CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Fluent UDF and Scheme Programming

how to use UDF with cylinderical coordinate system in fluent

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

Reply
 
LinkBack Thread Tools Display Modes
Old   January 4, 2015, 21:27
Default how to use UDF with cylinderical coordinate system in fluent
  #1
Member
 
Peter Aestas
Join Date: Dec 2013
Posts: 42
Rep Power: 3
aestas is on a distinguished road
Hi my friends,
i am working on plasma distribution problems, and it is more convenient for me to written the set of equations and boundary conditions in cylindrical component form, but as far as i knew, fluent only has Cartesian coordinate system

so how should i do to put the cylindrical component form into UDF and use them in fluent? I am desperate for your help~
aestas is offline   Reply With Quote

Old   January 5, 2015, 04:59
Default
  #2
Sun
Member
 
Join Date: Nov 2010
Posts: 86
Rep Power: 6
Sun is on a distinguished road
Hi,
Can you provide more details on the nature of equations?
Meanwhile, have a look at this doc, a nice summary of field variables/functions in Fluent. You might be able to find most of the access functions you need.
hope it helps.
cheers!
Sun is offline   Reply With Quote

Old   January 5, 2015, 07:57
Default
  #3
Member
 
Peter Aestas
Join Date: Dec 2013
Posts: 42
Rep Power: 3
aestas is on a distinguished road
Thanks for your replay, my friend.

it is in the paper titled "2D expansion of the low-density interelectrode vacuum arc plasma jet in an axial magnetic field",with a 2D MHD model, but the energy equations are not considered.The pdf is too large to upload.~

i wonder whether the equation set 3 can be calculated in fluent.

And you can see, the self magnetic field Bθ is more simple to express in cylinder system~

Quote:
Originally Posted by Sun View Post
Hi,
Can you provide more details on the nature of equations?
Meanwhile, have a look at this doc, a nice summary of field variables/functions in Fluent. You might be able to find most of the access functions you need.
hope it helps.
cheers!
Attached Images
File Type: jpg 111.jpg (30.5 KB, 11 views)
File Type: jpg 2222.jpg (65.7 KB, 12 views)
File Type: jpg 3333.jpg (62.1 KB, 6 views)
aestas is offline   Reply With Quote

Old   January 5, 2015, 09:39
Default
  #4
Sun
Member
 
Join Date: Nov 2010
Posts: 86
Rep Power: 6
Sun is on a distinguished road
Peter,
Unfortunately, I don't have access to the full paper. But Looking at Eqs. 3.1 to 3.6, you need to convert the Cartesian velocities into axial, radial, and tangential ones. I've googled around a bit and stumbled upon these slides.
On slide 34 and 35, you'll find a way to convert the velocities. However, I am not quite sure if you can use the very same approach for other terms in the equations. It might be a bit tricky.
cheers
Sun is offline   Reply With Quote

Old   January 5, 2015, 10:37
Default
  #5
Member
 
Peter Aestas
Join Date: Dec 2013
Posts: 42
Rep Power: 3
aestas is on a distinguished road
Thanks my friend, i got what you mean by the slides, use Cartesian in fluent while use cylinder system in UDF.
It is a bit tricky to me, but i will try two ways, to take the same approach in the slides, or just convert the basic equation set 2 into Cartesian system, and the tangential component has to be divided.
BTW, the original auther of the paper didnot use fluent to calculate, insead they program themselves
aestas is offline   Reply With Quote

Old   January 5, 2015, 11:00
Default
  #6
Member
 
Peter Aestas
Join Date: Dec 2013
Posts: 42
Rep Power: 3
aestas is on a distinguished road
Hi, Sun,
I think if it's a 3D model in Cylinder Coordinate, it can't directly be used in fluent, because the momentum components are written as Vx,Vy,Vz in fluent.As a consequence, the source terms in the momentum equation can't directly be used from Cylinder to Cartesian.

But my problem is a 2D axisymmetric model, the z and r component in the figure just equals the x and y component in Cartesian, the only difference is the tangential component vs y compenent. I think this may be done by the approach you told me. I would give it a try
aestas is offline   Reply With Quote

Old   January 5, 2015, 12:49
Default
  #7
Sun
Member
 
Join Date: Nov 2010
Posts: 86
Rep Power: 6
Sun is on a distinguished road
Alright great and thanks for the update. I guess that method might actually work for the 2D case.
good luck.
Sun is offline   Reply With Quote

Reply

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
problem in using parallel process in fluent 14 aydinkabir88 FLUENT 1 July 10, 2013 02:00
fluent udf problem: write specific data for every iteration in a file. nnvoro Fluent UDF and Scheme Programming 1 May 27, 2013 15:26
Change to local Coordinate system in Fluent Constantine FLUENT 3 November 12, 2010 02:05
Compiling UDF in Fluent 12 jsm FLUENT 1 July 22, 2009 07:40
On Coordinate system used in Fluent varghese FLUENT 9 March 22, 2002 12:16


All times are GMT -4. The time now is 06:27.