Learning Forum

[Nicola Menga]

Hello everyone. 

I'm new to Ansys fluent and I'm trying to simulate the flo around a 2D airfoil.
In many cases in my simulations, comparing results with some available in literature, values of cl are accurated for the Angles of Attack (AoAs) before the stall, while for AoAs beyond the stall angle, no.
In detail, according to the results I've obtained, the stall occurs for greater AoAs and at higher cl values.
So my questions are:
- Is there a more suitable turbulence model for this problem? According to the literature, k omega SST seems to be the most suitable for the case;
- What is a suitable value for y+?;
- Are there any important details to keep in mind when creating the mesh?

I add two figures that describe the above. In both figures, the thicker curve relates to data found in the literature, while the other curves are the results of my simulations.

Thank you very much.

 

[Rob]

Check the NACA tutorials for the reference value checks. Forces are all good, but the coefficients may need some checking. 

Re the mesh, don't just focus on y+. You also need to resolve the bulk flow, and around stall the separation point(s). High aspect ratio cells are fine if the solution doesn't change along the cell (ie attached boundary layer), not so good where the solution does change (separation or reattachment). 

[Nicola Menga]

Thank you for your suggestions. 

[bilal ojaily]

Hi Nicola!

How could you solve in different angles? did you solve each one separately ?

[Nicola Menga]

Hi Bilal.

No, I run the simulations for the different angles of attack automatically one after the other setting the direction of the airspeed vector as input and the values ​​of cl and cd as output parameters

[bilal ojaily]

Ok, thank you my friend

Have a nice day