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Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

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Memory Error

Posted 26.02.2013, 05:42 GMT-5 Heat Transfer & Phase Change, Geometry, Mesh Version 4.3a 1 Reply

Lele, Dipl.-Phys. & Msc.
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Hi everyone,
When computing recently a 3D geometry with conjugate heat transfer module, I got this error:

"Failed to find a solution.
Out of memory during LU factorization.
Returned solution is not converged."

Please what does it means? And how to solve this kind of error.
Thanks in advance for your answer.
--
A. Fopah Lele

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1 Reply Last Post 26.02.2013, 09:28 GMT-5
Josh Thomas Certified Consultant
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Posted: 1 decade ago 26.02.2013, 09:28 GMT-5
Well, this means you need more RAM on your system if you are going to solve the problem as is. Required RAM for solving is directly related to the number of degrees of freedom you are solving for which is directly related to how fine of a mesh you are using and how many physics variables you are solving for (amongst other things).

A couple suggestions for overcoming this error:

1) Decrease mesh resolution -- fewer elements means fewer degrees of freedom
2) Consider if your model has symmetry then reduce your geometry and apply symmetry boundary conditions
3) Switch from a Direct solver to an Iterative solver -- Direct solvers use more RAM

Hopefully at least one of these tricks will be the answer for you.

Best regards,
Josh Thomas
AltaSim Technologies
Well, this means you need more RAM on your system if you are going to solve the problem as is. Required RAM for solving is directly related to the number of degrees of freedom you are solving for which is directly related to how fine of a mesh you are using and how many physics variables you are solving for (amongst other things). A couple suggestions for overcoming this error: 1) Decrease mesh resolution -- fewer elements means fewer degrees of freedom 2) Consider if your model has symmetry then reduce your geometry and apply symmetry boundary conditions 3) Switch from a Direct solver to an Iterative solver -- Direct solvers use more RAM Hopefully at least one of these tricks will be the answer for you. Best regards, Josh Thomas AltaSim Technologies

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