Concept explainers
It is a common practice when examining a fluid's viscous behavior to plot the shear strain rate (velocity gradient)
on the abscissa versus shear stress
where
For Bing hamplastics, the reis a yields tress
FIGURE P20.55
A common example is toothpaste.
For pseudoplastics, or “shear thinning” fluids, the shear stress is raised to a power n less than one,
Such fluids, such as yogurt, mayonnaise, and shampoo, exhibit a decrease in viscosity with increasing stress. Note that for cases where
The following data show the relationship be tween the shear stress
Stress
|
3.25 | 4.25 | 4.65 | 5.65 | 6.05 |
Shear strain rate
|
0.9 | 2.1 | 2.9 | 4.1 | 4.9 |
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EBK NUMERICAL METHODS FOR ENGINEERS
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