Fluid Mechanics Lesson 5.3 Quiz

What is the behavior of a Bingham plastic fluid?

Which type of viscometer would primarily be used to measure viscosity through the flow of liquid in a tube?

What characterizes a pseudoplastic fluid?

Which viscosity measurement method uses a rotating element to determine fluid viscosity?

What is the new velocity of the top plate when water is replaced with a fluid of viscosity 100 centipoise and the shear stress remains constant?

Which property is defined as the resistance of a fluid to flow?

What does the proportionality constant µ represent in Newton’s Law of Viscosity?

If the viscosity of water is 1 cp, what would be the likely consequence of replacing it with a fluid of 100 cp and keeping the momentum flux constant?

What flow behavior model would best describe materials that do not flow unless a certain yield stress is exceeded?

How is momentum flux defined in the context of fluid between two parallel plates?

Which of the following statements is true regarding viscous materials?

In Newton's Law of Viscosity, what is the relationship between shear stress and the velocity gradient?

What is a characteristic feature of a viscoelastic material?

Lesson 5.3 Rheological Flow Properties of AB Materials

Rheological flow properties of plastic and viscous materials are differentiated
Various flow behavior models describing plastic and viscous material flow behaviors are discussed

Viscosity

Defined as the resistance of a fluid to flow

Flow of Materials

Materials are classified as plastic or viscous
Plastic materials further categorized as Bingham or Non-Bingham
Viscous materials are categorized into Newtonian or Non-Newtonian

Newton's Law of Viscosity

Experimental results indicate force needed to maintain lower plate motion is proportional to the velocity gradient.
The constant of proportionality, μ, represents the fluid's viscosity
Formula: F/A = -μ (dv/dy)

Sample Problem

Two parallel plates separated by 0.1 m, with the upper plate moving at a velocity V, and water (viscosity of 1 cp) in between
Part (a): Calculate momentum flux needed to maintain the top plate's motion at 0.30 m/s
Part (b): If water is replaced with a fluid of 100 cp viscosity, calculate the new velocity of the top plate, assuming momentum flux remains constant

Viscosity Measurements

Capillary Flow Viscometers: Fluid is pulled into a reservoir, and the time taken for it to flow through a capillary section is measured.
Orifice Type Viscometers: Fluid flows through an orifice, and the time is measured.
Falling Ball Viscometers: A ball falls through a liquid, and the time taken is measured.
Rotational Viscometers: Use rotating spindles to measure viscosity. Subtypes include concentric cylinder, cone-plate, and parallel plate viscometers.
Vibrational (Oscillation) Viscometers: Measure material viscosity using vibration.
Bostwick Consistometer: Instrument used for measuring the consistency of viscous materials.

Other Fluid Behaviors

Dilatant Fluids: Shear viscosity increases when shear stress is applied
Bingham Plastics: Behave as solids when shear stress is below a specific yield point, and then flow like a Newtonian fluid once that stress threshold is met.
Pseudoplastic Fluids: Viscosity decreases as shear stress is applied.
Thixotropic and Rheopectic Behavior: Viscosity changes over time under applied stress. Shear thinning and thickening are specific examples.

What About Blood?

Blood's rheological properties are discussed.

Test your understanding of the rheological flow properties of plastic and viscous materials. This quiz covers the various models of flow behavior, definitions of viscosity, and applications of Newton's Law of Viscosity, including practical problems. Prepare to differentiate between plastic and viscous materials and assess their flow behaviors.