Water Experiments Related To The “Von Karman Sodium” Dynamo Project.

The purpose of the "Von Karman Sodium" (V.K.S.) experiment is to study the "Dynamo Effect", namely the spontaneous generation of magnetic field in a flow of electrically conducting fluid. The device has been built at CEA / Cadarache, in collaboration with CEA / Saclay, Ecole Normale Supérieure de Lyon and Ecole Normale Supérieure de Paris. It consists of a cylindrical vessel, filled with liquid Sodium, in which two coaxial rotating disks induce a Von-Karman type flow. Several experimental runs have taken place since June 2000. In order to optimize the V.K.S. set-up, a half-scale water prototype has also been built. It has allowed us to measure mean velocity profiles, as well as pressure fluctuations and mechanical power dissipation. We have observed that under certain circumstances the mean component of the turbulent flow can undergo a global bifurcation. [ABSTRACT FROM AUTHOR]