|October 2, 2008, 04:11||
Dear OpenFOAM users! I've s
Join Date: Mar 2009
Location: Moscow, Russian Federation
Posts: 172Rep Power: 7
Dear OpenFOAM users!
I've started verification of OpenFOAM with abrupt area change studies. The goal - is to calculate total pressure loss and compare it with experimental data.
I found, that for sudden expansion i have difference 3-15%, which is normal
but for sudden contraction difference for loss coefficient is bigger then 20%, this is unsatisfactory.
below are formulas for loss coefficients
Cf_contraction = dP_tot/(w0^2/2)=0.5*(1-F0/F1) (1)
Cf_expansion = dP_tot/(w0^2/2)=(1-F0/F1)^2 (2)
where F0 - area with small section
F1 - area with large section
w0 - average velocity in section F0
formulas (1) and (2) obtained from Idelchik; this formulas has been used for many years, so, i think, they are right
for example, for F0/F1
My values are much larger!
What i am doing wrong?
y+ varies from 20 to 90 in both cases
turbulenceModel = k-omega SST with wall-functions
Sorry for bad English!
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