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Dear. Ivar

Posted Feb 12, 2012, 9:39 p.m. EST Version 4.2 1 Reply

JiYoung Park
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Hi,

I want to simulate moving material in natural convection condition.

Therfore, I added Fluid-matter interaction and Conjugate heat transfer modules.

I got error messages "Failed to find consistent initial values.Last time step is not converged."

Can you give me an idea ?

THanks!


1 Reply Last Post Feb 13, 2012, 1:33 a.m. EST
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Feb 13, 2012, 1:33 a.m. EST
Hi

You know, when you hadd multiphysics, the complexity goes rather as n^n and not 1+1=2. You should always sketch out your model by defining individual physics, their degrees of freedom and dependent variables, AND their interactions. then when you select the physics in COMSOl check the Dependent variables. If you mix FSI + NITF oyu are doubling up the dependent variables, which will make a mess out of your model, as you need to define several BC twice. So first select just once the number and type of dependent variables.

Then you nbeed to ensure that you have defined enough BC to geet a unique solution PER PHYSICS, + that you have all cross links (interactions) between the physics correctly set up.

My best guess is that you have missed at least one, and that you have duplicated dependent variables ;)

--
Good luck
Ivar
Hi You know, when you hadd multiphysics, the complexity goes rather as n^n and not 1+1=2. You should always sketch out your model by defining individual physics, their degrees of freedom and dependent variables, AND their interactions. then when you select the physics in COMSOl check the Dependent variables. If you mix FSI + NITF oyu are doubling up the dependent variables, which will make a mess out of your model, as you need to define several BC twice. So first select just once the number and type of dependent variables. Then you nbeed to ensure that you have defined enough BC to geet a unique solution PER PHYSICS, + that you have all cross links (interactions) between the physics correctly set up. My best guess is that you have missed at least one, and that you have duplicated dependent variables ;) -- Good luck Ivar

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