slap, stroke, and protraction

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slap, stroke, and protraction
f
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hydrodynamic drag
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• impulse
• force dt mass x velocity
• velocity impact velocity
• mass virtual mass
• virtual mass impulse/velocity

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hydrodynamic drag
h
Drag coefficient is constant with depth and
velocity
Drag CD (1/2 r u2 S r g h S)
dynamic component
static component
depth
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Time for bubble to seal
Step duration of real lizards
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Note most force due to stroke
Could humans do this? no it would require a
foot velocity of 30 m/sec.
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Three important descriptors of fluid motion
2. vorticity, w(x,y)
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Fstroke r G A /t
Fslap m U / t where m is bolus of accelerated
water, moving atvelocity, u impulse (F x t)
mass x velocity

• Momentum
• of vortex ring
• r G A
• G circulation

A
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