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Anisotropic Diffusion

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Hi,

I have a 2D geometry in which I want to define anisotropic diffusion. When I select this option in the menu and solve the problem I get weird results. When I check again the options, 'anisotropic diffusion' has been automatically changed to 'Diagonal' and I think this is what is causing the problem.


Any suggestion is much appreciated


2 Replies Last Post 9 lug 2013, 09:22 GMT-4
Nagi Elabbasi Facebook Reality Labs

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Posted: 1 decade ago 9 lug 2013, 08:12 GMT-4
Dear Borja,

I have seen this before, it does not cause problems. If you select anisotropic diffusion but provide constants that are only diagonal COMSOL automatically does that switch. Similarly if you put off-diagonal terms symmetrically then COMSOL switches to symmetric.

Nagi Elabbasi
Veryst Engineering
Dear Borja, I have seen this before, it does not cause problems. If you select anisotropic diffusion but provide constants that are only diagonal COMSOL automatically does that switch. Similarly if you put off-diagonal terms symmetrically then COMSOL switches to symmetric. Nagi Elabbasi Veryst Engineering

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Posted: 1 decade ago 9 lug 2013, 09:22 GMT-4
Thanks for the answer.

You are right, that seems to work fine when I solve the diffusion equation in my particle with a constant concentration boundary condition. However, when I couple this, via flux term, with a convection diffusion equation to solve for the macroscopic concentration in a packed bed, the concentration profile does not make sense.

Borja
Thanks for the answer. You are right, that seems to work fine when I solve the diffusion equation in my particle with a constant concentration boundary condition. However, when I couple this, via flux term, with a convection diffusion equation to solve for the macroscopic concentration in a packed bed, the concentration profile does not make sense. Borja

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