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

Schemes to improve pressure drag?

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   December 2, 2009, 04:55
Default Schemes to improve pressure drag?
  #1
Senior Member
 
Charles
Join Date: Apr 2009
Posts: 185
Rep Power: 13
CapSizer is on a distinguished road
I'm analysing a series of 3D streamlined shapes with simpleFoam, using meshes created with snappyHexmesh. As far as I can make out, the meshes are OK, as they produce drag figures in Fluent that quite closely match what I was able to achieve with a very high quality block-structured hexahedral mesh. The Fluent results make sense, with pressure drag making up about 10% of the total drag. Re-number based on length is about 10 million, and the finess ratio is around 7. In Fluent I know that least squares interpolation combined with second order momentum differencing is required to get the accuracy. However, in simpleFoam I'm getting pressure drag that is about 4 times too high. FWIW, I'm using the SST turbulence model with wall functions, but changing the turbulence model does not make much difference here. I suspect that although I'm using higher order schemes, there is something important that I am missing. Any suggestions, please?
CapSizer is offline   Reply With Quote

Old   December 10, 2009, 05:39
Default
  #2
Senior Member
 
Robert Castilla
Join Date: Apr 2009
Location: Spain
Posts: 106
Rep Power: 12
rcastilla is on a distinguished road
Maybe it is a problem with wall function. Have you checked the value of yPlus?
rcastilla is offline   Reply With Quote

Reply

Tags
pressure drag, schems, simplefoam

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Pressure BC for combustion chamber Giuki FLUENT 1 July 19, 2011 12:35
How to read pressure at discrete points paka OpenFOAM 15 July 21, 2008 06:03
Does star cd takes reference pressure? monica Siemens 1 April 19, 2007 12:26
Pressure Condition sidd Siemens 0 April 2, 2007 10:31
what the result is negatif pressure at inlet chong chee nan FLUENT 0 December 29, 2001 06:13


All times are GMT -4. The time now is 15:46.