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Sami March 30, 2006 17:25

Aircraft Mesh Recommendation
 
I have only recently started using Fluent/Gambit and I am looking for recommendations on the best method to mesh an aircraft in 3D. (I only have access to Gambit and will not have any other mesh generation software available).

I wish to model a small scale RC aircraft. The aircraft is approximately 3 metres in length, has a chord length of 0.25 metres and will fly at 30 mph.

I have tried to use the boundary layer mesh function, which works good for part of the fuselage, but around the wing and where it connects to the fuselage I always get highly skewed mesh. I then followed the Gambit tutorial for meshing an aircraft, but this results in a y+ value in my simulation that is pretty large (around 150). For the S-A solver, the User Guide recommends a y+ as small as 1. I have made the mesh smaller, but this doesn't reduce y+ by much yet takes a lot longer to run.

Therefore I am wondering if anyone has a standard method/recommendations for meshing an aircraft.

Thank you any assistance,

-Sami

Riaan March 30, 2006 19:54

Re: Aircraft Mesh Recommendation
 
The SA turbulence model is good for y+<1 and 30<y+<300, so if you are getting y+ 150, you are just fine.

Make sure you use T-grid, and build at least 5 prismatic cells in your boundary layer, and ensure that your mesh smoothly transitions from your boundary layer cells to your domain tet-cells.

Anycase, use T-Grid for volume meshes with boundary layers. It does take some time to learn, but is worth the effort (T-grid is part of the FLUENT package).

I only use Gambit to import and clean the geometry, build the surface meshes, and set the boundary conditions. The boundary layers are volume meshes are all done in T-Grid.

For a R/C aircraft, you should be carefull of low-reynolds number effects, and that your boundary layers may be laminar for a large % of chord. In Fluent, adding the turbulence models, means that all your boundary layers will be turbulent from the get go.


riaan April 2, 2006 13:23

Re: Aircraft Mesh Recommendation
 
*Edit

SA good for Y+<1 and 30<y+<300


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