We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.
We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.
In this introduction to Anthony, his life, family and science I will start — 90 years ago — with his birth in Cairo, where his father was a lecturer in economics at Fuad I University. The family returned to England, to join Anthony’s elder brother, in 1944. After schooling at Bedford Modern School, followed by military service in 1948, Anthony came up to Trinity to read mathematics and fall in love with Emma, his wife to be. After a year at Harvard, Anthony returned to Cambridge to become a research student with Ian Proudman.
His science flourished, as did his family, of Henry, George, Mark and Sophie. Anthony enjoyed playing cricket, hockey, squash and real tennis, each with enthusiasm and ability. He was appointed an Assistant Director of Research in Chemical Engineering at Cambridge University, a Fellow and Director of Studies in Mathematics at Trinity Hall from 1961 to 1972 and a hard-working Assistant Editor of the emerging and prestigious Journal of Fluid Mechanics, under the firm direction of its founder George Batchelor. Much more will be said about Anthony’s remarkable and effective career, reflected by his election as a Fellow of The Royal Society in 2005.
- Herbert Huppert
Herbert Huppert, FRS, has been a proud Fellow of King’s College Cambridge for more than 50 years. He was the Foundation Director of the Institute of Theoretical Geophysics and one of the initiators of the field of Geophysical Fluid Mechanics. He currently holds part-time positions at Westlake University in Hangzhou, Peter the Great St. Petersburg Technical University; Monash University; and the University of New South Wales. He was the (Australian!) Chair of the European Academies Science Advisory Committee reporting to the European President on Carbon Capture and Storage and also the chair of the Royal Society’s anti-terrorism Committee, which reported to the British government under the title Making the UK Safer. He was awarded a Royal Medal in 2020 for his contributions to the physical sciences.
An informal scan of Anthony Pearson’s publications suggests that more than a quarter of these exploit some form of lubrication approximation, i.e. achieve simplification by considering situations where transverse derivatives dominate those in the direction of flow. The present contribution uses similar methods to explore how weakly-bound particles might be transported away from the vicinity of the wall when two spatially periodic rough surfaces are sheared relative to one another at constant velocity while immersed in fluid. The aim is to model what could be an important process during decontamination of hands by washing, and is motivated by Mittal et al., J. Fluid. Mech., 894, F2 (2020), who remark “Amazingly, despite the 170+ year history of hand washing in medical hygiene, we were unable to find a single published research article on the flow physics of hand washing.”
Under the assumption that the roughness wavelength is large compared to the spacing of the surfaces, lubrication theory supplies expressions for the time-periodic velocity components. With various additional assumptions an unsurprising result if found that particles remain trapped unless the flow driven by the wall motion is strong compared to the depth of surface undulations. Perhaps less obvious is that the process of escape to large distances takes place over multiple periods.
Because of its simplicity, lubrication theory is a very valuable tool in calculations aimed at making an initial evaluation of problems, although it has clear limitations. Notwithstanding the caveat, the author’s view is that the answer to the question posed in the title is no.
- Paul Hammond
Paul Hammond studied applied mathematics at Cambridge, and first met Anthony Pearson as his PhD examiner. Subsequent to that he worked as scientist and research manager in the hydrocarbon services industry, with broad interests in multiphase fluid mechanics and flows in porous media. His last assignment was as Non-Executive Director of a start-up in airborne wind energy. Highlights include explaining the time evolution of the composition of a fluid sample taken from a newly drilled reservoir using only elementary mathematics, and having known Anthony as colleague, mentor and friend for nearly 40 years. He is now retired, and is a Trustee of, and cellist in, the City of Cambridge Symphony Orchestra.
Many manufacturing processes in the glass, polymer and textiles industries depend on the stretching of liquid fibres.
Mathematical modelling has been used since at least the 1960s to determine how the properties of the final product depend on the process parameters and when the process is or is not stable.
In this talk I will describe more recent developments, including the manufacture of non-cylindrical fibres with complicated cross-sectional geometries, ultra-thin glass sheets for smartphone and tablet screens, and polygonal glass tubes.
- Peter Howell
Peter Howell completed his doctorate at University of Oxford in 1994 on Extensional Thin Layer Flows, motivated by mathematical modelling problems in the glass industry. He held positions at Northwestern University and University of Nottingham before returning to Oxford in 2001, where he has held the position of Professor of Applied Mathematics since 2014.
My talk will cover technical work that I carried out at the instigation of my father between the ages of 14 and 23 and its formative effect on my future career. This involved my first introduction to computing, photographic measurement and analysis of 3D structures, analysis of X-Ray crystallography of polythene and non-Newtonian flow in the injection moulding of rubber.
- Henry Pearson
After gaining a first degree in Mathematics and a doctorate in Environmental Fluid Mechanics at Trinity College, Cambridge University, and undertaking a Research Fellowship at the California Institute of Technology in Pasadena, Los Angeles, Henry joined a small technical consultancy (Detica - now BAE Systems Applied Intelligence). In a series of senior management positions, he was involved in building the company up until returning to a full-time consulting role in 1999. He has run his own consultancy company since early 2007.
Between 2000 and 2013 Henry provided direct support on a wide range of information and security-related matters to the UK Ministry of Defence.
In June 2014, he took up a part-time role for CESG - now the National Cyber Security Centre (NCSC) as an NCSC Ambassador for Academic Engagement, the first such appointment. This involved working with UK University Cyber Security Departments who had been or hoped to be accredited by the NCSC as Academic Centres of Excellence in Cyber Security Research, as well as working closely with the 4 multi-university multi-disciplinary Cyber Security Research Institutes sponsored by the NCSC and other HMG Departments.
In November 2016 he took up a part-time role as an NCSC Government Cyber Adviser. This involved providing advice to a range of overseas Governments and Armed Forces on their Cyber Security strategies and academic and skills programmes. In April 2019 he was appointed to be the UK Cyber Security Ambassador in the Department of International Trade.
Over the past 20 years, Anthony has been a tremendous source of inspiration for the research of the BPI, with his regular attendance and participation in the BPI seminars. His interest, insight and knowledge about many problems involving multiphase flow has been especially valuable, and in that spirit, I describe some of recent developments in this challenging topic.
Particle-laden and bubble-laden flows have important applications for understanding the dynamics of large volcanic eruptions, particle plumes formed during deep sea mining and blowouts during subsea drilling operations. The dynamics of these flows involve buoyancy forces which drive the flow and mixing with ambient fluid, while the slip associated with the droplets can lead to dissipation of the buoyancy-driven flow and a cessation of the mixing. This can have important implications for the transport of both the fluid and the separated phase, especially in density stratified environments, where this can lead to particle intrusions which disperse particles considerable lateral distances prior to settling out. Recently the analogous problem of the dispersal of aerosols in buildings has assumed a pressing relevance. We discuss a series of simple laboratory experiments and models which illustrate the some of the controls on the transport patterns of the particles, bubbles or aerosols in a variety of contexts, Within confined spaces, the models demonstrate the very significant lateral transport which is possible before aerosols settle from the air, with important implications for the benefits of social distancing in closed spaces.
- Andy Woods
Andy Woods has been BP Professor and Head of the BPI, University of Cambridge since 2000; prior to this he was a lecturer in the ITG, University of Cambridge and Prof of Applied Mathematics in University of Bristol. He works in multiphase flow problems with interest in geological and environmental flow processes including volcanic eruption dynamics, multiphase turbulent plumes and fountains, flow and dispersion in porous media including carbon capture and storage and geothermal heat production, as well as air flows in buildings with relevance for aerosol transport and for low energy design of ventilation systems
Speech is a potent route for viral transmission in the COVID-19 pandemic. Informed mitigation strategies are difficult to develop since the relationship of speech to the exhaled flow has not been documented, nor has the aerosolization mechanism in the oral cavity been visualized.
We document the spatio-temporal structure of the expelled air flow and detail how drops form using high-speed imaging. Specifically, phonetic characteristics of plosive sounds like ‘P’ lead to enhanced directed transport, including jet-like flows that entrain the surrounding air. The transport features, including phonetics, are demonstrated using order-of-magnitudes estimates, numerical simulations, and laboratory experiments.
Also, we show with high-speed imaging how phonation of common stop-consonants form and extend salivary filaments in a few milliseconds as moist lips open or when the tongue separates from the teeth. Both saliva viscoelasticity and airflow associated with the plosion of stop-consonants are essential for stabilizing and subsequently forming centimetre-scale thin filaments, tens of microns in diameter, that break into speech droplets. We believe that this work will inform thinking about the role of ventilation, aerosol transport in disease transmission for humans and other animals and yield a better understanding of “aerophonetics”.
- Howard Stone
Howard A. Stone is the Donald R. Dixon ’69 and Elizabeth W. Dixon Professor in Mechanical and Aerospace Engineering at Princeton University. He received the Bachelor of Science degree in Chemical Engineering from the University of California at Davis in 1982 and the PhD in Chemical Engineering from Caltech in 1988. Following a postdoctoral year in the Department of Applied Mathematics and Theoretical Physics at the Cambridge University, in 1989 Stone joined the School of Engineering and Applied Sciences at Harvard University, where he eventually became the Vicky Joseph Professor of Engineering and Applied Mathematics. In July 2009, Stone moved to Princeton University. He is a Fellow of the American Physical Society (APS) and is past Chair of the Division of Fluid Dynamics (DFD) of the APS. He is the first recipient of the G.K. Batchelor Prize in Fluid Dynamics (August 2008), received the APS Fluid Dynamics Prize in 2016, and is currently an APS Councilor representing the DFD and the Topical Group on Climate. He was elected to the National Academy of Engineering in 2009, the American Academy of Arts and Sciences in 2011 and the National Academy of Sciences in 2014
Anthony Pearson has had an extended career in industry, bridging academia with commercial applications. This has included such diverse problems as heat transfer in non-Newtonian flows, solid mechanics, complex elastic and non-linear fluids, and dispersion and transport phenomena. Two specific examples will be briefly presented in which Anthony played a guiding role: the first being an unusual result on the Taylor Limit in long eccentric annuli, and the second on a lubrication approximation for multi-non-Newtonian fluid displacement, also in long eccentric annuli. This talk will relate these examples to real-world problems and give some insight into Anthony’s inimitable guiding and mentoring style, experienced by the many who have worked with him.
- Simon Bittleston
Simon Bittleston worked for 35 years in the hydrocarbon services industry, initially as a scientist in fluid mechanics; working alongside Anthony Pearson who was a mentor and advisor on a range of problems including heat transfer, multi-fluid displacement and multiphase transport phenomena. After becoming a science team manager, Simon moved to Norway, where he was project manager for the development of a major marine seismic system called Q-Marine. He invented streamer steering which became a differentiating feature of the Q system. In 1992 he was made a Research Director, and in 2001 VP for worldwide Product Development and manufacturing where he led an organization of about 10,000 staff. In 2005, he moved to Paris as VP of Mergers and Acquisitions completing more than 40 investments. In 2010, he returned to Cambridge, UK and was VP for the worldwide research organization. His final position was as VP Science and Technology for New Energy – a team formed to develop and commercialize renewable technologies. Simon holds a Bachelor’s degree in Mathematics from Imperial College London, and a Ph.D. in Fluid Mechanics from the University of Bristol, UK. He is also a By-Fellow of Churchill College Cambridge and Honorary Fellow of Darwin College Cambridge.
The talk will start by recounting the groundbreaking research conducted in the early 1990’s at the Cambridge Research Laboratory, SCR under the direction of Anthony on the “Crack Tip Region in Hydraulic Fracturing” (PRSA, 1994). This work opened the gate to a progressive recognition of the existence of different regimes of a hydraulic fracture and to the understanding of the link between the multiscale nature of the tip asymptote and competing dissipative processes. The talk will conclude by demonstrating that incorporating the multiscale tip asymptote in numerical algorithms leads to robust, accurate, and computationally efficient numerical simulators of hydraulic fractures.
- Emmanuel Detournay
Emmanuel Detournay is currently the Theodore W Bennett Chair Professor in Mining Engineering and Rock Mechanics in the Department of Civil, Environmental, and Geo- Engineering of the University of Minnesota (UMN). He holds a Mining Engineering degree from the University of Liège, Belgium and MSc and PhD degrees in Geoengineering from the UMN. Prior to joining the UMN in 1993 as a faculty member, he held various positions in consulting companies (Itasca, Minneapolis, MN; Agbabian Associates, El Segundo, CA) and in R&D (Dowell-Schlumberger, Tulsa, OK; Schlumberger, Cambridge, UK). His expertise is in Petroleum Geomechanics. In 2016 he was elected into the US National Academy of Engineering (Foreign Member).
For polymers it is entirely appropriate to neglect the second normal stress difference (NSD), because it is so much smaller than the first NSD, to the extent of being difficult to measure. For colloidal dispersions and emulsions, the second NSD is not negligible, and for concentrated non-Brownian suspensions it is the first NSD which is negligible and immeasurably small. The dynamical consequences of the first NSD is well understood in terms of a tension in the streamlines, and this explains rod-climbing, the migration of particles to the centreline of a pipe flow, a co-extrusion instability and many other phenomena. The second NSD should be thought of as a tension in the vortex lines. Such a tension explains rod-dipping (the opposite of rod climbing), an edge instability in rotational rheometers and the lopsided coating of a vertical fibre.
- John Hinch
John Hinch is an Emeritus Professor of Fluid Mechanics at the University of Cambridge. His PhD was supervised by George Batchelor and examined by Anthony Pearson in 1972. His research interests include suspensions of particles and other mobile particulate systems, the flow of non-Newtonian fluids, and applications of mathematics to industrial problems