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to avoid inverted mesh elements

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In 2D, how to avoid inverted mesh elements? Would triangular or rectangular meshing matter?


8 Replies Last Post Dec 26, 2021, 9:45 a.m. EST
Robert Koslover Certified Consultant

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Posted: 2 years ago Dec 5, 2021, 9:42 p.m. EST

This usually is due to a problematic geometry. If you can, edit your geometry to specify all the boundaries, inside and out, without any extremely thin pieces or nearly-tangent lines, etc. Consider posting your model (.mph file) to the forum if you want more specific help.

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Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
This *usually* is due to a problematic geometry. If you can, edit your geometry to specify all the boundaries, inside and out, without any extremely thin pieces or nearly-tangent lines, etc. Consider posting your model (.mph file) to the forum if you want more specific help.

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Posted: 2 years ago Dec 7, 2021, 3:26 a.m. EST

Thanks Dr Koslover, all I use is just a domain of a square. Is that a poor geometry?

Thanks Dr Koslover, all I use is just a domain of a square. Is that a poor geometry?

Edgar J. Kaiser Certified Consultant

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Posted: 2 years ago Dec 7, 2021, 5:26 a.m. EST

Hm, a square gives you inverted elements?

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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Hm, a square gives you inverted elements?

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Posted: 2 years ago Dec 8, 2021, 3:16 a.m. EST

at least as far as what the warning message says, though a glance of the deformed square doesn't show obvious inverted elements

at least as far as what the warning message says, though a glance of the deformed square doesn't show obvious inverted elements

Robert Koslover Certified Consultant

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Posted: 2 years ago Dec 8, 2021, 10:52 a.m. EST

I suggest you post your model (the .mph file) to the forum.

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Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
I suggest you post your model (the .mph file) to the forum.

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Posted: 2 years ago Dec 20, 2021, 4:43 a.m. EST

Most strangely, the warning suggest inverted elements near coordinate (1e5,1e5) while the domain size is only about 1*1.

Most strangely, the warning suggest inverted elements near coordinate (1e5,1e5) while the domain size is only about 1*1.

Henrik Sönnerlind COMSOL Employee

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Posted: 2 years ago Dec 20, 2021, 4:38 p.m. EST

I assume that this happens during solution, and not in the initial configuration.

It seems that you have an ill-posed problem where, for example, a solid mechanics model 'blows up'. Such problems are, for example, common with some hyperelastic models that are not unconditionally stable. For an even more common and unexpected case, see the section about linear elasticity under geometric nonlinearity in https://www.comsol.com/blogs/modeling-linear-elastic-materials-how-difficult-can-it-be/ .

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Henrik Sönnerlind
COMSOL
I assume that this happens during solution, and not in the initial configuration. It seems that you have an ill-posed problem where, for example, a solid mechanics model 'blows up'. Such problems are, for example, common with some hyperelastic models that are not unconditionally stable. For an even more common and unexpected case, see the section about linear elasticity under geometric nonlinearity in .

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Posted: 2 years ago Dec 26, 2021, 9:45 a.m. EST
Updated: 2 years ago Dec 26, 2021, 9:45 a.m. EST

I assume that this happens during solution, and not in the initial configuration.

It seems that you have an ill-posed problem where, for example, a solid mechanics model 'blows up'. Such problems are, for example, common with some hyperelastic models that are not unconditionally stable. For an even more common and unexpected case, see the section about linear elasticity under geometric nonlinearity in .

Thank you! However, though the warning suggests inverted elements near coordinate (1e5,1e5), the domain (1*1) after the computation looks normal in shape rather than sth that blows up and the whole computation is completed without error messages.

>I assume that this happens during solution, and not in the initial configuration. > >It seems that you have an ill-posed problem where, for example, a solid mechanics model 'blows up'. Such problems are, for example, common with some hyperelastic models that are not unconditionally stable. For an even more common and unexpected case, see the section about linear elasticity under geometric nonlinearity in . Thank you! However, though the **warning** suggests inverted elements near coordinate (1e5,1e5), the domain (1*1) after the computation looks normal in shape rather than sth that blows up and the whole computation is completed without **error** messages.

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