CFD Online Logo CFD Online URL
Home > Forums > FLUENT

Using Transient Boundary condition

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

LinkBack Thread Tools Display Modes
Old   September 22, 2014, 14:27
Default Using Transient Boundary condition
New Member
Join Date: Sep 2014
Posts: 1
Rep Power: 0
raamek is on a distinguished road
I plan to use FLUENT to simulate fluid flow and heat transfer in tubes/channels. But the inlet boundary condition is going to TRANSIENT , i.e., inlet flow rate varies with time. Flow rate can change from a very small value (hence laminar) to a very high value (hence turbulent) and a very high value to a very low value OVER A PERIOD OF TIME. Can FLUENT switch over from LAMINAR to TURBULENT and TURBUELENT TO LAMINAR automatically over a time period based on the transient boundary condition (inlet flow rate or velocity changing with time)?
If yes, can anyone please explain how it can be done.
raamek is offline   Reply With Quote

Old   September 23, 2014, 11:00
Senior Member
Andrew Kokemoor
Join Date: Aug 2013
Posts: 122
Rep Power: 7
Kokemoor is on a distinguished road
You can use Automatic Case Modifications (See Fluent User's Guide 28.18) to enter commands after a fixed number of time steps. This will probably work for what you're trying to do, but it will bring its own issues with it. You'll need to initialize the turbulent variables when you activate the model and you may see unphysical results in the time steps right after model changes. It might be best simply to leave the turbulent model on for the entire simulation; it will increase the solve time a bit, but shouldn't affect accuracy.
Kokemoor is offline   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
sliding mesh problem in CFX Saima CFX 45 September 22, 2015 10:53
Low Mixing time Problem Mavier CFX 5 April 29, 2013 00:00
External Radiation Boundary Condition for Grid Interface CFD XUE FLUENT 0 July 9, 2010 02:53
External Radiation Boundary Condition (Two sided wall), Grid Interface CFD XUE FLUENT 0 July 8, 2010 06:49
vorticity boundary condition bearcharge Main CFD Forum 0 May 14, 2010 11:32

All times are GMT -4. The time now is 17:34.