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Accessing the motionU matrix in OF ver 14

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Old   April 16, 2007, 14:03
Default Hello, I recently upgraded
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Philippose Rajan
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I recently upgraded to OpenFOAM ver.1.4, but noticed that the tetDecompositionMotionSolver does not exist anymore. (I had read that this was being replaced by the finite Volume based motion solvers "fvMotionSolver")

In the tutorial for "icoDyMFoam", the changes required seem to be quite trivial....I did not see any change to the icoDyMFoam solver itself.

My question is, now that "tetPointVectorField" does not exist anymore, what can I do to modify the motionU matrix? Will it be a "volVectorField" like the velocity matrix?

And also, do I need to include any new header files or libraries when compiling a solver which needs to modify the motionU matrix? Or can I just remove the "tetFemMatrices.H" and "tetPointFields.H" and redefine the motionU matrix as a "volVectorField"?

The other question is.... in the tutorial, there are two files in the "0" folder... "pointMotionUx" and "cellMotionUx", which are of type "pointScalarField" and "volScalarField" (I assume they are scalars because they only define the "X" direction of the velocity).

Both the files have exactly the same boundary conditions.... What was the intention of having a separate file for the point motion and for the cell motion? Do I always need to define both these files?

Is it right, that when I have a 3D case, these files would be "pointMotionU" and "cellMotionU", with "pointVectorField" and "volVectorField" as the types?

I am sorry if that was an overload of questions :-)! Just thought I should get the solver I have been working on (turbForceFoam) working in the latest version of OpenFOAM.

Have a nice day!

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Old   April 16, 2007, 16:53
Default I'm not sure why this would ge
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Hrvoje Jasak
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I'm not sure why this would get removed - probably because noone at OpenCFD could support it (they had nothing to do with it + the copyright does not belong to them). In any case, the cell-based diffusion equation which "replaces it" is so pathetically useless that I have abandoned it more than 10 years ago in 1996. Since all of the tet decomposition mesh motion is a perfectly working code and necessary for anything but trivial mesh motion (e.g. engines), I will sort out the updates when the work gets re-based. This will also include all the mesh motion bug fixes that may or may not have made it.

In the meantime I would suggest sticking with the updated 1.3 version for another week or two.

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Old   April 16, 2007, 18:16
Default Hello Hrv, Well :-) Must sa
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Philippose Rajan
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Hello Hrv,

Well :-) Must say... that was not the reply I was expecting to see :-)! But interesting nevertheless!

Just to confirm whether I have really understood what you meant.... do you mean to say, that the following statement in the OpenFOAM 1.4 release notes:

"- Flexible and efficient finite volume based mesh motion solvers (replacing the finite element mesh motion solvers)."

is not necessarily true in all cases? Or to put it in another manner... the tetDecompositionMotionSolver which works on the concept of a hybrid FEM / FVM technique is better than the "fvMotionSolvers" in the current version 1.4?

In that case, maybe I should wait for your next release before jumping in to converting my code to work with OpenFOAM 1.4.

I guess in the meantime I can continue using the latest Development release of OF 1.3 you made available a week ago.

Would you be interested in telling me why the FEM method is better than the method used in OF 1.4 or would that be me once again sticking my neck into too much theory :-)!?

Thanks for your response and have a nice day!


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