David Crighton

An obituary by Keith Moffat

An edited version appeared in The Times

As Head of the Department of Applied Mathematics and Theoretical Physics in Cambridge since 1991, and as Master of Jesus College since 1997, David Crighton carried a huge burden of responsibility, and did so with a combination of authority, wisdom, and energy that was (by common consensus) almost superhuman. Tragically, he was struck by cancer early in 1999, when at the height of his powers; in the face of increasing difficulties, and to the immense, indeed overawed, admiration of his colleagues, he continued to work at full stretch, relinquishing none of his heavy responsibilities, until just two weeks before his death. It was a sad twist of fate that his last letter to his Department, dictated from his hospital bed on 31 March, reported the death of his distinguished predecessor as Professor of Applied Mathematics in the University of Cambridge, G.K.Batchelor FRS, whose Times obituary appeared on 12th April, the very day that David Crighton died.

Crighton's speciality was the field of Aeroacoustics, in which he followed in the footsteps of Sir James Lighthill, who had established the fundamental principles of the subject in the 1950s. Crighton was one of a group who applied these principles to a range of problems of great practical importance in Aerodynamics, with particular attention to the vital problem of noise control in relation to aircraft design. He studied particularly the problem of noise generation by the high-speed jets from aeroengines, by rotating propellors and fans, and by flow over parts of the aircraft fuselage and wing flaps, of crucial importance during aircraft take-off and landing.

David George Crighton was born in 1942 in Llandudno, to where his mother, being pregnant, had been evacuated from London during the blitz. He was educated at Watford Grammar School, and enjoyed relating in later life that his decision to study mathematics was triggered by a master's comment that "whatever else, he will never be any good at mathematics". Thus challenged, he read mathematics at St John's College, Cambridge, where he played rugby six times a week and still emerged as a Wrangler (1st Class Honours) in 1964. Following two years as a lecturer at the Woolwich Polytechnic (now the University of Greenwich), he became Research Assistant to John Ffowcs Williams (now Master of Emmanuel College, Cambridge) at Imperial College, taking his PhD in 1969.

Within a further five years, Crighton had written or co-authored a series of 18 influential papers on jet noise, scattering of sound waves, acoustic beaming and reflection from wave-bearing surfaces, and related topics. His publications in this field continued unabated throughout his subsequent career, and diversified into other areas: generation of sound and vibration by underwater structures (important in naval architecture and for submarine detection); intense sound waves, as generated by supersonic aircraft, and the manner in which shock waves develop when these propagate over large distances; and the phenomenon of 'Anderson localisation' whereby wave disturbances in the neighbourhood of periodic structures can remain trapped near the region of excitation.

In 1974, at the early age of 33, Crighton was appointed to the Chair of Applied Mathematics at Leeds, where his organisational and administrative talents were soon evident. The Leeds Department of Applied Mathematics, which in 1974 was modest in its achievements and expectations, was transformed under his influence over the next 12 years into one of the top three or four departments of its kind in the country. Crighton's successive spells as Head of Department, Chairman of School, and Chairman of the Science Board (effectively Dean), left in every case indelible marks of his imagination and effectiveness, tough decisions being invariably coupled a caring interest in the individuals affected by these decisions.

In 1986, Crighton was elected to the Professorship of Applied Mathematics at the University of Cambridge. Here, his boundless energy and talents were to find full scope. In 1991, he became Head of his Department (DAMTP) and immediately took steps to establish new professorships, first in the rapidly emerging field of Nonlinear Dynamics, then in the field of Solid Mechanics. The Department flourished under his inspired leadership, its quality being recognised by the award of a coveted grade 'five star' in the 1996 Research Assessment Exercise. He played a key role in the planning of the impending move of the Department from its antiquated buildings in Silver Street to the new Centre for Mathematical Sciences now under construction in West Cambridge, and in the massive fund-raising campaign that this entailed.

Crighton was already (since 1979) an Associate Editor of the Journal of Fluid Mechanics, whose volumes, each of some 350 pages, appear every two weeks. This was a position of great exposure, involving an immense correspondence with contributors to the Journal from all round the world; from 1996, he gradually took over the reins of Editorship from George Batchelor. Crighton was elected to Fellowship of the Royal Society in 1993, and for two years (1994-6) took on the additional burden (excessive by any normal standard) of the Editorship of the Proceedings(A) of the Royal Society. He carried this double Editorial burden with effortless poise and efficiency.

Crighton was a member of the Committee of EUROMECH from 1984, and as its Chairman was instrumental in effecting its transformation in 1993 to the European Mechanics Society and in expanding the range of Conferences in the whole field of fluid and solid mechanics that it promoted at European level; he was President of this Society till 1997, and then continued to serve as Vice-President. He was elected a member of Academia Europeae in 1999, in recognition as much for his services to European science as for his own considerable achievements in research.

Within Cambridge, Crighton was a Fellow of St John's College from 1986 until his appointment as Master of Jesus College in 1997. In this latter role, as in his role as Head of DAMTP, he governed with consummate diplomatic skill, great good humour, and a selfless concern for the members and staff of the College at all levels.

Outside science, David Crighton's passion was music in general, and the opera of Wagner in particular. He never missed an opportunity to attend the Bayreuth Festival, and would always seek to incorporate at least one opera in each of his many lecturing engagements around the world. A final achievement, that gave him great personal satisfaction just a few weeks before his death, was to conduct his College Orchestra in a moving performance of the Overture to Tannhauser.

He is survived by his mother, his wife Johanna, and by a son and daughter of a previous marriage.

David Crighton, Professor of Applied Mathematics in the University of Cambridge and Master of Jesus College, Cambridge, was born on 15th November 1942. He died on 12th April, aged 57.

Keith Moffatt