Vascular materials: Predicting design evolution

Department of Hydrology and Atmospheric Sciences
12 pm on Wednesday, March 1, 2023
Available via zoom only
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Adrian Bejan
J.A. Jones Distinguished Professor, Duke University


Porous materials are usually thought of as amorphous mixtures of two or more things, solids, fluids, and voids. The research field started that way, and so did my own activity in it. Along the way, I was drawn to the part of nature (the physics) that was missing from the amorphous view: the structure, flow, configuration, drawing (design), purpose, and evolution. The lecture is pictorial. It begins with defining the terms, because words have meaning: vascular, design, evolution, and prediction (theory). Next, the lecture shows that vascular (tree shaped) architectures flow more easily than parallel channels with only one length scale (the wall to wall spacing). Transport across channels is facilitated when the spacing is such that the channel flow length matches the entrance (developing) length of the flow. The tendency to evolve with freedom toward flow configurations that provide greater access is universal in nature, bio, and non-bio. This tendency is the Constructal Law, which empowers us to predict the evolution toward flow access, miniaturization, high density of heat transfer, and the scaling up (or down) of an existing design. Multiscale vasculatures occur naturally because they flow more easily than their counterparts with a few length scales. The future of evolutionary design everywhere points toward vascular, hierarchical flow architectures that will continue to morph with freedom and directionality.


Adrian Bejan was awarded the 2018 Benjamin Franklin Medal for “his pioneering interdisciplinary contributions in thermodynamics…and constructal theory, which predicts natural design and its evolution in engineering, scientific, and social systems.” He earned all his degrees from the Massachusetts Institute of Technology: B.S. (1971, Honors Course), M.S. (1972, Honors Course) and Ph.D. (1975). He was Fellow of the Miller Institute for Basic Research in Science, University of California Berkeley (1976-1978). Since 1989 he is the J.A. Jones Distinguished Professor at Duke University. Prof. Bejan’s research is in applied physics, thermodynamics, theoretical biology, and design and evolution everywhere in nature, bio, and non-bio. He created original methods of theory, modeling, analysis, and design, which today are associated with his name: entropy generation minimization, scale analysis, intersection of asymptotes, heatlines, constructal law, and evolutionary design everywhere in nature, bio and non-bio.

He is the author of 30 books and 700 peer-refereed journal articles. Google Scholar: h = 105, total citations 82,000. According to the 2019 ‘citations impact’ world rankings, he is 9th among all Engineering authors in the world, all disciplines. He was awarded 18 honorary doctorates from universities in 11 countries, for example, Swiss Federal Institute of Technology (ETH Zurich), University of Rome I “La Sapienza”, National Institute of Applied Sciences (INSA) Lyon, and University of Pretoria. He is a member of the Academies of Europe, Mexico, Turkey, Romania, and Moldova.