Arthur B. Metzner, a pioneer in the development of rheology as a significant field of applied science, died of a sudden heart attack on 4 May 2006 in Washington, DC.
Born on 13 April 1927 in Gravelbourg, Saskatchewan, Art spent his formative years in Barrhead, Alberta, where he met Elizabeth (Betty), his wife of 58 years. Art studied chemical engineering at the University of Alberta (BS, 1948) and MIT (ScD, 1951). After a brief stint in industry, he joined the chemical engineering faculty of the University of Delaware in 1953. He took emeritus status in 1993 but remained professionally active until his death.
Art’s contributions to rheology and the mechanics of non-Newtonian fluids encompass the major problems in those topics over the past 50 years. The unusual behavior of complex liquids became technologically important in the 1950s, and he quickly recognized that existing analyses were not applicable to these nonlinear materials. In a series of papers he wrote with his students, Art showed how to treat pipeline flow and determine the transition to turbulence for non-Newtonian fluids, how to analyze mixing, and how to analyze heat transfer. His chapter on non-Newtonian fluids in the first volume of Advances in Chemical Engineering (Academic Press, 1956) served as the sole introduction to this important new area of engineering for a generation of practitioners and students. He and a few colleagues subsequently convinced NASA to establish a major research effort in non-Newtonian flow, thus providing a stable funding base for a large number of young investigators. Art’s contributions were quickly recognized. He received the Junior (now Allan P. Colburn) Award from the American Institute of Chemical Engineers (AIChE) in 1958, and he was the first recipient of the American Society for Engineering Education’s Chemical Engineering Lectureship in 1963.
Turbulent drag reduction, whereby very small quantities of polymers of high molecular weight in a solvent can substantially reduce the pumping energy, was an important discovery during World War II. In a 1967 experimental study, Art and Fred Seyer demonstrated that a polymer’s presence changes the structure of the wall sublayer. Their picture of polymer behavior near a wall, validated by modern calculations, enhanced the development of drag-reduction methodology by George Savins and others. Drag reduction is an essential component of modern oil-pipeline practice.
In the early 1960s, rheological measurement—determining the nonlinear mechanical properties of complex fluids—was in its infancy. Theoretical results abounded, but practical measurements were difficult; even the algebraic sign of the “second normal stress difference,” a small quantity that determines the onset of some instabilities and is a sensitive test of rheological constitutive equations, was unknown. Art and his students attacked the measurement problem for steady shear, and in a landmark 1969 paper with Bob Ginn, he demonstrated that the full stress distribution can be measured reliably. For the next three decades, despite improvements in mechanical and electronic components, that work defined the scope and limits of measurement. (When one of us mentioned once to Art that the paper was required reading in our rheology course, he mused that it would have become a classic if they hadn’t included the error bars.)
Through their demonstration of a dramatic increase in frictional resistance for flow of dilute polymer solutions through porous media, Art and his undergraduate student Ronald Marshall revolutionized the understanding of the role of so-called pusher fluids in advanced oil-field recovery. With Jan Mewis, he published a definitive experimental confirmation of George Batchelor’s theory of the extensional flow of fiber suspensions, in which the fibers greatly increase the tensile stress.
Art was primarily an experimentalist, with great intuition and a knack for choosing just the right experiment, but his contributions also include clever analyses that cut to the essence of difficult problems. His 1966 “Deborah number” scaling arguments for defining elastic and dissipative flow regimes, together with confirming experiments on sudden viscoelastic deformation, are an integral part of polymer flow culture. His extensional primary field approximation, published in 1971 with his son Arthur P., established a scaling framework for finding the dominant stress contribution in polymer processes. The White-Metzner constitutive equation for stress is still a feature of computer codes for polymer-processing applications.
This catalog of Art’s accomplishments is incomplete, albeit representative, and it hardly reflects the enormous contributions of this gifted man. Through his teaching and consulting, he brought his remarkable insight to a broad community. As chair of Delaware’s highly rated chemical engineering department from 1970 to 1977, he hired and nurtured a group of outstanding young faculty who have themselves become leaders in their field. A valued consultant to numerous companies, he not only provided technical advice but also effectively interacted with management personnel to ensure that projects were completed on time and advocated the importance of publication by industrial scientists when it could be done without compromising the value of those results to the corporations. In his 10 years as editor of the Journal of Rheology, he established the standards that resulted in the highest Institute for Scientific Information (ISI) impact factor of any research journal in rheology, fluid mechanics, or polymer processing. His professional recognitions include being elected to the National Academy of Engineering and receiving the Society of Rheology’s Bingham Medal and Distinguished Service Award, numerous awards from AIChE, and honorary doctorates from Katholieke Universiteit Leuven in the Netherlands and the University of Delaware. He was also a member of the Governing Board of the American Institute of Physics.
Those of us who were privileged to have worked with him and to have been mentored by him recall mostly his unremitting commitment to excellence, coupled with extraordinary warmth, humor, and generosity.
