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

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    17-Jan-2016

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INVERTEBRATES AND FLUID DYNAMICS:

OFF THE GROUND & MOVIN AROUNDFLIGHT

FLIGHTChord Thickness Angle of attackAirfoilFLIGHTStandard airfoilArea of relatively low pressureArea of relatively high pressureLIFTBUT THIS IS ONLY FOR AIRCRAFT4FLIGHTLiftDragResultant forceIn flapping flight, need to compromise1) lift2) propulsion3) Lowering of dragAs you increase angle of attackgenerated

H.G. Magnus (1802 1870)+LIFT=translationcirculationMAGNUS EFFECT

Same principle is used in various sports

Curve ball

Overall flow-Translational flowcirculation=

Circulation around wingAt the beginning of flightEstablish a counter vortexSome coefficients of liftBirdRe 70002.0

LocustRe 20001.3

Drosophila Re 2000.9Hovering Flight

Encarsia formosa

Wing 0.6 mm

Mass - .000025 gm

Re - 15Coefficient of lift (predicted) = 0.02Coefficient of lift (actual) = 5.0

Clap-and Fling MechanismHovering flight

Flip Mechanism - DragonflyHovering flightTranslational PhaseA) upstrokeB) downstrokeHigh angle of attackRotational PhaseA) pronationB) supinationWhen wing reverses direction

Hovering Flight

Hovering flightRed arrows total force and direction 1. Delayed Stall2. Rotational lift 3 Forward motionBlue arrows wing positionHovering flight

Hovering flight

Vortices around a flying animalBound vortexTip vorticesTip vortices

Tip vorticesPropulsion at very low Res

Rowing a boat propulsive stroke is in lower Re (water) than recovery stroke (air)Propulsion at very low ResWhat about smaller animals that have to do both in low Re?

CladoceranDytiscid beetleThrips Nepticulid mothMymarid waspPtiliid beetleAquatic AerialPropulsion at very low ResWhat about smaller animals that have to do both in low Re?

Relative sizesSize difference and different viscosity of medium similar low Res Fringed propelling mechanism

Power stroke (fringe expands)Recovery stroke(fringe collapses)