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-   -   how to smooth the juncture with Gambit easily? (http://www.cfd-online.com/Forums/fluent/29038-how-smooth-juncture-gambit-easily.html)

 Zhang Junmei November 5, 2001 04:23

how to smooth the juncture with Gambit easily?

Hello,everyone,

As a enterprising new learner of Fluent, I need your help indeed.

Now,I am using GAMBIT to build the geometry of one model,which is composed of two cylinders with different diameter.These cylinders intersect each other with 30 degree.If I just set up the two cylinders,then unite them,the juncture is sharp. However I want to smooth the joint of these cylinders, which seems like the shape of a saddle.Therefor how can I realize it easily with Gambit?

Thanks a lot!And I am looking forward to hearing from you!

Best Wishes,

Zhang Junmei

Sep.12,2001

 AJ01 November 6, 2001 11:26

Re: how to smooth the juncture with Gambit easily?

Is it 3D or 2D problem? 2D would be comparatively much easier to mesh. Use a sphere and split the volumes as given in Gambit training manual for pipe joints. Remove the unwanted volumes Then you can use cooper hex meshing! Or use a plane at 30deg to connect the two volumes. I hope there could be several ways of doing this! Enjoy!

 Zhang Junmei November 7, 2001 09:05

Re: how to smooth the juncture with Gambit easily?

Thanks for AJ01 very much!

Your suggestion give me a great help to mesh the geometry.However I still have some problems about building the geometry,that is to say I don't want the two cylinders intersect each other sharply.I want it have some smooth joint.Whould you please to give me some advice?

Thanks a lot!

I am looking forward to hearing from you!

Zhang junmei

 Erwin November 7, 2001 14:16

Re: how to smooth the juncture with Gambit easily?

You can't use a 2D approach with 2 intersecting pipes because it is not axisymmetrical.

Instead, use the 'Fillet' function to smooth the intersection between the faces.

 Zhang Junmei November 7, 2001 22:56

Re: how to smooth the juncture with Gambit easily?

Thanks very much for Erwin!

Do you mean that I shall set up several cross-sections around joints,then sweep them to build the volume of joint?

That is a good idea!

However do you know how to set up cross-sections quickly? Is there any mathmatical formulas?

Thanks for your help very much!

I am looking forward to hearing from you! Best wishes,

Zhang Junmei

 Erwin November 12, 2001 10:51

Re: how to smooth the juncture with Gambit easily?

Why don't you try the 'Blend Volumes' function? It's basically the 3D version of a fillet. Join your pipes, and then select 'blend volumes' option. Use 'Edge' as your blend type, which opens a new panel, in this panel select the intersecting edge(s) and define the radius of your smoothed edge. Select 'Apply' to close this panel and select 'Apply' in the main panel.

The one problem with this approach is that you end up with volumes/faces that are difficult to mesh with hex/quads cells, so you may need to create some virtual faces to overcome that.

 Zhang Junmei November 12, 2001 22:22

Re: how to smooth the juncture with Gambit easily?

Erwin,thanks for your help very much! Your suggestion gives me a good idea to smooth the geometry. However,for the cylinders in my model just intersects each other partly,not wholely,it looks like the three-way pipe,one inlet,two outlets.So the interface is a face with one edge.Therefore maybe it is difficult to choose edge in the "blend volumes".Would you please to give me some advise about this? Thanks for your help very much! I am looking forward to hearing from you! Best wishes, Zhang Junmei

 Erwin November 14, 2001 15:04

Re: how to smooth the juncture with Gambit easily?

My advice: just experiment. Check how Gambit handles the blending and decompose the geometry further if you need to. This is where the creativity comes in!

 Zhang Junmei November 15, 2001 22:16

Re: how to smooth the juncture with Gambit easily?

Hi,Erwin,Thanks for your idea very much!

When I split the edge of intersect face,I can blend the volume successfully.Therefore I appreciate for your help very much.

However the gambit seems only can blend one intersect corner of the volume.If I also blend the other edge,it will say-too complex.Is it due to the complex geometry after blend one edge of the volume?

Thanks for your help very much! Best wishes, Zhang Junmei

 Erwin November 16, 2001 16:15

Re: how to smooth the juncture with Gambit easily?

Try selecting both edges simultaneously in the 'Edge Blend Type' panel, rather than trying to do blending in series. Also, be careful not to create slivers, something that sometimes happens easily with this operation.

It is hard for me to visualize your problem, if this doesn't work then it is maybe better to contact your Fluent support engineer...

 Shyam Kishor November 19, 2001 13:48

Re: how to smooth the juncture with Gambit easily?