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teguhtf October 22, 2009 00:42

How work with grid interface??
Hi All,
In Modeling airfoil, I want to just make some variation of Angle of Attack. I hear that Grid Interface can make my job simpler. i read in tutorial of FLUENT there is correlation with TGRID. But i don't understand how it works. can you tell me How to make simulation by using grid interface??:confused:

-mAx- October 22, 2009 02:16

You need to have 2 separated zones which are not connected.
At the interface between the 2 zones, you will have 2 superposed entities (edge for 2d, surface for 3d).
Just define each entity as separated interface. Then in Fluent, define the couple of interfaces (define/interfaces)
In your case, you create a circle around your airfoil, the interfaces will be the 2 superposed circles.
Check Help (11. Modeling Flows Using Sliding and Deforming Meshes)

teguhtf October 22, 2009 12:44

Thanks For your response. I've tried. But i doesnt work. Here is my file. I jut want to rotate my foil.
Thanks for your help!!!:)

-mAx- October 22, 2009 13:55

Will check it on Monday

-mAx- October 26, 2009 02:55

I check the dbs file and it is alright regarding the interface definitition.
So you shouldn't have proble to define them in fluent.
What kinds of error do you get?
2 points on your gambit session.
* your mesh should be refined around your moving body (in your case the mesh get coarser near the body)
*you have to define the rotating domaine (surface) as separated fluid domain, because you will also rotate this region

teguhtf October 26, 2009 05:59

I'm not using dynamic meshing!!!
In my case, i don't use dynamic mesh in rotating things. I use Grid Interface to make my geometry become less than make geometry in each angle of attack. I hear that in ANSYS, I just make 2 geometry to complete my Angle of attack (I mean geometry of circle & rectangle and I just rotate my circle by using grid interface).
I'm sorry if my mesh is very poor. My focus on meshing is objected in quality of meshing. I don't know what is the best meshing!!
Thanks for your help!!:D

-mAx- October 26, 2009 06:36

Ah ok, I thought you wanted your airfoil rotating. Sorry.
So you just have to rotate you middle surface in Gambit with your specific angle, and then export your mesh.
I have no idea with Ansys.
Regarding your mesh, and especially your grid interface, the mesh in this region has to be +/- with the same size.
Best mesh is always quad/map, but the question is: can you afford spending many days trying to mesh your model with full hexa.
In your case, don't hesitate you can easy mesh your stuff with hexa

teguhtf October 26, 2009 07:36

yes, I'll try it!:)
In this problem, I use 2D solver. By the way, what is the meaning of "Regarding your mesh, and especially your grid interface, the mesh in this region has to be +/- with the same size"??
Is it meaning that the meshing of interface one and other must similar??
thank you very much!!

-mAx- October 26, 2009 07:44

not exactily similar, but not 5x bigger (resp. smaller).

teguhtf October 27, 2009 05:58

I'll try it.
Anyway, do you know the basic calculation of FLUENT in computing Lift Coefficient in 2D?? because There is no Area in 2D.
Thank you!!

-mAx- October 27, 2009 06:35

I assume you have to enter a reference length in place of the area.
The coeff will be still dimensionless, as the force is computed on an edge (and not a surface)

teguhtf October 28, 2009 22:48

what is voume statistic in FLUENT 2D
Thanks, by the way. when i use FLUENT 2D there is volume statistics when i check my *.msh. what is that?? I have thought before that the value of Cl based on that volume.:confused:

-mAx- October 29, 2009 02:56

check Mesh is only informations about your mesh topology/quality/etc...
No link with Cl

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