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Superfluid helium consists of two inter-penetrating fluids, a viscous normal fluid and an inviscid superfluid, coupled by a mutual friction. We develop a two-fluid shell model to study superfluid turbulence. We investigate the energy…

Statistical Mechanics · Physics 2015-05-30 D. H. Wacks , C. F. Barenghi

We discuss heat conductivity from the point of view of a variational multi-fluid model, treating entropy as a dynamical entity. We demonstrate that a two-fluid model with a massive fluid component and a massless entropy can reproduce a…

Fluid Dynamics · Physics 2011-09-07 N. Andersson , G. L. Comer

We calculate the important quantity of superfluid hydrodynamics, the relativistic entrainment matrix for a nucleon-hyperon mixture at arbitrary temperature. In the nonrelativistic limit this matrix is also termed the Andreev-Bashkin or…

Solar and Stellar Astrophysics · Physics 2009-08-18 M. E. Gusakov , E. M. Kantor , P. Haensel

Mutual entrainment effects in cold neutron-proton mixtures are studied in the framework of the self-consistent nuclear energy-density functional theory. Exact expressions for the mass currents, valid for both homogeneous and inhomogeneous…

Nuclear Theory · Physics 2021-02-05 Nicolas Chamel , Valentin Allard

We develop a general formalism to treat, in general relativity, the nonradial oscillations of a superfluid neutron star about static (non-rotating) configurations. The matter content of these stars can, as a first approximation, be…

General Relativity and Quantum Cosmology · Physics 2009-11-07 N. Andersson , G. L. Comer , D. Langlois

We consider a simple experimental setup, based on a harmonic confinement, where a Bose-Einstein condensate and a thermal cloud of weakly interacting alkali atoms are trapped in two different vessels connected by a narrow channel. Using the…

Quantum Gases · Physics 2012-12-12 Tomasz Karpiuk , Benoit Gremaud , Christian Miniatura , Mariusz Gajda

We develop a flux-conservative formalism for a Newtonian multi-fluid system, including dissipation and entrainment (i.e. allowing the momentum of one fluid to be a linear combination of the velocities of all fluids). Maximum use is made of…

Fluid Dynamics · Physics 2016-09-08 Nils Andersson , G. L. Comer

We study the effects of finite stellar temperatures on the oscillations of superfluid neutron stars. The importance of these effects is illustrated with a simple example of a radially pulsating general relativistic star. Two main effects…

Solar and Stellar Astrophysics · Physics 2011-06-07 E. M. Kantor , M. E. Gusakov

We present a geometrical derivation of the relativistic dynamics of the superfluid inner crust of a neutron star. The resulting model is analogous to the Hall-Vinen-Bekarevich-Khalatnikov hydrodynamics for a single-component superfluid at…

High Energy Astrophysical Phenomena · Physics 2021-02-23 Lorenzo Gavassino , Marco Antonelli , Brynmor Haskell

We discuss vortex-mediated mutual friction in the two-fluid model for superfluid neutron star cores. Our discussion is based on the general formalism developed by Carter and collaborators, which makes due distinction between transport…

Astrophysics · Physics 2009-11-13 N. Andersson , T. Sidery , G. L. Comer

General relativistic superfluid neutron stars have a significantly more intricate dynamics than their ordinary fluid counterparts. Superfluidity allows different superfluid (and superconducting) species of particles to have independent…

General Relativity and Quantum Cosmology · Physics 2009-11-07 G. L. Comer , R. Joynt

The entrainment matrix (also termed the Andreev-Bashkin matrix or the mass-density matrix) for a neutron-proton mixture is derived at a finite temperature in a neutron star core. The calculation is performed in the frame of the Landau…

Astrophysics · Physics 2007-05-23 M. E. Gusakov , P. Haensel

We consider the hydrodynamics of the outer core of a neutron star under conditions when both neutrons and protons are superfluid. Starting from the equation of motion for the phases of the wave functions of the condensates of neutron pairs…

Quantum Gases · Physics 2017-03-02 D. N. Kobyakov , C. J. Pethick

From flow without dissipation of energy to the formation of vortices when placed within a rotating container, the superfluid state of matter has proven to be a very interesting physical phenomenon. Here we present the key mechanisms behind…

Quantum Gases · Physics 2020-12-09 Annette Lopez , Patrick Kelly , Kaelyn Dauer , Ettore Vitali

This paper provides the first study of a new dynamical instability in superfluids. This instability is similar to the two-stream instability known to operate in plasmas. It is analogous to the Kelvin-Helmholtz instability, but has the…

Astrophysics · Physics 2007-05-23 N. Andersson , G. L. Comer , R. Prix

Helium nanodroplets and trapped Bose-Einstein condensates in dilute atomic gases offer complementary views of fundamental aspects of quantum many-body systems. We discuss analogies and differences, stressing their common theoretical…

Condensed Matter · Physics 2009-11-07 F. Dalfovo , S. Stringari

A unified formulation of the density functional theory is constructed on the foundations of entropic inference in both the classical and the quantum regimes. The theory is introduced as an application of entropic inference for inhomogeneous…

Statistical Mechanics · Physics 2021-12-20 Ahmad Yousefi

In this work, we develop a new compatible finite element formulation of the thermal shallow water equations that conserves energy and mathematical entropies given by buoyancy-related quadratic tracer variances. Our approach relies on…

Fluid Dynamics · Physics 2025-03-18 Tamara A. Tambyah , David Lee , Santiago Badia

Both relativistic and non-relativistic two-fluid models of neutron star cores are constructed, using the constrained variational formalism developed by Brandon Carter and co-workers. We consider a mixture of superfluid neutrons and…

Astrophysics · Physics 2008-08-05 N. Chamel

We have observed the superfluid phase transition in a strongly interacting Fermi gas via high-precision measurements of the local compressibility, density and pressure down to near-zero entropy. Our data completely determine the universal…

Quantum Gases · Physics 2012-02-23 Mark J. H. Ku , Ariel T. Sommer , Lawrence W. Cheuk , Martin W. Zwierlein