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Old   June 23, 2011, 12:02
Default Help with choosing a viscosity model
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Tom
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Hi, I am trying to model a sort of extended foil shape 2D section and I would like to get a second opinion on the setup. The shape is a narrow rectangular section with the leading edge of a NACA foil on the front and the trailing edge on the back.

The flow is moving at 0.5 m/s with no angle of attack and the reynolds number is around 415000. I chose laminar flow for the simulation but I got some results that were unexpected. I think it is either because of vortex induced vibration or I chose the wrong viscosity model.

The mesh has more than 300000 elements and is a C-shaped mesh.

Any comments on this setup and model choice would be appreciated.
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Old   July 1, 2011, 11:42
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Adrien Lemoine
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Hi,

the best for an airfoil profil in Fluent is to do the geometry as shown in the picture and use a far field fonction on the outside.
You should also think about adding prism layer (3 would be enough) around the airfoil and use a k epsilon realizable with enhanced wall treatment viscosity model

sincerly

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Old   July 4, 2011, 09:42
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According to the reynolds number the flow wont be fully turbulent, which is why I close laminar flow. Are you saying it will be turbulent?

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Old   July 4, 2011, 11:07
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Adrien Lemoine
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Yes, it will be turbulent because the velocity will increase near the naca profil.
So you should use a k epsilon model (or spalart allmaras if the computing is too slow).
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Old   July 4, 2011, 12:05
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Right, I forgot about that. I will give your suggestion a try then. One question though, what do you mean by a prism layer?
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Old   July 4, 2011, 17:09
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I mean the cells that will enable you to get the boundary layer
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