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Use previous time step solution in a function

Posted Sep 17, 2010, 3:30 a.m. EDT 2 Replies

Sébastien Janas
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Hi all,

I want to build an external function solving some stuff by finite differences. I need to give the solution of the previous time step to my function. Do you know how to get these solution in COMSOL ? Is there something like Ut or Ux for the time or space derivative of U ?

I will also need the value of the time step.

I know I can do this using Matlab scripting, but the Matlab API is very very slow, so useless for optimization purpose.

Thanks a lot for your help !

Sébastien
2 Replies Last Post Dec 3, 2010, 1:35 a.m. EST
COMSOL Moderator

Hello Sébastien Janas

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If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base.

Ivan Gruber
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Posted: 1 decade ago Dec 2, 2010, 3:22 p.m. EST
Hi,

I am wondering if you were able to solve the problem?

Ivan
Hi, I am wondering if you were able to solve the problem? Ivan
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Dec 3, 2010, 1:35 a.m. EST
Hi

check the 4.1 doc on the operator at(), with(), prev() and d(,)

there are a few threads on the Forum on different simple tricks how to get time derivatives for PDEs too

--
Good luck
Ivar
Hi check the 4.1 doc on the operator at(), with(), prev() and d(,) there are a few threads on the Forum on different simple tricks how to get time derivatives for PDEs too -- Good luck Ivar

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