interFoam solver needs pdRefCell?

openTom · May 9, 2009, 10:25

Hi Foamers,
i've got a question about the interFoam solver. I have implemented a new case in OpenFoam. I'm using a closed box (4 walls and empty frontAndBack) and when I'm trying to solve my case with the interFoam solver, i have to set pdRefCell and pdRefValue in the fvsolution file. Why is this neccessary? If i have a look in the damBreak test case, there isn't set a pdRefCell/pdRefValue, too. Is this because of the damBreak test case having an atmosphere boundary condition?
Thanks

ngj · May 10, 2009, 10:14

Hi Tom (?)

If you are solving the poisson equation specifying only zeroGradient type boundary conditions, then in the mathematical sense there is a unique solution _plus_ an unknown constant. This constant can only be determined (obtain a truely unique solution), by specifying the pressure at an internal located point.
In the case of the damBreak case a Dirichlet boundary condition is specified for the pressure at the atmospheric boundary, hence it is not needed to specify pdRefCell/pdRef.

Best regards,

Niels

openTom · May 10, 2009, 11:20

Hi Niels,
All right. That makes sense.
Thank you.
Tom

May 9, 2009, 10:25	interFoam solver needs pdRefCell?	#1
openTom New Member Join Date: May 2009 Posts: 13 Rep Power: 17	Hi Foamers, i've got a question about the interFoam solver. I have implemented a new case in OpenFoam. I'm using a closed box (4 walls and empty frontAndBack) and when I'm trying to solve my case with the interFoam solver, i have to set pdRefCell and pdRefValue in the fvsolution file. Why is this neccessary? If i have a look in the damBreak test case, there isn't set a pdRefCell/pdRefValue, too. Is this because of the damBreak test case having an atmosphere boundary condition? Thanks

May 10, 2009, 10:14		#2
ngj Senior Member Niels Gjoel Jacobsen Join Date: Mar 2009 Location: Copenhagen, Denmark Posts: 1,903 Rep Power: 37	Hi Tom (?) If you are solving the poisson equation specifying only zeroGradient type boundary conditions, then in the mathematical sense there is a unique solution _plus_ an unknown constant. This constant can only be determined (obtain a truely unique solution), by specifying the pressure at an internal located point. In the case of the damBreak case a Dirichlet boundary condition is specified for the pressure at the atmospheric boundary, hence it is not needed to specify pdRefCell/pdRef. Best regards, Niels tonnykz likes this.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
About interFoam solver	zou_mo	OpenFOAM Running, Solving & CFD	129	December 2, 2019 06:39
Working directory via command line	Luiz	CFX	4	March 6, 2011 21:02
Open Channel Flow using InterFoam type solver	sxhdhi	OpenFOAM Running, Solving & CFD	3	May 5, 2009 22:58
Wmake problem interFoam solver	feijooos	OpenFOAM Running, Solving & CFD	4	December 8, 2008 12:01
compressible two phase flow in CFX4.4	youngan	CFX	0	July 2, 2003 00:32

May 10, 2009, 11:20		#3
openTom New Member Join Date: May 2009 Posts: 13 Rep Power: 17	Hi Niels, All right. That makes sense. Thank you. Tom