Material for this volume first began to be assembled in 1999 when a six-month Programme
on Turbulence was held at the Isaac Newton Institute for Mathematical
Sciences in Cambridge. The Programme had its own origins in an Initiative on Turbulence
by the UK Royal Academy of Engineering, which had identified the prediction
of turbulent flow as a key technology across a range of industrial sectors. Researchers
from different disciplines gathered together at the Newton Institute building in Cambridge
to work on aspects of the turbulence problem, one of the most important of
which was closure of the averaged (or filtered) turbulent flow equations. An InstructionalWorkshop
on Closure Strategies for Modelling Turbulent and Transitional Flows
was held from April 6 to 16th. The aim of the workshop was for the experts on closure
to present material leading up to the current state-of-the-art in a form suitable for
research students and others requiring a broad overview of the field, together with
an appreciation of current issues. A sequence of 38 lectures by 19 different lecturers
provided background to techniques, examples of current applications, and reflections
on possible future developments. Recognising that a gathering of so many experts
from a variety of backgrounds was somewhat unusual, it was felt that a more polished
version of the lecture material would be of interest to a wider audience, as a reflection
upon the current state of prediction methods for turbulent flows. The result has taken
rather longer to appear than originally intended, but the opportunity has been taken
for contributions to be updated wherever possible, to take account of the most recent
developments.