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

Dynamic Mesh UDF question

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

LinkBack Thread Tools Display Modes
Old   June 1, 2010, 01:30
Exclamation Dynamic Mesh UDF question
New Member
amin gh
Join Date: Apr 2009
Posts: 1
Rep Power: 0
amin62gh is on a distinguished road
Dear users,

I want to assign a movement to a rigid wall in order to generate wave. But problem is here, having no velocity function ( vel (time)) , how can I make the wall move with a time-history of displacement.

Best Regards,
amin62gh is offline   Reply With Quote

Old   June 1, 2010, 03:45
O.D.Y.'s Avatar
Join Date: Mar 2009
Posts: 49
Rep Power: 10
O.D.Y. is on a distinguished road

you can do it via DEFINE_CG_MOTION.
It can be used to give walls velocities w.r.t. to any functional relation to time.

The function is pretty well explained in the UDF User Guide including an example. And if you search for it in the forum you will find some examples of others.

O.D.Y. is offline   Reply With Quote

Old   June 1, 2010, 10:48
New Member
Join Date: Mar 2010
Posts: 19
Rep Power: 9
Randre is on a distinguished road

If you want to simulate a flap-type wave maker (I suppose yes, regarding your description), I advise you to check the following paper (wow, was right in front of me at this moment :O) where are defined the flap displacement functions - For those, you need to write an UDF with the macro above (DEFINE_CG_MOTION):

Lal, Anant; CFD Simulation and Validation of Flap-Type Wave-Maker. World Academy of Science, Engineering and Technology vol. 46 pp 76-82, 2008

But you don't need to simulate the displacement of the flap in order to create waves in FLUENT. You can assign Velocity-Inlet BC to your wave-maker wall and input an UDF with the x and y wave velocities from the linear wave theory or stokes theory.

And it gets easier if you have the last version of FLUENT. go to
Define - Models - Multiphase - VOF - Open Channel Flow / Open Channel Wave BC (check them both), and then in wave maker wall: BC Velocity Inlet and input in FLUENT GUI your wave info.

Check V12.0 and V12.1 FLUENT users guide for more info.
Randre 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
UDF CG_MOTION rotation dynamic mesh Mads FLUENT 2 April 15, 2014 03:30
Dynamic Mesh, (Define_Geom) UDF ROOZBEH FLUENT 3 August 28, 2009 08:28
help me for dynamic mesh speedcat FLUENT 0 May 17, 2005 21:32
Problem related with UDF for dynamic mesh Ryan FLUENT 6 April 29, 2004 09:29
A question about the dynamic mesh UDF Tango FLUENT 1 November 27, 2003 03:56

All times are GMT -4. The time now is 23:08.