Dear community,
I’m working in a NACA0012 simulation, following a tutorial that I found on SimScale, but I also want to validate it doing Cl x Cd, Cl x Alpha, Cl/Cd x Alpha and Cd x Alpha graphs.
The problem is that I don’t know how to acquire this graphs in my simulations.
Anyone can help me with that?
Thank you.
Matheus
Hi @mgrandi,
our Power Users @pfernandez, @dylan, @1318980 might be able to help you there.
Cheers,
Jousef
Hi @mgrandi, I actually did one of these last week. Firstly setup your mesh with an inlet-outlet condition, this allows you to alter the AOA iteratively without changing the mesh.
I set up a MATLAB file that produces values at the different angle of attacks with different velocities. since the aerofoil is symmetric in your case running with an AoA between 0 and 25 will give a nice curve. The data you need is the velocity, lift direction and drag directing in vertical and horizontal components.
Run a simulation for AoA of 0 degrees. You will need to define a forces coefficient result control. Duplicate the simulation and change the velocity, and lift/drag direction components at say 2 degrees AoA. Keep doing this until you have the lift and drag coefficients at the various AoA’s and then input the data to Matlab (or Excel) to plot your various graphs.
I’ll post my graphs when I get home and pop the link here.
Kind regards,
Darren Lynch
Out of curiosity, are you able to get the correct Cl and Cd at 25 degrees in 3D steadystate?
Hi @dylan, I ran until 24 degrees and got realistic results. I did have an image of the plots on this post I don’t know where its gone. Did you not get good results?
Kind regards,
Darren
edit: or do you mean for NACA0012?
Yes I mean NACA0012. I havent tried 3D steadystate at large stall angles of a wing, but I do a lot of automotive CFD. From my experience RANS wont predict the correct trend of Cl and Cd in flows with such large separation. RANS also completely misses Cl at times.
If it is multi-element, probably wont stall at 15 degrees.
I am keen to see the curve you had, even if it wasnt for NACA0012.
I guess what you did wasnt NACA0012, and was likely multi-element? Any experimental data?
Hello,
For the inlet velocity, how can I use the table function? It needs 4 columns after U, U and U, what should be the last column ?
Also, for the lift and drag directions, what value for the metres? and why did you say to change direction as lift and drag are always perpendicular and parallel respectively.
Thanks
Sorry, I meant Ux, Uy and Uz, I used the brackets but it removed the letters.
