the effect of the particle size distribution on non-newtonian turbulent ...

Chapter 2 Literature Review Page 2.33
• Yield pseudoplastic fluids (Thomas & Wilson, 1987). Their analysis showed
that as <strong>the</strong> value <strong>of</strong> <strong>the</strong> flow behaviour index decreases from unity, <strong>the</strong> plot
<strong>of</strong> friction factor vs Reynolds number converges towards <strong>the</strong> Newtonian line.
The plot <strong>the</strong>n parallels <strong>the</strong> Newtonian line and eventually diverges downwards
from <strong>the</strong> Newtonian line. It was found that <strong>the</strong> converging behaviour was
exhibited by low concentration slurries compared to <strong>the</strong> diverging behaviour,
exhibited by high concentration slurries.
The equations <strong>of</strong> <strong>the</strong>ir turbulel)t flow model as applying to pseudoplastic fluids is presented
below.
The thickness <strong>of</strong> <strong>the</strong> viscous sub-layer increases by a factor called <strong>the</strong> area ratio A. shown
graphically in Figure 2.13. The figure shows that <strong>the</strong> area ratio is defined as <strong>the</strong> ratio <strong>of</strong> <strong>the</strong>
integrals <strong>of</strong> <strong>the</strong> non-Newtonian and assumed Newtonian rheograms under identical shear
conditions.
Figure 2.13: Illustration <strong>of</strong> <strong>the</strong> area ratio
Shear Rate ---...