Research Papers

The Constructal Law and the Design of the Biosphere: Nature and Globalization

[+] Author and Article Information
Adrian Bejan1

Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC 27708-0300abejan@duke.edu

Sylvie Lorente

Department of Civil Engineering, Laboratory of Materials and Durability of Constructions, University of Toulouse, INSA, 135 Avenue de Rangueil, 31077 Toulouse, France


Corresponding author.

J. Heat Transfer 133(1), 011001 (Sep 27, 2010) (7 pages) doi:10.1115/1.4002223 History: Received March 18, 2010; Revised May 11, 2010; Published September 27, 2010; Online September 27, 2010

“Design in nature” is a topic of growing interest throughout science. The constructal law is the physics law of design generation and evolution in nature: “for a flow system to persist in time (to live), it must evolve such that it provides easier and easier access to its currents.” In this paper, we show how the constructal law accounts for the main features of the design of the biosphere: global movement of mass as the action of constructal engines (geophysical, animal, and human made) that dissipate their power into brakes, animal locomotion, vision, cognition, and hierarchy. The architecture and hierarchy of vegetation results from the constructal tendency to generate designs that facilitate the flow of water and “the flow of stresses” (i.e., mechanical strength per unit volume). Natural porous media have multiple scales because their flows are also configured as trees. The paper concludes with the oneness of design in nature, global design, and science and technology evolution—all as manifestations of the natural tendency captured by the constructal law and unified constructal theory of evolution.

Copyright © 2011 by American Society of Mechanical Engineers
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Figure 1

The solar heat current (Q) that hits the earth and ultimately sinks into the cold universe. The earth temperature settles at a steady level between the sun temperature and the sky temperature. It is as if the current Q passes through the earth as it flows from high temperature (sun) to low temperature (sky).

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Figure 2

The biosphere on the move: the two phenomena that the solar heat drives as it passes through the earth (2,7). First, Q drives flows (natural mechanisms with moving parts) that function as “engines” and produce work W. Second, the work dissipated in the “brakes” that form between these flows and their immediate environments (neighbors). Seen as a whole, the flowing earth (engines+brakes) receives Q from the sun and rejects Q completely to the sky. This is in agreement with the simpler model of Fig. 1.

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Figure 3

The physics phenomenon of design generation and evolution facilitates the circuit executed by water in nature: tree-shaped river basins and deltas, vegetation, and all the features of animal design and human and machine species (10)

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Figure 4

Space, speed, and time: The evolution of the biosphere from prehistory to today (12). Animal flow has been spreading vertically in space and toward higher speeds, longer ranges, and better vision. This montage fits on the left plane of Fig. 5.

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Figure 5

Space, speed, mass, and time: The third dimension (mass) of the diversity in the flow of animal mass (12). At any point in time, the biosphere churns itself with a huge diversity of animate bodies organized according to a pattern. The larger bodies tend to have higher speeds lower body frequencies and larger forces.

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Figure 6

City sizes versus city rank in Europe during 1600–1980 and the Zipf distribution predicted with the constructal law (17)

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Figure 7

Distribution of tree canopy sizes versus rank in the constructal design of the forest floor (10). The Zipf distribution is insensitive to the pattern (e.g., triangular versus square) in which the multiscale tree canopies are arranged on the forest floor.

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Figure 8

The origin of multiscale porous media. The flow from plane to plane encounters considerably less resistance through tree-shaped structures than the flow through parallel channels (19).

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Figure 9

The global design as a multitude of distributed energy systems of all scales, designed and interwoven in accordance with the constructal law



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