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

Chapter 4 Results and Analysis Page 4.21
Overall <strong>the</strong> Slatter model (APE - 13.9%, LSE - 0.0325) best modelled <strong>the</strong> test data.
Although <strong>the</strong> Torrance model (19.15%) and <strong>the</strong> Wilson & Thomas model (19.66%) are both
below an average percentage error <strong>of</strong> 20 %, which is acceptable in engineering practice
(Cheng, 1970), <strong>the</strong> fact still remains that <strong>the</strong>se models diverge from <strong>the</strong> data at higher shear
stresses, indicating that <strong>the</strong>y do not accurately describe <strong>the</strong> turbulent flow behaviour <strong>of</strong> <strong>the</strong>
solid-liquid suspensions.
The turbulent model performance can also be seen in Figure 4.25 to Figure 4.29 which
shows a log-log plot <strong>of</strong> TO ob' vs To'""" for <strong>the</strong> five <strong>the</strong>oretical models which were considered.
A 20 % error line is included in <strong>the</strong> plot. It can be seen from <strong>the</strong> five figures that <strong>the</strong> Slatter
model yields <strong>the</strong> best results with virtually all <strong>the</strong> data points within <strong>the</strong> 20% error lines.
Large discrepancies for mixture 1 for all models can be seen.
From <strong>the</strong> performance <strong>of</strong> <strong>the</strong> various <strong>the</strong>oretical models (visual appraisal <strong>of</strong> <strong>the</strong> model lines,
average percentage error, log standard error and <strong>the</strong> log-log plots) it would appear that <strong>the</strong>
Slatter model provides better predictions than <strong>the</strong> o<strong>the</strong>r models for <strong>the</strong> slurries tested.
1000,.---------------:'71,-----,
o
Kaolin
..
Ntxtu.-. 1
+
Nbcv. 2
Figure 4.25: A log-log plot <strong>of</strong> TO"", vs To""" for <strong>the</strong> Dodge & Metzner
model