[Irstea]

Hello everybody,

I'm post Processing some calculations made with OpenFoam in order to confront them against some experimental data. These simulations are diphasic RANS with RSM turbulence Model.

I'm struggling right know with the Reynolds Stresses tensor compute by OpenFaom.
To be sure that I'll compare the same thing between xp and sim, I exported U and R fields from Openfoam and check that I manage to find OpenFoam results from U.

From U, I recalculated the Reynolds Stresses tensor from the basic :

Rij = Mean(u'iu'j)

That is just to calculate the covariance Matrix of U (Cov(U)).

Unfortunetly, when I compare the post process values of U with the R exported from OpenFoam, it does not match.

I've got R(openFoam)=\sqrt{R(postprocess)}.

It means for the diagonal, it seems that Openfoam calculates the standard deviation of U instead of the variance U.

However, when you check the units of R(openfoam), the R file tells you that is in m²/s².

I exported results calculated directly from the simulation and those made by the post-process function 'R', and I've got the same issue.

Is it just that definition of R in openfoam is not quite the same than in litterature? But why is it still in m²/s²?