Question

A power-law fluid has a shear stress versus shear rate relationship that is described by the expression τ=K(-dv/dr)^n where the parameters have their usual meaning. Which of the following is correct for dilatant fluids?

A. n>1
B. n=1
C. n<1
D. n=0

Answer 1

For dilatant fluids, the flow behavior index n is greater than 1, which characterizes their shear-thickening behavior where the fluid's resistance to flow increases as the shear rate increases.

Step-by-step explanation:

The correct answer for dilatant fluids is A. n>1. Dilatant fluids, also known as shear-thickening fluids, increase in viscosity as the shear rate increases. This means that when such a fluid is under stress, it behaves more solid-like by resisting flow. The power-law fluid behavior is dictated by the equation τ=K(-dv/dr)^n, where τ represents the shear stress, K is the consistency index, dv/dr is the shear rate, and n is the flow behavior index. For dilatant fluids, the flow behavior index n is greater than 1 because the resistance to flow increases with increasing shear rate.