His own research was first into the phenomenon of turbulence -- described by Einstein as the most challenging unsolved problem of classical physics -- and subsequently into the field that became known under his leadership as "microhydrodynamics". Batchelor wrote with exceptional precision and lucidity and, by example and his firm but kindly control as an editor, he played a crucial role in establishing exacting standards in fluid mechanics.
As founding head of the department of applied mathematics and theoretical physics at Cambridge, he established an environment in which research in all applications of mathematics flourished, and in which generations of research students were encouraged to develop their creative skills. Under his leadership between 1959 and 1983 the department became the centre of a worldwide network of collaborative research.
George Keith Batchelor was born and educated in Melbourne, Australia. He studied physics and maths at Melbourne University, and then, at the start of the Second World War, undertook research in a range of practical problems in aerodynamics relating to the war effort. During this period, he recognised turbulence as the greatest challenge in aerodynamics, and resolved to devote his energies to it as soon as the war ended.
He wrote to G.I. Taylor, the great British authority on turbulence at the time, offering his services. Taylor agreed to supervise his research, and in January 1945, together with his wife, Wilma, also of Melbourne, Batchelor embarked on a marathon ten-week voyage via New Zealand, the Panama Canal and New York, and thence in a convoy of 80 ships across the Atlantic to reach Cambridge.
Batchelor was fiercely ambitious and totally committed, making very rapid progress. Recognising the significance of a theory published by the Russian mathematician Kolmogorov in 1941, Batchelor presented a critique at the sixth International Congress for Applied Mechanics, held in Paris in 1946. This marked him as a rising star, and in 1947 he became a Fellow of Trinity.
Over the next 15 years, Batchelor published a succession of increasingly detailed studies exposing the intense difficulty of understanding turbulence -- a difficulty matched only by its importance in aerodynamics, chemical engineering, the dynamics of ocean and atmosphere, and in the magnetohydrodynamics of interstellar gas clouds. Batchelor made fundamental contributions in all these fields.
His 1953 research monograph Homogeneous Turbulence virtually defined the subject. At the age of 33, Batchelor had created a new field which was to offer an extreme challenge to succeeding generations of mathematicians, physicists and engineers. He was elected a Fellow of the Royal Society in 1957.
The administrative work involved in establishing his department at Cambridge was enormous, and somewhat distracted Batchelor's energies from research throughout the 1960s. He did, however, publish his definitive Introduction to Fluid Dynamics (1967), a textbook of characteristic thoroughness which is still widely used for university courses.
In the course of writing this book, Batchelor recognised that the techniques of turbulence theory could equally be applied to problems involving the dynamics of fluids in which small particles or bubbles are in suspension. He developed these ideas in a powerful sequence of papers in the early 1970s, and so microhydrodynamics was born.
Perceiving a need for more European co-operation in scientific research, Batchelor was instrumental, in 1964, in establishing the European Mechanics Committee (now the European Society for Mechanics), which he chaired until 1987. He was also for many years a member of the congress committee of the International Union of Theoretical and Applied Mechanics, and during the Cold War he maintained scientific links with Soviet and East European colleagues, notably at the biennial meetings on fluid mechanics held in Poland throughout that era.
He edited the four volumes of Sir Geoffrey Taylor's collected papers, and in the 1980s spearheaded a successful fundraising campaign to endow the G.I. Taylor Chair of Fluid Mechanics at Cambridge. In 1996 he published a biography of Taylor.
Batchelor received the Royal Medal of the Royal Society in 1988, and was elected to a number of foreign academies of science, including that of Australia, to which he often returned.
His house in Cambridge was designed on strict scientific principles: an early paper on the optimal spacing of the two sheets of glass in double-glazed windows resulted from this phase of domestic activity.
His wife died in 1997. He is survived by three daughters.
George Batchelor, FRS, Emeritus Professor of Applied Mathematics at Cambridge, was born on March 8, 1920. He died on March 30 aged 80.
© The Times, 2000