The viscosity is a function of the velocity gradient both in laminar and turbulent flows. I don't think you can evaluate the non-newtonian viscosity function only from your data.

In fact, Non-Newtonian fluids exhibit an apparent viscosity that varies with shear rate. Consequently, the determination of the shear stress-shear rate curve must be an initial consideration. You should also distinguish what kind of Non-Newtonian fluid behavior do you have because there are many : power law fluids (pseudoplastic or dilatant), Bingham plastics, viscoplastic…

Regards.

I think you can use the rheometer to know the viscosity although it varies with the shear rate. You can first establish whether the fluid is newtonian or non-newtonian through the shear stress-shear rate curve. Then you can find the shear-rate v/s apparent viscosity curve which can give you an idea of the viscosity of the fluid.

See attached file for the answer.

Hi all,

I want to calculate the apparent viscosity of a viscoelastic fluid. I found a formula that is:

etaA = Txy/q , q = sqrt(0.5*Inv2) , Inv2=trace(gama^2) , gama = gradU+transpose(gradU)

but the results are not correct!

Thanks

How would I calculate pseudoplastic viscosity? Can anyone explain how they would calculate peudoplastic viscosity from the graph given in the attachment? please someone explain it if you really know about it