CFD Online Logo CFD Online URL
Home > Forums > FLUENT

why default pressure & momentum URFs 0.3 & 0.7????

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

LinkBack Thread Tools Display Modes
Old   December 9, 2008, 06:21
Default why default pressure & momentum URFs 0.3 & 0.7????
Posts: n/a
Can any body tell me why FLUENT is using default pressure and momentum URFs as 0.3 and 0.7. Based on what FLUENT decided these default values for URF's
  Reply With Quote

Old   December 9, 2008, 18:06
Default Re: why default pressure & momentum URFs 0.3 & 0.7
Posts: n/a
Have a look at section 25.9.2 of the user manual. Here is an extract:

In FLUENT, the default under-relaxation parameters for all variables are set to values that are near optimal for the largest possible number of cases. These values are suitable for many problems, but for some particularly nonlinear problems (e.g., some turbulent flows or high-Rayleigh-number natural-convection problems) it is prudent to reduce the under-relaxation factors initially.
  Reply With Quote

Old   December 10, 2008, 06:25
Default Re: why default pressure & momentum URFs 0.3 & 0.7
Posts: n/a
I never use the default, get faster convergence and lower residuals level when others. What is the logic on using 0.3 for pressure when using simple or simpler

  Reply With Quote


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
2D momentum source for pressure loss Bernhard Dobmeier CFX 0 December 5, 2006 05:05
Pressure BC by solving momentum eq sshyu OpenFOAM Running, Solving & CFD 3 January 23, 2006 11:23
the pressure in Momentum eq. Beginner Main CFD Forum 6 April 13, 2005 23:30
Dynamic URFs? swarup FLUENT 0 April 3, 2005 02:07
default pressure guess value Jackie CFX 0 July 23, 2003 13:24

All times are GMT -4. The time now is 21:50.