FE Exam Fluids Review
Xiaofeng Liu, Ph.D., P.E.,
Department of Civil and Environmental Engineering
University of Texas at San Antonio
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Fluids properties: Density, specific volume, specific weight, and specific gravity
Stress, pressure, and viscosity
Surface tension and capillarity
The pressure field in a static liquid
Manometers
Forces on submerged surfaces and the center of pressure
Archimedes principle and buoyancy
One-dimensional flows
The field equation (Bernoulli equation)
Fluids measurements (Pitot tube, Venturi meter, and orifices)
Hydraulic Grade Line (HGL) and Energy Line (EL)
Reynolds number
Drag force on immersed bodies
Fluid flow (Pipe flow; Energy equation)
The impulse-momentum principle (Linear momentum equation)
Dimensional analysis and similitude
Open-channel flow
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1. Fluid properties
• Density, specific volume, specific weight, and specific gravity
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2. Stress, pressure and viscosity
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3. Surface tension and capillarity
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4. Pressure field in static fluid
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4. Pressure field in static fluid
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5. Manometers
• General procedure of reading manometer
– Starting from a point where pressure is know (such as the open end
of the manometer)
– Travel through the entire tube until the point of measurement
– Pressure change over a column of fluid (γi) is hi (head in terms of this
fluid); convert it to head of specific fluid if desired (h= γi/γ hi)
• If traveling downward, pressure increases (plus)
• If traveling upward, pressure decreases (minus)
• Two points at the same elevation in a continuous fluid are at the same
pressure
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6. Forces on submerged surfaces
Force on a plane surface
F = γhc A
Means the magnitude to the pressure force equals
the pressure at the centroid times the area.
It doesn’t mean the location of the force is at centroid
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6. Forces on submerged surfaces
• Center of pressure
I0
Ayc2 + I c
I
=
= yc + c
yp =
yc A
yc A
yc A
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Force on a curved surface
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7. Archimedes principle and buoyancy
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A 24 cm long rod floats vertically in water. It has a 1
cm2 cross section and a specific gravity of 0.6. Most
nearly what length, L, is submerged?
L
24 cm
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8. One-dimensional flow
 Continuity equation: conservation of mass
 Let’s look at a simple version: continuity in a tube
 If the volume of the tube does not change, then what ever comes in
should goes out.
V1 A1 − V2 A2 = 0
Continuity equation (steady)
 If the volume of the tube does change with time
V1 A1 − V2 A2 =
dVol
dt
Continuity equation (unsteady)
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9. Bernoulli equation
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11. HGL and EL
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12. Reynolds number
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13. Drag force on immersed bodies
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14. Fluid flow (pipe flow)
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15. The impulse-momentum principle
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16. Dimensional analysis
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18. Open-channel flow
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