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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 The information provided may be out of date.

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initial value set-up

Posted 2013年1月24日 GMT-5 11:41 Parameters, Variables, & Functions, Results & Visualization, Studies & Solvers Version 4.2 3 Replies

Jifeng Hu
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Hi,


I have a 2D simulation running from T=0 to T=100. First, I run the simulation from T=0 to T= 50. Then I want to use the solution at T=50 plus some value changes in specific domain as the initial value for my simulation from T=50 to T=100.
Can anyone help me out?

Another simple question is: can I find the solution value of variable PIP at T= 50 by PIP(t=50)? if not, how can I reference the variable at specific time point and/or spatial points as well?

Thanks in advance,

John
3 Replies Last Post 2013年1月25日 GMT-5 00:19
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 2013年1月24日 GMT-5 15:13
Hi

you need to set up the solver node setting for thesecond study step to use the initial conditions from the first study. This is (in the most recent version) done under one of the tabs of the main study node, while earlier it was on the "dependent variable" subnode in the solver tree. here you can define separately where the initial values are taken from, for dependent and unsolved variables

--
Good luck
Ivar
Hi you need to set up the solver node setting for thesecond study step to use the initial conditions from the first study. This is (in the most recent version) done under one of the tabs of the main study node, while earlier it was on the "dependent variable" subnode in the solver tree. here you can define separately where the initial values are taken from, for dependent and unsolved variables -- Good luck Ivar
Jifeng Hu
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Posted: 1 decade ago 2013年1月24日 GMT-5 16:16
Hi Ivar,

Thank you for your suggestion. Howver, I want the initial value for the second study is the last time point from the first study PLUS some changes. So how to add these changes to the last time point from the first study? Let's say I want the initial value of 2nd study to be the half of the last time point of 1st study?

Thank you,
John
Hi Ivar, Thank you for your suggestion. Howver, I want the initial value for the second study is the last time point from the first study PLUS some changes. So how to add these changes to the last time point from the first study? Let's say I want the initial value of 2nd study to be the half of the last time point of 1st study? Thank you, John
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 2013年1月25日 GMT-5 00:19
Hi

that you cannot easily, anyhow what if "half the stress" ? the stress tensor components are far from linearly dependent,

but you can refer directly to previous values or, to a given point (parameter value) if you have done a previous parametric sweep, then you can get the corresponding value at param = 0.5 if this one was stored so with some care you might get where you want

--
Good luck
Ivar
Hi that you cannot easily, anyhow what if "half the stress" ? the stress tensor components are far from linearly dependent, but you can refer directly to previous values or, to a given point (parameter value) if you have done a previous parametric sweep, then you can get the corresponding value at param = 0.5 if this one was stored so with some care you might get where you want -- Good luck Ivar

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