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-   -   [GAMBIT] problems in boundary layer (http://www.cfd-online.com/Forums/ansys-meshing/75153-problems-boundary-layer.html)

yubaibai88 April 18, 2010 02:32

problems in boundary layer
 
3 Attachment(s)
dear all:
I'm new in gambit and recently I am going through the gambit modeling guide for study.but met some problems unable to work out about boundary layer.

first I creat a rectangle.then creat boundary layers in the bottom and right edge.shown in picture 1.

then I mesh the rectangle with QUAD/MAP scheme,and 0.1 interval size.
shown in picture 2.

I want to change the verticle type in buttom-right corner into side.but gain the same result in both unable/disable Boundary layer only option.shown in picture 3.

here is my problem:
1.what does boundary layer do in meshing process.or what effect it has on my meshing result after QUAD/MAP mesh in the rectangle.

2.how could I change the vertex type in meshing.in SET FACE VERTEX TPYES option,I have no choice to determin the domain in which the vertex type could be change(meshing or boundary layer characteristic).

thanks in advance!

-mAx- April 19, 2010 02:40

once you modified your Vertex type(enable "BL only") (and also the BL), delete the face mesh, and remesh the face.
The surface mesh won't be updated if you modify one of it's BL

yubaibai88 April 19, 2010 08:36

Quote:

Originally Posted by -mAx- (Post 255180)
once you modified your Vertex type(enable "BL only") (and also the BL), delete the face mesh, and remesh the face.
The surface mesh won't be updated if you modify one of it's BL

hi mAx:
thanks for your advance.

can you tell me what are the diffenentials/relationship between boudary layers and face meshing.

I mesh the face after creat boundarys along the edge.but as I see there are no association between them.

thank you!

-mAx- April 19, 2010 09:20

Face mesh should be attached to your BL.
Post a picture of what you get (-->" no association between them")

yubaibai88 April 19, 2010 09:43

3 Attachment(s)
Quote:

Originally Posted by -mAx- (Post 255263)
Face mesh should be attached to your BL.
Post a picture of what you get (-->" no association between them")

hi mAx:
thanks for your advances!

here is where my problem come from:

1.I draw a square the side of which is 5.

2.mesh the bottom and right edge with interval count 5.

3.creat boundary layers on the edge meshed in step 2. then I gained image shown in picture 1.

4.then I meshed the face with QUAD/MAP scheme with interval size 1.gained image shown in picture 2.
as you see in picture 2,the face mesh and boundary seem as if they are coincide.

5.it goes without saying that the type of four vertexs on the face are END.now I change the type of button-right corner vertex to SIDE.it gained the image shown in picture 3.

you can see the bounday layers distort and boundary layers remains prior shape.
can you tell me why they perform like this.if the face mesh attach to boundary layer,why it doesn't change shape while boundary layers distort.

thanks you!

-mAx- April 19, 2010 09:54

at point5: delete the mesh, and remesh the face. Gambit will take the new BL in count

yubaibai88 April 19, 2010 10:12

2 Attachment(s)
Quote:

Originally Posted by -mAx- (Post 255271)
at point5: delete the mesh, and remesh the face. Gambit will take the new BL in count

hi:
I solve it,gained the picture 1.and after I hide the boundary gained picture 2.
thank you very much!

-mAx- April 19, 2010 12:55

while changing vertex type, enable "BL only". Thus you will still be able to mesh the face with map schema (because in the face the vertex will still have a End value). In your case, you cannot anymore, that's why you get a mesh with pave schema

yubaibai88 April 19, 2010 21:07

1 Attachment(s)
Quote:

Originally Posted by -mAx- (Post 255309)
while changing vertex type, enable "BL only". Thus you will still be able to mesh the face with map schema (because in the face the vertex will still have a End value). In your case, you cannot anymore, that's why you get a mesh with pave schema

hi mAx:

as you say,I trid again by enable 'boundary layer only',gained image shown in picture 1.that's what I want!

thank you!


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