exam1 closed Flashcards
What is hydrostatic pressure?
the pressure exerted by a fluid at rest (equilibrium) due to the force of gravity
Real fluids exhibit finite viscosity and non-uniform velocity distributions. There are two types
of real fluids. What are they? Define each one of them.
Newtonian Fluid: A fluid obeying Newton’s law of viscosity is known as a Newtonian fluid. E.g., glycerol thin motor oil.
Non-Newtonian Fluid: A fluid not obeying Newton’s law of viscosity is said to be a Non-Newtonian fluid. E.g., corn flour and water
The head pressure of a pump used for pumping water is 200 feet. What is the head
pressure given in psi?
1psi=2.31 feet (86.6 psi)
Define, what is a bingham plastic fluid? Give two examples of this type of fluid.
Bingham plastics mimic solids under low shear stresses
mayo and toothpaste
A centrifuge having a diameter of 30 cm is rotated at 1000 rpm. Calculate the centripetal
acceleration at the wall of the centrifuge.
Fluids in contact with a surface can be defined as strong wetting, moderate wetting, and nonwetting. Draw schematically fluids on surface for a strong wetting case, moderate wetting and nonwetting cases. Show the contact angle and the direction of surface tension for each case.
strong wetting less than 90
moderate wetting 90
nonwetting greater than 90
There are two types of fluid flows: Laminar and Turbulent. What are the criteria for a fluid
flow to be considered a laminar or a turbulent flow? Draw the schematics of velocity distribution of
a laminar flow and a turbulent flow.
Laminar Flow: Re less than or equal to 2000
Turbulent flow greater than or equal to 4000
A swimmer weighs 175 lbf. When he floats in a pool (water density 62.4 lbm/ft3
), what is the
buoyancy force that keeps him floating?
Give the names of two types of fluids that are categorized as Non-Newtonian. Explain why
these fluids behave as Non-Newtonian.
A fluid has a viscosity of 100 cP and specific gravity of 0.9. What is the kinematic viscosity
of the fluid in centistokes (cSt)?
Define, what is specific gravity of a substance? What do we need to know to determine specific
gravity?
There are two types of viscosities. What are they? Define each one of them.
Dynamic Viscosity (Absolute Viscosity): measure of the fluid’s resistance to flow when an external force is applied
Kinematic Viscosity: measure of the resistive flow of a fluid under the weight of gravity
The following can be explained by the principle of fluid statics
The following are the related to surface tension property of a fluid-surface system
a. Contact angle can be used to determine the capillarity behavior of a fluid in a column
b. Whether a liquid is a wetting or non-wetting is strongly affected by its surface tension property
The pressure at the bottom of a tank filled with a fluid is 50 m. What is the value of the head pressure expressed in kPa? Specific gravity of the fluid 0.9.
