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-   -   Help with choosing a viscosity model (http://www.cfd-online.com/Forums/fluent/89849-help-choosing-viscosity-model.html)

xTamx420 June 23, 2011 12:02

Help with choosing a viscosity model
 
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.

AdrienL July 1, 2011 11:42

1 Attachment(s)
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

Adrien

xTamx420 July 4, 2011 09:42

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?

Tom

AdrienL July 4, 2011 11:07

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).

xTamx420 July 4, 2011 12:05

Right, I forgot about that. I will give your suggestion a try then. One question though, what do you mean by a prism layer?

AdrienL July 4, 2011 17:09

I mean the cells that will enable you to get the boundary layer


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