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Stefano December 10, 2002 07:13

Ground Effect & Turbolence Model
 
I have to study the Ground effect. Anyone knows which one is the best model for this kind of problems? - ke hi reynolds - ke low re - ke RNG - two layers Thanks

Nicola December 11, 2002 06:25

Re: Ground Effect & Turbolence Model
 
Hi Stefano,

what do you mean with "Ground effect"? The turbulence models are depending on Reynolds-number, wall roughness, the grid, etc. Read about them in the methodology-manual.

Stefano December 11, 2002 07:09

Re: Ground Effect & Turbolence Model
 
Nicola, i have a profile moving near a wall so i have zone at low Re number but also zone ( throw profile and wall ) at high velocity and high viscous effect. IN the past i used ke Hi Re number, now i'm using RNG model but the coefficients i found ( lift and drag) are different from ke ( expecially lift ), and the y+ values are often really high. I refine the mesh more times but y+ changes any time i change the value of U inlet velocity Have i to try 2-layers model?

marco December 17, 2002 07:59

Re: Ground Effect & Turbolence Model
 
Hallo Stefano!

For your problem the 2-Layer model should be the best choice. Anyway you need a very fine mesh: more then 10 cells should be contained in the boundary Layer! That means Y+ < 1.

Moreover, as the y+ values are depending on the flow velocity, you need feiner meshes for higher velocities.

Regards

Marco



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