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

Dynamic Mesh: Deforming Problem

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

Reply
 
LinkBack Thread Tools Display Modes
Old   November 9, 2012, 07:06
Default Dynamic Mesh: Deforming Problem
  #1
New Member
 
Christopher Mai
Join Date: Aug 2012
Location: Dresden, Germany
Posts: 5
Rep Power: 5
rudelmops is on a distinguished road
Hello,

I'm simulating the flow of a journal bearing. I created a grid for the bearing gap with ICEM.
My problem is that only the layer of cells nearest to the shaft are deforming although I used the command: define/dynamic-mesh/controls/smoothing-parameters/s-o-a-s.
Can anybody help me with this?
Attached Images
File Type: jpg fluent.jpg (90.0 KB, 41 views)
rudelmops is offline   Reply With Quote

Old   November 9, 2012, 08:56
Default
  #2
Senior Member
 
Marion
Join Date: Jul 2012
Location: France
Posts: 122
Rep Power: 6
Marion is on a distinguished road
Hi,

In which direction is the wall supposed to move?
Could you put an image of the whole domain to get a better idea of your issue?

Marion.
Marion is offline   Reply With Quote

Old   November 9, 2012, 10:12
Default
  #3
New Member
 
Christopher Mai
Join Date: Aug 2012
Location: Dresden, Germany
Posts: 5
Rep Power: 5
rudelmops is on a distinguished road
Hi,

the shaft (wall) moves to the right. So the hole grid should be deformed to the right when I preview mesh motion.
Attached Images
File Type: jpg fluent1.jpg (90.6 KB, 22 views)
File Type: jpg fluent2.jpg (86.4 KB, 17 views)
rudelmops is offline   Reply With Quote

Old   November 9, 2012, 10:23
Default
  #4
Senior Member
 
Marion
Join Date: Jul 2012
Location: France
Posts: 122
Rep Power: 6
Marion is on a distinguished road
Ok, in the smoothing options try increasing the number of iterations (500), decreasing tolerance (0.0001).
Then play with the spring factor. if it's close to 1 I think it only moves nodes close to the moving wall and when it's close to 0 the nodes further away are moved (or is it the contrary? sorry I have to check).
I personnaly use 0.4 for the spring constant.

Maybe hex mesh is not the best for this kind of motion though... except if the displacement is very small.

Marion.
Marion is offline   Reply With Quote

Old   November 9, 2012, 10:24
Default
  #5
Senior Member
 
Marion
Join Date: Jul 2012
Location: France
Posts: 122
Rep Power: 6
Marion is on a distinguished road
Also: don't forget to put EVERYTHING that is deforming as deforming zones: fluid domain + walls or other Boundary Conditions.

If you have nodes on a cylinder that are supposed to be deforming then you should put the cylinder equation in the "geometry" tab.


Marion.
Marion is offline   Reply With Quote

Old   November 9, 2012, 11:00
Default
  #6
New Member
 
Christopher Mai
Join Date: Aug 2012
Location: Dresden, Germany
Posts: 5
Rep Power: 5
rudelmops is on a distinguished road
Hi,

the problem is that only that one layer of cells deform. Adjusting the smoothing options doesn't change that. I did this bearing in 2D and it worked fine. I'm not simulating yet, I just want the whole mesh to deform.

The picture attached shows the deformed mesh of the same bearing gap in 2D.

~Chris
Attached Images
File Type: jpg fluent2d.jpg (91.9 KB, 12 views)
rudelmops is offline   Reply With Quote

Old   November 9, 2012, 11:07
Default
  #7
Senior Member
 
Marion
Join Date: Jul 2012
Location: France
Posts: 122
Rep Power: 6
Marion is on a distinguished road
Ok, but when you changed from 2D to 3D, did you define the geometry of the deforming walls?
Marion is offline   Reply With Quote

Old   November 9, 2012, 11:52
Default
  #8
New Member
 
Christopher Mai
Join Date: Aug 2012
Location: Dresden, Germany
Posts: 5
Rep Power: 5
rudelmops is on a distinguished road
Hi,

the problem is the mesh. I couldn't find the mistake so I started from scratch and now it works perfectly. Thanks for your help though.

~Chris
rudelmops 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
Dynamic mesh problem jojo FLUENT 7 November 18, 2011 05:22
Dynamic Mesh problem Paul_321 FLUENT 11 August 11, 2009 11:32
problem on dynamic mesh zone erkan FLUENT 2 January 8, 2009 17:01
dynamic mesh without defining deforming zone erkan gunaydinoglu FLUENT 0 November 30, 2008 10:03
CFD-3D flow problem using Dynamic mesh method. Sar_mech FLUENT 1 November 27, 2008 22:17


All times are GMT -4. The time now is 09:54.