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

Dynamic Mesh Issues

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

Reply
 
LinkBack Thread Tools Display Modes
Old   November 11, 2010, 16:13
Default Dynamic Mesh Issues
  #1
Senior Member
 
Daniel
Join Date: Jul 2009
Location: Montreal, Canada
Posts: 154
Rep Power: 9
dancfd is on a distinguished road
Hello all,

I have been struggling with a dynamic mesh problem for some time now. The model is a 2D C-grid wrapped around an airfoil, the back 25% of which is a different patch: a flap, which I intend to rotate relative to the rest of the wing. The issue is that I cannot find a suitable diffusivity that will prevent the mesh from turning inside-out at the trailing edge. I have tried all of the solver and diffusivity options within the dynamicFvMotionSolver approach, and found that solver displacementLaplacian (using angularOscillatingDiscplacement in the pointDisplacement file) and diffusivity inverseDistance work best. However, the mesh is still very poor at the TE (see pic inverseDist-TE - zoomed in view of trailing edge). I am using OF 1.7.0.

I tried RBFMotion from 1.5-dev, which solved the TE problem but introduced additional problems at the wing. I set the focalPoint at the TE, with an inner radius equal to the flap size and the outer radius beyond the airfoil and then again with the outer radius halfway through the airfoil. Form the pics, it is clear that RBFMotion distorted the rest of the wing, regardless of inner/outer radius selections.

Is there another option available? I have seen discussion about overset grids, however it looks like this is not available. Has anyone dealt with a similar problem - moving part of a piece of geometry, but not the whole thing, and making the diffusivity work? Is there something that can be done using topological changes?

Thanks in advance for any tips/ideas.

Dan
Attached Images
File Type: jpg largeOuterRadiusZoomIn.jpg (93.0 KB, 31 views)
File Type: jpg smallOuterRadiusZoomIn.jpg (93.3 KB, 27 views)
File Type: jpg inversedist-TE.jpg (99.8 KB, 26 views)
dancfd is offline   Reply With Quote

Old   November 11, 2010, 17:20
Default
  #2
Senior Member
 
Ralph Moolenaar
Join Date: Aug 2010
Location: 's-Hertogenbosch, the Netherlands
Posts: 120
Rep Power: 8
Ralph M is on a distinguished road
Hi Dan,

I've never used RBF but was planning to in the near future. However, I was at a OF symposium in Delft last week and Hester Bijl (kind of developer of RBF) showed us that it would be possible to define several points around your object of interest to keep the mesh steady. Not sure how it works though!

Keep us updated on your progress!

Cheers,

Ralph
Ralph M is offline   Reply With Quote

Old   November 11, 2010, 18:46
Default
  #3
Senior Member
 
Daniel
Join Date: Jul 2009
Location: Montreal, Canada
Posts: 154
Rep Power: 9
dancfd is on a distinguished road
Hi Ralph,

Thank you for taking the time to reply. Maybe that multi-point feature is in development; the only point I can define is the focalPoint in dynamicMeshDict.

There must be another way to do this. There is a "frozenPointsZone" set of data that can be read from dynamicMeshDict courtesy of displacementLaplacianFvMotionSolver, however I have put tried everything next to the frozenPointsZone phrase (patch name, set of two coordinates to make bounding box) and though it runs there is no discernible effect. Would loading diffusivities from a file do it?

Thanks,

Dan
dancfd is offline   Reply With Quote

Old   November 12, 2010, 03:41
Default
  #4
Senior Member
 
Ralph Moolenaar
Join Date: Aug 2010
Location: 's-Hertogenbosch, the Netherlands
Posts: 120
Rep Power: 8
Ralph M is on a distinguished road
Maybe try to put the word "banana" at the position where you put your arguments. When you run the case you'll get an error with a list of possible/suitable arguments you can choose from.

Thanks to prof Jasak for the banana-trick

Ralph
Ralph M is offline   Reply With Quote

Old   August 6, 2014, 03:06
Default
  #5
New Member
 
Chen Yu
Join Date: Sep 2013
Posts: 19
Rep Power: 4
chery1986 is on a distinguished road
Hi, have you solved your problem to define frozenPointsZone in dynamicsMeshDict? I encounter the same problem, How to combine dynamic mesh and static mesh

Can you share your solution?

Quote:
Originally Posted by dancfd View Post
Hi Ralph,

Thank you for taking the time to reply. Maybe that multi-point feature is in development; the only point I can define is the focalPoint in dynamicMeshDict.

There must be another way to do this. There is a "frozenPointsZone" set of data that can be read from dynamicMeshDict courtesy of displacementLaplacianFvMotionSolver, however I have put tried everything next to the frozenPointsZone phrase (patch name, set of two coordinates to make bounding box) and though it runs there is no discernible effect. Would loading diffusivities from a file do it?

Thanks,

Dan
chery1986 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
Incylinder dynamic mesh with volumetric reaction mas FLUENT 4 May 3, 2012 10:22
Dynamic Mesh on Pintle type injector. herntan FLUENT 15 January 4, 2012 04:31
dynamic mesh on a hexa grid Manoj Kumar FLUENT 0 August 21, 2007 07:41
Dynamic mesh + grid adapt = Crash! (Files included BillH FLUENT 4 July 24, 2007 15:31
Gambit problems Althea FLUENT 21 February 6, 2001 08:05


All times are GMT -4. The time now is 09:13.