 Constructal design of a cooling system The constructal theory of global optimization under local constraints explains in a simple manner the shapes that arise in nature. It is the thought that flow architecture comes from a principle of maximization of flow access, in time, and in flow configuration that are free to morph. Image File history File links Download high resolution version (1499x1132, 155 KB)First, second and third order constructs of the constructal design of a cooling system. ...
Image File history File links Download high resolution version (1499x1132, 155 KB)First, second and third order constructs of the constructal design of a cooling system. ...
The constructal law proclaims a tendency in time about the generation of animate and inanimate flow systems: "the maximization of access for the currents that flows through a morphing flow system ". This theory replaces the belief that nature is fractal, and allows one to design and analyse systems under constraints in a quest for optimality. The Mandelbrot set, named after its discoverer, is a famous example of a fractal. ...
This theory allows the design and understanding of natural systems, thermal dissipators, communication networks, etc.
History
The constructal theory was developed by Adrian Bejan in the late 90's. Adrian Bejan (born September 24, 1948), Ph. ...
Professor Bejan taught at MIT until 1976 and is now J.A. Jones Distinguished Professor of Mechanical Engineering at Duke University, Durham. The Massachusetts Institute of Technology, or MIT, is a research and educational institution located in the city of Cambridge, Massachusetts, USA. MIT is a world leader in science and technology, as well as in many other fields, including management, economics, linguistics, political science, and philosophy. ...
The Ford Essex V6 engine Mechanical engineering is a very broad field of engineering that involves the application of physical principles for analysis, design, manufacturing, and maintenance of mechanical systems. ...
Duke Chapel Duke University is a private, coeducational, research university located in Durham, North Carolina, USA. Although founded in 1924, Duke traces its roots back to 1838. ...
Nickname: City of Medicine Motto: Official website: http://www. ...
Bejan's research areas cover: entropy generation minimization, exergy analysis, condensation, convection in porous media, transition to turbulence, etc. In thermodynamics and statistical mechanics, the thermodynamic entropy (or simply the entropy) S is a key physical variable in describing a thermodynamic system. ...
This article needs to be cleaned up to conform to a higher standard of quality. ...
"Constructal" is a word coined by Bejan, coming from the latin verb construere, to construct, in order to designate, in the constructal theory's point of view, the naturally optimized forms such as rivers, trees and branches, lungs and also the engineered forms coming from a constructal optimization process. Latin is an ancient Indo-European language originally spoken in the region around Rome called Latium. ...
Constructal design of a cooling system The constructal theory of global optimization under local constraints explains in a simple manner the shapes that arise in nature. ...
Principles For example, in point-area and point-volume flows, constructal theory predicts tree architectures, such flows have displaying at least two regimes: one highly resistive and a less resisitive one, and it can be applied at any scale: from macroscopic to microscopic systems. Some domains of application | Application | What flows | Tree channels | Interstitial spaces | | Packages of electronics | Heat | High-conductivity inserts (blades, needles) | Low conductivity substrate | | Urban traffic | People | Low-resistance street car traffic | Street walking in urban structure | | River basins | Water | Low-resistance rivulet and rivers | Darcy flow through porous media | | Lungs | Air | Low-resistance airways, bronchial passages | diffusion in alveoli tissues | | Circulatory system | Blood | Low-resistance blood vessels, capillaries, arteries, veins | diffusion in capillaries tissues | The main principle of the constructal theory is that every system is destined to remain imperfect.
According to this, the best that can be done is to optimally distribute the imperfections of the system, and this optimal distribution of imperfection will generate the geometry or shape of the studied system.
The constructal way of distributing the system's imperfection is to put the more resistive regime at the smallest scale of the system. The constructal law is the principle that generates the perfect form, which is the least imperfect form possible.
Constructal law The constructal principle was stated by Bejan in 1996 as follows: "For a finite-size system to persist in time (to live), it must evolve in such a way that it provides easier access to the imposed currents that flow through it."
Thermodynamical analogy Analogies between thermodynamics and constructal theory | Thermodynamics | Constructal theory | | State | Flow architecture (geometry, structure) | | Process | Change of structure | | Properties | Global objective and global constraints | | Equilibrium state | Equilibrium flow architecture | | Fundamental relation | Fundamental relation | | Constrained equilibrium states | Nonequilibrium architectures | | Removal of constraints | Increased freedom to morph | | Energy minimum principle | Maximization of flow access | Thermodynamics (from the Greek thermos meaning heat and dynamis meaning power) is a branch of physics that studies the effects of temperature, pressure, and volume changes on physical systems at the macroscopic scale. ...
Achievements The constructal theory is predictive and thus can be tested experimentally. So far, it has succeeded in prediciting a wide variety of phenomena.
 allometric law of cruising speed vs body mass The constructal principle of optimized tree-flow architecture allowed to predict many allometric laws, e.g.: Image File history File links The proportionality between the optimal cruising speed of flying bodies (insects, birds, airplanes) and body mass in kg raised to the power is an allometric law predicted by the Constructal theory of Adrian Bejan: 2000 Adrian Bejan File history Legend: (cur) = this is the current...
Image File history File links The proportionality between the optimal cruising speed of flying bodies (insects, birds, airplanes) and body mass in kg raised to the power is an allometric law predicted by the Constructal theory of Adrian Bejan: 2000 Adrian Bejan File history Legend: (cur) = this is the current...
Allometric law (or power-law) are relationships between living organisms body parts or process, usually expressed in power-law form: or in a logarithmic form: Examples allometric law of cruising speed vs body mass Some examples of allometric laws: Kleibers law, the proportionality between metabolic rate and body...
- Kleiber's law, the proportionality between metabolic rate q0 and body size M raised to the power 3 / 4:
 - the proportionality between breathing and heart beating times t and body size M raised to the power 1 / 4:
 - mass transfer contact area A and body mass M:
 - the proportionality between the optimal cruising speed Vopt of flying bodies (insects, birds, airplanes) and body mass M in kg raised to the power 1 / 6:
 Bejan's constructal law also explains why we have a bronchial tree with 23 levels of bifurcation. The constructal theory of the flow architecture of the lung predicts and offers an explanation for: Kleibers law, named after Max Kleibers biological work in the early 1930s, is the observation that, for the vast majority of animals, an animals metabolic rate scales to the 3/4 power of the animals mass. ...
The lungs flank the heart and great vessels in the chest cavity. ...
- the dimensions of the alveolar sac,
- the total length of the airways,
- the total alveolar surface area,
- the total resistance to oxygen transport in the respiratory tree.
See also Adrian Bejan (born September 24, 1948), Ph. ...
The Ford Essex V6 engine Mechanical engineering is a very broad field of engineering that involves the application of physical principles for analysis, design, manufacturing, and maintenance of mechanical systems. ...
External links
References - A. Bejan, Advanced Engineering Thermodynamics, Wiley-Interscience, 2nd edition, 896 p. ISBN 0471148806
- A. Bejan, Shape and Structure, from Engineering to Nature, Cambridge University Press, Cambridge, UK, 2000m 324 p. ISBN 0521793882
- Proceedings of the Symposium "Bejan’s Constructal Theory of Shape and Structure" Edited by Rui N. Rosa, A. Heitor Reis & A. F. Miguel, Centro de Geofísica de Évora, Évora Geophysics Center, Portugal, 2004, ISBN 972-9039-75-5
- A. Bejan, Constructal theory of organization in nature: dendritic flows, allometric laws and flight, Design and Nature, CA Brebbia, L Sucharov & P Pascola (Editors). ISBN 1-85312-901-1
- A. H. Reis, A. F. Miguel , M. Aydin, Constructal theory of flow architecture of the lungs, Journal of Medical Physics, May 2004, Volume 31, Issue 5, pp. 1135-1140.
- A. H. Reis, A. Bejan, Constructal theory of global circulation and climate, International Journal of Heat and Mass Transfer.
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