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.