Flow visualization techniques, which allow following the motion of relatively small particles suspended in the fluid, have in recent years given significant contributions to our understanding of the underlying physics. Indeed, the cryogenic visualization laboratory of the Department of Low Temperature Physics, the first to be established in Europe, can be regarded as one of the leading laboratory in this research field.
The research is partly supported by the Czech Science Foundation (GAČR).
The still unsolved physical problems to be addressed include (but are not limited to):
- behaviour of superfluid helium flows in the proximity of boundaries, that is, how does a solid boundary influence the motion of a fluid with an extremely small viscosity?
- flow development as a function of flow geometry, for example, how does the shape of an obstacle oscillating in superfluid helium affect the generated flow behaviour?
- features of large-scale vortices in superfluid helium flows, that is, what are similarities and differences between macroscopic vortex rings generated in superfluid helium and in viscous fluids?
Visualization of vortex rings in He II
The currently available projects focus on the following tasks:
- preparation of new low-temperature visualization experiments, including (i) the design and manufacturing of experimental cells, and (ii) the implementation in the current setup of flow sources, such as electric motors, and sensors, e.g. accelerometers
- performing of cryogenic visualization experiments
- processing of experimental data, by using adequate software, to be partly developed
- physical interpretation of the obtained results and preparation of scientific reports