Grid Turbulence in Superfluid 3He-B at Low Temperatures

Abstract

Quantum turbulence consists of a tangle of quantised vortex lines which interact via their self induced flow. At very low temperatures there is no normal fluid component and no associated viscosity. These are very simple conditions in which to study turbulence which might eventually lead to a better understanding of turbulence in general. There are a number of interesting questions, such as how closely does quantum turbulence resemble classical turbulence and how does it decay in the absence of the viscous dissipation. We have recently developed techniques for detecting quantum turbulence in superfluid 3He-B in the low temperature limit. Using a vibrating grid, we find an unexpected sharp transition to turbulence via the entanglement of emitted vortex rings. Measurements also suggest that the quantum turbulence produced by the grid decays in a manner similar to that expected for classical turbulence, but the decay rate appears to be governed by the circulation quantum rather than viscosity.