Adrian Bejan J. A. Jones Distinguished Professor Duke University Constructal Theory of Flying,...

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.