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

unphysical pressure increase at outlet

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

Reply
 
LinkBack Thread Tools Display Modes
Old   January 21, 2010, 06:13
Default unphysical pressure increase at outlet
  #1
New Member
 
Martin Becker
Join Date: Sep 2009
Posts: 5
Rep Power: 6
mbecker is on a distinguished road
I am simulating a waterturbine stator flow channel (with cyclicGgi) with two fixed blade rows (1 stayvane & 2 guidevanes).
I have stable and converging results that are not too much away from reality, except in one point:
In the outlet region, I get an unphysical increase in static pressure and decrease in velocity.

My boundary conditions are:
- inlet velocity profile, defining Q and the inlet flow angle
- walls (hub, shroud, guidevanes, stayvane)
- cyclic periodic symmetry (cyclicGgi)
- outlet pressure: fixedMeanValue = 0
- average y+ is ~40

I am using the k-omega-SST turbulence model, as I found the exaggeration of k-epsilon in the stagnation point to be too extreme.
I already tried to use a finer mesh in the outlet region, but that doesn't help.
The mesh quality is fine (worst angle 30).
I also tried to use fixedValue = 0 at outlet for pressure, same result.

I simulated the case on the same mesh with same bcs with CFX and attached some pictures that show the solution in a middle plane (static pressure and velocity magnitude for CFX and OpenFoam). I also attached my 0-files + fvSolution, fvSchemes and boudary files.

Thanks for your help,
Martin
Attached Images
File Type: jpg p_CFX.jpg (85.3 KB, 13 views)
File Type: jpg p_OpenFoam.jpg (82.4 KB, 10 views)
File Type: jpg Uabs_CFX.jpg (83.3 KB, 10 views)
File Type: jpg Uabs_OpenFoam.jpg (88.0 KB, 9 views)
Attached Files
File Type: gz 0_boundary_fvSchemes_fvSolution.tar.gz (2.6 KB, 4 views)
mbecker 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
circumferential pressure profile on outlet -> error when writing results mhsr CFX 0 August 14, 2009 10:54
Collocated SIMPLE and outlet pressure yhoarau Main CFD Forum 1 April 16, 2009 09:16
Pressure outlet Vidya FLUENT 6 July 13, 2006 13:20
Terrible Mistake In Fluid Dynamics History Abhi Main CFD Forum 12 July 8, 2002 09:11
UDF in Fluent to Match Mass Flow at Pressure Outlet Jonas Larsson Main CFD Forum 1 April 29, 1999 10:44


All times are GMT -4. The time now is 18:05.