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

imposing normal velocity on wall boundary

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

Reply
 
LinkBack Thread Tools Display Modes
Old   September 14, 2012, 01:10
Default imposing normal velocity on wall boundary
  #1
New Member
 
chiwonkim
Join Date: Sep 2012
Posts: 4
Rep Power: 4
chiwonkim is on a distinguished road
hello,

Some problem drives me crazy.

i tried to solve oscillating plate of speaker.(transient)

Can i impose normal velocity(not tangential) on stationary wall boundary?

if not, please allow me to know which method is appropriate

i already used 'morper' but the magnitude of displacement is too high relative to mesh size, so after several iteration/time step my solver diverged, generating negative volume mesh.

my 2D, axisymmeric model is attached.

Any help can save my life.

thank you
Attached Images
File Type: png speaker.png (5.2 KB, 18 views)
chiwonkim is offline   Reply With Quote

Old   September 15, 2012, 16:00
Default
  #2
Senior Member
 
Join Date: Oct 2009
Location: Germany
Posts: 637
Rep Power: 11
abdul099 is on a distinguished road
No, you can't set up a normal velocity on a wall without except by use of the morpher. All other models will not work since you need to change the topology of your mesh (position of the oscillating membrane relative to the housing of the speaker etc.)

Monitor the mesh quality, and when the mesh starts to get bad, remesh your geometry. Also consider to reduce the time step size. It's better (with respect to mesh quality) to morph several small steps instead of morphing one huge step.
When the oscillation is a constrained motion and therefore the position of the oscillating plate is defined for every time step, you might create several meshes and replace the existing mesh instead of remeshing every period.
__________________
We do three types of jobs here:
GOOD, FAST AND CHEAP
You may choose any two!
abdul099 is offline   Reply With Quote

Old   September 16, 2012, 00:54
Default
  #3
New Member
 
chiwonkim
Join Date: Sep 2012
Posts: 4
Rep Power: 4
chiwonkim is on a distinguished road
Thank you for your help.

So you meen that my computer has a lot of work to do....
i will try remeshing, but i wonder star ccm+ can regenerate 2d mesh because original mesh profile is generated from 'Ansys'.

anyway, thank you again
chiwonkim is offline   Reply With Quote

Old   July 21, 2013, 03:29
Default
  #4
Member
 
Henry Arrigo
Join Date: Jun 2010
Location: Italy
Posts: 91
Rep Power: 6
Henry Arrigo is on a distinguished road
I have been struggling with the same problem and I could not solve the problem yet. I checked almost everything but I could not find the cause. I thought maybe the Morpher solver does not function very well in star-ccm+. Wedge and morpher
Henry Arrigo 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
Difficulty in calculating angular velocity of Savonius turbine simulation alfaruk CFX 8 December 3, 2013 16:51
Wind turbine simulation Saturn CFX 32 October 8, 2013 07:53
External Radiation Boundary Condition (Two sided wall), Grid Interface CFD XUE FLUENT 0 July 8, 2010 06:49
No results for solid domain Gary Holland CFX 10 March 13, 2009 04:30
WALL normal velocity Luca Main CFD Forum 0 August 16, 2005 11:30


All times are GMT -4. The time now is 14:14.