QFS2016 Book of Abstracts

Abstracts

P3.4 Mechanical momentum transfer in wall-bounded superfluid turbulence A. Pomyalov, D. Khomenko, V.S. L’vov, and I. Procaccia Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel Unlike classical turbulence, the dissipation of energy and mechanical momentum in quantum turbulence is governed by different mechanisms. We show, using an analogy of the classical Reynolds stress, that the transfer of mechanical momentum to the wall is caused by the presence of a quantum vortex tangle, giving rise to an effective “momentum” viscosity with the temperature dependence different from the effective viscosity for the energy dissipation. We also show that the notion of vortex-tension force can be understood as the gradient of the Reynolds stress, determined by the new effective “momentum” viscosity. P3.5 Some recent results from the one-fluid model of He II Sciacca Michele(1,2), Galantucci Luca(2,3), Jou David(4), Mongiovi’ Maria Stella(2,5), Sellitto Antonio(2,6) 1) Universit`a di Palermo, Dipartimento Scienze Agrarie e Forestali (SAF), Palermo, Italy; 2) Istituto Nazionale di Alta Matematica, Roma, Italy; 3) Newcastle University, Joint Quantum Centre (JQC) Durham and School of Mathematics and Statistics, Newcastle upon Tyne, United Kingdom; 4) Universitat Aut`onoma de Barcelona, Departament de F´ısica, Bellaterra, Catalonia, Spain; 5) Universit`a di Palermo, Dipartimento Ingegneria Chimica, Gestionale, Informatica, Meccanica (DICGIM), Palermo, Italy; 6) Universit´a di Salerno, Dipartimento di Ingegneria Industriale, Salerno, Italy. Heat transport in He II has several special features related to the relative presence of phonons and rotons, the laminar or turbulent flow and the relation between phonon mean-free path and the diameter of the container. We propose an application of the one-fluid model of He II able to describe the transition between these three different regimes (Landau, ballistic and Gorter-Mellinck regime). The previous regimes appear in the refrigeration of heat-producing systems. As a particular illustration, we consider counterflow refrigeration of an array of cylindrical heat-producing systems between two parallel plates.

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