Fluid Mechanics Fundamentals Prep Exam
2024 | Fluid Mechanics Fundamentals Prep
Actual Exam Latest 2024 Questions and
Correct Answers Rated A+
3 Major Classifications -ANSWER-1. Hydrodynamics: using math to
describe fluid motion (like physics)
2. Hydraulics: using empirical correlations to solve engineering
problems
3. Computational Fluid Dynamics (CFD): using computers to solve
field eqns (PDE's) modeling fluid motion
Definition of a Fluid -ANSWER-a substance that deforms continuously
when acted on by a shear stress of any magnitude.
Continuum -ANSWER-A homogenous and infinitely divisible
substance. All fluid characteristics we care about (e.g. velocity,
pressure, etc.) vary continuously throughout the field.
Properties of fluids -ANSWER-Density: mass per unit volume
- density of liquids varies little with pressure and temperature
- density of gases varies greatly with pressure and temperature
specific weight: weight per unit volume
Specific gravity -ANSWER-ratio of the density of a fluid to the density
of water at 4C
Pressure -ANSWER-The normal force per unit area exerted on a
plane surface (real or imaginary) within a fluid
,"No slip" condition -ANSWER-an extremely thin layer of fluid sticks to
all solid boundaries
Viscosity -ANSWER-A measure of how easily a fluid flows
A measure of the resistance of a fluid to an extremely applied shear
How does absolute viscosity depend on pressure and temperature? -
ANSWER-Absolute viscosity has a low dependence on pressure but a
high dependence on temperature. At higher temperatures, mu of
liquids goes down and mu of gases goes up. (mu being the coefficient
of viscosity).
Bingham Plastic -ANSWER-a linear variation of tau with respect to
du/dy after an initial shear stress is achieved.
ex: toothpaste, mayo
Shear Thickening -ANSWER-The harder it is sheared/strained, the
more viscous it becomes
ex: oobleck
Shear Thinning -ANSWER-apparent viscosity decreases with
increasing shear rate
ex: ketchup, blood, latex paint
Surface Tension -ANSWER-Occurs at a liquid-gas or immiscible
liquid-liquid interface. Acts like a "skin" holding liquid together.
Owing to unbalanced cohesive forces
- molecular forces in interior are equally distributed
- molecules on surface are down more strongly to interior
Hydrophobic -ANSWER-Water does not stick to hydrophobic surfaces
and forms spherical shaped droplets
, Hydrophilic -ANSWER-Water sticks to surface and spreads out more.
Fluid Statics -ANSWER-A fluid is considered static if all fluid particles
are at rest or have the same velocity relative to an internal reference.
Fluid is undergoing rigid body motion
How does pressure vary with direction? -ANSWER-It doesn't
What does it mean that pressure is independent of direction and that it
varies with depth? -ANSWER-1. Pressure is independent of container
shape
2. Through a continuous fluid, all the fluid at the same depth has the
same pressure
3. The pressure acts normal to any surface
The pressure difference between two points -ANSWER-can be
specified by the distance h, which is called the pressure head
Pressure head -ANSWER-(P2-P1)/gamma, gamma being specific
weight
Absolute pressure -ANSWER-Pressure relative to a vacuum (zero
pressure)
Gage Pressure -ANSWER-Pressure measured relative to atmospheric
pressure
In a container, how does the hydrostatic force vary across the bottom?
-ANSWER-The force is distributed evenly and a resultant force acts
through the centroid of the bottom.
2024 | Fluid Mechanics Fundamentals Prep
Actual Exam Latest 2024 Questions and
Correct Answers Rated A+
3 Major Classifications -ANSWER-1. Hydrodynamics: using math to
describe fluid motion (like physics)
2. Hydraulics: using empirical correlations to solve engineering
problems
3. Computational Fluid Dynamics (CFD): using computers to solve
field eqns (PDE's) modeling fluid motion
Definition of a Fluid -ANSWER-a substance that deforms continuously
when acted on by a shear stress of any magnitude.
Continuum -ANSWER-A homogenous and infinitely divisible
substance. All fluid characteristics we care about (e.g. velocity,
pressure, etc.) vary continuously throughout the field.
Properties of fluids -ANSWER-Density: mass per unit volume
- density of liquids varies little with pressure and temperature
- density of gases varies greatly with pressure and temperature
specific weight: weight per unit volume
Specific gravity -ANSWER-ratio of the density of a fluid to the density
of water at 4C
Pressure -ANSWER-The normal force per unit area exerted on a
plane surface (real or imaginary) within a fluid
,"No slip" condition -ANSWER-an extremely thin layer of fluid sticks to
all solid boundaries
Viscosity -ANSWER-A measure of how easily a fluid flows
A measure of the resistance of a fluid to an extremely applied shear
How does absolute viscosity depend on pressure and temperature? -
ANSWER-Absolute viscosity has a low dependence on pressure but a
high dependence on temperature. At higher temperatures, mu of
liquids goes down and mu of gases goes up. (mu being the coefficient
of viscosity).
Bingham Plastic -ANSWER-a linear variation of tau with respect to
du/dy after an initial shear stress is achieved.
ex: toothpaste, mayo
Shear Thickening -ANSWER-The harder it is sheared/strained, the
more viscous it becomes
ex: oobleck
Shear Thinning -ANSWER-apparent viscosity decreases with
increasing shear rate
ex: ketchup, blood, latex paint
Surface Tension -ANSWER-Occurs at a liquid-gas or immiscible
liquid-liquid interface. Acts like a "skin" holding liquid together.
Owing to unbalanced cohesive forces
- molecular forces in interior are equally distributed
- molecules on surface are down more strongly to interior
Hydrophobic -ANSWER-Water does not stick to hydrophobic surfaces
and forms spherical shaped droplets
, Hydrophilic -ANSWER-Water sticks to surface and spreads out more.
Fluid Statics -ANSWER-A fluid is considered static if all fluid particles
are at rest or have the same velocity relative to an internal reference.
Fluid is undergoing rigid body motion
How does pressure vary with direction? -ANSWER-It doesn't
What does it mean that pressure is independent of direction and that it
varies with depth? -ANSWER-1. Pressure is independent of container
shape
2. Through a continuous fluid, all the fluid at the same depth has the
same pressure
3. The pressure acts normal to any surface
The pressure difference between two points -ANSWER-can be
specified by the distance h, which is called the pressure head
Pressure head -ANSWER-(P2-P1)/gamma, gamma being specific
weight
Absolute pressure -ANSWER-Pressure relative to a vacuum (zero
pressure)
Gage Pressure -ANSWER-Pressure measured relative to atmospheric
pressure
In a container, how does the hydrostatic force vary across the bottom?
-ANSWER-The force is distributed evenly and a resultant force acts
through the centroid of the bottom.
