1. dynamic viscosity

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Lecture 19 Fluid Dynamics I
7 fundamental concepts of fluid mechanics
1. dynamic viscosity
force m S x U x L, where m viscosity
(dynamic viscosity) Fundamental units M /
LT SI unit Pascal-secondcgs unit Poise
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2. density
density, r mass / volume Fundamental units M
/ L3
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4. no slip condition(boundary layer)
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uinf
d (x) 0.95 x uinf
flat plate with upstream edge
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5. Law of continuity(conservation of mass)
mass flux r2 s2u2
mass flux r1 s1u1
S1U1
s2u2
gravity accelerates water downward
For incompressible fluid r1 r2 Thus,
s1u1s2u2
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lung
rightventricle
body
rightventricle
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flow tank
pump
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6. Bernoulli Equation(conservation of energy)
consider flow in one stream tube
Apply conservation of energy within tube
pressureenergy
kinetic energy
gravitationalenergy
consider two pointsalong tube
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u1
u2
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7. Reynolds number
Ratio Re (Reynolds number) r u L / m u L /
v
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Low Reynolds numbers
Forces proportional to u
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Copepod Re 300
Sperm whaleRe 300,000,000
ThripsRe 30
TunaRe 30,000,000
Whale spermRe 0.00003
DuckRe 300,000
DragonflyRe 30,000
BacteriumRe 0.00003