Quiz Two

Question 1

What is Rheology?

Answer 1

Rheology is the study of flow

Question 2

What is viscosity? How is it calculated?

Answer 2

Viscosity describes the resistance to flow. It is calculated by dividing the shear stress by the shear rate.

Question 3

What is shear stress? How is it calculated?

Answer 3

Shear stress is the force that acts parallel to the direction of flow. It is calculated by dividing the force by the area

Question 4

What is shear rate? How is it calculated?

Answer 4

Shear rate is the velocity gradient that occurs when a liquid is pumped through a tube (faster in the middle and slower towards the sides). It is calculated by dividing the change in velocity by the change in the distance from the sides of the tube.

Question 5

What is the viscosity equation for Newtonian fluids? What are the units for each variable?

Answer 5

The equation for Newtonian fluids is tau = mu*gamma dot. Tau is in Pascals, mu is in Pascal seconds, and gamma dot is in 1/seconds.

Question 6

What is gamma dot?

Answer 6

Gamma dot is shear rate

Question 7

What is tau?

Answer 7

Tau is shear stress

Question 8

What is the most common non-Newtonian fluid?

Answer 8

The most common non-Newtonian fluid is shear thinning (pseudoplastic)

Question 9

What is the Herschel-Buckley model? What are the units for each variable?

Answer 9

The Herschel-Buckley Model is tau = m*(gamma dot)^n + tau(sub y). Tau is the shear stress in Pascals, m is the consistency coefficient in Pascal seconds^n, gamma dot is shear rate in 1/seconds, n is the power law/flow index and it is dimensionless, and tau sub y is the yield stress in Pascals

Question 10

What is the power law/flow index for a shear thinning fluid?

Answer 10

The power law/flow index for a shear thinning (pseudoplastic) fluid is less than one

Question 11

What is the power law /flow index for a shear thickening fluid?

Answer 11

The power law/flow index for a shear thickening (dilatant) fluid is greater than one

Question 12

What is the power law/flow index for a Newtonian fluid?

Answer 12

The power law/flow index for a Newtonian fluid is one

Question 13

What is the Power Law model? What are the units for each variable?

Answer 13

The Power Law model is tau = m*(gamma dot)^n. Tau is shear stress in Pascals, m is the consistency coefficient in Pascal seconds^n, and n is the power law/flow index and it is dimensionless

Question 14

How do you linearize the Power Law model? What is the x, y, the y intercept and slope?

Answer 14

You can linearize the Power Law model by taking the log10 of both sides. Log10tau is y, log10m is the y intercept, n is the slope, and log10gamma dot is x

Question 15

What is the Casson equation? What are the units for each variable?

Answer 15

The Casson equation is tau^0.5 = eta*gamma dot^0.5 + tau sub y^0.5. Tau is shear stress in Pascals, eta is the plastic viscosity, gamma dot is the shear rate, and tau sub y is the yield stress

Question 16

What is the Casson equation used for?

Answer 16

The Casson equation is used to describe the flow properties of chocolate

Question 17

How is kinematic viscosity measured?

Answer 17

Kinematic viscosity is the viscosity divided by density

Question 18

What are three types of viscometers?

Answer 18

Three types of viscometers are capillary, rotational, and parallel plate viscometers

Question 19

What is the Arrhenius equation?

Answer 19

The Arrhenius equation shows the relationship between temperature and its reaction rate. For this chapter it is most focused on the change in viscosity due to the change in temperature. It is mu(T1) = mu(Tinitial)e^(activation energy/universal gas constantabsolute temperature

Question 20

How do you linearize the Arrhenius equation?

Answer 20

To linearize the Arrhenius equation take the log e of both sides to make ln(muT1) = ln(muTinitial) + activation energy/gas constant *1/temperature