boundaryField on outlet for a non fully developed flow ?

adrieno · March 25, 2016, 09:11

Hi all,

What type would you choose for the outlet boundaryField on U with a flow non fully developed ?

Because, I can't use zeroGradient ( neither inletOut which is much like zeroGradient if I've understand...).

In my case I'm want to simulate a turbulent and incompressible flow in a pipe.
I will set:

a fixed value for the static pressure on outlet
a zeroGradient for pressure inlet
a fixedValue for velocity

But what about outlet velocity ??

adrieno · March 30, 2016, 10:02

No one ?
Should I post my question elsewhere on the forum ?

jherb · March 30, 2016, 10:27

Perhaps fixedMeanFvPatchField does what you are looking for:

https://github.com/OpenFOAM/OpenFOAM...FvPatchField.H

It allows different values for the different faces of the surface, but fixes the mean value. The mean value is calculated by weighting the different face values with the size of each face. Perhaps you have to modify the boundary condition sum up the fluxes of the faces and fix that value.

Still, you can only set the velocity on one face (if you have only two non-wall boundaries). Then your inlet should probably be set to zeroGradient.

But why does zeroGradient for U on the outlet not work? You could also try this (zeroGradient for U) together with fixedMeanFvPatchField for the pressure on the outlet and fixedValue for U on the inlet.

adrieno · April 4, 2016, 03:43

I've seen an interesting post which helped me.
Here it is if someone need it too one day.
http://www.cfd-online.com/Forums/ope...tvelocity.html
Have a nice project,
Adrien

March 25, 2016, 09:11	boundaryField on outlet for a non fully developed flow ?	#1
adrieno Member AdOo Join Date: Mar 2016 Location: Bordeaux Posts: 91 Rep Power: 10	Hi all, What type would you choose for the outlet boundaryField on U with a flow non fully developed ? Because, I can't use zeroGradient ( neither inletOut which is much like zeroGradient if I've understand...). In my case I'm want to simulate a turbulent and incompressible flow in a pipe. I will set: a fixed value for the static pressure on outlet a zeroGradient for pressure inlet a fixedValue for velocity But what about outlet velocity ??

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March 30, 2016, 10:02		#2
adrieno Member AdOo Join Date: Mar 2016 Location: Bordeaux Posts: 91 Rep Power: 10	No one ? Should I post my question elsewhere on the forum ?

March 30, 2016, 10:27		#3
jherb Senior Member Joachim Herb Join Date: Sep 2010 Posts: 650 Rep Power: 21	Perhaps fixedMeanFvPatchField does what you are looking for: https://github.com/OpenFOAM/OpenFOAM...FvPatchField.H It allows different values for the different faces of the surface, but fixes the mean value. The mean value is calculated by weighting the different face values with the size of each face. Perhaps you have to modify the boundary condition sum up the fluxes of the faces and fix that value. Still, you can only set the velocity on one face (if you have only two non-wall boundaries). Then your inlet should probably be set to zeroGradient. But why does zeroGradient for U on the outlet not work? You could also try this (zeroGradient for U) together with fixedMeanFvPatchField for the pressure on the outlet and fixedValue for U on the inlet.

April 4, 2016, 03:43		#4
adrieno Member AdOo Join Date: Mar 2016 Location: Bordeaux Posts: 91 Rep Power: 10	I've seen an interesting post which helped me. Here it is if someone need it too one day. http://www.cfd-online.com/Forums/ope...tvelocity.html Have a nice project, Adrien