Obituary: Professor David Leslie

David Clement Leslie, consultant engineer: born Australia 18 December 1924; staff, Sir WG Armstrong Whitworth Aircraft, Coventry 1951- 54; Guided Weapons division, RAE Farnborough, 1954-58; UKAEA, Harwell and Winfrith 1958-68; Professor of Nuclear Engineering, Queen Mary College, London 1968-84, Director, Turbulence Unit 1975-90 (Senior Consultant 1990-93), Dean, Faculty of Engineering 1980-83; Safety Adviser to Local Authorities for the Sizewell Inquiry 1981-87; married 1952 Thea Wenborn (three sons, two daughters); died Great Missenden, Buckinghamshire 27 August 1993.

DAVID LESLIE worked in the aerospace and nuclear industries, and made his greatest contributions in teaching and research, notably as Director of the Turbulence Unit at Queen Mary and Westfield College, London, from 1975 to 1990.

Leslie's love of physics and mathematics led him from Oxford University in 1950 to apply his considerable skills in the aerospace industry, first at Armstrong Whitworth, where he was responsible for aerodynamic design, and later at Farnborough. He was then attracted by the nuclear industry, which in the Fifties was one of the newest and fastest-growing high- technology industries in the UK. He joined the United Kingdom Atomic Energy Authority and his initial work at the Harwell and Winfrith laboratories in 1958-59 was in neutron physics and in particular into how graphite- moderated reactors, the then preferred British reactor system, should be designed for the efficient production of energy. He later led a theoretical thermal-hydraulic programme associated with a British design for a steam-generating heavy-water reactor system.

Leslie believed passionately that nuclear power would enhance the quality of life and would benefit the environment. He worked on nuclear reactor safety cases and in the then relatively new area of safety analysis.

He was always fascinated by inherently complex physical phenomena and was keen to use his extensive mathematical and numerical skills to analyse them. He kept beautifully hand-written and indexed notebooks. Secretaries and typists had no problems in typing his manuscripts, although it was always a pleasure to read from his originals.

It was while he was working for the Atomic Energy Authority that he developed an interest in turbulence, which he took with him when, in 1968, he left Winfrith to become the head of the Nuclear Engineering Department at Queen Mary and Westfield College. Turbulence became his main area of research and in 1973 he wrote what has now become a classic in this field, Developments in the Theory of Turbulence.

Later in the Seventies he set up a research group, the Turbulence Unit, which was the first systematically to study the computer simulation of generic turbulence for the fast breeder reactor, mixing flows in the environment and turbulence behind wings of aircraft. The unit obtained funds from SERC (the Science and Engineering Research Council), the DTI, and the MOD as well as a number of industrial concerns. The unit still exists at QMWC and continues to work in areas pioneered by Leslie. A number of his student and co-workers have gone on to work in the similar areas at other institutes.

Leslie contributed a great deal to QMWC, serving on numerous committees as well as becoming Dean of the Engineering Faculty. He was an extraordinarily conscientious teacher, keen to ensure that his students were constantly encouraged and given whatever support he could provide. As one of his undergraduate tutees, I remember being in his office when he was carefully showing me how to obtain a solution to a differential equation. The telephone rang. He picked it up and said, 'Will you please call me back in 15 minutes?' and put the receiver back. I must have looked puzzled, because he turned to me and said, 'I regard teaching as very important,' and continued solving the differential equation.

His family and religious belief provided him with great inner strength. He was a practising Christian Scientist who gave his time freely to his church. He was a committed father, who, even during the most demanding phase of his career, found time to read stories to each of his five children.

(Photograph omitted)