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

Simulate a micro valve with fsi

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

Reply
 
LinkBack Thread Tools Display Modes
Old   July 13, 2011, 04:52
Default Simulate a micro valve with fsi
  #1
Member
 
Frank Weise
Join Date: Mar 2009
Location: Germany
Posts: 39
Rep Power: 9
FrankW is on a distinguished road
Hi,

i try to simulate a micro valve with cfx. My first results of a simple 2D design are bad, because the mesh is distorted on the flap tip at the gap. I have tested many settings at the Mesh Deformation->Mesh Stiffness and i get not really a good deformed mesh. How can get i a good deformed mesh? The goal is to simulate a 3D model of a valve and if does'nt work in 2D i thing there is no chance to get a good 3d model. Has anyone a idea to modify the Mesh Stiffness so that i get usable mesh.

regards
Frank
Attached Images
File Type: jpg Fluid3.jpg (57.4 KB, 30 views)
File Type: jpg Fluid4.jpg (33.8 KB, 18 views)
File Type: jpg Fluid5.jpg (36.0 KB, 16 views)
File Type: jpg Fluid6.jpg (40.3 KB, 19 views)
File Type: jpg Fluid7.jpg (41.0 KB, 17 views)
FrankW is offline   Reply With Quote

Old   July 13, 2011, 09:05
Default
  #2
Senior Member
 
Join Date: Apr 2009
Posts: 532
Rep Power: 13
stumpy is on a distinguished road
Try the expert parameter 'meshdisp diffusion scheme = 3'
stumpy is offline   Reply With Quote

Old   July 13, 2011, 19:38
Default
  #3
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 12,837
Rep Power: 100
ghorrocks is a jewel in the roughghorrocks is a jewel in the roughghorrocks is a jewel in the rough
I would us a GGI to connect the two regions. Then the outer region does not move (or at least not much), and the inner thin region can deform without constraint of the outer region. This will be much easier than thrying to get mesh motion to work across both regions together.
ghorrocks is offline   Reply With Quote

Old   July 14, 2011, 02:45
Default
  #4
Member
 
Frank Weise
Join Date: Mar 2009
Location: Germany
Posts: 39
Rep Power: 9
FrankW is on a distinguished road
Hi,

@stumpy The expert parameter does'nt work. I've seen no effect of this to the deformed mesh.

@glenn What do you mean with inner and outer region? Can you make a sketch. I've defined one subdomain under the flap without meshmotion.
FrankW is offline   Reply With Quote

Old   July 14, 2011, 07:56
Default
  #5
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 12,837
Rep Power: 100
ghorrocks is a jewel in the roughghorrocks is a jewel in the roughghorrocks is a jewel in the rough
How does this look?

Fluid6.jpg
ghorrocks is offline   Reply With Quote

Old   February 14, 2013, 04:21
Default FSI mesh trouble
  #6
u22
Member
 
Anthony Nitski
Join Date: Aug 2009
Location: Earth
Posts: 35
Rep Power: 9
u22 is on a distinguished road
Hello all!

I am trying 3d FSI simulation with CFX 14, it crashes cause negative element is formed (see pic.). Setting meshdisp diffusion scheme 3 not avoid that error... How to get fixed wall mesh to "slide" along Y direction (but Z must be fixed) and to follow Y displacement of mesh on "Moving wall" side?
Attached Images
File Type: jpg BadMesh.jpg (58.7 KB, 11 views)
u22 is offline   Reply With Quote

Old   February 14, 2013, 05:01
Default
  #7
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 12,837
Rep Power: 100
ghorrocks is a jewel in the roughghorrocks is a jewel in the roughghorrocks is a jewel in the rough
Split your fluid domain into 3 joined fluid domains like this, as shown by the orange lines:
fix.jpg

Give the vertical line the same X displacement as the piston, and the horz one the same vertical displacement. Then your mesh will stay nice and orthogonal.
ghorrocks is offline   Reply With Quote

Old   February 18, 2013, 08:55
Default
  #8
u22
Member
 
Anthony Nitski
Join Date: Aug 2009
Location: Earth
Posts: 35
Rep Power: 9
u22 is on a distinguished road
Thanks for the tip, Glenn!

I divided domain into 3 sub-domain. But I did not get how to give to points at stationary wall same displacement as moving wall for corresponding directions.
"Give the vertical line the same X displacement as the piston, and the horz one the same vertical displacement."

I have to use CEL ? Or set some specific conditions at subdomain or walls, like "mesh motions = unspecified"
u22 is offline   Reply With Quote

Old   February 18, 2013, 17:21
Default
  #9
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 12,837
Rep Power: 100
ghorrocks is a jewel in the roughghorrocks is a jewel in the roughghorrocks is a jewel in the rough
On second thoughts this is trickier than I originally thought - I do not know how to specify one dimension but leave another dimension unspecified. I cannot see how to do that. But it would be nice if you could do that, it would make a number of motions simpler to specify. Sorry if I mislead you.
ghorrocks 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
Valve simulation with spring - FSI? Help! farianka CFX 1 April 17, 2011 18:04
Simulation of air flow inside valve - FSI? Help! farianka Main CFD Forum 0 April 17, 2011 16:30
Ansys FSI and CFX (valve simulation) farianka ANSYS 0 April 17, 2011 16:20
How can i simulate a valve motion ???????? popi CFX 6 September 19, 2006 10:54
How to simulate valve with pressure BC? Luk FLUENT 8 June 20, 2006 08:06


All times are GMT -4. The time now is 08:49.