where o (Pa):shear stress, [o.sub.0] (Pa): yield stress (minimum force required for the fluid to move, and is related to the internal structure of the material to be broken [23]),K (Pa sn):coefficient consistency (proportionality constant indicating the degree of
non-Newtonian viscosity), (s-1): shear rate and, n (-):index of rheological behavior (indicating the proximity of the fluid to a Newtonian fluid.
In industrial production there are many coating liquids with a
non-Newtonian viscosity behavior, such as polymeric solutions or dispersions.
In the laboratory experimental measurements, the density and
non-Newtonian viscosity behavior of drilling mud are evaluated.
Scheraga, H.A.: 1955,
Non-Newtonian viscosity of solutions of ellipsoidal particles.
In this section, the model of the
non-Newtonian viscosity was introduced first, and the formulation for the plastic melt flow was then derived for optimization.
where [eta]([absolute value of [gamma]]) is the apparent
non-Newtonian viscosity given by the power-law model, which is a function of the magnitude [absolute value of [gamma]] of the rate-of-strain tensor [bar.[gamma]] = [gradient][bar.u] + [gradient][[bar.u].sup.T], given by:
NOMENCLATURE [C.sub.p] Specific heat capacity D Rate of strain tensor F Volume concentration function [kappa] Conductivity P Pressure t Time T Temperature [T.sub.g] Glass transition temperature [T.sub.m] Melting temperature [U.sub.x] Velocity [DELTA][U.sub.x] Velocity difference V Velocity vector [dot.[gamma]] Shear rate [eta]
Non-Newtonian viscosity [rho] Density [tau] Stress tensor Table 1.
The effects of a
non-Newtonian viscosity of a polymer on the amount of die swell can be much larger than the Newtonian examples presented here.
If the
non-Newtonian viscosity [eta] were constant (i.e.