NACA 0012 2D - SA model - Drag overprediction

Panglos · March 27, 2019, 17:04

Hi everyone!

As the title suggests I am facing some problems while trying to simulate the flow around a NACA 0012 airfoil. Basically, I obtain drag coefficient values which are overestimated compared against the experiments.

I am using a Spalart-Allmaras model with nu_tilda = nu and nut/nu_tilda = 3. I tried different meshes, boundary conditions and numerical scheme by I always end up with some discrepancies. E.g. for the 0 angle of attach I obtain 1e-3 instead of 6e-4

Find at this link the setup for my case:
https://we.tl/t-10bcvAXo4n

Thank you in advance for your time.

mzzmrt · March 28, 2019, 11:40

It may be mesh or boundary condition related.

Could you try another meshing approach other than blockMesh? I strongly recommend Construct2D for this purpose.

sheaker · March 28, 2019, 13:55

Hello.

I think You need a transitional model like k-omega SST or gamma re theta.
In Spalart-Allmaras model flow is fully turbulent everywhere so drag coefficient is overestimated.

Please correct me if I am wrong.

Best regards,
Oskar

March 27, 2019, 17:04	NACA 0012 2D - SA model - Drag overprediction	#1
Panglos New Member Join Date: Sep 2015 Posts: 5 Rep Power: 11	Hi everyone! As the title suggests I am facing some problems while trying to simulate the flow around a NACA 0012 airfoil. Basically, I obtain drag coefficient values which are overestimated compared against the experiments. I am using a Spalart-Allmaras model with nu_tilda = nu and nut/nu_tilda = 3. I tried different meshes, boundary conditions and numerical scheme by I always end up with some discrepancies. E.g. for the 0 angle of attach I obtain 1e-3 instead of 6e-4 Find at this link the setup for my case: https://we.tl/t-10bcvAXo4n Thank you in advance for your time.

March 28, 2019, 13:55		#3
sheaker Senior Member Oskar Join Date: Nov 2015 Location: Poland Posts: 184 Rep Power: 11	Hello. I think You need a transitional model like k-omega SST or gamma re theta. In Spalart-Allmaras model flow is fully turbulent everywhere so drag coefficient is overestimated. Please correct me if I am wrong. Best regards, Oskar __________________ How to set two stroke engine with scavenging? Salome, sliding interface and "Zero length edge detected."

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March 28, 2019, 11:40		#2
mzzmrt Senior Member Join Date: Mar 2014 Posts: 112 Rep Power: 12	It may be mesh or boundary condition related. Could you try another meshing approach other than blockMesh? I strongly recommend Construct2D for this purpose.