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FE Review Course – Fluid
Mechanics
Spring 2012
Frank T.-C. Tsai, Ph.D., P.E.
Dept. of Civil & Environmental Engineering, LSU
ftsai@lsu.edu
(O) 578-4246
Get the handbook!!
• SUPPLIED-REFERENCE HANDBOOK
• 8th edition, 2nd revision, April 2011
Visualize questions
• Draw diagrams
• Annotate diagrams with numbers,
symbols, equations, etc.
• Find right equations from the reference
handbook
• Skip questions if you cannot quickly find
equations from the reference handbook
CoOH
fluid
CoOH
fluidSG
4@24@2
/d
dpEv
vE
c
4 cosh
d
1 mm 4 0.025 1
1000 0.82 9810 d
(Page 62)
Units and Scales of Pressure
Measurement
Standard atmospheric pressure
Local atmospheric pressure
Absolute zero (complete vacuum)
Absolute pressure
Gage pressure
1 atmosphere
101.325 kPa
14.7 psi
10.34 m H20
760 mm Hg
Suction vacuum
(gage pressure) Local
barometer
reading
6894.76 Pa/psi
atmgageabs ppp Absolute pressures are often indicated as psia, and
gage pressure as psig.
Fluid Statics •Pressure vs. elevation
•Manometers
•Force over submerged plane and
curved surfaces
•Buoyancy
Fluid Statics •Pressure vs. elevation
•Manometers
•Force over submerged plane and
curved surfaces
•Buoyancy
(z=0 at water surface and z is negative below surface)
(for gas)
12 Wabove fluid ofweight ,projection verticalon the FFFFF vRh
submergedfluidbuoyancyF "= g
For curved surface, separate the pressure force into horizontal and vertical part. The
horizontal part becomes plane surface and the vertical force becomes weight.
If an object is submerged in several different fluids, must calculate the
buoyancy in each of them, then add together. When using buoyancy in
problems, FBD is often needed.
31 3
12* 0.53
3 12
z
(page 63)
The diameter of the pipe is 0.3 m.
g
Vz
p
2EGL
2
ag
++=z
p+=
gHGL
Pressure head (w.r.t.
reference pressure)
velocity
head
Elevation head (w.r.t.
datum)
Piezometric
head
zg
vp
2
2
zp
EGL: line connecting
(total head line)
HGL: line connecting
(piezometric head line)
Example EGL & HGL
(page 64)
60+20 mph=80mph=117.3 ft/s
W Q h
Turbine :
Dimensionless parameters
Example
If a flow rate of sm /2.0 3 is measured over a 9 to1 scale model of a weir, what flow rate
can be expected on the prototype?
Flow over a weir is an openchannel flow. Use Froude number for modeling.
24332
222
mm
pp
m
p
m
p
m
p
p
p
m
m
lv
lv
Q
Q
l
l
v
v
gl
v
gl
v
If the model force is at 1000N, what will be the force on the prototype?
72993)(
)(22
22
22
2222
m
p
m
p
pmlv
lv
F
F
lv
F
lv
F
(use drag force)
(continuity eq.)
2 2 2F VQ V A V
F
WW Q h h
Q
point ,friction Turbineafter Lh h h h
before Pumpafterh h h
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