CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM

pressure or porous jump boundary condition

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   April 3, 2011, 13:18
Default pressure or porous jump boundary condition
  #1
New Member
 
Join Date: Jul 2009
Posts: 7
Rep Power: 9
Rezaslosh is on a distinguished road
Dear Foamers,

Does any one know if OF supports pressure or porous jump boundary condition?
Rezaslosh is offline   Reply With Quote

Old   April 4, 2011, 02:50
Default
  #2
Senior Member
 
maddalena's Avatar
 
maddalena
Join Date: Mar 2009
Posts: 436
Rep Power: 14
maddalena is on a distinguished road
Quote:
Originally Posted by Rezaslosh View Post
Dear Foamers,

Does any one know if OF supports pressure or porous jump boundary condition?
Hi,
I do not know if this is the answer to what you are looking for but...
  1. a positive pressure jump can be set using the fan BC.
  2. a porous jump is usually modelled using porousSimpleFoam or its variation (see here)
cheers,

mad
maddalena is offline   Reply With Quote

Old   April 5, 2011, 03:48
Default
  #3
New Member
 
Join Date: Jul 2009
Posts: 7
Rep Power: 9
Rezaslosh is on a distinguished road
Thanks for reply. I'm trying to model a thin porous screen using experimental pressure loss values. I'm using porousInterfoam in which a porous zone should be defined in the computational domain. But this is not consistent with the physics. I mean the pressure loss values K=(p2-p1)/(0.5*rho*U^2) are based on a jump in the pressure and a horizontal approach velocity U in a distance from the screen. Therefore something like a pressure jump condition like in Fluent is more physical than introducing a negative source in the momentum equation that we have in OpenFoam. Apparently it is available in a non-official version of Openfoam. I'll wonder if you know where I can get that version.

Regards,
Reza
Rezaslosh is offline   Reply With Quote

Old   April 5, 2011, 07:32
Default
  #4
Senior Member
 
maddalena's Avatar
 
maddalena
Join Date: Mar 2009
Posts: 436
Rep Power: 14
maddalena is on a distinguished road
Quote:
Originally Posted by Rezaslosh View Post
Therefore something like a pressure jump condition like in Fluent is more physical than introducing a negative source in the momentum equation that we have in OpenFoam. Apparently it is available in a non-official version of Openfoam. I'll wonder if you know where I can get that version.

Regards,
Reza
Is that not the fan bc?
What non official version are you referring? 1.6-ext? if so, it is here: http://extend-project.de/

mad
maddalena is offline   Reply With Quote

Old   August 18, 2011, 11:43
Default
  #5
Member
 
Sylvain Aguinaga
Join Date: Feb 2010
Posts: 39
Rep Power: 8
Sylvain is on a distinguished road
Hi,

there is a new BC in 2.0 called porousBafflepressure which looks like the one in Fluent.

Actually if you look into the code it is the same thing as in fluent. it is employed in the interFoam tutorial called damBreakwithporousbaffles.

I tried to use it in my case, by it is highly instable when coupled with a fan BC (like in fluent)

Sylvain
Sylvain is offline   Reply With Quote

Old   October 31, 2011, 11:23
Default
  #6
Member
 
Join Date: Nov 2009
Posts: 34
Rep Power: 9
stawrogin is on a distinguished road
Hi Sylvain,

thanks for sharing the experiences.

Did you made some progress with the porousBafflepressure BC? I made similar experience with this BC: It seems to work for rather low pressure losses across the patch. But if the resistance becomes large and dominates the pressure field I didn't manage to get any stable solution. This happens also with very easy in- and outflow conditions. For my applications (filters etc.) I think I have to back to volumues zones.

Best regards

Stawrogin
stawrogin is offline   Reply With Quote

Old   October 31, 2011, 23:30
Default sorry, may I know where is the tut for porousBafflepressure
  #7
New Member
 
Chen Xiaobing
Join Date: Aug 2011
Posts: 11
Rep Power: 7
xbchen168 is on a distinguished road
is it in Openfoam 2.0.0?

I can not find it under the path: opt/openfoam200/tutorial/multiphase/interfoam/laminar...

thanks.
xbchen168 is offline   Reply With Quote

Old   November 1, 2011, 04:27
Default
  #8
Member
 
Join Date: Nov 2009
Posts: 34
Rep Power: 9
stawrogin is on a distinguished road
Hi Chen,

this example comes along with 2.0.x (not 2.0.1or 2.0.0) and can be found in the interFOAM ras-Dir.

You also have to add an entry for the lib to make use of this BC in your controlDict (see example case).


Stawrogin
stawrogin is offline   Reply With Quote

Old   November 15, 2011, 04:51
Default
  #9
Member
 
Sylvain Aguinaga
Join Date: Feb 2010
Posts: 39
Rep Power: 8
Sylvain is on a distinguished road
Hi Stawrogin,


I used the porous baffles to model an heat exchanger in a wind tunnel.

It worked well, but the the flow is uniform and the pressure loss quite low at the location of the baffle.

From my previous experience in fluent, those BC are very instable, but they are very handful. So i understand your problem; I'm not familiar with the porousZone, but I think I will take a closer look at it.

Sincerely

Sylvain
Sylvain is offline   Reply With Quote

Old   August 24, 2012, 09:53
Default
  #10
New Member
 
laurent dilain
Join Date: Mar 2012
Location: France
Posts: 3
Rep Power: 6
laurent257 is on a distinguished road
Hey everyone !

I'm new on this forum and quite beginner on Openfoam.

I have exactly the same problem as described upper.
I want to simulate a pressure loss as for a filter and I try to use the porousBafflePressure BC on a simple case (for the moment).

This cas is simple, to start, with an incompressible flow, no heat transfer, one phase, etc... It's just a cylinder with a surface supposed to act as a filter.
This model works fine with the fan BC with simpleFoam but I am unable to make it work with the porousBafflePressure BC under porousSimpleFoam...

I have modified my controlDict file by adding a lib refernce as in the example of the dambreakPorousbaffle but it doesn't wotk.

My questions are :
- Do have I to use interFoam to use this porousBaffle BC, even with a so simple case ?
- If not, where can I find a detailed explanation of what to do to use it ?

Thank you very much for your answers or help !!
I used to work with Fluent or Star-CD and my first experiences with OpenFoam are very encouraging but now, I can't go further...

Laurent
laurent257 is offline   Reply With Quote

Old   March 5, 2014, 07:00
Default
  #11
Member
 
Yogesh Bapat
Join Date: Oct 2010
Posts: 43
Rep Power: 8
ybapat is on a distinguished road
Hello,

I have also been trying to use porous jump. It works well when jump values are small, but for larger value case diverges. Anyone knows what to do when pressure jump values are large?

-Yogesh
ybapat is offline   Reply With Quote

Old   November 18, 2014, 17:25
Default porousBafflePressure boundary condition for foam-extend-3.1
  #12
New Member
 
Mahdi
Join Date: Sep 2013
Posts: 11
Rep Power: 5
Masgar is on a distinguished road
Hi foamers,

I would like to employ the porousBafflePressure as a boundary condition for my simulation in extended version of OpenFOAM: foam-extend-3.1. As you know this boundary condition is not available in this version, so I would like to ask if one of you has compiled the boundary condition on this version and if so, what are the requirements to consider.

Thanks for your response in advance and Best,
Mahdi
Masgar is offline   Reply With Quote

Old   June 29, 2016, 04:43
Question
  #13
New Member
 
Justin Wiegmann
Join Date: Aug 2015
Posts: 19
Rep Power: 3
SirIsaac90 is on a distinguished road
Quote:
Originally Posted by ybapat View Post
Hello,

I have also been trying to use porous jump. It works well when jump values are small, but for larger value case diverges. Anyone knows what to do when pressure jump values are large?

-Yogesh
Hi,
Same problem in my case..

Anyone who could give some advices?

Regards
JW
SirIsaac90 is offline   Reply With Quote

Old   July 5, 2016, 16:08
Default
  #14
Member
 
Sylvain Aguinaga
Join Date: Feb 2010
Posts: 39
Rep Power: 8
Sylvain is on a distinguished road
Hi everybody,

Yes, if you prescribed a pressure jump too large the calculation is likely to explode.

My trick is too increase step by step the pressure jump ( or the inlet velocity). Once your calculation is stabilized you slightly increase the pressure jump. You iterate till you got the pressure jump you want.

You might want use the changeDictionnay tool to easily change the value of the pressure jump between each calculation.

Hope it will be useful!

Sylvain
Sylvain is offline   Reply With Quote

Old   July 6, 2016, 02:28
Default
  #15
New Member
 
Justin Wiegmann
Join Date: Aug 2015
Posts: 19
Rep Power: 3
SirIsaac90 is on a distinguished road
Quote:
Originally Posted by Sylvain View Post
Hi everybody,

Yes, if you prescribed a pressure jump too large the calculation is likely to explode.

My trick is too increase step by step the pressure jump ( or the inlet velocity). Once your calculation is stabilized you slightly increase the pressure jump. You iterate till you got the pressure jump you want.

You might want use the changeDictionnay tool to easily change the value of the pressure jump between each calculation.

Hope it will be useful!

Sylvain
Thank you very much!

I already tried it, but with quite large steps. I am going to try it again with smaller steps for the pressure drop. Maybe that helps
SirIsaac90 is offline   Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Pressure boundary condition C-H Kuo Main CFD Forum 18 September 16, 2016 03:19
Pressure Inlet Boundary Condition Prasad FLUENT 6 April 9, 2013 21:32
Fluent natural ventilation pressure boundary condition pierresandre FLUENT 24 November 8, 2011 15:32
RPM in Wind Turbine Pankaj CFX 9 November 23, 2009 05:05
pressure jump in fan boundary condition Vijay FLUENT 0 February 12, 2009 19:19


All times are GMT -4. The time now is 02:59.