Standard workbench mesh convergent issues
 

Hello CFD-online,

At the moment, I am busy working on a design of a wind tunnel contraction. For this problem, I made a solidworks CAD drawing and imported it in Ansys workbench. The mesher I am using is the standard ANSYS 14.0 workbench mesh (this one is recommended for its simplicity). I learned that for more complex shapes, the ICEM mesher is a better choice.

Well, now my question:

First, I made a medium refined mesh with no refinement/inflation. This mesh gave me some reasonable results, the mesh was tested in invsicid, as well as laminar and turbulence models. However, since I am interested in the boundary layer (separation/thickness), it is recommended to use inflation at the walls. So I did this using automatic inflation at the wall and set the transition ratio at 0,05 with 20 layers. Now the rectangular elements are replaced by triangular shaped elements with thin layers at the walls. When I now try to calculate the results (even with inviscid flow), the residuals are not going down to 1e-6 (convergence criteria learned in some tutorials). So, I think my mesh quality is poor. How can I increase this? I followed several tutorials but that did not bring me closer to my answers.

Thank you all in advance!