CFD Online Logo CFD Online URL
Home > Forums > CFX

separate time step for mass fraction?

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

LinkBack Thread Tools Display Modes
Old   August 10, 2007, 06:40
Default separate time step for mass fraction?
Posts: n/a
hello, i simulate a problem with cfx 11 including a mass fraction. since that mass fraction moves with a very low settling velocity (downwards slip velocity)- in comparison to the flow of the constraint, i would like to solves the equation of the mass fraction with a bigger time step than the "global time step size". Does anyoune kmow if this is possible with a transient simulation? thanks! joe
  Reply With Quote

Old   August 12, 2007, 18:30
Default Re: separate time step for mass fraction?
Glenn Horrocks
Posts: n/a

Why would you want to do this in a transient simulation? You won't get a true time history then. You should be able to use quite a large timestep if the bulk flow is pretty much steady state.

An alternative if the velocity and mass equations do not change but the mass fraction evolves then you can turn the velocity and mass equations off and only solve the mass fraction. This will speed the simulation up hugely if this assumption is valid.

Glenn Horrocks
  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
Moving mesh Niklas Wikstrom (Wikstrom) OpenFOAM Running, Solving & CFD 122 June 15, 2014 06:20
Upgraded from Karmic Koala 9.10 to Lucid Lynx10.04.3 bookie56 OpenFOAM Installation 8 August 13, 2011 04:03
Full pipe 3D using icoFoam cyberbrain OpenFOAM 4 March 16, 2011 10:20
Restarting interDyMFoam hsieh OpenFOAM Bugs 4 January 25, 2009 16:19
Differences between serial and parallel runs carsten OpenFOAM Bugs 11 September 12, 2008 11:16

All times are GMT -4. The time now is 05:48.