John has been in the Imperial College Mathematics Department since September 1980. His research interests lie in the study of turbulence in fluid dynamics from a mainly mathematical perspective. One of the major unsolved problems of modern applied mathematics concerns the regularity of solutions of the 3D incompressible Navier-Stokes equations. Related to this is the behaviour of solutions of the incompressible 3D Euler equations. Both problems, and particularly the former, suggest that vorticity clusters on fractal-like sets. The aim is to provide a general theory of this phenomenon which has applications to many areas of physics & applied mathematics.