CFD Online Logo CFD Online URL
Home > Forums > CFX

Mesh Stiffness Option for Mesh Deformation

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

Like Tree1Likes
  • 1 Post By Mike

LinkBack Thread Tools Display Modes
Old   January 9, 2006, 09:00
Default Mesh Stiffness Option for Mesh Deformation
Posts: n/a
I am returning to a problem I encountered previously regarding the modelling of an oscillating aerofoil, and the mesh stiffness when using a prescribed sinusoidally varying oscillation.

In the manual it suggests the following for mesh stiffness:

1 [m^3 s^-1]/Wall Distance

Could anyone expand further as to what this term will do, particularly in relation to the term Wall Distance (does this require substituting with a value based on my mesh geometry?).

Thanks in advance
  Reply With Quote

Old   January 10, 2006, 10:41
Default Re: Mesh Stiffness Option for Mesh Deformation
Posts: n/a
The mesh stiffness controls which parts of the mesh will deform. The absolute value is not important - so a constant mesh stiffness of 1 or 1 million will give the same result. What is important is how the mesh stiffness varies throughout the domain. Areas with a lower stiffness will deform more that areas with a high stiffness. Generally speaking, you want the mesh near the walls to remain stiff so that your boundary layer mesh remains "nice"; therefore the volume mesh away from the walls will deform to any motion of the boundaries. Wall Distance is a variable equal to the distance from the nearest wall boundary. So a mesh stiffness = 1/Wall Distance will keep the boundary layer mesh stiff and cause deformations to be absorbed in the volume mesh. Another useful formula for mesh stiffness is: 1/Volume of Finite Volumes This will make small elements stiff - the boundary layer usually has small elements. Also, elements that have already deformed a lot and are close to folding will become stiff. M
Omran likes this.
  Reply With Quote

Old   January 10, 2006, 11:19
Default Re: Mesh Stiffness Option for Mesh Deformation
Posts: n/a
Thanks Mike, will give these a go

  Reply With Quote

Old   January 19, 2006, 17:33
Default Re: Mesh Stiffness Option for Mesh Deformation
Posts: n/a

depending on the geometry you are deforming it could be that there no difference between the formulations

<1/wall distance> or <1/volume of finite volumes>!

Perhaps you can also try the formulation

<1/wall distance^n> with n > 2

  Reply With Quote


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
CFX Parameters Settings Flaky CFX 21 October 28, 2010 18:16
increasing mesh quality is leading to poor convergence tippo CFX 2 May 5, 2009 10:55
Icemcfd 11: Loss of mesh from surface mesh option? Joe CFX 2 March 26, 2007 18:10
about compresive phase James CFX 10 September 12, 2006 03:16
Two-Phase Buoyant Flow Issue Miguel Baritto CFX 4 August 31, 2006 12:02

All times are GMT -4. The time now is 07:01.