non newtonian liquid

[delplace]

How to calculate the shear rate for the flow of a shear thinning liquid in a non circular duct

[Andy Resnick]

With the constitutive equation relating viscosity (shear stress) to the shear rate. There are many models of shear thinning fluids; pick one.

[delplace]

Sorry Sir, I know for shear thinning fluids you have rheological equations linking share stress to shear rate. For example the power law model : T = k j^n. But when you have a shear thinning fluid flowing in a complex duct, you need a viscosity to calculate the Reynolds number. And to have the viscosity (apparent = T/j = kj^(n-1)) you need to calculat j in the duct ! It was the meening of my question. How to calculate the shear rate j ?