Modeling and Simulation of a Biopolymer Processing in a Single Screw Extruder - Selected Topics of Computational and Experimental Fluid Mechanics - page 446

Fig. 5 Temperature profile
at different screw speeds
with: P = 3,000 psi,

n = 1 / 3

Φ =1

Φ =0.5

Φ =0.25

Fig. 6 Stress depending on
the deformation rate for a
Newtonian fluid

Figure 6 presents the flow curve for a Newtonian fluid which shows that the rela-
tionship between the stress tensor and the shear rate is linear. In this case the viscosity
is independent of the shear rate according to Tadmor and Gogos ( 2006 ). For a non-
Newtonian fluid the shear stress varies non-linearly with the shear rate as shown in
Fig. 7 . The behavior in Fig. 7 describes a pseudoplastic or shear thinning fluid, which
is correct for the biopolymer considered in this work.