Ebook: Constructal Human Dynamics, Security and Sustainability

Globalization, security infrastructure and energy sustainability can be designed based on a scientific principle. In this book, these objectives are approached based on constructal theory, which means to design such projects as global “flow” architectures that are “alive” with movement of personnel, equipment, information, education, etc.

Constructal theory is a new physics theory, which views the generation of flow configuration as a natural evolutionary phenomenon governed by the Constructal Law:

“For a finite-size flow system to persist in time (to live, to survive), its configuration must change in time such that it provides easier and easier access to its currents (fluid, energy, species).”

Successful designs are those in which “imperfections” (flow resistances, costs, danger, choke points) are balanced and distributed optimally throughout the flow territory. This integrative approach to the design of human movement and infrastructure leads strategically to maximum global performance (efficiency, cost, safety, security, sustainability). Freedom is good for design: the flow configuration must be free to morph in order to be brought to a level of greater and greater global performance.

This book highlights the progress made during the NATO Advanced Research Workshop “Constructal Human Dynamics, Globalization, Security and Sustainability”, held in Évora, Portugal on 20-23 May 2008. This workshop put social scientists in the same room with physicists, engineers and biologists, who addressed together main topics such as human dynamics viewed as natural phenomena of design generation, flow networks for distribution and collection, large-scale construction projects (e.g., airports, waste storage), logistics, decontamination, energy supply routes, distributed energy systems, water resources management, environmental security sustainability, and globalization.

The chapters selected for this book are representative of the interdisciplinary approach and team atmosphere that emerged in Évora. We thank the participants and, in particular, our colleagues who contributed to this book: Gilbert W. Merkx, Wayne Miller, Fabien Frizon and Stephen Périn. We thank NATO for the financial support of the Évora workshop. A community of scholars has emerged around the new paradigm of social organization centered on the constructal law. Further progress is put on display at www.constructal.org.

Adrian Bejan

Sylvie Lorente

Antonio F. Miguel

A. Heitor Reis

Constructal theory is the view that the generation of “designedness” in nature is a universal (physics) phenomenon that can be based on a physics principle (the constructal law): “For a finite-size flow system to persist in time (to live) its configuration must change in time so that it provides greater and greater access to its currents”. This principle predicts and explains natural form across the board, from river basins to animal design, engineering and social dynamics. In this opening chapter we present the principle by using examples of vascular designs at large scales (urban traffic, water distribution), multi-objective flow configurations (heat and fluid flow, beams loaded mechanically and subjected to terrorist attack by fire), characteristic sizes of organs and distributed energy systems. Constructal theory is a new paradigm for how to pursue globalization, and how to engineer the proper balance between human flow architectures and the flow architectures of the environment.

Cities are viewed as lively systems with internal flow structure of people, energy and goods. By appropriately defining concepts as metabolic rate, pulsating period, and mass previous studies have shown that cities follow known allometric laws of animals, then allowing rules for self-organization. The distributions of street lengths and nodes follow inverse-power distribution laws. That means that the smaller the network components, the more numerous they have to be. In addition, street networks show geometric self-similarities over a range of scales. Based on these features many authors claim that street networks are fractal in nature. What we show here is that both the scaling laws and self-similarity spring out of the underlying dynamics, together with the purpose of optimizing flows of people and goods in time, as predicted by the Constructal Law. The results seem to corroborate the prediction that cities fractal dimension approaches 2 as they develop and become more complex. Examples from History show that the Constructal Law provides a basis for understanding the internal structure both of roman and medieval cities. Finally, it is shown that the Constructal Law also provides the base for the design of flow structures (street networks, corridor networks) which perform optimally with respect to evacuating people from disaster areas.

The Constructal Law provides a basis for analyzing public policy with respect to natural and social flow systems, including catastrophic events. Whether or not social actors are individual or collective, there are four basic types of behavioral response to flow systems: obstruction, avoidance, facilitation, and inaction. Responses can be directed either at the flow system or to competing flow systems. The success of different responses is determined by four dimensions of flow systems: scale, velocity, pressure, and time.

Constructal theory may become a powerful tool for solving problems of global security and sustainability. However there are three challenges that must be met for this to occur. First, constructal theory must become known and trusted by the various communities that work on global problems. Second, the practitioners of constructal theory must develop a compelling portfolio of successful examples that highlight value and applicability to global problems. Third, constructal theory should be augmented with additional theoretical tools that will, in total, create a forward predictive capability that can improve sub-optimal existing systems and create new systems as needed to tackle the most complex global problems. Examples are included that illustrate the classes of problems for which constructal theory may be successfully applied.

The occurrence of flow configuration (pattern, shape, structure) is a universal phenomenon. From atmospheric circulation to living cells, the occurrence of flow configuration is associated to the very existence of these systems. Why is configuration a characteristic of natural flow systems? Is there a physical law from which rhythms (flows) and patterns (configurations) can be deduced? It is shown here that the occurrence of flow configuration can be both explained and predicted on the basis of a single law - the constructal law. This law states that for a flow system to persist in time it must evolve in such way that it provides easier access to its currents. Coral colonies and pedestrian crowd dynamics occur in very different physical environments and form dissimilar patterns. The flow configuration phenomena at work in either of these systems are, however, one and the same and can be explained by the constructal law. Within the same framework, strategies for optimization of pedestrian flows in a real-world environment are also presented.

Decontamination of agents, whatever they are, chemical, biological, or nuclear, requires an optimal location of equipment. This chapter presents the theoretical basis of the transport of ionic species through porous media enhanced by an external electrical source. Constructal theory is used to determine the optimal positioning of the electrodes used for the ionic decontamination.

The main objective of long-term management of radioactive wastes is to protect man and environment from the risks linked with existing wastes, during industrial exploitation of storage site as on long-term. The geological repository’s safety relies on a multi-barrier strategy and on a multifunctional concept, involving the complementary properties of the geological site, the design provisions and the primary package. Each of the safety functions concerns flow management in a global system composed of the repository and its environment. One of the most important fluxes, the radioactive nuclide flux, is here phenomenologically described from its source, after alteration of wastes packages, to the biosphere.

The Air Traffic System is composed of many superimposed complex flows structures following power-law distributions. We try to show that Air Traffic System flows such as airport and air traffic flows are bundles of refracted paths, which owe their global shape to the maximization of flow access, in accordance with the Constructal law. We investigate in parallel the development and evolution of Information Systems, which appear to follow the same underlying principle dictating the emergence of optimal airport architectures or street network geometries, with the apparition of typical tree shaped geometries, multiple scales architectures, self similarity, and power-law distribution in Information networks. The development in the last decades of approaches such as Emergent Design, Service Oriented Architecture, and sustainable management of Information System in general is then considered from the Constructal point of view.

Societal patterns of flow, movement and organization can be rationalized based on the constructal law. People, goods, money and information move on earth as a conglomerate of point-area and area-point flows, all superimposed, and each morphing toward configurations that provide easier and easier access for what flows. This application of the constructal law has become the constructal theory of social dynamics, which is illustrated here with three examples: the multiscale distribution of city sizes on the landscape, the rigidity of the hierarchy of universities in the annual rankings, and the coexistence of large research groups with individual researchers in the same university. The constructal theory of social dynamics also predicts trends of natural design that until now were known empirically, for example, Zipf’s law.