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Questions and Answers
What is the behavior of a Bingham plastic fluid?
What is the behavior of a Bingham plastic fluid?
- It remains a solid until a critical temperature is reached.
- It flows only when shear stress exceeds its yield stress. (correct)
- It behaves like a Newtonian fluid at all shear stresses.
- Its viscosity decreases with increasing shear stress.
Which type of viscometer would primarily be used to measure viscosity through the flow of liquid in a tube?
Which type of viscometer would primarily be used to measure viscosity through the flow of liquid in a tube?
- Cone and Plate Viscometer
- Rotational Viscometer
- Falling Ball Viscometer
- Capillary Flow Viscometer (correct)
What characterizes a pseudoplastic fluid?
What characterizes a pseudoplastic fluid?
- Its viscosity decreases as shear stress is applied. (correct)
- It behaves like a solid under all conditions.
- It has a constant viscosity regardless of shear stress.
- Its viscosity increases with higher temperature.
Which viscosity measurement method uses a rotating element to determine fluid viscosity?
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?
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?
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?
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?
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?
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?
How is momentum flux defined in the context of fluid between two parallel plates?
Which of the following statements is true regarding viscous materials?
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?
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?
What is a characteristic feature of a viscoelastic material?
Flashcards
Viscosity
Viscosity
Resistance of a fluid to flow.
Newton's Law of Viscosity
Newton's Law of Viscosity
The force needed to move a fluid is proportional to the velocity gradient and the fluid's viscosity.
Velocity Gradient
Velocity Gradient
Rate of change of velocity across a fluid.
Viscosity Unit
Viscosity Unit
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Momentum Flux
Momentum Flux
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Plastic Material
Plastic Material
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Viscous Material
Viscous Material
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Fluid Flow
Fluid Flow
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Dilatant Fluid
Dilatant Fluid
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Bingham Plastic
Bingham Plastic
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Pseudoplastic Fluid
Pseudoplastic Fluid
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Thixotropic
Thixotropic
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Rheopectic
Rheopectic
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Study Notes
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.
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Description
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.
