Summary: Turbulence is widespread, indeed almost the rule, in the flow of classical fluids. It is a complex non-linear phenomenon, for which the development of a satisfactory theoretical framework has long been a challenge. Numerical and laboratory experiments are therefore fundamental to making progress, and in this vein, a concerted experimental effort has been made to take advantage of the unique properties of liquid and gaseous helium at low temperatures near or below the critical point. At these low temperatures, helium also undergoes a transition to a superfluid, and flow in that case is strongly influenced, directly or indirectly, by quantum effects. Turbulence in the quantum fluid is probably very similar to that in the classical case on length scales large compared with a characteristic quantum length scale equal to the spacing between vortex lines (having quantized circulation). Aside from its inherent interest, an understanding here of turbulent flow is needed to account for the increasingly important application of flowing superfluid helium as a coolant for superconducting devices such as the superconducting bending magnets of the Large Hadron Collider (LHC) at CERN.

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(*) Dr. Joseph Niemela is the Coordinator of the Fluid Dynamics Laboratory of the Abdus Salam International Centre for Theoretical Physics. In 1988 he obtained his Ph.D. His advisor was Professor Russell J. Donnelly of the University of Oregon, United States of America.

He was awarded an IBM Fellowship to the University of California at Santa Barbara. His post-doctoral mentors were Professors Guenter Ahlers and David Cannell.

Dr. Niemela returned to the University of Oregon, where he held position as Research Professor and project manager for an NSF-funded Cryogenic Turbulence Laboratory.

In April 2003 he came to the Abdus Salam ICTP as a visiting scientist and since July, 2003 has been a member of the scientific staff and coordinator of the Fluid Dynamics Laboratory. Currently ICTP's Optics and Laser Physics activities are co-ordinated by Dr. Niemela.

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