Edited volume on turbulence, first published in 2000.The articles in this volume, derived from a symposium held at the Newton Institute in Cambridge, examine a number of key questions that have engaged turbulence researchers for many years. Most involve mathematical analysis, but some describe numerical simulations and experimental results that focus on those questions. However, all are addressed to a wide cross-section of the turbulence community, namely mathematicians, engineers and scientists.The articles in this volume, derived from a symposium held at the Newton Institute in Cambridge, examine a number of key questions that have engaged turbulence researchers for many years. Most involve mathematical analysis, but some describe numerical simulations and experimental results that focus on those questions. However, all are addressed to a wide cross-section of the turbulence community, namely mathematicians, engineers and scientists.The articles in this volume, derived from a symposium held at the Newton Institute in Cambridge, examine a number of key questions that have engaged turbulence researchers for many years. Most involve mathematical analysis, but some describe numerical simulations and experimental results that focus on these questions. However, all are addressed to a wide cross-section of the turbulence community, namely mathematicians, engineers and scientists.Introduction; 1. Motion and expansion of a viscous vortex ring: elliptical slowing down and diffusive expansion Yasuhide Fukumoto and H. K. Moffatt; 2. Stretching and compression of vorticity in the 3D Euler equations J. D. Gibbon, B. Galanti and R. M. Kerr; 3. Structure of a new family of vortices of stretched non-axisymmetric vortices St?phane le Diz?s; 4. Core dynamics of a coherent structure: a prototypical physical-space cascade mechanism? Dhoorjaty S. Pradeep and Fazle Hussain; 5. Fundamental instabilities in spatially-developing wing wakes and temporally-developing vortex pairs C. H. K. WilÓ9