bfm1-dances with bio-physicsezphysics.nchu.edu.tw/chi/2008s_biofluidmechanics... · 槓桿原理–...
TRANSCRIPT
-
Bio-Fluid Mechanics- W1 2008/2/20
1
1
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
2
“Biology”
What’s in your mind?
3
Roles of Physics in Biology?
What if Darwin had met Newton?
從生物力學(Biomechanics)談起
4
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?
-
Bio-Fluid Mechanics- W1 2008/2/20
2
5Vogel, Comparative Biomechanics: Life's Physical World
Wal
king
Run
ning
ModelPhysics
6
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?
8
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?
-
Bio-Fluid Mechanics- W1 2008/2/20
3
9
Q: 貓能,為什麼我們不能?
10
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
11
I. 流體力學
12
Bernoulli’s Principle 伯努力定律(Conservation of Energy)
0)(21 2
12
2 =−+Δ+Δ vvzgp ρρ.21 2 constvgzp =++ ρρ
-
Bio-Fluid Mechanics- W1 2008/2/20
4
13
http://www.av8n.com/fly/vortex.htm
)(21 2
12
212 vvpp −−=− ρ
Applications of Bernoulli’s Principle:
14
• Spoonbill (琵鷺) feeding
Animals know Bernoulli’s, too!
15
vV PP
• Ventilation in burrows of prairie dog (北美土撥鼠)
Animals know Bernoulli’s, too!
16
Q: Challenges of a tree?
-
Bio-Fluid Mechanics- W1 2008/2/20
5
17
Q: Can leaves reduce drag?
18
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
Steven Vogel, Duke University
20
Bridgeand
amplifier
Digitalvolt-
meter
Windtunnel
LEAF
Beam,strain
gauges
Measuring drag…
Steven Vogel, Duke University
-
Bio-Fluid Mechanics- W1 2008/2/20
6
21
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
Steven Vogel, Duke University
22
II. 材料力學
23
http://www.nike.com/nikerunning
Example: Shoes
24
Nature’s Shoes–“Footpads” (腳掌墊)
↑ SizePlantigrady Digitigrady
*
Structural adipose tissue
-
Bio-Fluid Mechanics- W1 2008/2/20
7
25
Friction
ProtectionWeight bearing
Elastic pad Viscoelastic pad
Alexander et al. 1986
Force
Time
No pad
Foot
Body
Q: Function?
26
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)
27
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:
28
Previous studies: constrained setup
• In vitro• In vivo
(Kinoshita et al. 1993)(Ker, 1996)
Compressive tests
-
Bio-Fluid Mechanics- W1 2008/2/20
8
29
Animal Locomotion Laboratory (Duke BAA)
Trackway
Force Plate
PC & Video system
• 6 human subjects
• Different gaits (walking, running, crouched walking)
My study: Locomotion
30
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:
31
III. 生物附著&表面科學
32
1. Mucus
-
Bio-Fluid Mechanics- W1 2008/2/20
9
33
from Autumn’s website
2. Capillary force
34
3. Suction
e.g. 章魚
35
4. Microinterlocking
36
Lesser burdock (Arctium minus)
Velcro (魔鬼氈)
Colored SEM
-
Bio-Fluid Mechanics- W1 2008/2/20
10
37
e.g. Tokay Gecko
Bob Full, UC, Berkeley
5. Van der Waals force
38
Gecko feet
2 x 106 setae/ gecko102-103 spatulae/ seta
108-109 spatulae/ gecko
Lamellae
Setae
from Autumn’s website
39
40
IV. 應用
(模仿大自然的歷史紀錄)
-
Bio-Fluid Mechanics- W1 2008/2/20
11
41
E.g. Trout, Dolphins, and Streamlined Bodies
Cayley: drawing of dolphin & streamlined body (1809)
42
Bird Wings and Cambered Airfoils
43
Eardrums and Telephone Transducers
Bell’s patent, US # 174,465
Mouthpiece Earpiece
44
Burrs and Velcro
Lesser burdock (Arctium minus)
Velcro (魔鬼氈)
Colored SEM
-
Bio-Fluid Mechanics- W1 2008/2/20
12
45
V. 未來:
效法大自然的仿生科技
46
E.g. “Gecko"tape
(courtesy of Prof. Kellar Autumn, Lewis & Clark College, Portland Oregon http://lclark.edu/~autumn/)
47
In theory,
1300N force/ gecko
48
Polyimide hairs
2µm
Artificial gecko tape
-
Bio-Fluid Mechanics- W1 2008/2/20
13
49
Carrying capacity of more than 200 g/cm2Sticky & clear
50
How to self-clean?
51
2. 「壁貝」膠 (Geckel)
=壁虎(gecko)+貽貝(mussel)
52
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