chtMultiRegionSimpleFoam + incompressible thermo type

Taukiki · November 16, 2015, 09:56

Hello!

I'm new here and I hope I found the right forum for this topic. Please let me know if I should post my question somewhere else. And here we go:

I simulate a heat exchanger with water on the one and air on the other side. I know I can use chtMultiRegionSimpleFoam for that (that’s also what I’m doing right now) by setting water in the constants folder to incompressible. By doing so I use all the equations for compressible flow for water except that I set the density to constant. Now my question is:
Is it physically correct to do so? I mean, of course if I set the density to be constant the equations of conservation should become the same in the compressible and incompressible case, but is there something that I'm missing? I assume yes cause there must be a reason why for incompressible solvers like simpleFoam different equations are being used with a transport model (instead of a e.g. basicRhoThermo).
Does anybody have experience with this and knows if the error that I introduce by using chtMRSF that way is negligible?
Thak you so much for reading this post. I would be very grateful for some ideas

Best
Kiki

Taukiki · November 17, 2015, 04:41

Anyone? Or is the reason for the usage of different equation in the incompressible case that they are easyer to be solved?

Best
Kiki

vineet_bhola · November 17, 2015, 04:54

I don't have much experience into programming part of the solver but seems like this might help.

http://www.cfd-online.com/Forums/ope...egionfoam.html

Thanks
Vineet

user10600 · November 17, 2015, 04:57

Thank you Vineet, that was really helpful!

Cordialement.

Taukiki · November 17, 2015, 05:04

Thank you Guys. I know that threat but I found no answer to my question in that link.
Any ideas?

Kiki

shiromaniac · January 1, 2019, 00:15

Hey Taukiki,
I am also trying the same thing. It has been quite a while since you posted this question! I just wanted to ask whether you got any answer. Please respond it will be of great help!

November 16, 2015, 09:56	chtMultiRegionSimpleFoam + incompressible thermo type	#1
Taukiki New Member Join Date: Oct 2015 Posts: 5 Rep Power: 10	Hello! I'm new here and I hope I found the right forum for this topic. Please let me know if I should post my question somewhere else. And here we go: I simulate a heat exchanger with water on the one and air on the other side. I know I can use chtMultiRegionSimpleFoam for that (that’s also what I’m doing right now) by setting water in the constants folder to incompressible. By doing so I use all the equations for compressible flow for water except that I set the density to constant. Now my question is: Is it physically correct to do so? I mean, of course if I set the density to be constant the equations of conservation should become the same in the compressible and incompressible case, but is there something that I'm missing? I assume yes cause there must be a reason why for incompressible solvers like simpleFoam different equations are being used with a transport model (instead of a e.g. basicRhoThermo). Does anybody have experience with this and knows if the error that I introduce by using chtMRSF that way is negligible? Thak you so much for reading this post. I would be very grateful for some ideas Best Kiki shiromaniac likes this.

November 17, 2015, 04:54		#3
vineet_bhola Member Vineet Bhola Join Date: Jun 2015 Location: Chemnitz, Germany Posts: 49 Rep Power: 10	I don't have much experience into programming part of the solver but seems like this might help. http://www.cfd-online.com/Forums/ope...egionfoam.html Thanks Vineet user10600 likes this.

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November 17, 2015, 04:41		#2
Taukiki New Member Join Date: Oct 2015 Posts: 5 Rep Power: 10	Anyone? Or is the reason for the usage of different equation in the incompressible case that they are easyer to be solved? Best Kiki

November 17, 2015, 04:57		#4
user10600 New Member Join Date: Aug 2015 Posts: 17 Rep Power: 10	Thank you Vineet, that was really helpful! Cordialement.

November 17, 2015, 05:04		#5
Taukiki New Member Join Date: Oct 2015 Posts: 5 Rep Power: 10	Thank you Guys. I know that threat but I found no answer to my question in that link. Any ideas? Kiki

January 1, 2019, 00:15		#6
shiromaniac New Member Shiromani Chandra Join Date: Oct 2018 Location: India Posts: 12 Rep Power: 7	Hey Taukiki, I am also trying the same thing. It has been quite a while since you posted this question! I just wanted to ask whether you got any answer. Please respond it will be of great help!