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INVERTEBRATES AND FLUID DYNAMICS : OFF THE GROUND & MOVIN’ AROUND

INVERTEBRATES AND FLUID DYNAMICS : OFF THE GROUND & MOVIN’ AROUND. FLIGHT. FLIGHT. Airfoil. Thickness . Chord . Angle of attack. FLIGHT. Standard airfoil. Area of relatively low pressure. LIFT. Area of relatively high pressure. FLIGHT. Lift. Resultant force. Drag.

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INVERTEBRATES AND FLUID DYNAMICS : OFF THE GROUND & MOVIN’ AROUND

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  1. INVERTEBRATES AND FLUID DYNAMICS: OFF THE GROUND & MOVIN’ AROUND

  2. FLIGHT

  3. FLIGHT Airfoil Thickness Chord Angle of attack

  4. FLIGHT Standard airfoil Area of relatively low pressure LIFT Area of relatively high pressure

  5. FLIGHT Lift Resultant force Drag

  6. In flapping flight, need to compromise As you increase angle of attack 1) lift 2) propulsion generated 3) Lowering of drag

  7. H.G. Magnus (1802 – 1870)

  8. MAGNUS EFFECT LIFT translation circulation + =

  9. Same principle is used in various sports

  10. Curve ball

  11. - Overall flow = Translational flow circulation

  12. Circulation around wing

  13. At the beginning of flight Establish a counter vortex

  14. Some coefficients of lift Bird Re – 7000 2.0 Locust Re – 2000 1.3 Drosophila Re – 200 0.9

  15. Hovering Flight

  16. Encarsiaformosa Wing – 0.6 mm Mass - .000025 gm Re - 15 Coefficient of lift (predicted) = 0.02 Coefficient of lift (actual) = 5.0

  17. Clap-and Fling Mechanism Hovering flight

  18. Flip Mechanism - Dragonfly

  19. Hovering flight Translational Phase A) upstroke High angle of attack B) downstroke Rotational Phase A) pronation When wing reverses direction B) supination

  20. Hovering Flight

  21. Hovering flight Red arrows – total force and direction Blue arrows – wing position 3 Forward motion 2. Rotational lift 1. Delayed Stall

  22. Hovering flight

  23. Hovering flight

  24. Vortices around a flying animal Tip vortices Bound vortex Tip vortices

  25. Tip vortices

  26. Propulsion at very low Re’s Rowing a boat – propulsive stroke is in lower Re (water) than recovery stroke (air)

  27. Propulsion at very low Re’s What about smaller animals that have to do both in low Re? Mymarid wasp Thrips Cladoceran Nepticulid moth Ptiliid beetle Dytiscid beetle Aerial Aquatic

  28. Propulsion at very low Re’s What about smaller animals that have to do both in low Re? Relative sizes Size difference and different viscosity of medium similar low Re’s

  29. Fringed propelling mechanism Power stroke (fringe expands) Recovery stroke (fringe collapses)

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