Fluid Mechanics Midterm Solutions Questions AND Correct Answers
4 primary dimensions - ✔✔ Mass{M}, length{L}, time{T}, temperature{Θ}
5 flow mechanics laws - ✔✔ (1)Conservation of mass ->(continuity)
(2) Conservation of momentum /Newton's 2nd law → ∑𝐹 = 𝑑/𝑑𝑡(𝑚𝑣) (linear
momentum)
(3) Conservation of Energy -> (1st law of thermodynamics)
(4) Some sort of state relation (ex. 𝑝 = 𝜌(𝑝, 𝑇))
(5) Boundary conditions
Assumptions for Bernoulli's equation - ✔✔ Steady flow, incompressible flow,
inviscid flow, fluid acts along a streamline.
At surface - ✔✔ 𝜏𝑤𝑎𝑙𝑙 = 𝜇(𝑑𝑢/𝑑𝑦)𝑤𝑎𝑙𝑙➔ DRAG due to friction
BL thickness - ✔✔ δ as the locus of points where the velocity u parallel tothe
plate reaches 99% of the velocity U. BL's on surface are very thin, so
displacement of outer inviscid flow is very small
blunt bodies - ✔✔ cylinders and spheres
Body Forces - ✔✔ Forces that act throughout the volume of a body (e.g.,
gravity).
Boundary types - ✔✔ solid wall
inlet/outlet
liquid-gas interface
, Buoyancy (Archemedes principles) - ✔✔ Body immersed in fluid experiences
a vertical buoyant (upward) forceequal to the weight of the fluid it displaces
Center of pressure - ✔✔ Point where hydrostatic force actually acts, lower
than CG.
Centroid - ✔✔ the center of mass of a geometric object of uniform density
Continuum Approximation - ✔✔ Treats material as having a continuous
distribution of mass.
Control surface - ✔✔ Geometric boundaries of the control volume
separating it from the surrounding
Control volume - ✔✔ An arbitrary region in space through which fluid flows.
Can be at rest or in motion
Darcy friction factor - ✔✔ f(Epsilon, duct shape, Re)
Enthalpy - ✔✔ A thermodynamic property. It is equal to the internal energy
of the system plus the product of pressure and volume. Has energy-like units,
Joule per Kg.
Entropy - ✔✔ A measure of the unavailable energy in a closed
thermodynamic system. unit of joules per kelvin (J⋅K−1).
4 primary dimensions - ✔✔ Mass{M}, length{L}, time{T}, temperature{Θ}
5 flow mechanics laws - ✔✔ (1)Conservation of mass ->(continuity)
(2) Conservation of momentum /Newton's 2nd law → ∑𝐹 = 𝑑/𝑑𝑡(𝑚𝑣) (linear
momentum)
(3) Conservation of Energy -> (1st law of thermodynamics)
(4) Some sort of state relation (ex. 𝑝 = 𝜌(𝑝, 𝑇))
(5) Boundary conditions
Assumptions for Bernoulli's equation - ✔✔ Steady flow, incompressible flow,
inviscid flow, fluid acts along a streamline.
At surface - ✔✔ 𝜏𝑤𝑎𝑙𝑙 = 𝜇(𝑑𝑢/𝑑𝑦)𝑤𝑎𝑙𝑙➔ DRAG due to friction
BL thickness - ✔✔ δ as the locus of points where the velocity u parallel tothe
plate reaches 99% of the velocity U. BL's on surface are very thin, so
displacement of outer inviscid flow is very small
blunt bodies - ✔✔ cylinders and spheres
Body Forces - ✔✔ Forces that act throughout the volume of a body (e.g.,
gravity).
Boundary types - ✔✔ solid wall
inlet/outlet
liquid-gas interface
, Buoyancy (Archemedes principles) - ✔✔ Body immersed in fluid experiences
a vertical buoyant (upward) forceequal to the weight of the fluid it displaces
Center of pressure - ✔✔ Point where hydrostatic force actually acts, lower
than CG.
Centroid - ✔✔ the center of mass of a geometric object of uniform density
Continuum Approximation - ✔✔ Treats material as having a continuous
distribution of mass.
Control surface - ✔✔ Geometric boundaries of the control volume
separating it from the surrounding
Control volume - ✔✔ An arbitrary region in space through which fluid flows.
Can be at rest or in motion
Darcy friction factor - ✔✔ f(Epsilon, duct shape, Re)
Enthalpy - ✔✔ A thermodynamic property. It is equal to the internal energy
of the system plus the product of pressure and volume. Has energy-like units,
Joule per Kg.
Entropy - ✔✔ A measure of the unavailable energy in a closed
thermodynamic system. unit of joules per kelvin (J⋅K−1).
