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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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