Aerodynamics
- Two effective forces
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- For cyclists, pressure effect is much larger than friction due to non-streamlined body.
Attached and separated flow around a cylinder
- Streamlined bodies incorporate gradual tapering to minimize pressure effect and separation of flui
Attached flow and pressure recovery along a streamlined body
- Drag Coefficient
- CD = drag/(area x dynamic pressure)
- Dynamic Pressure can be approximated for speeds under 100 mi/h as:
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- Drag
- The force in the direction of relative flow.
- Propulsion power to overcome drag:
- Ŵ = drag force x relative vehicle velocity
Drag coefficients of various geometries
- Laminar Flow
- Layers of fluid flow slide smoothly over one another
- Turbulent Flow
- Boundary layer is composed of vortices that increase surface friction
- Common at rear end of non-streamlined vehicle