dnsFoam parameters ?

harshad88 · November 13, 2014, 20:22

Hello all,

I am studying the dnsFoam tutorial to generate isotropic turbulence for a 32 X 32 X 32 grid on a cube of side 10mm.

How do the parameters kUpper, kLower, alpha and sigma depend on the domain size and the reynolds number etc.

Anyone has any idea or any references I can look into? Please help

Thanks!

harshad88 · November 14, 2014, 16:56

So I found this paper online:

Quote:

V. Eswaran and S. B. Pope, "An examination of forcing in Direct Numerical Simulations of turbulence, Computers and Fluids, Vol. 16, 1988"

It seems that the forcing technique that OpenFoam uses for its FFT in dnsFoam is derived from this paper (using the Weiner Process). From the paper I could guess that

kLower = 2*pi/L (L is the length of the cube)
kUpper = sqrt(2)*kLower

I still havent been able to figure out what values of Eo, alpha and sigma to put for a size L cube. Any ideas anyone?? Please help

Thanks!

November 13, 2014, 20:22	dnsFoam parameters ?	#1
harshad88 New Member Harshad Lalit Join Date: May 2013 Posts: 26 Rep Power: 12	Hello all, I am studying the dnsFoam tutorial to generate isotropic turbulence for a 32 X 32 X 32 grid on a cube of side 10mm. How do the parameters kUpper, kLower, alpha and sigma depend on the domain size and the reynolds number etc. Anyone has any idea or any references I can look into? Please help Thanks!

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