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Problem calculating the residual of momentum eq. in a dynamically changing mesh

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Old   September 26, 2015, 11:35
Default Problem calculating the residual of momentum eq. in a dynamically changing mesh
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I am trying to do some programming in OF and I need some help. I have added to the pimpleDyMFoam solver the calculation of some kind of residual of the momentum equation (I attach the corresponding file, also I am working with OF 2.4.0) lines 134-160. In the problem at hand, the code also make a dynamic refinement of the mesh at each time step (I have use dynamicMeshDict to do it). The thing is:

1) I have first tested the coding of the calculation of the residual on a simpler case with a fix mesh in icoFoam and it works.
2)When I run the case with the dynamic mesh refinement, the field uResidual is created but when I try to visualize the solution with paraFoam I get the following error:

p, li { white-space: pre-wrap; } ERROR: In /build/buildd/paraview-4.0.1/VTK/IO/Geometry/vtkOpenFOAMReader.cxx, line 6584
vtkOpenFOAMReaderPrivate (0x27de4a0): Number of cells/points in mesh and field don't match: mesh = 5960, field = 6002

Then I think that I am missing some detail between the calculation of the uResidual with the dynamic mesh. Does anyone could give me a clue of what I am doing wrong?

Thank you very much for your time.
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File Type: c scalarPimpleDyMFoam.C (5.0 KB, 14 views)
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Old   October 2, 2015, 15:07
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Kyle Mooney
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Hi towanda,

The issue here is that you're writing out your residual field at a different frequency as the rest of the case (other fields + mesh).

Because you're adding dynamic refinement the mesh is changing (i.e. addiing/removing cells) but you're not writing out the mesh along with the residual field. Thus the size of the field you're writing out doesn't match the size of the latest mesh you're writing out. Manual .write() calls can be troublesome with dynamic mesh cases.

If you remove

and have the field write out normally via setting AUTO_WRITE in the IO constructor like this:

        volScalarField uResidual
                  + fvc::div(phi, U)
		  - fvc::laplacian(nuEff,U)	
                  + fvc::grad(p)
it should resolve your problem.

good luck!
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Old   October 2, 2015, 16:58
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Hello Kyle,
Thanks for the answer, you are right I was writing the outputs at different times, it works now. I also solved the problem by using the runTime.outputTime() function and I get the same result.

Info<<"ESCRIBE: "<<runTime.value()<<endl;

Thank you very much indeed for your time.
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