BFM1-Dances with Bio-Physicsezphysics.nchu.edu.tw/chi/2008s_BioFluidMechanics... · 槓桿原理–...

Bio-Fluid Mechanics- W1 2008/2/20

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2/20/2008物理系及生物物理學研究所

紀凱容

與生物+物理共舞

生物流體力學Bio-fluid Mechanics

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“Biology”

What’s in your mind?

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Roles of Physics in Biology?

What if Darwin had met Newton?

從生物力學(Biomechanics)談起

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Wal

king

Run

ning

Pho

togr

aphe

d by

Ead

wea

rdM

uybr

idge

in 1

880’

s［生物］

Q: Difference b/w walking & running?


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5Vogel, Comparative Biomechanics: Life's Physical World

Wal

king

Run

ning

ModelPhysics

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Wal

king

Run

ning

Potential energy ↔Kinetic energy

Potential energy + Kinetic energy ↔ Elastic energy

Mechanical energyModel

Physics

7Hutchinson et al., 2003 Nature(pictures from Summers, 2007, Natural History Magazine)

Q: Are fast moving elephants really running?

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Q: 貓真的有九條命嗎？

［生物］

tvΔΔ

↓避震器：增長運動中的物體停止的時間

［物理］

刺蝟的刺也有同樣功能！

Q: 貓為何總能安然降落？


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Q: 貓能，為什麼我們不能？

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槓桿原理– 食肉、食草大不同

顳肌

嚼肌關節

嚼肌力臂

顳肌力臂

貓顳肌

嚼肌

關節

嚼肌力臂

顳肌力臂

兔

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I. 流體力學

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Bernoulli’s Principle 伯努力定律(Conservation of Energy)

0)(21 2

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2 =−+Δ+Δ vvzgp ρρ.21 2 constvgzp =++ ρρ


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http://www.av8n.com/fly/vortex.htm

)(21 2

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212 vvpp −−=− ρ

Applications of Bernoulli’s Principle:

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• Spoonbill (琵鷺) feeding

Animals know Bernoulli’s, too!

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vV PP

• Ventilation in burrows of prairie dog (北美土撥鼠)

Animals know Bernoulli’s, too!

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Q: Challenges of a tree?


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Q: Can leaves reduce drag?

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Test in wind tunnel72.4 - 105 kph (8-11級風)

Tulip poplar - still air

5 m/s10 m/s15 m/s20 m/s

Steven Vogel, Duke University

19Tulip poplar cluster - 10 m/s

black locust

Still air5 m/s10 m/s15 m/s20 m/s


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Bridgeand

amplifier

Digitalvolt-

meter

Windtunnel

LEAF

Beam,strain

gauges

Measuring drag…



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leaves

rigid plate

Dra

g co

effic

ient

0.4

0.3

0.1

0

Wind speed, m/s10 15 20

0.2

flexible square


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II. 材料力學

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http://www.nike.com/nikerunning

Example: Shoes

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Nature’s Shoes–“Footpads” (腳掌墊)

↑ SizePlantigrady Digitigrady

*

Structural adipose tissue


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Friction

ProtectionWeight bearing

Elastic pad Viscoelastic pad

Alexander et al. 1986

Force

Time

No pad

Foot

Body

Q: Function?

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Stabilize foot(Alexander et al., 1986)

Brake & cushion impact(Valiant, 1984; Kinoshita et al. 1993)

Transmit force

Return elastic energy(Ker, 1996)

Breaking PropulsionDuring locomotion?

Pad properties to consider—Resists deformation (stiff or compliant)Loses energy (resilient or damped)

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Paradox

Q: Can footpad perform multiple functions? How?

Functions:

Brake & Cushion impact

Return elastic energy

Stabilize foot

Transmit propulsive force

Compliant

Resilient

Damped

Stiff

Properties:

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Previous studies: constrained setup

• In vitro• In vivo

(Kinoshita et al. 1993)(Ker, 1996)

Compressive tests


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Animal Locomotion Laboratory (Duke BAA)

Trackway

Force Plate

PC & Video system

• 6 human subjects

• Different gaits (walking, running, crouched walking)

My study: Locomotion

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ti = 0 ms tf = 14 ms

2 cm

2 mm

x

z

t i

t f

-100

0

100

200

300

400

500

600

0 0.01 0.02 0.03

Time (s)

GR

F (N

)

A-PM-L

VImpact

-200

0

200

400

600

800

1000

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Time (s)

GR

F (N

)

A-P

M-L

V

Impact

Load

(N)

Compressive deformation (mm)

WalkingSx = 1.5m/s, Vzi =0.57m/s

RunningSx = 3.5m/s, Vzi =1.23m/s

0

200

400

600

800

1000

1200

1400

1600

1800

0 2 4 6 8

Chi & Schmitt, 2005J. Biomechanics

Load:

Deformation:

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III. 生物附著&表面科學

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1. Mucus


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from Autumn’s website

2. Capillary force

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3. Suction

e.g. 章魚

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4. Microinterlocking

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Lesser burdock (Arctium minus)

Velcro （魔鬼氈）

Colored SEM


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e.g. Tokay Gecko

Bob Full, UC, Berkeley

5. Van der Waals force

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Gecko feet

2 x 106 setae/ gecko102-103 spatulae/ seta

108-109 spatulae/ gecko

Lamellae

Setae

from Autumn’s website

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IV. 應用

(模仿大自然的歷史紀錄)


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E.g. Trout, Dolphins, and Streamlined Bodies

Cayley: drawing of dolphin & streamlined body (1809)

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Bird Wings and Cambered Airfoils

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Eardrums and Telephone Transducers

Bell’s patent, US # 174,465

Mouthpiece Earpiece

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Burrs and Velcro

Lesser burdock (Arctium minus)

Velcro （魔鬼氈）

Colored SEM


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V. 未來:

效法大自然的仿生科技

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E.g. “Gecko＂tape

(courtesy of Prof. Kellar Autumn, Lewis & Clark College, Portland Oregon http://lclark.edu/~autumn/)

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In theory,

1300N force/ gecko

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Polyimide hairs

2µm

Artificial gecko tape


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Carrying capacity of more than 200 g/cm2Sticky & clear

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How to self-clean?

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2. 「壁貝」膠 (Geckel)

=壁虎(gecko)＋貽貝(mussel)

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3. Spider silk

生物物理期刊俱樂部 (BJC)(每週四中午,系會議室)

本週活動：

環境中風的干擾對蜘蛛絲及蜘蛛網強度的影響

BFM1-Dances with Bio-Physicsezphysics.nchu.edu.tw/chi/2008s_BioFluidMechanics... · 槓桿原理–...

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