Oldroyd Early Career Award

In commemoration of the scientific achievements of James Gardner Oldroyd, pioneer of rheology, the European Society of Rheology (ESR) decided in 2023 to introduce a “Oldroyd Early Career Award” for outstanding, early-career achievements in the field of rheology and for commitments to the rheological community.

The award is awarded annually and eligible to rheologists regardless of their geographical location.

Awardees

Duncan Hewitt (2023)

Oldroyd Awardee 2023

Duncan Hewitt is Associate Professor at University College London. He is an applied mathematician and rheologist, interested in using mathematics to model and understand physical processes in the world around us most notably for yield stress and other complex fluids. He holds undergraduate degrees (BA and MMath) in Mathematics and a PhD in Applied Mathematics, all from the University of Cambridge. Following the award of his PhD in 2014, he held Research Fellowships firstly in the Department of Mathematics at the University of British Columbia, Vancouver (2014-2015) as a Killam Postdoctoral Research Fellow, followed by a Research Fellowship at Gonville and Caius College, University of Cambridge (2015-2019). In 2019 he was appointed Lecturer in the Department of Applied Mathematics at University College London and promoted to Associate Professor in 2022.

The most significant early contribution of Duncan on the topic of yield stress fluids is with the paper “Viscoplastic boundary layers” published in JFM. In this paper, Duncan and the team revisited one of Oldroyd’s 1947 papers concerned with the same problem. Oldroyd derived a nonlinear form of the boundary-layer equations for a Bingham model but there were significant doubts within the literature that these were actually correct. In revisiting the problem using theoretical and numerical approaches, Duncan and the team were able to demonstrate that the viscoplastic boundary layers postulated by Oldroyd (based on theoretical arguments alone) did form exactly as envisioned by him. Duncan’s strongest contribution to the field is in the area of “swimming” in yield stress fluids. Starting with an analysis of GI Taylor's canonical ‘swimming sheet', idealised versions of squirming organisms, and long, thin worm-like motions have been studied by Duncan, the latter of which involves a generalisation of classical slender-body theory for viscoplastic fluids. Duncan has also made important contributions to our understanding of viscoplastic dam breaks, viscoplastic free surface flow around obstacles, and viscoplastic flow through Hele-Shaw cells featuring various obstructions. In an entirely separate series of papers, he has also made important contributions to our understanding of how rheology affects the compressional mechanics of deformable porous suspensions.

Award Citation: Dr Duncan Hewitt is an applied mathematician, responsible for a series of beautiful fundamental studies investigating yield stress fluids, most notably for probing locomotion through such “viscoplastic” fluids. Duncan combines rigorous analytical work with high-quality simulations to provide fundamental physical understanding and insight.