Possibly Incorrect Cs used in the Tutorial: channel395DFSEM
Hi,
Please consider tutorials/incompressible/pimpleFoam/LES/channel395DFSEM
In the tutorial's README
file, it is stated that:
Channel test case for ReTau=395,based on the reference: Poletto, R., Craft, T., and Revell, A., "A New Divergence Free Synthetic Eddy Method for the Reproduction of Inlet Flow Conditions for LES", Flow Turbulence Combust (2013) 91:519-539
In the page 531 of the above reference, it was reported that the Cs=0.065
was used for the case.
In constant/turbulenceProperties
, the model coefficients that determine Cs
are given as:
kEqnCoeffs
{
Ce 1.048;
Ck 0.07; // 0.094;
}
Considering the Cs = f(Ce, Ck)
relation (also assumed by the community) is as follows:
Cs^2 = Ck * sqrt(Ck/Ce)
Computing Cs
according to this relation yields Cs~0.1345
rather than Cs=0.065
. Assuming Ce=1.048
constant, Ck~0.02654
produces Cs=0.065
according to this definition. In practice, this means, the tutorial is more diffusive than the benchmark. (Admittedly, Cs~0.1345
is approximately twice the Cs=0.065
. May explain this.)
If all aforementioned premises are correct, the tutorial in OpenFOAM currently does not exactly replicate the channel test case, as was mentioned, that the tutorial was based on.
Kind regards