Jeffrey F. (Jeff) Morris, Professor of Chemical Engineering and Director of the Benjamin Levich Institute at the City College of New York, the flagship science and engineering
college of the City University of New York, is the recipient of the 2023 Bingham Medal of The Society of Rheology “in recognition of his transformative research on the flow of
suspensions, particularly of the mechanics of discontinuous shear thickening, and his application of rheology to practical problems in suspension flow, including his novel work
on the rheology of hydrate-forming emulsions.” This is the culmination of a series of major awards for Jeff, including the 2022 Weissenberg Award of the European Society of
Rheology, the 2020 Stanley Corrsin Award in Fluid Mechanics of the American Physical Society, and the 2017 Shell Thomas Baron Award in Fluid Particle Systems of the American
Institute of Chemical Engineers.
Jeff is the youngest of four children. He grew up in Cullowhee, North Carolina, in the Smoky Mountains, where his father taught chemistry at Western Carolina University. His
mother worked as a nutritionist for the county and sometimes taught at the University. Jeff was offered a scholarship to Georgia Tech, and he decided to study chemical engineering
because of the close connection to science, with three full years of chemistry in the curriculum; to our benefit he stuck it out, despite finding the early courses in chemical
engineering to be less inspiring than those in physical chemistry, mathematics, and mechanics. He had two meaningful industrial summer jobs: The first, after his third year at
Georgia Tech, was at Exxon’s Baton Rouge refinery and included visits to the nearby petrochemical plant; this experience gave him an appreciation of the process industries and
the realization that his interest was on individual phenomena, and not the process scale. The other, after graduation, was at Mobil’s Paulsboro, New Jersey laboratory working
with catalysts, where he found that he loved doing research.
Jeff went to CalTech for graduate study, and his interest in transport properties and fluid mechanics led him to do his PhD research with John Brady. He was excited by Brady’s
description of the statistical aspects of the problems that he was studying and the relation to ideas from thermodynamics, and that excitement is clearly exhibited in his own
subsequent work. His first important publications on suspension rheology come from his joint work with Brady. After completing the PhD he did a post-doc with Shell in Amsterdam,
working with Willem Boersma, who as a post-doc himself at Caltech a few years before had introduced Jeff to shear thickening.
Jeff’s first job after completing his PhD and postdoc was a chemical engineering faculty position at Georgia Tech. He then spent two years working with Halliburton on a range of
rheology problems involving particle-laden flows in petroleum exploration and production, particularly fracturing fluids (gels at the time) and proppant slurries and cement. Those
years at Halliburton are reflected in his deep understanding of the practical issues associated with the processing of particulate systems. When a position opened at the Levich
Institute (City University of New York, CCNY), we made sure to bring it to his attention. He stood out in the pool of applicants, and we were pleased to be able to hire him in 2005.
He served as Chair of the CCNY Chemical Engineering Department from 2013 to 2016 and has been the Director of the Levich Institute since 2015. Jeff has had active collaborations and
visiting positions in France, including continuous appointments in the French national laboratory system (CNRS) from 1999 until 2010 as a research leader of a major research program
funded by the FERMAT Foundation from 2016 to 2020. He has been named as an inaugural CNRS Ambassador-Fellow for 2023-2026.
The nomination for the Bingham Medal addressed several distinct but related contributions. A body of work that started with his PhD research with Brady employed Stokesian Dynamics
and Smoluchowski theory to establish the micromechanical basis for the normal stresses in suspensions and the coupling of flow to non-equilibrium structure and bulk properties. Jeff
and his students developed the suspension balance concept to show that a gradient in the particle contribution to the continuum stress, known as the particle pressure, will drive
particle migration. They have shown that the particle pressure in the shear flow of a non-Brownian suspension is a rigorous continuation of the equilibrium osmotic pressure. With
colleagues at Laboratoire FAST in Orsay they have shown that the particle pressure can be directly measured under shear.
In landmark papers in Physical Review Letters and Journal of Rheology (JOR), the latter the recipient of the 2015 JOR Publication Award, Jeff and co-workers
demonstrated the minimal ingredients needed to reproduce experimentally observed discontinuous shear thickening, wherein the viscosity undergoes a large discontinuous increase at a
critical shear rate. They demonstrated that the dominant stress transmission mechanism at the transition must change from lubrication to contact friction, providing a rational basis
for shear thickening and showing how it is related to shear jamming. This study forms the basis for the widely used Wyart-Cates model of suspension shear viscosity, which was
generalized by Jeff and coworkers to a consistent model for the rheology of concentrated suspensions of spheres (the winner of the 2020 JOR Publication Award). This transformative body
of work has propelled the field forward by prompting theoretical work to describe the coupling of the macroscopic behavior to the microstate and experimental work to assess the
controlling physics at interparticle contacts. More recent work combines network theory with simulations to show the existence of states that provide a theoretical foundation for the
Gas hydrates, or clathrates, form when a small guest molecule is captured in a “cage” of hydrogen-bonded water to form a crystalline solid. An emulsion will undergo an abrupt change
in properties with the formation of clathrates, and clathrates can cause jamming in petroleum pipelines carrying oil and gas along with water and brine. Jeff and his coworkers at
CCNY and Chevron have focused on understanding hydrate formation and its impact for the design of new mitigation strategies. By coupling rheology to visualization, they showed that
hydrate morphology at the particle surface has a significant effect on the rheological transition associated with hydrate growth, and they related this morphology to oil-soluble
surfactants and asphaltenic components in the organic phase. Jeff then developed a novel approach using salt to control the thermodynamic state, hence the material composition
(hydrate/aqueous/organic) for modeling the rheology. This body of work has developed a framework in which the control of material composition allows study of the mechanical basis for
behavior, creating a rational foundation of constitutive and flow models needed for flow assurance and other applications.
Jeff has been an active member of the rheology and complex fluids community. For The Society of Rheology, he was an Annual Meeting Technical Program Chair and he chaired the Nominating
and Bingham Medal Committees. He was one of the organizers of an extended Kavli Institute Workshop on the Physics of Dense Suspensions, and he co-edited a special issue of JOR on the
subject, as well as co-organizing a widely attended on-line symposium with discussions published in JOR. He is an Associate Editor of the Journal of Fluid Mechanics. In addition to his
many well-written reviews, he is the co-author with Élisabeth Guazzelli of A Physical Introduction to Suspension Dynamics, a textbook for those new to an area that requires the
integration of concepts from fluid mechanics and statistical physics.