Upload
arissa
View
42
Download
0
Tags:
Embed Size (px)
DESCRIPTION
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. - PowerPoint PPT Presentation
Citation preview
INVERTEBRATES AND FLUID DYNAMICS:
OFF THE GROUND & MOVIN’ AROUND
FLIGHT
FLIGHT
Chord
Thickness
Angle of attack
Airfoil
FLIGHT
Standard airfoil
Area of relatively low pressure
Area of relatively high pressure
LIFT
FLIGHT
Lift
Drag
Resultant force
In flapping flight, need to compromise
1) lift
2) propulsion
3) Lowering of drag
As you increase angle of attack
generated
H.G. Magnus (1802 – 1870)
+
LIFT
=
translation circulation
MAGNUS EFFECT
Same principle is used in various sports
Curve ball
Overall flow
-
Translational flow
circulation
=
Circulation around wing
At the beginning of flight
Establish a counter vortex
Some coefficients of lift
Bird Re – 70002.0
Locust Re – 20001.3
Drosophila Re – 2000.9
Hovering Flight
Encarsia formosa
Wing – 0.6 mm
Mass - .000025 gm
Re - 15
Coefficient of lift (predicted) = 0.02
Coefficient of lift (actual) = 5.0
Clap-and Fling Mechanism
Hovering flight
Flip Mechanism - Dragonfly
Hovering flight
Translational Phase
A) upstroke
B) downstrokeHigh angle of attack
Rotational Phase
A) pronation
B) supinationWhen wing reverses direction
Hovering Flight
Hovering flight
Red arrows – total force and direction
1. Delayed Stall2. Rotational lift 3 Forward motion
Blue arrows – wing position
Hovering flight
Hovering flight
Vortices around a flying animal
Bound vortex Tip vortices
Tip vortices
Tip vortices
Propulsion at very low Re’s
Rowing a boat – propulsive stroke is in lower Re (water) than recovery stroke (air)
Propulsion at very low Re’s
What about smaller animals that have to do both in low Re?
Cladoceran
Dytiscid beetle
Thrips
Nepticulid moth
Mymarid wasp
Ptiliid beetle
Aquatic Aerial
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
Fringed propelling mechanism
Power stroke (fringe expands)
Recovery stroke(fringe collapses)