Problem in using chtMultiRegionFoam for steady-state

mep · May 3, 2021, 12:09

Hello all,

A physical problem occurs when I am configuring chtMultiRegionFoam as steady-state. Previous releases of OpenFOAM had included chtMultiRegionSimpleFoam for steady problems before OpenFOAM foundation merged transient and steady solver.
My problem is that even if it is not a transient case, the behaviour of my model is quite similar to transient due to higher diffusion number. I have three bodies where one of them is placed for conduction and other two are for both convection and conduction. Because of the relatively larger volume of region for conduction heat tranfer, convergence delays enormously.
The question, therefore, is about whether I can modify this problem so that it satisfies a quick convergence? Else, is it possible to integrate chtMultiRegionSimpleFoam in OF v8?

Thanks a lot for your replies.

Zeppo · May 4, 2021, 05:59

Very slow convergence might be attributed to the fact that cht solver in question can only solve multiregion problems in segregated way, region by region, which makes solving a problem with lots of regions very annoying. Steady version will not resolve your issue.

mep · May 6, 2021, 10:36

Quote:

Originally Posted by Zeppo

Very slow convergence might be attributed to the fact that cht solver in question can only solve multiregion problems in segregated way, region by region, which makes solving a problem with lots of regions very annoying. Steady version will not resolve your issue.

Thank you for your reply, Zeppo. Then, my question is to be evolved. I would like to set Pseudo transient approach to reach steady-state condition faster. I have attempted many times but have not accomplished yet. Is it not embedded in chtMultiRegionFoam solver in OF?

olesen · May 6, 2021, 14:23

Just for this reason there is possibility to add additional cycles for the temperature equation. Can't remember exactly, but I think it went into the 1706 or 1712 release.

Zeppo · May 16, 2021, 10:42

Alternatively, you can go for foam-extend version which offers coupled solver.

May 3, 2021, 12:09	Problem in using chtMultiRegionFoam for steady-state	#1
mep New Member Muhammed Emin POLAT Join Date: Sep 2020 Posts: 7 Rep Power: 5	Hello all, A physical problem occurs when I am configuring chtMultiRegionFoam as steady-state. Previous releases of OpenFOAM had included chtMultiRegionSimpleFoam for steady problems before OpenFOAM foundation merged transient and steady solver. My problem is that even if it is not a transient case, the behaviour of my model is quite similar to transient due to higher diffusion number. I have three bodies where one of them is placed for conduction and other two are for both convection and conduction. Because of the relatively larger volume of region for conduction heat tranfer, convergence delays enormously. The question, therefore, is about whether I can modify this problem so that it satisfies a quick convergence? Else, is it possible to integrate chtMultiRegionSimpleFoam in OF v8? Thanks a lot for your replies.

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May 4, 2021, 05:59		#2
Zeppo Senior Member Sergei Join Date: Dec 2009 Posts: 261 Rep Power: 21	Very slow convergence might be attributed to the fact that cht solver in question can only solve multiregion problems in segregated way, region by region, which makes solving a problem with lots of regions very annoying. Steady version will not resolve your issue.

May 6, 2021, 14:23		#4
olesen Senior Member Mark Olesen Join Date: Mar 2009 Location: https://olesenm.github.io/ Posts: 1,684 Rep Power: 40	Just for this reason there is possibility to add additional cycles for the temperature equation. Can't remember exactly, but I think it went into the 1706 or 1712 release.

May 16, 2021, 10:42		#5
Zeppo Senior Member Sergei Join Date: Dec 2009 Posts: 261 Rep Power: 21	Alternatively, you can go for foam-extend version which offers coupled solver.