The Key to Sustainability: Flows of Water and Electricity

European ReviewIn this publication, A. Bejan draws attention  to the emerging literature and physics principle (constructal law) that provide the scientific foundation for sustainability. He shows that the sustainability need is about flow: the flow of energy and the flow of water through the inhabited space.

All the flows needed for human life such as transportation, heating, or cooling, water are driven by the purposeful consumption of fuels, and this is why the wealth of a country (the GDP) is directly proportional to the annual consumption of fuel in that country.

Sustainability comes from greater freedom in changing the organization – the flow architecture – that sustains life. Greater freedom to change the design (from water and power to laws and government) leads to greater flow, wealth, life and staying power, i.e. sustainability


Evolving into a Better Design: Humans and Technology as One

Tree-like architectures and a river deltaThe Constructal Law is the law of physics that accounts for the natural tendency of designs to evolve freely over time to flow more easily.

As research has been conducted to support this pattern of design evolution, an even greater phenomenon has come to light: Humans and technology are one species, evolving together.

Adrian Bejan, the discoverer of the constructal law and a professor at Duke University, recently spoke about this topic at the 27th Annual Conference of the Academia Europaea 2015 in Germany.

Why humans build fires shaped the same way

The clashing asymptotes define this behavior, and the method of intersecting the asymptotes18 pinpoints the architecture, the design. Photographs taken by Adrian Bejan.This article, published in the Nature Scientific Report, explain “why humans unwittingly build fires that look the same: edifices of fuel, as tall as they are wide. The pile of fuel is permeable, air invades it by natural convection and drives the combustion.“. The article “show that the hottest pile of burning fuel occurs when the height of the pile is roughly the same as its base diameter. Future studies may address the shape effect of wind, material type, and packing. Key is why humans of all eras have been relying on this design of fire “unwittingly”. The reason is that the heat flow from fire facilitates the movement and spreading of human mass on the globe“.

Constructal Law: Optimization as Design Evolution

Constructal invasion of a conducting tree into a conducting body, Kobayashi, H., Lorente, S., Anderson, R., and Bejan, A., 2013, “Trees and Serpentines in a Conducting Body,” Int. J. Heat Mass Transfer, 56(1–2), pp. 488–494. This article from the Journal of Heat Transfer unveils the physics meaning of optimization, knowledge and design evolution, and why these concepts and human activities are profoundly useful for human life.

The design in nature phenomenon facilitates access for everything that flows, evolves, spreads, and is collected: river basins, atmospheric and ocean currents, animal life and migration, and technology (the evolution of the “human-and machine species,” wealth, life). This phenomenon is summarized by the constructal law: the occurrence and evolution of designs in nature, its time direction.

Notably, the constructal law accounts for contradictory end-design statements such as minimum entropy production and maximum entropy production, and minimum flow resistance and maximum flow resistance.