Turbulent Length Scale and Intensity for Airfoil
I am running a simulation of 3D wing (NACA 2412) of chord length 1m and span 0.3m in STAR CCM 4.04. I am using Spalart-Allmaras model. Now, I am in great trouble on setting the value of Turbulent Length Scale and Intensity. I am not getting any clue how to set the value of this parameter.
Anybody can help me- how can I set the value of Turbulent Length Scale and Intensity? I highly appreciate your suggestions.
Let me say that the wing you are on to is very interesting. Due to its very low aspect ratio the tip-vortex will dominate the entire flow which is essentially very hard to investigate.
However if you would like to calculate lift and drag, you can google some NACA papers and find some focused on determining 3D characteristics of an airfoil from 2D characteristics. As input, you can find easily 2D characteristics of 2412 or calculate via CFD.
I think turbulence length scale and intensity are should be thought secondarily. While simulating the flow around an airfoil, those parameters are applied to the boundary conditions, especially to the free-stream. For a such flow, turbulence intensity can be taken between %1 and %5. Turbulence length scale isn't very easy to determine but initially you can accept it 10 or 25 percent of the wing chord.
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