Study of a precessing flow. Transition to turbulence and application to dynamo effect.

In the perspective to make a dynamo experiment, we study the precessing forcing flow in a cylinder (ATER experiment). The effect of precession can be seen as a Kelvin waves modes forcing (linearized solution) with a laminar flow when the precession rate (control parameter) is far the critical violent-breakdown to turbulence transition. However, the PIV studies show a “non linear” regime (from an boundary layer instability) of cyclonic and quasi stationnary vortices in differential rotation. The central symetry breakingcaused by this regime is encouraging for obtaining a dynamo regime.