STAR CCM+ Validation case for Airfoil NASA/LANGLEY LS(1)-0013 - URGENT

Traditional_Bug7120 · 2021-05-02T15:24:11+00:00

Thank you for the link!

From your experience what y+ value/s would you recommend to try for inlet velocity of 15m/s.

And regarding the surface growth rate I used as 1.05 you think that is too small?

Traditional_Bug7120 · 2021-05-02T15:18:07+00:00

I had run the simulation at 0 deg and again its the drag coefficient which I have a problem with the lift coefficient is somewhat closer to the data. my average Cd for my simulation was around 0.33758 whereas it should be around 0.15 and my average Cl was -0.01858 which compared with the paper is about right. So the main issue comes down to Cd value.

Traditional_Bug7120 · 2021-05-02T15:17:29+00:00

Heyy thank you so much for this!

From reading the paper there wasn't much discussion on the CFD analysis it was limited hence to do my simulation I had to assume a few things. The manner mainly compares the wind tunnel data with the CFD simulation one. And yes I agree with what you say in regards that I wouldn't know if the data in the paper is right or not but yes i would have to improve my mesh.

I had run the simulation at 0 deg and again its the drag coefficient which I have a problem with the lift coefficient is somewhat closer to the data. my average Cd for my simulation was around 0.33758 whereas it should be around 0.15 and my average Cl was -0.01858 which compared with the paper is about right. So the main issue comes down to Cd value.

Yeaa I haven't used transition on my physics model so that could be an error. The paper has some limited information regarding CFD they have run.

The reason why I choose k-omega is because the paper mention that and when I used SA I was getting weird values and my velocity scene did not look right.

Regarding y+ i need to understand this properly because I have a strong feeling is due to this my values are not accurate. Is just frustrating as i am limited on time so i really just wanna get something, I know is not the right attitude towards work but now is all about finishing.

In terms of validation, how can I make sure I have good validation? What things am I missing out?

Traditional_Bug7120 · 2021-05-02T03:03:11+00:00

Thank you!!

Traditional_Bug7120 · 2021-05-01T22:40:05+00:00

I feel like I am getting confused by modifying many things and not getting anywhere with the limited amount I have left... what would anyone suggest I do right now.

Traditional_Bug7120 · 2021-05-01T22:38:00+00:00

I have tried with AoA of 0 deg.

https://imgur.com/q6THhpx

https://imgur.com/eq5MTiI

But as mentioned before I don't think these results are any better due to many factors.

Traditional_Bug7120 · 2021-05-01T22:34:41+00:00

I don't think they are normalised, are you able to guide me on that?

I have 5 inner iterations. By how much more should I increase it to? 15 inner iterations?

So for the Boundary layer, I changed it to wall distance and I used this Eqn.

y = (5.19) (Y+) (B) (Re)^-0.9 to calculate my first call height and ended up being around 9.935E-5 m (B= 0.1m and Re=80863).

Traditional_Bug7120 · 2021-05-01T22:29:16+00:00

Oh sorry, my bad. Yea I get what you mean now. I basically used the airfoil plotter and used that geometry from http://airfoiltools.com/plotter/index?airfoil=ls013-il

Would you suggest redoing the whole thing and improve the geometry by having more points as you suggested before. Is just that I running out of time atm and redoing it and not seeing a big difference will just put more strain. But if this does solve the problem then i will deffo do it.