Thomas J. Hanratty
University of Illinois

Thomas J. Hanratty has been a leader in applying large Reynolds number fluid dynamics to problems of interest to chemical engineers. He is particularly recognized for his studies in multiphase flows, turbulence, heat & mass transfer. He received a BChE degree from Villanova in 1947, an MS degree in the night program of Ohio State University in 1950, and a PhD degree from Princeton University. He worked for Fischer & Porter Co. and was involved with research on the catalytic production of hydrazine at Battelle in Columbus. His PhD thesis on mixing in fluidized beds was a part of the program on reactor design that was directed by Richard Wilhelm.

In February, 1953, he joined the faculty of Chemical Engineering at the University of Illinois which, at that time, was a Division in the Department of Chemistry. The graduate course in fluid dynamics was assigned to him, so Hanratty's interests in chemical reactors were broadened. With the exception of a sabbatical leave with the Applied Mathematics Department of Brown University in 1962-63, Hanratty remained at the University of Illinois for the rest of his career. He was Interim Head of the School of Chemistry during a period (1997-98) in which a reorganization was occurring.

Three of his papers were published in the second volume of the AIChE Journal. One suggested that theoretical understanding of turbulent heat transfer could be improved by using a Lagrangian approach which considers the temperature field to be the result of contributions from arrays of sources and sinks of heat. Another attacked the notion that velocity fluctuations close to a wall are not merely a response to turbulence in the outer flow (as suggested by the concept of a laminar sub-layer). These papers were recognized by AIChE with the Colburn Award in 1957.

 In the ensuing years he pursued a number of areas which are basic to the profession of chemical engineering: wave generation, gas-liquid flows, suspension flows, electrochemical diagnostics, structure of turbulence, drag-reduction, modification of turbulence by imposed spatial and temporal oscillations, reactor design, turbulent mass/heat transfer, gas transfer at an interface, wavelike dissolution patterns. These studies were aided by the invention of new techniques, the development of several novel flow systems, and the imaginative use of direct numerical simulations of turbulent fields. Examples of three of these thrusts are given below:

Recognition that a critical issue in dealing with multiphase flows is the understanding of interfacial instabilities motivated studies which provided new understanding of wave generation and a long series of papers that explained how the phases distribute in a pipeline. These efforts provided a scientific basis for describing the behavior of gas-liquid flows which was recognized with the inaugural award of the Multiphase International Prize in 1998.

 Hanratty's pioneering work on electrochemical diagnostics began when his student, Phil Reiss, was exploring the possibility of studying wall sources by carrying out a chemical reaction on a small electrode mounted flush with the wall. They soon realized that they could measure the mean and fluctuating velocity closer to a wall than had previously been possible.  Hanratty used this technique, along with a DNS of turbulence, to provide new understanding of the structure of turbulence generated at a boundary. His work in this area prompted an invitation to present a keynote address on the occasion of the 100th anniversary of Heyrovsky, who won the Nobel Prize for his invention of polarography. He also used electrochemical techniques to study local and fluctuating mass transfer rates to a mass transfer surface in contact with a turbulent field. The fluctuations had length scales similar to the velocity gradient at the wall but had frequencies which are an order of magnitude smaller. The resolution of this apparent paradox produced the first major contribution to the field of turbulent mass transfer since the development of the concept of a Nernst diffusion layer.

Hanratty's contributions have been recognized with four awards from AIChE, two awards from ASEE, the Distinguished Engineering and Lamme Awards of Ohio State, honorary doctorate degrees from Villanova and l' Institut National Polytechnique de Toulouse. He was elected to the National Academy of Engineering, the American Academy of Arts and Sciences, and the National Academy of Sciences. His work is described in 243 publications and 77 PhD theses.