chtMultiRegionSimpleFoam problem

cfdsolver1 · October 3, 2016, 10:59

Hello everyone. I am struggling with chtMultiRegionSimpleFoam recent days and I need someone help. I am trying to solve fluid-solid multi region problem, steady state and incompressible. Which boundary conditions do I need to set at fluid-solid interface(mappedWall)? For instance, for pressure, whatever I select except from uniform value, solver fails with the famous error starts with

Code:

#0  Foam::error::printStack(Foam::Ostream&)

If my problem was not multi-region, I would set fixedFluxPressure boundary condition at walls. If I set it for multi-region, it fails. I have checked all the tutorials and that problems are not suitable for my case.

For temperature, I want k1*dT2/dn = k2*dT2/dn. I found that

Code:

compressible::turbulentTemperatureCoupledBaffleMixed

can be a good option but I am not sure, if this is good or not for incompressible problem. I think I can not create a pressure difference between inlet and outlet due to my boundary conditions I guess, so I have nearly zero velocity after a threshold point.

I am open to any suggestions of yours for inlet, outlet and interface boundary conditions for pressure and temperature for chtMultiRegionSimpleFoam.

Bloerb · October 4, 2016, 01:46

the compressible tag is because the solver is compressible. When you choose rhoConst in your thermoPhysicalProperties file it solves incompressible. Hence, this boundary works for incompressible cases as well. You can choose the same boundaries as you would for any other case with only one region. chtmultiregion is essentially two (or more) solvers executed one after another. The only coupling is done by boundary conditions. And the only boundary you can couple by default is the temperature field.

Your problem is not in the fixedFluxPressure on your walls but somewhere deeper.

cfdsolver1 · October 4, 2016, 03:08

Dear Bloerb, thanks for your answer. As I know, fixedFluxPressure is evaluated as gradP = (PhihbyA - Phi) / (Sf*Dp). So, when I try to apply this BC, I think Sf or Dp is zero, so it fails. What do you think? How can I solve this problem, if this is my problem? By introducing baffles?

October 3, 2016, 10:59	chtMultiRegionSimpleFoam problem	#1
cfdsolver1 Member Join Date: Jul 2013 Posts: 39 Rep Power: 12	Hello everyone. I am struggling with chtMultiRegionSimpleFoam recent days and I need someone help. I am trying to solve fluid-solid multi region problem, steady state and incompressible. Which boundary conditions do I need to set at fluid-solid interface(mappedWall)? For instance, for pressure, whatever I select except from uniform value, solver fails with the famous error starts with Code: #0 Foam::error::printStack(Foam::Ostream&) If my problem was not multi-region, I would set fixedFluxPressure boundary condition at walls. If I set it for multi-region, it fails. I have checked all the tutorials and that problems are not suitable for my case. For temperature, I want k1dT2/dn = k2dT2/dn. I found that Code: compressible::turbulentTemperatureCoupledBaffleMixed can be a good option but I am not sure, if this is good or not for incompressible problem. I think I can not create a pressure difference between inlet and outlet due to my boundary conditions I guess, so I have nearly zero velocity after a threshold point. I am open to any suggestions of yours for inlet, outlet and interface boundary conditions for pressure and temperature for chtMultiRegionSimpleFoam.

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October 4, 2016, 01:46		#2
Bloerb Senior Member Join Date: Sep 2013 Posts: 353 Rep Power: 20	the compressible tag is because the solver is compressible. When you choose rhoConst in your thermoPhysicalProperties file it solves incompressible. Hence, this boundary works for incompressible cases as well. You can choose the same boundaries as you would for any other case with only one region. chtmultiregion is essentially two (or more) solvers executed one after another. The only coupling is done by boundary conditions. And the only boundary you can couple by default is the temperature field. Your problem is not in the fixedFluxPressure on your walls but somewhere deeper.

October 4, 2016, 03:08		#3
cfdsolver1 Member Join Date: Jul 2013 Posts: 39 Rep Power: 12	Dear Bloerb, thanks for your answer. As I know, fixedFluxPressure is evaluated as gradP = (PhihbyA - Phi) / (Sf*Dp). So, when I try to apply this BC, I think Sf or Dp is zero, so it fails. What do you think? How can I solve this problem, if this is my problem? By introducing baffles?