration true;
        nCellsInCoarsestLevel 10;
        agglomerator    faceAreaPair;
        mergeLevels     1;
Do you have any idea, what am I doing wrong or how to move the profile without obtaining errors?
Attached Images
File Type: jpg mesh_time0.0_1.jpg (37.9 KB, 12 views)
File Type: jpg mesh_time0.5_1.jpg (37.9 KB, 10 views)
File Type: png mesh_time0.5_treilingEdge_1.png (51.6 KB, 13 views)
petr.f. is offline   Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
snappyhexmesh remove blockmesh geometry philipp1 OpenFOAM Running, Solving & CFD 2 December 12, 2014 11:58
Moving mesh Niklas Wikstrom (Wikstrom) OpenFOAM Running, Solving & CFD 122 June 15, 2014 06:20
snappyHexMesh won't work - zeros everywhere! sc298 OpenFOAM Native Meshers: snappyHexMesh and Others 2 March 27, 2011 21:11
Problems of Duns Codes! Martin J Main CFD Forum 8 August 14, 2003 23:19
Adding cells during mesh motion Serkan Cetin CD-adapco 1 December 23, 2002 04:22

All times are GMT -4. The time now is 09:42.