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"Nonsymmetric matrix found" error and meshing

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Hello,

1 - I'm simulating a Newtonian incompressible fluid flow in a porous medium (medium formed by 1000 solid grains). For a mesh of 124816 elements, the computation runs normally and I get results. But when I refine the mesh, I get the error message (Nonsymmetric matrix found) and solver stops working.
Do you have any idea of ​​the origin of this error?

2 - Can you please tell me how can I generate a structured mesh or a mesh of hexahedral elements for the geometry of the model here attached.

Thank you.

Mehrez Agnaou


1 Reply Last Post 22 févr. 2013, 13:41 UTC−5
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 22 févr. 2013, 13:41 UTC−5
Hi

I'm not by my WS so I cannot open your model, but a non-symmetric matrix could come from too poor mesh quality, and that imposes far more RAM as each matrix double their RAM reuirement, hence possible RAM overflow...

For random porosity, I do not know hoe to make any structure mesh, I would say standard "teth" is better as it should become more evenly distributed

--
Good luck
Ivar
Hi I'm not by my WS so I cannot open your model, but a non-symmetric matrix could come from too poor mesh quality, and that imposes far more RAM as each matrix double their RAM reuirement, hence possible RAM overflow... For random porosity, I do not know hoe to make any structure mesh, I would say standard "teth" is better as it should become more evenly distributed -- Good luck Ivar

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