CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Running, Solving & CFD

Increasing mesh resolution yields big difference in pressure?

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   September 24, 2014, 07:58
Default Increasing mesh resolution yields big difference in pressure?
  #1
New Member
 
Join Date: Sep 2014
Posts: 12
Rep Power: 12
Wizze is on a distinguished road
Hey everyone

I am quite new to CFD and to OpenFOAM so please bear with me if this is a stupid question.

I have been looking at the cavity tutorial and when I increase the mesh resolution there is a pressure increases in the top left of the cavity and decreases at the top right. The increase and decrease of the pressure will continue as the mesh resolution gets better. I can basically obtain any pressure by changing the mesh resolution. I use the pressure legend in Paraview to determine the upper and lower pressure values.

How can this be right? Shouldn't OpenFOAM/Paraview try to depict the actual pressures regardless what the resolution is?
Wizze is offline   Reply With Quote

Old   September 26, 2014, 08:53
Default
  #2
Senior Member
 
Tom Fahner
Join Date: Mar 2009
Location: Breda, Netherlands
Posts: 646
Rep Power: 32
tomf will become famous soon enoughtomf will become famous soon enough
Send a message via MSN to tomf Send a message via Skype™ to tomf
Hi Wizze,

This is due to the fact that there is a singularity right at those corners. On one side there is a moving lid on the other side a stagnant wall. No-slip conditions on those sides make that there is no actual solution for the pressure in the corner. When refining the mesh this will cause the behavior you see. So it is actually the correct behavior.

Regards,
Tom
tomf is offline   Reply With Quote

Old   September 26, 2014, 09:15
Default
  #3
New Member
 
Join Date: Sep 2014
Posts: 12
Rep Power: 12
Wizze is on a distinguished road
Thank you very much Tom :-)
Wizze is offline   Reply With Quote

Reply


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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Pressure Inlet VS velocity Inlet difference Mohsin FLUENT 9 January 4, 2021 11:34
Mesh Resolution to resolve turbulent boundary layer tongx051 FLUENT 1 October 22, 2013 01:18
Difference between pressure, absolute pressure and Total Pressure shaswat CFX 1 September 6, 2012 07:12
Icemcfd 11: Loss of mesh from surface mesh option? Joe CFX 2 March 26, 2007 19:10
Increasing resolution of mesh in GAMBIT Vidya Raja Main CFD Forum 1 October 10, 2005 04:11


All times are GMT -4. The time now is 08:17.