Prof. Wei Guo (Florida State University) gives a research seminar at the School of Mathematics, UEA. The talk is on “Visualization study of quantum fluid dynamics in superfluid He-4”. The abstract is below.

Helium-4 in the superfluid phase (He II) is a two-fluid system that exhibits fascinating quantum fluid dynamics with important scientific and engineering applications. It supports the most efficient heat-transfer mechanism (i.e. thermal counterflow), and it also allows the generation of flows with extremely high Reynolds numbers for turbulence modelling. However, the lack of high-precision flow measurement tools in He II has impeded the progress in understanding and utilizing its hydrodynamics. In recent years, there have been extensive efforts in developing quantitative flow visualization techniques applicable to He II. Two types of techniques based on the use of either particle tracers (i.e. micron-sized frozen particles) or molecular tracers (i.e. He2* excimer molecules) have been developed. We will discuss the advantages and issues associated with these visualization techniques and will highlight some recent progresses in our visualization study of counterflow and quasiclasscial turbulence in He II. We will also briefly introduce our on-going work on developing the next generation flow visualization techniques and our effort on imaging quantized vortices in a levitated drop of He II.