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

Moving/diforming mesh

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

Reply
 
LinkBack Thread Tools Display Modes
Old   August 9, 2000, 15:59
Default Moving/diforming mesh
  #1
Ali
Guest
 
Posts: n/a
Hi

I am trying to simulate a petrol engine using Fluent software.I have started with a simple cylinder & piston. I have faced a few problems, especially with moving boundries & moving meshes. I would appreciate if can get some help regarding this matter.

Ali
  Reply With Quote

Old   August 11, 2000, 02:49
Default Re: Moving/diforming mesh
  #2
Ahmed Hassaneen
Guest
 
Posts: n/a
Hi Ali, I don't think Fluent has the capability of moving grid by changing the geometrical boundary condition which is the case in Piston engine. However, I believe you can do so by changing the flow boundary with time as the piston moves from BDC to TDC. Goodluck. =Ahmed=
  Reply With Quote

Old   August 11, 2000, 06:02
Default Re: Moving/diforming mesh
  #3
Maurizio
Guest
 
Posts: n/a
Dear Ali,

to better understand your question, can you tell me which approach are you using in Fluent? Did you already set up a moving boundary representing the piston or you have imposed some sort of boundary condition to simulate this motion?

Looking for your answer.

Cheers

Maurizio
  Reply With Quote

Old   August 11, 2000, 09:29
Default Re: Moving/diforming mesh
  #4
Kai Kang
Guest
 
Posts: n/a
Fluent can model the sliding motion of the piston, but not has the deforming mesh capability, so I would be interested to know, too, how to set up the boundary condition in this case...
  Reply With Quote

Old   August 13, 2000, 10:08
Default Re: Moving/diforming mesh
  #5
Ali
Guest
 
Posts: n/a
Thanks everybody who contributed towards solving my problem. I think, I could managed to sort out the problem by considering the piston as dead region (shown below). While the piston is in different position, I created geo & grid files, keeping the same number of nodes (for the geometry) and I & J for dead cells. The results for 2-D steady state and without valves seem OK. Regarding the movement of the valves I can do the same but since the valves touch the intake wall when they are closed, some meshes are disappeared and there will be two mesh regions upatream and downstream of the valves. I am studying this problem and I will appreciate if some one can help me.

With regards,

Ali

IIIIIII IIIIIII

W W W W

W W W W

WWWWWWW WWWWWWWWW WWWWWWW

W W

W . . . . . . . . . . . . . . . W TDC Position

W W

W W

W W

W W

W W

W W

W . . . . . . . . . . . . . . . W Int. position

W W

W W

WDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDW BDC position

WDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDW

W W

W W

W W

W W

WIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIW
  Reply With Quote

Old   August 24, 2000, 13:51
Default Re: Moving/diforming mesh
  #6
oliver
Guest
 
Posts: n/a
Hi Ali

There is a tutorial in fluent user manuals, Fluent 4.5/4.4 (structured), I think. Which shows how to use fluents deforming mesh module.

Read this, this alone should be a good starting point

Regards

Oliver
  Reply With Quote

Old   August 26, 2000, 01:39
Default Re: Moving/diforming mesh
  #7
Ali
Guest
 
Posts: n/a
Dear Oliver; Thank you very much for you comment. It is good for moving objects like a piston. But for the valves which touch the wall and the mesh in between valve and the cylinder (or intake) wall will be destroyed (as the valve get close to the wall) there is noting mentioned. In this position the meshing topology will be different. This is the point I am trying to sort it out !!!???

Ali
  Reply With Quote

Old   August 28, 2000, 16:03
Default Re: Moving/diforming mesh
  #8
oliver
Guest
 
Posts: n/a
Hi Ali

If the valve touches the wall, the cells around this location will have to become dead or wall cells, therefore the identical domain topology will be destroyed so it will not work. However you can simulate the value prior to the point of complete closure.

Regards

oliver
  Reply With Quote

Old   August 29, 2000, 10:39
Default Re: Moving/diforming mesh
  #9
Ali
Guest
 
Posts: n/a
Dear oliver, Thanks again. I am working on it. I will let you know if I could get any positive result.

Ali
  Reply With Quote

Old   August 31, 2000, 20:05
Default Re: Moving/diforming mesh
  #10
Sung-Eun Kim
Guest
 
Posts: n/a
FLUENT 4.5 has a limted capability to handle deforming mesh. There are users who have come up with workarounds and tricks to deal with non-trivial deforming mesh applications. Yet there will still be a limit to what 4.5 can offer.

FLUENT 6.0 will have a far more comprehensive, easy-to-use moving/deforming mesh capability.
  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
[ICEM] surface mesh merging problem everest ANSYS Meshing & Geometry 39 June 5, 2013 19:02
Converting Starccm+ mesh Ladnam OpenFOAM 0 September 14, 2011 06:30
Meshing aifoil in ICEM student123a ANSYS Meshing & Geometry 13 December 8, 2010 11:40
2d irregular grid Remy Main CFD Forum 1 December 22, 2008 05:49
basic of mesh refinement arya CFX 4 June 19, 2007 12:21


All times are GMT -4. The time now is 16:37.