Learning Forum

[Bradipo70]

Hello everyone,

I am trying to validate for my corse of study the NACA 6412 airfoil, reproducing the diagrams AOA-CL and AOA CD. I generated the geometry with Catia as surface. In the last attempt I followed the example of the NACA 0012 validation, the pictures in attachment show the configuration that I adopted, without any results.
I would like to remind you that Ansys is new to me.

Thanks in advance for your help.

 

 

 

[Keyur Kanade]

what is the  question. can you please be more clear. 

https://confluence.cornell.edu/display/SIMULATION/FLUENT+-+Flow+over+an+Airfoil

 

[Bradipo70]

Yes, you are right.

I am not capable to get the right value for the Cd and Cl at different angles of attack. I tried different kind of meshes without positive results, which I suppose aren't good to validate a wing.

In attachment there are the two charts that I obtained with the AOA from zero to six.

I think the mesh is good and I am doing some errors about the software set up but I can't understand where is my mistake.

Best regards

Andrea

 

[Bradipo70]

   I forgot the picture about the mesh and its set up.

 

Best regards

Andrea

[Rob]

There are a few tutorials on YouTube covering aerofoils (airfoils) which will give some pointers. There are also several threads on here on the same subject. 

[Bradipo70]

Hi there,

I had look on most of them, but the key point is all of them follow a different plan to get the same results and I am not so experienced to understand some differences about the set up.

Best regards

Andrea

[Rob]

As we're supposed to teach as much as fix stuff on here:

What are the differences, and then on reading around the subject why would they effect the solution?  Think about things like y+ ,  density and Reynolds Number (turbulence modelling). 

[Bradipo70]

Hello there,

 

I followed your advice, I modified the mesh setting up the Y+>30.

Now I am capable to get the right lift and drag coefficients in a range of 3.2% for few points with different set up after many trials.

Could be the high Reynold's number (10^6) that I am using the problem?

I don't know if I have change the density set up, and eventually how I can do that.

 

Best regards

Andrea

[Karthik Remella]

Hello,

For these kind of problems, it all comes down to which model you are using, how good your mesh is, and what sort of convergence are you getting. It might be dependent on either one or any of these combinations. You might want to make sure the model and mesh you are using are compatible. Once you get a converged solution, it is a good practice to check your Y+ values.

On a good mesh, even with a high Re number, you should still be able to solve the problem with reasonable accuracy.

Thanks.

Best,

Karthik