Convergence problem due to meshing one area
 

Hello.

I'm doing 2D paraglider airfoil simulation and I have some convergence problem due to meshing.
As you guess, paraglider's leading edge is open in order to fill the air inside and inflate the paraglider.
I use y+ = 1 and use spalart allmaras or SST-Kw model. I even try the RSM model.

When I'm meshing, I mesh outside and the inside of the paraglider, as you can see in the attachment "1".
BUT! I can not make it converged. It oscillates.

I wondered and tried to close the leading edge, to act it like a normal airfoil, As you can see in the attachment "2". Then, it converged easily.

So, I wonder why It doesn't converges when I opened the leading edge and mesh in it too. I use same methodology in 2 cases.

Thank you for your answers.

use Kinsey Barth parameter in the smoothing parameters when you are trying to extrude your boundary and creating you domain. It will help you to create high quality cells which are fairly orthogonal.