Experiments in cryogenic helium : from quantum turbulence to thermal plumes
Cryogenic liquid helium-4 is the fluid with the lowest known kinematic viscosity (1e-8 m²/s) making it a fluid of peculiar interest for the turbulence community as it allows to reach extreme Reynolds numbers.
Moreover, when its temperature is lowered below 2.17K at saturation, it undergoes a phase transition from its classical phase (He I) to its so-called superfluid phase (He II) which exhibits remarkable properties inherited from the quantum world. The most peculiar of these is probably the appearance of ’quantum vortex lines’ around which the superfluid velocity field circulates with a fixed quantum of circulation κ = h/m. In this talk, I will present experimental results on the comparative properties of He I and He II turbulent flows generated by a pair of oscillating grids. In particular, I will discuss the possible role of the inertial energy cascade in shaping the structure of the quantum vortex tangle in such He II coflow turbulence. Finally, I will also discuss some preliminary results on turbulent thermal plumes generated in a stably stratified He I bath.
Contact Nathanaël Machicoane for more information or to schedule a discussion with the seminar speaker.