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-   -   A question on "Specifying Boundary Layer Deformation Smoothing" (http://www.cfd-online.com/Forums/fluent/86470-question-specifying-boundary-layer-deformation-smoothing.html)

didiean March 23, 2011 11:56

A question on "Specifying Boundary Layer Deformation Smoothing"
 
Hi, everyone!
I am trying to use dynamic mesh of Fluent 6.3, but I meet with some problems when reading the Fluent 6.3 Help document.
It's about "Specifying Boundary Layer Deformation Smoothing" on Page 11-69 of Chapter 11.7. It describes the steps to define a moving and deforming boundary layer as flows:
"1. Select the moving and deforming zone in the Zone Names drop-down list.
2. Select the User-Defi ned option under Type.
3. In the Motion Attributes tab, select the user-defi ned function that defi nes the geometry and motion of the zone from the Mesh Motion UDF drop-down list.
4. Click Create.
5. Create a deforming dynamic zone for the boundary layer fluid zone by selecting the zone in the Zone Names drop-down list. Note that the boundary layer has to be a separate fluid zone from the adjacent fluid zone. Select Deforming under Type and enable Smoothing on the boundary layer fluid zone.
6. Click Create.
7. Create a deforming dynamic zone for the fluid zone outside the boundary layer by selecting the appropriate zone from the Zone Names drop-down list. Select Deforming under Type and enable Smoothing and Remeshing Methods on the fluid zone. Enabling both methods is necessary because the deforming boundary layer will deform the adjacent cells.
8. Click Create."

It seems to me that the 1st and 7th step have two different operations on the same zone. And the results of the 1st step will be altered by the 7th step. How can this happen?

In addition, can this operation be used for any deformed wall with boundary layers? For example, a beam with one end fixed moves in the way y=x^2*sin(2*t).
Hope I have described my question clearly. Thanks for your attention!

bbhv January 16, 2012 20:20

Boundary Layer does not deform
 
Hi didiean,

I also have a doubt regarding this procedure.
I mesh my boundary layer with prism cells and then meshed the rest of the domain with tetrahedral cells.
The boundary layer and the remaining domain is not separated. There is only one interior zone in the model.
The wing and the boundary layer moves, but the tetrahedral cells do not, so it always hits negative volume at the 1st or 2nd time-step.
Any hints will be greatly appreciated.

Regards,
bbhv

didiean January 16, 2012 22:39

Hi, bbhv.
Maybe you could use spring and remesh for the out tetrahedral cells.


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