Wind tunnel visualization of air flow

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Wind tunnel visualization of air flow
streamlines
AIR
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Streamlines and fluid flow

• The black lines are the paths that the fluid
  takes as it flows.
• Wider spacing indicates low speed flow, narrow
  spacing indicates high speed flow
• Color indicates pressure

High
Low pressure
pressure
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Figure 11-29
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Streamlines around a wing
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Airflow around a baseball that is NOT spinning

• The ball is moving but from the balls
  perspective the air moves relative to the ball
• The streamlines are bunched at the top and bottom
  indicating higher flow speed
• The pressure forces are balanced

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Curveballs
The ball is rotating clockwise. The layer of air
adjacent to the ball is dragged along by the
rotation, causing the flow speed to be higher on
the top side. The higher pressure on the
bottom causes the ball to curve upward.
High speed, Low P
the lift on a rotating body moving through a
fluid is called the MAGNUS FORCE
low speed, high P
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Curveballs
The ball is rotating clockwise. The layer of air
adjacent to the ball is dragged along by the
rotation, causing the flow speed to be higher on
the top side. The higher pressure on the
bottom causes the ball to curve upward.
High speed, Low P
the lift on a rotating body moving through a
fluid is called the MAGNUS FORCE
low speed, high P
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Pitch drop experiment at the University of
Queensland in Brisbane, Australia

• Pitch- used as a roofing material to prevent
  leaks
• Must be heated to be applied
• viscosity 1011 water
• Experiment began in 1927
• 8 drops have since fallen, one every decade or so