CFD Online Logo CFD Online URL
Home > Forums > Fluent UDF and Scheme Programming

random velocity fluctuation udf

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

LinkBack Thread Tools Display Modes
Old   January 30, 2014, 02:43
Default random velocity fluctuation udf
New Member
Join Date: Jan 2014
Posts: 1
Rep Power: 0
sunny89 is on a distinguished road
Hello, I want to give randomly varying (temporal) velocity (about a mean value) as inlet boundary condition. Which function do I have to use in UDF and how can I set the range ??
sunny89 is offline   Reply With Quote

Old   March 12, 2014, 14:12
Join Date: Sep 2011
Posts: 43
Rep Power: 8
Komon is on a distinguished road

sorry for this not being an answer to your question but rather a new question. I have a similar problem to yours. But instead of putting velocity fluctuations on the inlet I'd like to impose them on whole domain. Namely, I'm trying to run LES simulation of a periodic channel flow with which I'd like to get results for turbulent inflow that will be used in other simulations. I've noticed that there are some simulations that impose fluctuations on the mean velocity profile in whole domain (namely Lund et al, 1998 mentions this)...but I haven't noticed that they use periodic bc (again, Lund uses semi implicit periodic conditions). Neither have I seen how these fluctuations are described. The only recommendation I got was to use 10% amplitude of mean velocity. So I'd like to ask if anyone can give some advice/further info on my intention-is it ok to make such simulations, what kind of fluctuations should I use....basically what to look for.

As for the moment, I'll try to initialize simulations with some sort of sinusoidal velocity in the domain....and I'll see what comes out.

thanks for the answers and all the best
Komon 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
Axisymmetric swirl - angular velocity for UDF NTSbike Fluent UDF and Scheme Programming 10 September 21, 2015 15:03
UDF for velocity profile egge24 Fluent UDF and Scheme Programming 0 April 4, 2012 19:57
Simulation with UDF for species mass fraction and velocity profile virgy Fluent UDF and Scheme Programming 8 February 7, 2012 05:30
Urgent! Help on UDF to set inlet velocity Ray Hong FLUENT 4 December 30, 2005 13:32
UDF velocity profile problem Steve FLUENT 0 January 18, 2005 13:11

All times are GMT -4. The time now is 22:55.