CFD Online Logo CFD Online URL
Home > Forums > Software User Forums > ANSYS > FLUENT

Limitation of Global Courant Number (VOF Model)

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

Like Tree8Likes
  • 8 Post By vig

LinkBack Thread Tools Search this Thread Display Modes
Old   February 14, 2013, 05:34
Default Limitation of Global Courant Number (VOF Model)
Blue's Avatar
Join Date: Jul 2012
Location: India
Posts: 32
Rep Power: 12
Blue is on a distinguished road
The default value of Global Courant Number is given 2 in Ansys Fluent, But how much this value can be changed? What is optimum value? What will be impact on results by increasing and decreasing this value? I am modeling a tank drainage problem and monitoring the interface.

Thank you
Blue is offline   Reply With Quote

Old   February 15, 2013, 06:35
New Member
Join Date: Jan 2011
Posts: 23
Rep Power: 13
vig is on a distinguished road
Global Courant number could be experimented in the range of 1-5.

Ideally, Interface should not cross more than 1 cells in 1 time step, which is stability criterion for explicit scheme. In that way, optimal value should always be lesser than or equal to 1.

However, other equations should not be affected by the time restriction imposed on the volume fraction tracking. Fluent internally breaks the actual time step into sub-time steps, so that each sub-time step satisfies the Courant based criterion.

There is another entry for Courant number on the multiphase panel, by default 0.25.

Therefore the number of internal sub-time steps = Global Courant number devided by Local Courant number

For Global Courant Number = 2, sub-time-steps = 8
rsaha, FarzinD, BlnPhoenix and 5 others like this.
vig is offline   Reply With Quote


cfl, fluent, global courant number, tank emptying, vof

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
AMI speed performance danny123 OpenFOAM 21 October 24, 2020 05:13
alphaEqn.H in twoPhaseEulerFoam cheng1988sjtu OpenFOAM Bugs 15 May 1, 2016 17:12
Problem with FloatingObject Leech OpenFOAM Running, Solving & CFD 10 March 29, 2012 16:24
directMapped problem panda60 OpenFOAM Bugs 4 July 8, 2010 11:23
Global courant number what mean erica FLUENT 0 November 24, 2007 06:41

All times are GMT -4. The time now is 02:16.