John Davidson
‘Founding father of fluidization’ whose diffident, understated manner belied a powerful intellect
JOHN DAVIDSON, who died on Christmas Day aged 93, was Shell Professor of Chemical Engineering at Cambridge University and was recognised as a founding father of fluidization – a process (widely used in manufacturing and energy industries) whereby the injection of a gas into a bed of solid particles makes the particles bubble up and behave as a liquid.
As well as being a distinguished scientist, Davidson was also a master of understatement. Though possessed of a fine figure and a majestic brow, his manner was retiring, and his conversation was delicate and simple – unadorned by the slightest reference to his scientific prowess.
Beneath this diffidence, however, there lurked not only a powerful intellect but also a considerable strength of opinion and of character. He engaged with vigour in the affairs of Trinity College, Cambridge (of which he was a fellow for 69 years), and was more than willing (albeit in a gentle way) to give as good as he got, often achieving the desired rhetorical effect by deploying an impish humour.
The strength of his character was no doubt formed by the conditions in which he grew up.
John Frank Davidson was born in Newcastle upon Tyne on February 7 1926. His father John (latterly a cashier with the city council) had served in the trenches during the First World War and his mother Katie had experienced the Zeppelin air raids of 1915-18 when working as a young teacher in the East End of London.
Following his father’s death when John was nine, his mother returned to teaching in a poor district of Newcastle. It was a slender living for a widow with two dependent children; but, during the Depression, it was enough for John and his sister to progress from a state elementary school (where they daily chanted the multiplication tables) to Heaton Grammar School.
There, making use of the school’s laboratories and learning mathematics from an intellectually powerful laid-off naval architect, John became sufficiently proficient to obtain (during the Second World War) a state bursary that enabled him to study what were then called “mechanical sciences” at Cambridge.
Knowing nothing about the
Cambridge colleges, he chose Trinity because of its association with the great physicist, JJ Thompson, the Nobel prizewinner credited with the discovery and identification of the electron. (In later life, Davidson was much amused to hear a rather self-satisfied industrialist seek to establish the futility of intellect by pronouncing that “Jimmy Thompson” had been the cleverest boy in his class – “and who ever heard of him?”)
From this point on, Davidson’s progression was smooth. The accolades accumulated: graduating at the top of his year, a brief period of research while working at Rollsroyce, a junior research fellowship at Trinity, a succession of other posts in the College and University (including, from 1957 to 1964, as the College’s steward responsible for the entire household), and the degree of Doctor of Science in 1968.
These culminated in his long and successful tenure as Shell Professor of Chemical Engineering from 1978 to 1993. In addition he served as Vicemaster of Trinity College from 1992 to 1996 and was elected to fellowships of the Royal Academy of Engineering (1976) and of the Royal Society (1974), of which he also served as Vice President in 1988.
Davidson’s CV was a cursus honorum containing every glittering prize available to an applied scientist in Britain. But just as the diffidence of his character concealed the power of his intellect, so the glittering prizes concealed the real meaning of the work and of the man.
For Davidson was wholly opposed to the “high” Cambridge scientific tradition represented by Sir James Chadwick’s assertion that “there is no place in Cambridge for applied science”. Instead he believed with every ounce of his being that the ordinary, practical world was what mattered – a belief grounded in part by the circumstances of his own upbringing and by his sustained, lifelong engagement with the practical problems of manufacturing industry.
But he also believed, with equal force, that the modern demand for all academics to do “useful” research leads to absurdities. As he put it in a paper for the Institute of Chemical Engineering, “if research is genuinely looking into the unknown, as one hopes it is, who can foresee the useful aspects of the (unknown) outcome?”
It was in this spirit of genuine scientific inquiry, combined with an intense interest in the practical applications of good science, that he approached his life’s work. The centrepiece of that work was on the formation and motion of bubbles in liquids, a field in which he became, and for many years remained, the world’s greatest authority.
In a series of seminal papers he transformed the understanding of fluidization, and his advances have had numerous practical applications – including in the development of fluidised bed reactors and the technology of fluidised bed combustion. Fluidised Particles (1963), the book he wrote with Sir David Harrison, became the classic textbook on the subject; and through the supervising of research students, he fostered a multitude of distinguished successors around the world.
Among many other accolades, Davidson’s scientific achievements earned him the Royal Medal of the Royal Society, awarded in 1999.
Davidson’s belief in practicality pervaded the rest of his life. He was not one of those academics who regard teaching and administration as a bore. He relished undergraduate teaching – always taking the view that it was vitally important for academics to be made to explain things in ways that could be understood by the uninitiated.
He served for 18 years as head of Cambridge’s Department of Chemical Engineering – updating the curriculum and strengthening its relations with industry, continuing to be involved in research work in the department long after his retirement.
Unlike many academic engineers, Davidson was also eminently capable of repairing machines around the house – and indeed listed as a hobby in his Who’s Who entry “mending domestic artefacts” alongside “upholstery” and “gardening”.
Davidson’s modesty and restraint were never more apparent than in his last days. When responding from his hospital bed to a request from colleagues for a bulletin on his progress, the adjective he chose to describe his condition was “middling”.
Before being widowed in 2011, John Davidson was married for 62 years to Susanne Ostberg, a German Jewish refugee who, after arriving as an orphan on the Kindertransport, made with him an exceptionally happy home in Cambridge. He is survived by their son and daughter.