It is a common practice when examining a fluids viscous behavior to plot the shear rule (velocity
Question:
It is a common practice when examining a fluid’s viscous behavior to plot the shear rule (velocity gradient)
dυ/dy = γ
on the abscissa versus shear sires (τ) on the ordinate. When a fluid has a straight-line behavior between these two variables it is called a Newtonian fluid, and the resulting relationship is
τ = μγ
where μ is the fluid viscosity. Many common fluids follow this behavior such as water, milk, and oil. Fluids that do not behave in this way are called non-Newtonian. Some examples of non-Newtonian fluids are shown in Figure.
For Bingham plastics, there is a yield stress τy that must be over-come before flow will begin,
τ = τy + μγ
A common example is toothpaste.
For pseudoplastics, the shear stress is raised to the power n,
τ = μγn
Common examples are yogurt and shampoo.
The following data shows the relationship between the shear stress τ and the shear strain rate γ for a Bingham plastic fluid. The yield stress τy is the amount of stress that must be exceeded before flow begins. Find the viscosity μ (slope), τy and the r2 value using a regression method.
Step by Step Answer:
Numerical Methods For Engineers
ISBN: 9780071244299
5th Edition
Authors: Steven C. Chapra, Raymond P. Canale