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Adrian BejanJ. A. Jones Distinguished ProfessorDuke University
Constructal Theory of Flying, Running and Swimming
The generation of configuration is a physics phenomenon
Natural flow configurationstree networkslocomotionglobal circulation and climate
The constructal law
W2
W1
2 2b1 2a b1/ 2
M gHW W~ V L
L V(H / g)
Verticalloss
Horizontalloss
6/16/1b
2/13/1
a
bopt Mg~V
6/16/1b
2/13/1
a
b1opt
Mg~t
1 2 min(W W ) / L ~ 2Mg F ~ 2Mg
M = body mass
Lb = body length ~ H
a = air density
b = body density
A. Bejan, Shape and Structure, from Engineering to Nature, Cambridge University Press, 2000.
A. Bejan and S. Lorente, ASME Paper, IMECE2003-33158
3/ 2 2 2 2b b b1 2
3/ 2b
M g L V MW W~
L V A L
Vertical loss
Horizontalloss
2 2b b1 2a b1/ 2
b
M gLW W~ V L
L V(L / g)
Vertical loss
Horizontalloss
“Give me one firm spot on which to stand, and I will move the earth”
(Archimedes, 287-212 B.C.)
A. Bejan and J. H. Marden, J. Exp. Biol. 209 (2006) 238-248.
A. H. Reis and A. Bejan, Int. J. Heat Mass Transfer 49 (2006)
Constructal law (1996):
“For a flow system to persist in time (to survive) it must evolve in such a way that it provides easier and easier access to the currents that flow through it”.
This new law of physics stands behind all phenomena of configuration generation:
Darwin’s observations
Machine evolution (“human + machine species”)
River basin evolution, atmospheric circulation, climate, lightning, vascularization, vegetation, animals, turbulent flow, dendritic crystals, social organization, etc.