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-   -   L/Δ factor for LES mesh (http://www.cfd-online.com/Forums/ansys-meshing/85101-l-factor-les-mesh.html)

faisal_durr February 17, 2011 08:56

L/Δ factor for LES mesh
 
Hi guys, im going to run an LES case for buoyancy driven natural ventilation case. Guys i have been told by my supervisor that to check if the mesh i have selected is fine enough for LES i need to first run a RANS simulation on that mesh density. Once that is done i have to check if L/Δ > 20. If this condition is met then the mesh is ok for LES as well.
Now L = integral turbulence length scale = [k^(2/3)]/ε
and Δ = filter width (grid size)
and that L/Δ= (k/
kSGS) this is what i need to calculate.
Let me define:
KRES= resolved kinetic energy

KSGS= subgrid-scale kinetic energy

K = total turbulence energy = KRES + KSGS

Guys i hope u can tell me a way of how i can calculate this L/Δ factor as i have got the RANS results. Thank you :)


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