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k and omega values for 2D input simpleFoam

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Old   July 18, 2018, 05:37
Default k and omega values for 2D input simpleFoam
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Alberto Rinaldi
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Hi there,

I am approaching to run a 2D simulation of a profile. I initialize the flow with simpleFoam and then use steady-state fields as initialization for pimpleFoam.

My question is how to calculate k and omega at inlet for simpleFoam.

Experimental data are:
  • Airspeed U=13.33 m/s
    Turbulence intensity I= 0,003
    Wind tunnel sizes Lx=4m, Ly= 4m (hydraulic diameter dh=4m)

Should I use the values as for a 3D simulation?
k=3/2*(U*I)^2= 0.00239
omega=sqrt(k)/L=sqrt(k)/(0.038*dh)=0.32

do these values make sense for a 2D simulation?

Thanks
Alberto
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Old   August 2, 2018, 03:47
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The numbers are the same for 2D and 3D cases:

https://cfd.direct/openfoam/user-guide/v6-cavity/
Quote:
OpenFOAM always operates in a 3 dimensional Cartesian coordinate system and all geometries are generated in 3 dimensions. OpenFOAM solves the case in 3 dimensions by default but can be instructed to solve in 2 dimensions by specifying a ‘special’ empty boundary condition on boundaries normal to the (3rd) dimension for which no solution is required.
Instead of manually calculating values, I use boundary conditions:
  • turbulentMixingLengthDissipationRateInlet for omega
  • turbulentIntensityKineticEnergyInlet for k
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2d simulation, inlet boundary condition, k-omega sst, simple foam, turbulence model

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