Flow visualisation techniques such as particle image velocimetry have recently been implemented for investigations of cryogenic flows of liquid helium. Our Laboratory has successfully utilized the particle tracking velocimetry technique that uses frozen flakes of hydrogen and/or deuterium of few microns in size as tracers, which will become the main tool to study quantum turbulence in superfluid helium at quantum length scales - smaller than the mean distance between quantized vortices - where quantum turbulence differs in a fundamental way from classical turbulence in viscous fluids, as well as at quasi-classical scales. To perform these studies, an experimental apparatus consisting of a custom-built optical cryostat, powerful pumping system, solid state laser, fast sensitive camera, tracer producing unit, suitable hardware and software is available. In view of a number of technical and fundamental difficulties this technique will be optimised in various ways and applied for selected cryogenic flows such as thermal counteflow of flows past various bluff bodies. The results will be compared with complementary experiments in classical viscous fluids.
Seznam odborné literatury
L. Skrbek a kol., Fyzika nízkých teplot, Matfyzpress 2011
DR Tilley, J Tilley, 1990, Superfluidity and superconductivity, Institute of Physics Publishing;
SW Van Sciver and CF Barenghi, 2009, Visualisation of quantum turbulence, Progress in Low Temperature Physics: Quantum Turbulence, Springer, 247-303
Předběžná náplň práce v anglickém jazyce
Our Laboratory has successfully utilized the particle tracking velocimetry technique that uses frozen flakes of hydrogen and/or deuterium of few microns in size as tracers, which will become the main tool to study quantum turbulence in superfluid helium.
