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Subject: Carreau model/ Flotran
Author: sweber sweber@
Date: 1999-09-05 14:03:00Hello Folks Out There!
I do have a problem with the Flotran Carreau- model option.
This one is described as
eta= c2 + (c1-c2) * (1+ (c3*D)^2)^((c4-1)/2)
with D= root( I2), and I2= 2. invariant of the strain rate tensor.
A customer of ours delivered me the following Carreau- law which
is suitable for his plastics flow simulations (kind of standard in
plastics industry, constants are tabeled for many plastics)
eta= A/ (1+B*gamma)^C
with A= nominal viscosity
B= time constant
gamma= shear- or velocity gradient=dc/ ds; unit for gamma: [s^(-1)]
Both formulas are relatively identical, but formula 2 has a linear
dependence of eta from the shear whilst formula 1 has a quadratic
dependence of eta on D.
My question: Is D^2 equal to gamma and do these two formulas have the
same meaning?
Thank you very much,
Michael Goelzer