Constructal theory and flow architectures in living systems

• Main Authors: Reis Antonio Heitor, Miguel Ferreira Antonio
• Format: Article
• Language: English
• Published: VINCA Institute of Nuclear Sciences 2006-01-01
• Series: Thermal Science
• Subjects: flow architectures; living systems; constructal theory
• Online Access: http://www.doiserbia.nb.rs/img/doi/0354-9836/2006/0354-98360601057R.pdf

We apply Constructal theory to the study of the flow structure of the human respiratory tree. We show that the flow architecture that would per form oxygenation of the blood and removal of carbon dioxide best, i. e. with lowest resistance, would be composed of a channel system with 23 bifurcation with a diffusive zone (alveolus) at the end. As this tree matches the human respiratory tree we conclude that nature has optimized it in time. Two constructal relation ships also emerge: (1) the length l, de fined by the ratio of the square of the airway diameter to its length, is constant for all individuals of the same species, and (2) the length γ is related to the volume of the space al located to the respiratory process, to the length of the respiratory tree and to the area of the alveoli, and determines univocally the branching level of the respiratory tree.