|April 30, 2012, 14:05||
NACA 0012 K-omega model
Join Date: Jun 2011
Posts: 48Rep Power: 7
I'm struggling to get a k-omega model to run a FLUENT simulation of a naca 0012.
The 0012 is at zero degrees angle of attack, with a chord of 1 meter. The rectangular domain is a tet mesh whose inlet is 20 meters upstream and outlet is 40 meters downstream with the top and bottom of the domain at +/- 20 meters from the airfoil. It should be a big enough domain and a fairly simple and classic simulation.
This sounds like a very broad question but how would I get the k-w model to produce good results? My understanding is that k-w has the potential to predict transition so could k-w run at a Re# of say 1.3 million by specifying the inlet velocity of 20 m/s? It doesn't seem to work when I tried it. The velocity contours show a low velocity bubble around the airfoil and then acceleration way downstream.
k-w can also do compressibility apparently. So I tried running a density solver with the energy equation on, and the k-w compressibility option turned on. I used pressure-far-field conditions for the inlet, top and bottom of the domain (M=0.8) and a pressure outlet with a turbulent intensity of 0.1%. That solution diverged.
Sooooo it should be a fairly simple simulation. I'm not sure what I'm doing wrong here. I was able to get a k-epsilon model to run assuming a turbulent Re# (about 4.8 million; inlet velocity 70 m/s). If I step outside of this regime,I would have to change models because my flow would not be fully turbulent, which is my whole motivation for trying to get a k-w model to run at both low Re# and compressible flows.
One issue might be the turbulent intensity and viscosity ratio. I set 0.1% for the intensity because I read on cfd-online that's an estimate for intensity for external flows around aircraft/cars/etc. could be much less than 1%. I left the viscosity ratio as 10 and it worked out very well for the k-e turbulent case that I ran.
Any ideas of how to get some meaningful results?
|May 1, 2012, 14:41||
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 1,372Rep Power: 20
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