QFS2016 Book of Abstracts

Abstracts

P3.18 Small-scale universality of particle dynamics in turbulent flows of He II La Mantia Marco, ˇSvanˇcara Patrik, Duda Daniel, Rotter Miloˇs, Skrbek Ladislav Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, 121 16 Prague, Czech Republic The flow-induced motions of small particles suspended in He II are investigated experimentally, by visualization, above 1 K. We show that the statistically described particle dynamics does not depend on the type of imposed two-fluid flow, at scales smaller than the average distance between quantized vortices. Regardless of the mechanically or thermally driven nature of the large-scale flow, the tails of the observed particle velocity distributions display the same power-law shape. This property of quantum turbulence can be seen as analogous to the small-scale universality reported to occur in classical turbulent flows of viscous fluids. We acknowledge the support of GA ˇCR 16-00580S. Weizmann Institute of Science, Department of Chemical Physics, Rehovot Israel We present the results for the coupled dynamics of normal and superfluid components of the superfluid He4 in the channel. We consider the case of the counterflow turbulence with laminar normal component. In particular, we calculated profiles of the normal velocity, the mutual friction and the vortex line density, as well as other flow properties and compared them to the case when the dynamic of the normal component is “frozen”. We have found that the coupling between the normal and superfluid components leads to a flattening of the normal velocity profile, increasingly more pronounced with temperature as the mutual friction, and therefore coupling, become stronger. The commonly measured flow properties also change when the coupling between two components is taken into account. P3.19 Coupled dynamics for superfluid He4 in the channel. Khomenko Dmytro, Mishra Pankaj, Pomyalov Anna

94