Constructal flow
A five part depiction of Began's "constructal theory" of energy flow through structures.
In science, constructal theory or "constructal law" argues that the design of any open or closed system, animate, e.g. a human society, or inanimate, e.g. a river basin, is based on the postulate that: [1]

“For a finite sized flow system to persist in time (live or survive), its configuration must evolve (change in time) in such a way that it provides easier and easier access to the currents that flow through it.”

The constructal theory was conceived in 1996, by accident, at Duke University by Romanian-born American mechanical engineer Adrian Bejan, as a “thermodynamics principle that unites physics with biology”; a theory later argued to underlie the generation of design in societies. [1]

Overview
The theory was first presented in the 1997 book Advanced Engineering Thermodynamics (2nd edition) by Bejan. [3] The theory seems to have been culled from the subject of heat transfer, Bejan’s teaching curriculum at Duke University.

The term “constructal”, from the Latin construere “to construct”, was coined by Bejan. In 2005, an exploratory grant from the Human and Social Dynamics program of the National Science Foundation fueled cross-discipline research on the theory. The 2007 book Constructal Theory of Social Dynamics summarizes contributions made by prominent invited speakers at the First International Workshop on the constructal theory of social dynamics, held on 4-5 April 2006 at Duke University. The postulate, as stated above, in the view of Bejan, supposedly has become a new law of physics. Moreover, according to Bejan, his corpus of work has supposedly become a new addition of nonequilibrium thermodynamics: [5]

“This entire body of work represents a new extension of thermodynamics: the thermodynamics of flow systems of configuration.”

In 2007, Bejan argued that his new “constructal law” may be a new law of physics, similar to other “fourth laws” of thermodynamics, themed on flow states, such as Alfred Lotka’s 1922 fourth law, or Harold Morowitz’ 1968 fourth law, etc. [4] Bejan states that since the first and second laws are black box laws saying nothing about configuration, that a new law of thermodynamics or of physics is needed to explain the phenomenon of configuration generation in biology. On this premise, Bejan argues that just as the second law proclaims the existence of a final state (equilibrium for isolated system), the constructal law proclaims the existence of an “equilibrium flow architecture”, when all possibilities of increasing morphing freedom have been exhausted. [2]

Bejan's theory, to note, is very similar in theme and feel to Belgian chemist Ilya Prigogine’s 1955 dissipative structure theory based on heat flows and Bénard cell formations. The theory also seems to have overlap with chaos theory, emergence, and complexity theory.

Romanian-born American mechanical engineer Adrian Bejan explaining "constructal law" of design in nature, which he says unites the animate and inanimate realms of biology and geophysics.
See also
● Thermodynamic flow
● Entropy flow
● Gibbs energy flow
● Csíkszentmihályi flow

References
1. Bejan, Adrian and Merkx, Gilbert W. (2007). Constructal Theory of Social Dynamics (pg. xi). Springer.
2. ibid (pg. 2).
3. Bejan, Adrian. (1997). Advanced Engineering Thermodynamics (constructal theory). Wiley.
4. 15+ Variations of the Fourth Law of Thermodynamics - Institute of Human Thermodynamics.
5. Bejan, A. (2007). “Constructal Theory of Pattern Formation”, Hydrology and Earth System Sciences, Vol. 11, pgs. 753-68.

Further reading
● Bejan, A. and Lorente, S. (2008). Design with Constructal Theory (overview). Wiley.
● Bejan, A., Lorente, S., Miguel, A., and Reis, A.H. (2009). Constructal Human Dynamics, Security and Sustainability (abstract). IOS Press.

External links
● Constructal theory (portal) – Constructal.org.
● Constructal theory – Wikipedia.
● Adrian Bejan – Wikipedia.
● Adrian Bejan – ISIHighlyCited.com

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