chtMultiRegionSimpleFoam for forced convection.

granzer · August 29, 2021, 03:21

Hello,
I have read that chtMultiRegionSimpleFoam is a blend of buoyantsimplefoam and laplacefoam. I don't see any problem...but still wanted to confirm this can be used for forced convection as well as natural convection problem? Also, is there a blend of rhosimplefoam and laplacefoam?

piu58 · August 29, 2021, 05:02

I experimented with buoyantsimplefoam a while ago. Results for free convection are great and agreed with theoretical results.
I was never happy with combination of forced and free convection. Mosty, at some edge a region of unnatural high velocity occurred which captured all of the region until the case exploded.

My be, another combination of schemes and solvers, together with relaxation may cure this. All in all I felt it is not a stable case for this solver.

granzer · August 29, 2021, 08:30

Quote:

Originally Posted by piu58

I experimented with buoyantsimplefoam a while ago. Results for free convection are great and agreed with theoretical results.
I was never happy with combination of forced and free convection. Mosty, at some edge a region of unnatural high velocity occurred which captured all of the region until the case exploded.

My be, another combination of schemes and solvers, together with relaxation may cure this. All in all I felt it is not a stable case for this solver.

Thank you. Which CHT solver do you think is good for forced convection?

piu58 · August 29, 2021, 14:53

The most used and most time-tested solver is pimpleFoam. But you cannot take free convection into account with that.
I solution could be that you run two simulations and decide which type of convection influences the boundary layer most. There are some regions, of course, where both appear. You have to think about a method of blending them.

granzer · August 29, 2021, 22:29

Quote:

Originally Posted by piu58

The most used and most time-tested solver is pimpleFoam. But you cannot take free convection into account with that.
I solution could be that you run two simulations and decide which type of convection influences the boundary layer most. There are some regions, of course, where both appear. You have to think about a method of blending them.

I want to run multiregion case so are you suggesting chtMultiregionFoam but switching from PISO to pimple?

August 29, 2021, 03:21	chtMultiRegionSimpleFoam for forced convection.	#1
granzer Senior Member Mandeep Shetty Join Date: Apr 2016 Posts: 185 Rep Power: 10	Hello, I have read that chtMultiRegionSimpleFoam is a blend of buoyantsimplefoam and laplacefoam. I don't see any problem...but still wanted to confirm this can be used for forced convection as well as natural convection problem? Also, is there a blend of rhosimplefoam and laplacefoam?

August 29, 2021, 05:02		#2
piu58 Senior Member Uwe Pilz Join Date: Feb 2017 Location: Leipzig, Germany Posts: 744 Rep Power: 15	I experimented with buoyantsimplefoam a while ago. Results for free convection are great and agreed with theoretical results. I was never happy with combination of forced and free convection. Mosty, at some edge a region of unnatural high velocity occurred which captured all of the region until the case exploded. My be, another combination of schemes and solvers, together with relaxation may cure this. All in all I felt it is not a stable case for this solver. granzer and saidc. like this. __________________ Uwe Pilz -- Die der Hauptbewegung überlagerte Schwankungsbewegung ist in ihren Einzelheiten so hoffnungslos kompliziert, daß ihre theoretische Berechnung aussichtslos erscheint. (Hermann Schlichting, 1950)

August 29, 2021, 14:53		#4
piu58 Senior Member Uwe Pilz Join Date: Feb 2017 Location: Leipzig, Germany Posts: 744 Rep Power: 15	The most used and most time-tested solver is pimpleFoam. But you cannot take free convection into account with that. I solution could be that you run two simulations and decide which type of convection influences the boundary layer most. There are some regions, of course, where both appear. You have to think about a method of blending them. granzer likes this. __________________ Uwe Pilz -- Die der Hauptbewegung überlagerte Schwankungsbewegung ist in ihren Einzelheiten so hoffnungslos kompliziert, daß ihre theoretische Berechnung aussichtslos erscheint. (Hermann Schlichting, 1950)

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