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difference between segregated and fully coupled solver comsol

Posted Sep 1, 2012, 2:17 p.m. EDT Studies & Solvers Version 4.2, Version 4.2a, Version 4.3 2 Replies

Rui Silva
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Hi folks,

I am trying to understand the advantages of each of these solvers, and when to use or the other.

I looked through the docs but I am left with the same doubts.

Can anyone point out the main differences and pros/cons of these solvers, and perhaps the iterative solvers, also.

Thanks.

Cheers!

R.Silva
2 Replies Last Post Sep 2, 2012, 6:08 p.m. EDT
Pu
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Posted: 1 decade ago Sep 2, 2012, 5:11 a.m. EDT
Basically segregated solver is based on iteration. As for how it iterates it's well explained in the documentation.
Basically segregated solver is based on iteration. As for how it iterates it's well explained in the documentation.
Nagi Elabbasi Facebook Reality Labs
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Posted: 1 decade ago Sep 2, 2012, 6:08 p.m. EDT
Actually both the segregated and couple fully coupled solvers require iterations for nonlinear problems. They both also can use direct or iterative linear solvers. The main difference is that the fully coupled solver operates on the full Jacobian matrix as one entity. The segregated solver splits the Jacobian matrix into smaller sub-problems, usually by degree of freedom type. Different solution strategies can then be used for each sub-problem. The optimal choice between segregated and fully coupled as well as the optimal segregation technique is problem specific. COMSOL has done a great job in my opinion with their default solver selections.

The fully coupled solver generally requires less iterations but takes up more memory and solution time per iteration. This statement is based on my experience and I realize it has many exceptions.

Nagi Elabbasi
Veryst Engineering
Actually both the segregated and couple fully coupled solvers require iterations for nonlinear problems. They both also can use direct or iterative linear solvers. The main difference is that the fully coupled solver operates on the full Jacobian matrix as one entity. The segregated solver splits the Jacobian matrix into smaller sub-problems, usually by degree of freedom type. Different solution strategies can then be used for each sub-problem. The optimal choice between segregated and fully coupled as well as the optimal segregation technique is problem specific. COMSOL has done a great job in my opinion with their default solver selections. The fully coupled solver generally requires less iterations but takes up more memory and solution time per iteration. This statement is based on my experience and I realize it has many exceptions. Nagi Elabbasi Veryst Engineering

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