Critique Of Constructal Theory

Constructal theory has been extensively used to analyze and optimize many different shapes and structures in both living and non-living systems. It is generally considered to be a law that could govern the evolutions of shapes and structures in biology, physics, technology, and social organization. Accordingly, it seems that the constructal method is suitable for designing and analyzing all kinds of shapes and structures in the world. However, in most cases, the details for its applications were not carefully checked, meaning that it was often incorrectly applied, and that many unreasonable or inaccurate results were provided. This book systematically reviews and checks the applications of constructal theory in street design, economics, heat transfer optimization, flow systems, and explanations of natural structures and social phenomena. Every detail of the models, methods, optimizations, applications, results and conclusions is analysed, with careful consideration of theoretical derivations and typical examples. Accordingly, the problems and mistakes in the applications of the theory are directly pointed out and discussed in detail. The abuse and limitation of the constructal approach are also discussed. In many cases, it is shown that the theory has significant flaws and is even not applicable in certain circumstances. As constructal theory is widely used in the analysis and design of shapes and structures, this book will be essential for scientists, researchers, engineers, teachers, postgraduates and undergraduates in the fields of structure analysis, design and optimization in physics, biology, flow dynamics, heat transfer and thermodynamics.

Design course on the universal principle of configurations in nature and engineering-the constructal law Design with Constructal Theory offers a revolutionary new approach based on physics for understanding and predicting the designs that arise in nature and engineering, from the tree and the forest to the cooling of electronics, urban design, decontamination, and vascular smart materials. This book shows how you can use the method of constructal theory to design human-made systems in order to reduce trial and error and increase the system performance. First developed in the late 1990s, constructal theory holds that flow architecture arises from the natural evolutionary tendency to generate greater flow access in time and in flow configurations that are free to morph. It unites flow systems with solid mechanical structures, which are viewed as systems for the flow of stresses. Constructal theory unites nature with engineering, and helps us generate novel designs across the board, from high-density packages to vascular materials with new functionalities (self-healing, self-cooling), and from tree-shaped heat exchangers to svelte fluid-flow and solid structures. Design with Constructal Theory starts with basic principles and then shows how these principles are applied to understanding and designing increasingly complex systems. Problems and exercises at the end of each chapter give you an opportunity to use constructal theory to solve actual design problems. This book is based on a design course developed by the two authors for upper-level undergraduates and graduate students at Duke University and other universities all over the world. With the authors' expert guidance, students and professionals in mechanical, civil, environmental, chemical, aerospace, and biomedical engineering will understand natural systems, and then practice design as science, by relying on constructal strategies to pursue and discover novel and effective designs.

Constructal Theory of Social Dynamics brings together for the first time social scientists and engineers who present predictive theory of social organization, as a conglomerate of mating flows that morph in time to flow more easily. The book offers a new way to look at social phenomena as part of natural phenomena, and examines a new domain of application of engineering such as thermodynamic optimization, thermoeconomics and "design as science".

Design happens everywhere, whether in animate objects (e.g., dendritic lung structures, bacterial colonies, and corals), inanimate patterns (river basins, beach slope, and dendritic crystals), social dynamics (pedestrian traffic flows), or engineered systems (heat dissipation in electronic circuitry). This “design in nature” often takes on remarkably similar patterns, which can be explained under one unifying Constructal Law. This book explores the unifying power of the Constructal Law and its applications in all domains of design generation and evolution, ranging from biology and geophysics to globalization, energy, sustainability, and security. The Constructal Law accounts for the universal tendency of flow systems to morph into evolving configurations that provide greater and easier access over time. The Constructal Law resolves the many and contradictory ad hoc statements of “optimality”, end design, and destiny in nature, such as minimum and maximum entropy production and minimum and maximum flow resistance, and also explains the designs that are observed and copied in biomimetics. Constructal Law and the Unifying Principle of Design covers the fundamentals of Constructal Theory and Design, as well as presenting a variety of state-of-the-art applications. Experts from the biological, physical and social sciences demonstrate the unification of all design phenomena in nature, and apply this knowledge to novel designs in modern engineering, such as vascularization for self-healing and self-cooling materials for aircraft, and tree fins and cavities for heat transfer enhancement.

In this book, the author introduces an alternative perspective to understand thermal phenomena, the concept of entransy and its relevant principles, applications and extensions, which have been widely used in the analyses and optimizations of many transport processes. The scientific significance and application value of the theory have been clearly demonstrated. The theory is inevitably questioned, and there are even accusations that are not academically valid. These controversies are also introduced and discussed comprehensively. This book is an introduction to the entransy theory; the author has only selected a few cases that are sufficient to show the advantages and necessity of the application of the theory. This book is helpful to the undergraduates, graduates, teachers, engineers, scientists and researchers in thermal science and engineering.

In this groundbreaking book, Adrian Bejan takes the recurring patterns in nature—trees, tributaries, air passages, neural networks, and lightning bolts—and reveals how a single principle of physics, the constructal law, accounts for the evolution of these and many other designs in our world. Everything—from biological life to inanimate systems—generates shape and structure and evolves in a sequence of ever-improving designs in order to facilitate flow. River basins, cardiovascular systems, and bolts of lightning are very efficient flow systems to move a current—of water, blood, or electricity. Likewise, the more complex architecture of animals evolve to cover greater distance per unit of useful energy, or increase their flow across the land. Such designs also appear in human organizations, like the hierarchical “flowcharts” or reporting structures in corporations and political bodies. All are governed by the same principle, known as the constructal law, and configure and reconfigure themselves over time to flow more efficiently. Written in an easy style that achieves clarity without sacrificing complexity, Design in Nature is a paradigm-shifting book that will fundamentally transform our understanding of the world around us.

The book contains research results obtained by applying Bejan's Constructal Theory to the study and therefore the optimization of fins, focusing on T-shaped and Y-shaped ones. Heat transfer from finned surfaces is an example of combined heat transfer natural or forced convection on the external parts of the fin, and conducting along the fin. Fin's heat exchange is rather complex, because of variation of both temperature along the fin and convective heat transfer coefficient. Furthermore possible presence of more fins invested by the same fluid flow has to be considered. Classical fin theory tried to reduce the coupled heat transfer problem to a one-dimensional problem by defining an average temperature of the fin and writing equations using this parameter. However, it was shown that this approach cannot be used because of the effects of two-dimensional heat transfer, especially in the presence of short fins. CFD codes offer the possibility to consider bi-dimensional (and more generally, three-dimensional) effects and then a more real approach to the physic phenomena of finned surface's heat exchange. A commercial CFD code was used to analyse the case of heat exchange in presence of T-shaped fins, following an approach suggested by Bejan's Constructal Theory. The comparative results showed a significant agreement with previous research taken as a reference, and this result allows for the application of this approach to a wider range of systems. T-shaped optimized fin geometry is the starting point for further research. Starting from the optimal results (T-shape optimized fins), we show the trend of the assessment parameter (the dimensionless conductance) in function of the angle α between the two horizontal arms of the fin. A value for α, 90°

Function-Based Spatiality and the Development of Korean Communities in Japan utilizes the theoretical model of complex adaptive systems and introduces the concept of function-based spatiality to investigate the roles of the urban environments of Tokyo and Osaka in the development of Korean communities in Japan. Analysis of distinct Korean communities allows for the examination of urban factors of each city which contributed to the patterns of Korean immigration and community formation. By utilizing a comparative narrative of the two cities, distinctions between the organic growth of Osaka and the planned city of Tokyo are illuminated. Additionally, the discussion utilizes the concept of function-based spatiality to show how each city interacted with its surrounding regional, national, and global spheres. The functions of Tokyo, as a gateway to Western modernization and center of the Japanese state, shaped the interactions with Korean immigrants. Likewise, Osaka’s functions as a center of mercantilism and second city played a large role in how Koreans were incorporated into the urban ethnoscapes. Taken together, these two examples provide insight to the dynamics of urban systems on the development of immigrant communities.