Non-Newtonian Carreau Model Fluid

Hello,

While solving the Equation of carreau model. I got a doubt. Her is the doubt

The equation is given for the carreau model fluid as

mu_inf = mu_inf +(mu_0-mu_inf) [1+lamda(gamma_dot)^2]^(n-1/2)

here the units of lamda is s.

and gamma_dot units are (1/s)

If this term vanishes the important property of shear rate is missing which is the basic definition of the non newtonian fluids where shear rate is the function of viscosity. where shear rate becomes dimensionless.

How to understand this aspect.............


Thanks in advance