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Time Derivative Only Allowed With Respect To Mesh Time

Posted Apr 5, 2021, 10:14 a.m. EDT 4 Replies

Vedant Joshi
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I am trying to use 2-phase darcy law with deformed geometry model. The moving boundary is inside the domain and I have a boundary condition on that boundary itself. The above error arises when I try to compute the solution. Can anyone plz suggest how to convert d(XXX,t) to d(XXX,TIME)?

4 Replies Last Post Apr 6, 2021, 1:16 p.m. EDT
Robert Koslover Certified Consultant
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Posted: 4 years ago Apr 5, 2021, 10:44 a.m. EDT

I don't claim to understand your problem, but it sounds like maybe you want to access, dynamically during the time-domain computations, the value of a quantity that has been computed at a different (earlier) time in the model? If that is what you are saying, then you may find it useful to take a look at Comsol's "withsol" operator. See the help system for more about that. If that is not what you are asking about, then... nevermind.
:)

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Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
I don't claim to understand your problem, but it sounds like *maybe* you want to access, dynamically during the time-domain computations, the value of a quantity that has been computed at a different (earlier) time in the model? If that is what you are saying, then you may find it useful to take a look at Comsol's "**withsol**" operator. See the help system for more about that. If that is not what you are asking about, then... nevermind. :)
Vedant Joshi
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Posted: 4 years ago Apr 5, 2021, 12:15 p.m. EDT
Updated: 4 years ago Apr 5, 2021, 12:16 p.m. EDT

Hi,

Thanks for your reply Sir. I just wanted to know how to troubleshoot the error "Time Derivative Only Allowed With Respect To Mesh Time". I read a few replies on the discussion forum mentioning about conversion of d(XXX,t) to d(XXX,TIME) (i.e. conversion from time derivative toderivative w.rt. mesh time). None of the replies specified how exactly the above conversion can be done. Any help regarding the same would be helpful.

Thanks

Hi, Thanks for your reply Sir. I just wanted to know how to troubleshoot the error "Time Derivative Only Allowed With Respect To Mesh Time". I read a few replies on the discussion forum mentioning about conversion of d(XXX,t) to d(XXX,TIME) (i.e. conversion from time derivative toderivative w.rt. mesh time). None of the replies specified how exactly the above conversion can be done. Any help regarding the same would be helpful. Thanks
Edgar J. Kaiser Certified Consultant
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Posted: 4 years ago Apr 5, 2021, 12:40 p.m. EDT

I guess you opened a model from an older version in 5.5. In case you are using expressions like d(xxx, t) in your own settings just replace t by TIME. Otherwise check the equation view of the physics nodes for something like d(xxx, t) and replace t by TIME as well. You may need to activate equation view in the preferences.

Cheers Edgar

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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
I guess you opened a model from an older version in 5.5. In case you are using expressions like d(xxx, t) in your own settings just replace t by TIME. Otherwise check the equation view of the physics nodes for something like d(xxx, t) and replace t by TIME as well. You may need to activate equation view in the preferences. Cheers Edgar
Vedant Joshi
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Posted: 4 years ago Apr 6, 2021, 1:16 p.m. EDT

Hi Edgar,

Thank you very much. It worked.

Hi Edgar, Thank you very much. It worked.

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