Validation NACA 2412

DanijelB98 · May 19, 2021, 11:12

Hi guys,

I'm doing a validation of the NACA 2412 profile at Re=2200000. I used a C-grid with 20 chords in the front and 50 on the back. I did a first structured mesh with 60000 and 180000 knots using an adapted bias in order to have y_plus<1.

However, the results regarding Cl and Cd are so different when using K-q SST and SST transitional.

60000 nodes K-W: Cl=0.21314 and Cd=0.009669
60000 nodes SST transitional: Cl=0.23374 and Cd=0.0047277

180000 nodes K-w: Cl=0.21335 and Cd=0.0096094
180000 nodes SST transitional: Cl=0.23549 and Cd=0.0046394

The results of K-w SST are much more similar to the experimental ones. Could there be any problem regarding the mesh, geometry or the boundary condition?

LoGaL · May 19, 2021, 16:03

Which are the experimental results? Also at Re= 2 millions I see no reason to consider laminar to turbulent transition

DanijelB98 · May 20, 2021, 04:08

Thanks, I used tecnhical report of NASA. Considering that i do not have the turbolence for low attack angles, can I use SST transitional above 12 degres where i know the turbolence is going to start?

LoGaL · May 23, 2021, 04:06

You seem to have some confusion between turbulence and flow separation
At Re 2million your flow is going to be always turbulent, but will not always separate

DanijelB98 · May 27, 2021, 04:11

Thanks, i understand

May 19, 2021, 11:12	Validation NACA 2412	#1
DanijelB98 New Member Danijel Join Date: May 2021 Posts: 5 Rep Power: 4	Hi guys, I'm doing a validation of the NACA 2412 profile at Re=2200000. I used a C-grid with 20 chords in the front and 50 on the back. I did a first structured mesh with 60000 and 180000 knots using an adapted bias in order to have y_plus<1. However, the results regarding Cl and Cd are so different when using K-q SST and SST transitional. 60000 nodes K-W: Cl=0.21314 and Cd=0.009669 60000 nodes SST transitional: Cl=0.23374 and Cd=0.0047277 180000 nodes K-w: Cl=0.21335 and Cd=0.0096094 180000 nodes SST transitional: Cl=0.23549 and Cd=0.0046394 The results of K-w SST are much more similar to the experimental ones. Could there be any problem regarding the mesh, geometry or the boundary condition?

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May 19, 2021, 16:03		#2
LoGaL Senior Member Lorenzo Galieti Join Date: Mar 2018 Posts: 374 Rep Power: 12	Which are the experimental results? Also at Re= 2 millions I see no reason to consider laminar to turbulent transition

May 20, 2021, 04:08		#3
DanijelB98 New Member Danijel Join Date: May 2021 Posts: 5 Rep Power: 4	Thanks, I used tecnhical report of NASA. Considering that i do not have the turbolence for low attack angles, can I use SST transitional above 12 degres where i know the turbolence is going to start?

May 23, 2021, 04:06		#4
LoGaL Senior Member Lorenzo Galieti Join Date: Mar 2018 Posts: 374 Rep Power: 12	You seem to have some confusion between turbulence and flow separation At Re 2million your flow is going to be always turbulent, but will not always separate

May 27, 2021, 04:11		#5
DanijelB98 New Member Danijel Join Date: May 2021 Posts: 5 Rep Power: 4	Thanks, i understand