CFD Online Logo CFD Online URL
Home > Forums > FLUENT

Mesh rotation due to flow field

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

LinkBack Thread Tools Display Modes
Old   December 11, 2011, 23:30
Default Mesh rotation due to flow field
New Member
Ravinder Singh
Join Date: Dec 2011
Posts: 6
Rep Power: 5
ravindersingh is on a distinguished road

I am simulating unsteady flow over 2d wind turbine. I want the turbine to start rotating due to flow field.

For this I am writing a UDF using the macro DEFINE_CG_MOTION which will rotate the domain containing the blade.

I am following the example given in the UDF manual. But in my UDF I want to calculate the rotational velocity from the moment.

From the forums I came to know about the command "Compute_Force_and_Moment", however I have no idea how to use it and also didn't find much information from internet. Also I get Cm curve from the menu Solve->Monitor->Forces. How can I use it within the UDF?

Please help. Also advide if there is an alternate method available.
ravindersingh is offline   Reply With Quote

Old   September 11, 2012, 03:21
Default Facing the same problem
New Member
Tapan Shah
Join Date: Feb 2012
Posts: 5
Rep Power: 5
tapanshah001 is on a distinguished road
hey...i am trying to do similar thing.....please help me out if you have found a answer...
tapanshah001 is offline   Reply With Quote

Old   September 11, 2012, 08:42
New Member
Join Date: Apr 2011
Posts: 7
Rep Power: 6
Hypersonicflow is on a distinguished road

I have some UDF that calculate forces and moments at each time step. Send me your email adress than I could send them to you.
Hypersonicflow is offline   Reply With Quote

Old   September 11, 2012, 13:54
New Member
Join Date: Aug 2012
Posts: 21
Rep Power: 5
samidabest is on a distinguished road

I am trying to make a simple heat exchanger in my 2d rectangle shaped pipe flow model. Since heat exchangers aren't what I'm focusing on in this project, I'd like to implement a very simple heat exchanger model in a specified zone. Basically one where I can tell it what the 'auxiliary' temp. is, and what effectiveness it has for a given primary fluid temp and let fluent work out the rest.

My model is basically a 2d rectangle with simple zones. It doesn't have heat exchanger pipes or tubes going though any region

When I turn on the Heat exchanger model in fluent, I see the three options ( dual cell, ungrouped macro, and macro model group) but the bottom two are greyed out leaving only "Dual Cell Model" available to select.. I tried going though this but it seems to be a lot more elaborate than my model and requires actually making another zone for the auxiliary cooling/heating fluid.

Can someone please give me some advice on Fluents heat exchanger models and why the other two options (ungrouped macro and macro) are not available.

Please, Please, Please! help, On a project and the dead line is approaching, if any of this is unclear please let me know and I'll try to describe it better.
samidabest is offline   Reply With Quote

Old   October 13, 2012, 05:36
New Member
Join Date: Mar 2010
Posts: 25
Rep Power: 7
Dorit is on a distinguished road
Hi tapanshah001 and ravindersingh,

I'm also trying to model a wind turbines rotational speed based on the moment that it generates. I've also come across the DEFINE_CG_MOTION macro but I haven't quite figured how to use it. Did you get anywhere?

I tried to use the macro with some dummy values but it just won't update my rotational speed. It always uses 0.1 rather than increasing it. I'm using this equation inside the macro to update the rotational speed around the Y axis:


Do you know how it should be written?

Dorit is offline   Reply With Quote


fluent, fluent udf, fluent udfs, udf, wind turbine

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
Mesh refinement with Field Functions - error Dan Chambers STAR-CCM+ 7 January 30, 2014 09:01
Mesh motion with Translation & Rotation Doginal CFX 2 January 12, 2014 07:21
Fully Developed Turbulent Flow Mesh Convergence deji OpenFOAM 0 November 25, 2011 21:27
how 2 freeze 1 phase flow field & start lagrangian KK CFX 5 February 14, 2008 17:48
Creating a mesh of the flow field in GAMBIT Vidya Raja FLUENT 0 October 3, 2005 09:53

All times are GMT -4. The time now is 18:41.