CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM

3D axissymmetric problem

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

Reply
 
LinkBack Thread Tools Display Modes
Old   July 2, 2010, 07:12
Default 3D axissymmetric problem
  #1
New Member
 
Join Date: Jul 2010
Posts: 10
Rep Power: 7
noramat is on a distinguished road
hello,

i have to solve a axis-symmetric 3D-problem (cylinder) - magnetohydrodynamic problem coupled with boussinesq-approximation. Is there any way to solve it in OpenFoam without cylindrical coordinates and without the wedge condition, only with a special boundary condition!? So - maybe - through a constant azimuthal (theta direction) component!? But how could i implement such a condition?

Thanks a lot.

noramat
noramat is offline   Reply With Quote

Old   July 2, 2010, 07:30
Default
  #2
New Member
 
Join Date: May 2010
Location: Cologne
Posts: 27
Rep Power: 7
marcbest is on a distinguished road
i'm also a starter at OF and i'm not familiar with magnetohydrodynamics in OF but generally 2D Simulations can be done with wedges
if you want to define a new boundary condition you have to programm and compile it, have a look at:
http://www.tfd.chalmers.se/~hani/kurser/OS_CFD_2007/
http://www.tfd.chalmers.se/~hani/kur...yCondition.pdf
Implement boundary condition

i hope this helps

Last edited by marcbest; July 2, 2010 at 07:49.
marcbest is offline   Reply With Quote

Old   July 2, 2010, 07:45
Default
  #3
Senior Member
 
maddalena's Avatar
 
maddalena
Join Date: Mar 2009
Posts: 436
Rep Power: 12
maddalena is on a distinguished road
Hi,
Quote:
Originally Posted by noramat View Post
i have to solve a axis-symmetric 3D-problem (cylinder) ... Is there any way to solve it in OpenFoam without cylindrical coordinates and without the wedge condition, only with a special boundary condition!?
If your case is 3D, you should use a cyclic bc and not a wedge, which applies only on 2D problems (one cell thick). If you apply cyclic, it is not necessary to convert everything in cylindrical coordinates, but cartesian will be ok.
Hope this helps.

cheers,

mad
maddalena is offline   Reply With Quote

Old   July 13, 2010, 16:07
Default
  #4
New Member
 
Join Date: Jul 2010
Posts: 10
Rep Power: 7
noramat is on a distinguished road
thanks for your answers!

now i have another question to wedge-type ..

so - wedge-type is used for 2d-axisymmetric problems. Does the wedge-type imply, that all quantities are independent of the angular/azimuthal component phi (constant in phi direction) and that the angular/azimuthal velocity u_phi is zero?

If the last fact is not true (u_phi = 0), how could i implement that? Maybe through a special boundary condition again?

thanks a lot again!

noramat
noramat is offline   Reply With Quote

Old   July 13, 2010, 16:43
Default
  #5
Senior Member
 
maddalena's Avatar
 
maddalena
Join Date: Mar 2009
Posts: 436
Rep Power: 12
maddalena is on a distinguished road
Hi Noramat,
I am not sure I understand your question correctly but... Wedge type is 2D. OF does the trick of using a 3D mesh to solve a 2D case, but in reality all your properties are (and remain) constant along the third dimension, which is not solved indeed. Thus I would say yes:
Quote:
Originally Posted by noramat View Post
the wedge-type imply, that all quantities are independent of the angular/azimuthal component phi (constant in phi direction) and that the angular/azimuthal velocity u_phi is zero
hope that helps

mad
maddalena is offline   Reply With Quote

Old   July 14, 2010, 05:22
Default
  #6
New Member
 
Join Date: Jul 2010
Posts: 10
Rep Power: 7
noramat is on a distinguished road
thanks again!

that's one answer i need

but now i'm still not sure because of the other fact.. so i have to solve a axisymmetric problem (zylinder) with the condition that the angular velocity u_phi is zero. but is it realised by wedge-type?

thanks!

normat
noramat is offline   Reply With Quote

Old   July 14, 2010, 05:53
Default
  #7
Senior Member
 
maddalena's Avatar
 
maddalena
Join Date: Mar 2009
Posts: 436
Rep Power: 12
maddalena is on a distinguished road
Hi Noramat,
is U_phi the angular velocity? If it is, than u_phi will be zero, since the angular direction is not solved by OF. On the other hand, if you are interested on an angular direction, than your problem is not 2D. Indeed, you have two geometrical directions (radial and axial) + one phisical direction (circonferential, or angular, as you like), thus the problem is 3D. In that case, the wedge bc cannot be applied and you should use a cyclic instead.
hope that this makes things clearer.
cheers,

mad
maddalena is offline   Reply With Quote

Old   July 14, 2010, 05:58
Default
  #8
New Member
 
Join Date: Jul 2010
Posts: 10
Rep Power: 7
noramat is on a distinguished road
thanks very much!
noramat 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
UDF compiling problem Wouter Fluent UDF and Scheme Programming 6 June 6, 2012 04:43
Incoherent problem table in hollow-fiber spinning Gianni FLUENT 0 April 5, 2008 10:33
natural convection problem for a CHT problem Se-Hee CFX 2 June 10, 2007 06:29
Adiabatic and Rotating wall (Convection problem) ParodDav CFX 5 April 29, 2007 19:13
Is this problem well posed? Thomas P. Abraham Main CFD Forum 5 September 8, 1999 14:52


All times are GMT -4. The time now is 20:02.