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Ilu October 14, 2008 10:49

direction of boundary layer in gambit

I have an annoying problem in gambit. I'm trying to mesh a 2d geometry of airfoil. The problem is that when ever I make boundary layer for the airfoil, gambit decides to make it INSIDE the airfoil. So if you could tell how to make it outside (other side of the edge) the airfoil it would be great.

I have already read the tutorial where it says that you can change the direction by means of mouse (shift + middle-click) but that just makes the boundary layer to disappear and does no good.

I have also tried to understand the tutorial where it says that you could change the direction by adding another edge (or face) in the attachment box but I don't understand how to do that. In the attachment box it just shows the edge I have chosen and if I add another it just makes another boundary layer to that edge

I have imported my model in IGS format from Solid Edge, so do you think that might have an effect ?

doki October 14, 2008 11:55

Re: direction of boundary layer in gambit
I think that might be because you have defined the airfoil surface as a face. the point is you can generate mesh around an airfoil when you have defined the faces between inner and outer boundaries. other thing is you can not mesh outside of an airfoil having defined just the airfoil surface. that means you need to define an outer boundary too! defining the faces as mentioned, you can simply define the BL.

Ilu October 14, 2008 13:25

Re: direction of boundary layer in gambit
hmmm... I'm not quite sure I understood what you meant by inner and outer boundaries. Here is a picture of the situation:

the airfoil consists of 4 edges (which I have made as one face) which are meshed in this picture.

Prasad Dudhgaonkar October 15, 2008 06:11

Re: direction of boundary layer in gambit
Hi Ilu,Just out curiosity I would like to know whether you've modeled the domain around the airfoil with nothing inside the airfoil edges or the airfoil itself.

doki October 15, 2008 07:25

Re: direction of boundary layer in gambit
I could not open the link you sent, I mentioned before there is no need in meshing inside the airfoil. instead, you should define an outer boundary for the computational domain, which contains the airfoil, and then define some faces in the space between this boundary and the airfoil surface. then you should generate mesh inside these faces!

Ilu October 15, 2008 07:47

Re: direction of boundary layer in gambit
Sorry Prasad, I couldn't quite understand your question. And Thanks Doki for your advices, I try them today.

Ilu October 15, 2008 09:25

Re: direction of boundary layer in gambit
Ok, I got it working. What I did was that I subtracted (from the geometry -> face -> boolean operations menu) the airfoil face to the rectangular outer face. Now it makes the boundary-layer on the right side. Thanks for all :)

peyman October 16, 2008 03:20

Re: direction of boundary layer in gambit
Hello Its seems in gambit you can only by define new surface in that direction you want, change direction of boundary layer.

I do not know english very well, please forgot me.

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