International Journal of Heat and Mass Transfer 51 (2008) 5759–5761

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International Journal of Heat and Mass Transfer
journal homepage: www.elsevier.com/locate/ijhmt

In Celebration

Professor Adrian Bejan on his 60th birthday

Good theory grows out of freedom and fun. Adrian Bejan was bornand raised on the Danube, in Galati, Romania, under a dictatorialcommunist regime. The son of a veterinarian (his father) and apharmacist (his mother), he quickly showed inclination for analytical work, excelling in school. Freedom was not known to him, until
he won one of only six scholarships in a national contest, and got achance to migrate to the United States of America. He arrived at theMIT, as a shy, 19-year-old, tall boy who seemed more apt for basketball (in fact, he was a very good basketball player in Romania, having been a member of the national select team) than for science.
Freedom. Upon his arrival, and due to a bureaucratic mistake,
Adrian was enrolled in the graduate program in Mechanical Engineering at the MIT, even though he was a beginning undergraduatein Romania. The mistake was quickly corrected by Prof. Rohsenow,and Adrian soon demonstrated that his skills in science were atleast as good as in basketball. He went through to get all degrees(B.Sc. with Honors, M.Sc. with Honors, and Ph.D.) from the MIT in
Mechanical Engineering, with specialization in cryogenics and heattransfer, being mentored by people of the caliber of Profs. J.L. SmithJr., W.M. Rohsenow, J.P. Den Hartog, A.H. Shapiro, R.F. Probstein,H.M. Paynter, S.H. Crandall, J.H. Keenan, G. Hatsopoulos and E.P.
Gyftopoulos. His eight years at MIT taught Adrian the importanceof freedom as a fundamental component to stimulate curiosity,
which eventually blossoms into ideas, new ideas. This lesson was,and still is, evident in his professional work.
From MIT Adrian went on to the University of California Berkeley where he had the privilege to work as a post-doctoral Miller Fel-

doi:10.1016/j.ijheatmasstransfer.2008.06.027

low with Prof. Chang-Lin Tien during 1976–1978. Tien’s openness,curiosity and new ideas only ampliﬁed Adrian’s natural instincts.
The more application-driven science learned at the MIT was nowbeing balanced by the more fundamental-driven research of Berkeley. The MIT-Berkeley combination would shape Adrian’s future,
leading to a well balanced scientiﬁc pursuit characterized by anapplication-driven fundamental research. This characteristic wasalready presented in his early papers with Prof. Tien.
Make it simple. The beginning of Adrian’s academic career wasmarked by his proliﬁc writing ability. Four years after beginning
his academic career at University of Colorado, Boulder, Adrian published his ﬁrst book, Entropy Generation Trough Heat and Fluid
Flow (Wiley, 1982). A fresh look into the ideas behind the second
law of thermodynamics, but applied to the important ﬁeld of heatand ﬂuid ﬂow, this book brought down the intimidating barriersof second law analysis. It downplayed the philosophical conceptsof thermodynamics in favor of a practitioner’s view, with an innovative way to apply the same ideas to engineering. We can say that
his Entropy Generation book popularized (among engineers) concepts such as irreversibility, availability and exergy analysis bymaking them look simple. Moreover, this unique book brings out
not only the strong Thermodynamics inﬂuence of MIT, but also
Adrian’s ability to generate novel ideas and concepts, which others
follow today. This ability became one of his teaching trademarks.
Pencil and paper. While in Berkeley, Adrian was also inﬂuenced
by Prof. Jorg Imberger who exposed Adrian to new concepts of scale
analysis. In Boulder, just two years after the publication of his ﬁrst

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In Celebration / International Journal of Heat and Mass Transfer 51 (2008) 5759–5761

book, Adrian had his second book published, Convection Heat
Transfer (Wiley, 1984). One of the most important books in theﬁeld, Convection Heat Transfer brought not one, but three new research methods to the forefront: Scale Analysis, Heatlines, andIntersection of Asymptotes. At a time when most heat transfer
researchers were preoccupied with tackling very complicated differential equations using laborious numerical methods and supercomputers, Adrian was championing the back-of-the-envelope
method. This method had two immediate effects: some establishedresearchers reacted as if threatened, and students with limited
numerical background were made to feel hopeful. One should notinfer from these effects that Scale Analysis is ‘‘against” more exact
methods, or a panacea that somehow replaces them. It is simply amethod to teach the physics and correct scales of the problem athand, which is a very useful ﬁrst step toward more exact engineering solutions. By revealing to the user what dimensionless groups
and scales are important in a problem, and how they are related,
the Scale Analysis method reveals the fundamental physics characteristics and it allows for estimated results and trends, which aretrue in an order of magnitude sense.
While simple, Scale Analysis requires a deep understanding of
the physics of the problem, more so than many other existing methods. When studied carefully as a solution method, Scale Analysis reveals Adrian’s desire to look at what is really important in heattransfer, the physics. As a landmark, Convection Heat Transfer established Adrian in the heat transfer community as a man of scientiﬁccharacter, one who is a free thinker, and does not hesitate to question and evaluate the established work of others based on purely
scientiﬁc grounds.
In 1984, Adrian was appointed as full Professor at Duke University. In 1989 he was appointed to the prestigious J.A. Jones Chair.
Irreversibilities. Adrian’s third seminal book was Advanced Engineering Thermodynamics (Wiley, 1988). Some of us, his students,
lived through the years anteceding the publication of this book.
From the many trips to Washington, DC (to research the original
manuscripts at the US Library of the Congress, since electronic access to literature was practically nonexistent), to the requests forpaper copies from the Duke Library, the effort was Herculean. Thoseof us who were his doctoral students and have had the privilege towitness this period of Adrian’s creativity, took away a very important lesson: scientiﬁc controversy is good when based on merit,and should not be avoided simply to avoid possible conﬂict. The
main controversy of the ﬁrst edition of this book was to challenge
the view that thermodynamics is a boring, dead subject.
Adrian brought together the theory and practice of thermodynamics in line with the practical subjects of heat transfer and ﬂuids
engineering. Two details should not pass unnoticed in this book: (1)the use of graphical representation to visualize entropy generation;and (2) references to the history behind the ﬁeld. One of the main
contributions of this treatise is the contemporary method of Entropy Generation Minimization presented by Adrian as a method ofengineering optimization (also known as ‘‘thermodynamic optimization” or, more recently, as ‘‘ﬁnite-time thermodynamics”). By
combining basic principles of thermodynamics, heat transfer, andﬂuid mechanics, the method allows the modeling and optimizationof practical systems and devices by minimizing the predicted entropy generation rate. This characteristic sets the method apart fromthe known exergy analysis, and highlights the limitations of classical thermodynamics.
Adrian’s ﬁrst three books, already published in new editions,have been followed by additional books such as Convection in
Porous Media (Springer, 1992, 1999, 2006), Heat Transfer (Wiley,1993), Thermal Design and Optimization (Wiley, 1996), Entropy
Generation Minimization (CRC Press, 1996), Shape and Structure,from Engineering to Nature (Cambridge University Press, 2000),
Porous and Complex Flow Structures in Modern Technologies(Springer, 2004), and Constructal Theory of Social Dynamics(Springer, 2007).
Constructal theory. We see Adrian’s career as a building process,with a distinct ﬁrst phase leading to the publication of his Thermodynamics book. This ﬁrst phase was preparation for his second
phase, which is undoubtedly marked by his discovery of the Constructal Law in 1995.
Since then, Adrian’s research focused almost exclusively on constructal theory and its applications. He unveiled constructal theory
in the second edition of Advanced Engineering Thermodynamics(Wiley, 1997), and reviewed the emerging ﬁeld in Shape and Structure, from Engineering to Nature (Cambridge University Press, 2000).
The impressive growth in this new domain is reviewed again in thenew book Design with Constructal Theory (Wiley, 2008, by A. Bejanand S. Lorente) and at www.constructal.org.
Adrian postulated that ‘‘For a ﬁnite-size ﬂow system to persist
in time (to live) its conﬁguration must evolve in time in such away that it provides easier and easier access to its currents”.
Accordingly, (i) the generation of ﬂow conﬁguration is a universal
phenomenon in physics and (ii) this phenomenon should behave inaccordance with the constructal law (1996).
According to constructal theory, the phenomenon of generationof ﬂow conﬁguration is like an animated movie, where one screen
is replaced by another screen on which the currents ﬂow withgreater ease. The constructal law is the time direction of the movie:
toward ﬂow conﬁgurations (designs, drawings) that ﬂow moreeasily. Adrian sees the constructal law as a universal principle ofevolution, which applies in many ﬁelds, from physics to economics.
Indeed, the constructal literature of the past decade has focusedon showing that the constructal law covers ‘‘natural design”
phenomena across the board, from biology and geophysics to social
dynamics and technology evolution, for example: tree-shaped
architectures, river-basin and animal scaling laws, animal locomotion, the distribution of city sizes, dendrite crystals, vegetation,
turbulent structure, the evolution of power and refrigeration
plants, machine ﬂight, etc.
Adrian sees the constructal law not as a statement of ﬁnal drawing, optimum, maximum, minimum and ‘‘entropy”. He sees it as acompact summary of common observations, the tape of evolution
running in one direction, which may be expressed in physics terms
simply as: time and conﬁguration. He believes that it predicts natural phenomena, and it also covers the results that in the past were
attributed to ad hoc statements of ‘‘optimality”.
Engineering science. A detailed look at Adrian’s scientiﬁc contributions, revealed in the close to 500 papers that he has published,shows a cornucopia of important discoveries, such as the uniﬁcation of three different theories concerning the ideal conversion ofenclosed radiation, the scaling theory of melting with natural convection in an enclosure, the theory of heat transfer-irreversible
refrigeration plants, the fundamentals of sliding contact melting
and friction, the buckling theory of ﬂuid ﬂow, the scales of naturalconvection in porous media, and many more. Adrian is ranked
among the 100 most highly cited authors worldwide in engineering (all ﬁelds, all countries, living or deceased), by the Institutefor Scientiﬁc Information.
By all measures, the depth and breath of Adrian’s contributions
are in a class by themselves. For this reason he has been recognizedon numerous occasions and in many forms, for example, with two
distinct dimensionless groups discovered by his peers and namedthe ‘‘Bejan number (Be)”: the dimensionless pressure differencegroup in forced convection, electronic cooling, contact melting,and second law analysis of heat transfer, and for the dimensionlessratio of ﬂuid friction irreversibility divided by heat transfer irreversibility, in convection.
The 15 doctorates Honoris Causa received by Adrian from universities in Switzerland (ETH), France (Université Henri Poincaré),In Celebration / International Journal of Heat and Mass Transfer 51 (2008) 5759–5761

Brazil (UFPR), Portugal (University of Évora), South Africa (University of Durban-Westville), and many others, are evidence of theinternational impact of his work.
Adrian was honored with the Max Jakob Memorial Award in
1999, given jointly by the American Institute of Chemical Engineers
and the American Society of Mechanical Engineers, ‘‘for highly
imaginative and inspiring ideas in the thermal science and designof engineering and nature.”He also received the Heat Transfer Memorial Award – Science(1994), Worcester Reed Warner Medal (1996), Robert Henry
Thurston Lecture (1999), Gustus L. Larson Memorial Award(1988), James Harry Potter Gold Medal (1990), Charles Russ
Richards Memorial Award (2001), and the Edward F. Obert Award(2004), all from the American Society of Mechanical Engineers.
From the AIChE he received the Donald Q. Kern award (2008).
From the International Center of Heat and Mass Transfer hereceived the prestigious Luikov Medal (2006) and the JamesP. Hartnett Memorial Award (2007).
An excellent educator (in the classroom as witnessed by all theundersigned, and through his textbooks used worldwide), Adrian
has been honored with the Ralph Coats Roe Award (2000), fromthe American Society for Engineering Education.
With all these accomplishments, Adrian still found time to participate extensively in volunteer activities, such as organizing
many national and international conferences and symposia, helping students in less advanced countries and participating in theeditorial boards of 20 journals such as International Journal of Exergy, International Journal of Energy Research, International Journal of
Heat and Mass Transfer, International Communications in Heat andMass Transfer, International Journal of Thermal Sciences, Journal of
Heat Transfer, Journal of Porous Media, Acta Mechanica, International
Journal of Green Energy, Heat Transfer – Asian Research, InternationalJournal of Transport Phenomena, Numerical Heat Transfer, International Journal of Applied Thermodynamics.

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On behalf of his many students, colleagues, collaborators andfriends, from all around the world, including the editors of thisjournal, we feel honored to pay tribute to such a truly pioneering and trend setting spirit in engineering science. Happy 60thbirthday, Adrian, and we are looking forward to your futureideas!
José L. Lage *Ren Anderson
Vitor Costa
Marcelo R. Errera
Alex J. Fowler
Louis Gosselin
Shigeo Kimura
Gustavo A. Ledezma
Jong S. Lim
Sylvie Lorente
Antonio Miguel
W.J. Minkowycz
Alexandru M. Morega
Tunde Bello-Ochende
Juan C. Ordóñez
Dimos Poulikakos
Heitor Reis
Luiz A.O. Rocha
Alexandre K. da Silva
Osvair V. Trevisan
José V. Vargas
Wishsanuruk Wechsatol
Zongqin Zhang
Mechanical Engineering Department, Southern Methodist University,P.O. Box 750337, Dallas, TX 75275-0337, USA* Tel.: +1 214 768 2361; fax: +1 214 768 1473.
E-mail address: jll@engr.smu.edu (José L. Lage).