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FE Exam Fluids Review

Xiaofeng Liu, Ph.D., P.E.,

Department of Civil and Environmental EngineeringUniversity of Texas at San Antonio

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Content1. Fluids properties: Density, specific volume, specific weight, and specific gravity

2. Stress, pressure, and viscosity

3. Surface tension and capillarity

4. The pressure field in a static liquid

5. Manometers

6. Forces on submerged surfaces and the center of pressure

7. Archimedes principle and buoyancy8. One-dimensional flows

9. The field equation (Bernoulli equation)

10. Fluids measurements (Pitot tube, Venturi meter, and orifices)

11. Hydraulic Grade Line (HGL) and Energy Line (EL)

12. Reynolds number

13. Drag force on immersed bodies

14. Fluid flow (Pipe flow; Energy equation)

15. The impulse-momentum principle (Linear momentum equation)

16. Dimensional analysis and similitude

17. 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

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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 (i) is hi(head in terms of this

fluid); convert it to head of specific fluid if desired (h=i/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

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AhFc

=Means the magnitudeto the pressure force equals

the pressure at the centroid times the area.

It doesnt mean the locationof the force is at centroid

Force on a plane surface

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6. Forces on submerged surfaces

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Center of pressure

Ay

Iy

Ay

IAy

Ay

Iy

c

cc

c

cc

c

p +=+

==

2

0

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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

cm2cross section and a specific gravity of 0.6. Most

nearly what length, L, is submerged?

24 cmL

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8. One-dimensional flow

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Continuity equation: conservation of mass

Lets look at a simple version: continuity in a tube

If the volume of the tube does not change, then what ever comes inshould goes out.

02211 = AVAV

Continuity equation (steady)

dt

dVolAVAV =

2211

Continuity equation (unsteady)

If the volume of the tube does change with time

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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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18. Open-channel flow

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