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error: "problem setting up multigrid" upearing when the mesh is refined
Posted Jun 27, 2011, 5:46 a.m. EDT 1 Reply
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Hi,
I am carrying out a mesh refinement study on a lamiar flow model.
When I refine the mesh, I refine only a part of the mesh that is of most interest, while the rest stays in the same mesh size. (mesh elements gradually grow from the fine mesh to the coarser one). I do this by creating a fine free triangular mesh on some of the surfaces and then a free tetrahedral for the rest.
Ocasionally, I get an error: "problem setting up multigrid" when I run the simulation. While this occurs in certain geometries, there is no problem in geometries which are only slightly different.
sometimes, I can't even start runing the simulation because when I try to build the mesh I get an error: "The following features have problems. features- free tetrahedral 2"
Why does it happen? what can I do to overcome this problem?
Thanks,
Ramy
I am carrying out a mesh refinement study on a lamiar flow model.
When I refine the mesh, I refine only a part of the mesh that is of most interest, while the rest stays in the same mesh size. (mesh elements gradually grow from the fine mesh to the coarser one). I do this by creating a fine free triangular mesh on some of the surfaces and then a free tetrahedral for the rest.
Ocasionally, I get an error: "problem setting up multigrid" when I run the simulation. While this occurs in certain geometries, there is no problem in geometries which are only slightly different.
sometimes, I can't even start runing the simulation because when I try to build the mesh I get an error: "The following features have problems. features- free tetrahedral 2"
Why does it happen? what can I do to overcome this problem?
Thanks,
Ramy
1 Reply Last Post Jun 28, 2011, 10:41 a.m. EDT
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Posted:
1 decade ago
Hi,
Regarding the multigrid problem, you may want to go to Solver Configurations -> Solver -> Stationary Solver -> Iterative -> Multigrid and then change the 'Mesh coarsening factor' from 2 to a lower value, the multigrid meshes will be less coarse and they will not give you problems. As an 'extrema ratio' you may set a value of 1 or 1.1 even though that means that you are not using the multigrid tool at all but only the mesh you created.
Regarding the other problem it seems that you made some illicit operation while meshing, impossible to say without seeing the actual mesh.
Cheers
Regarding the multigrid problem, you may want to go to Solver Configurations -> Solver -> Stationary Solver -> Iterative -> Multigrid and then change the 'Mesh coarsening factor' from 2 to a lower value, the multigrid meshes will be less coarse and they will not give you problems. As an 'extrema ratio' you may set a value of 1 or 1.1 even though that means that you are not using the multigrid tool at all but only the mesh you created.
Regarding the other problem it seems that you made some illicit operation while meshing, impossible to say without seeing the actual mesh.
Cheers