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RBF motion solver implementation

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Old   March 12, 2015, 18:23
Default RBF motion solver implementation
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Hi all,

I am currently simulating a foil with sinusoidal pitching and heaving motion using dynamic mesh method. I am using Solid Body Rotation (SBR) Stress dynamic mesh motion solver, and I used the Laplacian dynamic mesh before as well. I was able to conduct the simulation and validate the results with the non-inertial reference frame method.

However, I would like to increase the mesh resolution of the current simulation, and both the SBR and Laplacian solvers are not robust enough, and mesh cells got too skewed. I would like to try the Radial Basis Function (RBF) motion solver and see whether it can cope with the large mesh cell deformation. I am looking into the tutorial and also source codes, but I am not sure quite what are the variables in the dynamicMeshDict refer to. Could someone show some insights or recommend some documentations?

I know there is the PhD thesis by Frank Bos, but it does not go into details about the implementation in OpenFOAM.

The following is the link to the tuturial case:
http://sourceforge.net/p/openfoam-ex...ovingBlockRBF/

The dynamicMeshDict is as follows:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM Extend Project: Open Source CFD        |
|  \\    /   O peration     | Version:  1.6-ext                               |
|   \\  /    A nd           | Web:      www.extend-project.de                 |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      dynamicMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dynamicFvMesh dynamicMotionSolverFvMesh;

solver RBFMotionSolver;

movingPatches ( block );

staticPatches ( left right top bottom );

coarseningRatio 5;

includeStaticPatches   no;
frozenInterpolation    yes;

interpolation
{
    RBF  IMQB;
    focalPoint (0 0 0);
    innerRadius 2.5;//5.0
    outerRadius 12.5;
    polynomials true;

    W2Coeffs
    {
        radius     1.0;
    }
    TPSCoeffs
    {
        radius     5.0;
    }
    GaussCoeffs
    {
        radius     0.1;
    }
    IMQBCoeffs
    {
        radius     0.001;
    }
}


// ************************************************************************* //
Thank you very much!

Last edited by wyldckat; April 3, 2015 at 13:25. Reason: Added [CODE][/CODE]
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Old   April 3, 2015, 13:30
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Quick answer:
  • This indicates the function used for the Radial Basis algorithm:
    Code:
    RBF  IMQB;
  • The respective coefficients used for this option "IMQB":
    Code:
        IMQBCoeffs
        {
            radius     0.001;
        }
  • These control the range of effect of the radial algorithm.
    Code:
        focalPoint (0 0 0);
        innerRadius 2.5;//5.0
        outerRadius 12.5;
Beyond this, I strongly suggest you do what is usually the way to learn how to use OpenFOAM: use a simple test case and try changing the values, one at a time.

In addition, have a look at the latest version, which is foam-extend 3.1.
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