conflict between boundary and blockMeshDict?

immortality · January 22, 2013, 01:23

a question!if i set a face to patch in boundary file.then at blockMeshDict i set its U to a value and p and T to zeroGradient(like a moving wall as in cavity)
Does it produce any conflict?then OF assumes it patch(fluid)or wall(solid)?
How about reciprocal of it.mean wall in boundary but patch in blockMeshDict?
Thanks.

ngj · January 22, 2013, 04:24

Hi Ehsan,

I believe you are a bit confused about the procedure. You create a blockMeshDict, which in turn writes in the file "boundary". You do not specify the actual boundary conditions for e.g. U, T or p in either of these. All you specify in blockMeshDict is whether the patch is a "patch", "wall", "cyclic", "empty", etc.

Furthermore, the boundary file is product of running blockMesh (acting on blockMeshDict), so the definitions in blockMeshDict and boundary should match.

To my knowledge the "wall" definition is used in e.g. wall functions for turbulence models, where it is only those boundary patches, which are defined as "wall", where the turbulent quantities are altered.

Kind regards

Niels

immortality · January 22, 2013, 06:50

thanks.i remembered the procedure.now i correct my written :in blockMeshDict I set a face to patch but this face is changing from fluid inflow/outflow to wall and vice versa whan I use groovyBC for that.it shows an printstack error when its at the middle of wall duration.when i used it with laminar(without wall function)this error occured again.
is it pssible that patch and wall are different at their instinct basically?and when i use patch expression in blockMeshDict it assumes a fluid flow at the face and is permeable although we want wall?
are there some parts at compressible code that distinguish between wall and patch inherently?
someone at this forum told me to use createPatch utility.can I use that by groovyBC?if yes how it works?!
thanks alot for reading and attention.

ngj · January 22, 2013, 07:06

I do not have any knowledge about those part of the code.

Good luck,

Niels

immortality · January 22, 2013, 07:11

can it cause an error in your opinion?

January 22, 2013, 01:23	conflict between boundary and blockMeshDict?	#1
immortality Senior Member Ehsan Join Date: Oct 2012 Location: Iran Posts: 2,208 Rep Power: 26	a question!if i set a face to patch in boundary file.then at blockMeshDict i set its U to a value and p and T to zeroGradient(like a moving wall as in cavity) Does it produce any conflict?then OF assumes it patch(fluid)or wall(solid)? How about reciprocal of it.mean wall in boundary but patch in blockMeshDict? Thanks.

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January 22, 2013, 04:24		#2
ngj Senior Member Niels Gjoel Jacobsen Join Date: Mar 2009 Location: Copenhagen, Denmark Posts: 1,900 Rep Power: 37	Hi Ehsan, I believe you are a bit confused about the procedure. You create a blockMeshDict, which in turn writes in the file "boundary". You do not specify the actual boundary conditions for e.g. U, T or p in either of these. All you specify in blockMeshDict is whether the patch is a "patch", "wall", "cyclic", "empty", etc. Furthermore, the boundary file is product of running blockMesh (acting on blockMeshDict), so the definitions in blockMeshDict and boundary should match. To my knowledge the "wall" definition is used in e.g. wall functions for turbulence models, where it is only those boundary patches, which are defined as "wall", where the turbulent quantities are altered. Kind regards Niels

January 22, 2013, 06:50		#3
immortality Senior Member Ehsan Join Date: Oct 2012 Location: Iran Posts: 2,208 Rep Power: 26	thanks.i remembered the procedure.now i correct my written :in blockMeshDict I set a face to patch but this face is changing from fluid inflow/outflow to wall and vice versa whan I use groovyBC for that.it shows an printstack error when its at the middle of wall duration.when i used it with laminar(without wall function)this error occured again. is it pssible that patch and wall are different at their instinct basically?and when i use patch expression in blockMeshDict it assumes a fluid flow at the face and is permeable although we want wall? are there some parts at compressible code that distinguish between wall and patch inherently? someone at this forum told me to use createPatch utility.can I use that by groovyBC?if yes how it works?! thanks alot for reading and attention.

January 22, 2013, 07:06		#4
ngj Senior Member Niels Gjoel Jacobsen Join Date: Mar 2009 Location: Copenhagen, Denmark Posts: 1,900 Rep Power: 37	I do not have any knowledge about those part of the code. Good luck, Niels

January 22, 2013, 07:11		#5
immortality Senior Member Ehsan Join Date: Oct 2012 Location: Iran Posts: 2,208 Rep Power: 26	can it cause an error in your opinion?