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The problem of quantum turbulence in a channel with an inhomogeneous counterflow of superfluid turbulent helium is studied. \ The counterflow velocity $V_{ns}^{x}(y)$ along the channel is supposed to have a parabolic profile in the…

Other Condensed Matter · Physics 2018-04-18 Sergey K. Nemirovskii

We provide a description of the dynamic structure factor of a homogeneous unitary Fermi gas at low momentum and low frequency, based on the dissipative two-fluid hydrodynamic theory. The viscous relaxation time is estimated and is used to…

Quantum Gases · Physics 2018-02-14 Hui Hu , Peng Zou , Xia-Ji Liu

We study numerically the propagation of a hot thermal transient through a U-bend via an ensemble of wall-resolved large eddy simulations. Conjugate heat transfer between fluid and solid domains is accounted for. The flow is in a fully…

We study the generation, nonlinear development and secondary instability of unsteady G\"ortler vortices and streaks in compressible boundary layers exposed to free-stream vortical disturbances and evolving over concave, flat and convex…

Fluid Dynamics · Physics 2024-12-11 Dongdong Xu , Pierre Ricco , Elena Marensi

We investigate the hydrodynamic stability and the formation of patterns in a continuum model of epithelial layers, able to account for the interplay between mechanical activity, lateral adhesion and the $6-$fold orientational order…

Soft Condensed Matter · Physics 2025-02-19 Josep-Maria Armengol-Collado , Leonardo Puggioni , Livio N. Carenza , Luca Giomi

We study motion of a phase transition front at a constant temperature between stable and metastable states in fluids with the universal Van der Waals equation of state (which is valid sufficiently close to the fluid's critical point). We…

Pattern Formation and Solitons · Physics 2009-10-31 Osamu Inomoto , Shoichi Kai , Boris Malomed

We suggest a "minimal model" for the 3D turbulent energy spectra in superfluids, based on their two-fluid description. We start from the Navier-Stokes equation for the normal fluid and from the coarse-grained hydrodynamic equation for the…

Chaotic Dynamics · Physics 2009-11-11 Victor S. L'vov , Sergei V. Nazarenko , L. Skrbek

Supersonic turbulence is a large reservoir of suprathermal energy in the interstellar medium. Its dissipation, because it is intermittent in space and time, can deeply modify the chemistry of the gas. We further explore a hybrid method to…

Astrophysics of Galaxies · Physics 2009-11-13 Benjamin Godard , Edith Falgarone , Guillaume Pineau Des Forêts

Recently, the characteristics, and dynamics of a persistent 1.7 h vortex flow, resembling a small-scale tornado, have been investigated with ground-base and space-based observations and for the first time in the Ha line centre. The vortex…

Solar and Stellar Astrophysics · Physics 2019-03-13 K. Tziotziou , G. Tsiropoula , I. Kontogiannis

Despite being a quantum two-fluid system, superfluid helium-4 (He II) is observed to behave similarly to classical fluids when a flow is generated by mechanical forcing. This similarity has brought up the feasibility of utilizing He II for…

Other Condensed Matter · Physics 2021-07-02 Yuan Tang , Shiran Bao , Toshiaki Kanai , Wei Guo

The characterization of heat and momentum fluxes in wall-bounded turbulence is of paramount importance for a plethora of applications, ranging from engineering to Earth sciences. However, how the turbulent structures associated with…

Fluid Dynamics · Physics 2020-11-12 Subharthi Chowdhuri , Thara V Prabha , Tirtha Banerjee

Supersonic turbulence occurs in many environments, particularly in astrophysics. In the crucial case of isothermal turbulence, the probability density function (PDF) of the logarithmic density, $s$, is well measured, but a theoretical…

Astrophysics of Galaxies · Physics 2024-10-31 Evan Scannapieco , Liubin Pan , Edward Buie , Marcus Brüggen

Laminar-turbulent transition on a rotating wind turbine blade at a chord Reynolds number of $1 \times 10^5$ and varying angles of attack ($AoA$) is studied with direct numerical simulations and linear stability theory. The rotation effects…

Fluid Dynamics · Physics 2023-08-01 Thales Coelho Leite Fava , Dan Henningson , Ardeshir Hanifi

We consider sound waves in superfluid nucleon-hyperon matter of massive neutron-star cores. We calculate and analyze the speeds of sound modes and their damping times due to the shear viscosity and non-equilibrium weak processes of particle…

Solar and Stellar Astrophysics · Physics 2009-08-26 Elena M. Kantor , Mikhail E. Gusakov

The experimentally observed disappearance below T = 0.5K of the second sound in liquid He II as a separate wave mode and its subsequent propagation at the speed of the first sound (Peshkov [3]) may be interpreted as a resonant mode…

Other Condensed Matter · Physics 2017-11-01 B. K. Shivamoggi

We use holography to develop a physical picture of the real-time evolution of the spinodal instability of a four-dimensional, strongly-coupled gauge theory with a first-order, thermal phase transition. We numerically solve Einstein's…

High Energy Physics - Theory · Physics 2020-02-14 Maximilian Attems , Yago Bea , Jorge Casalderrey-Solana , David Mateos , Miguel Zilhao

Using Landau's theory of two-fluid hydrodynamics we investigate the sound modes propagating in a uniform weakly-interacting superfluid Bose gas for values of temperature, up to the critical point. In order to evaluate the relevant…

Quantum Gases · Physics 2015-09-10 Lucas Verney , Lev Pitaevskii , Sandro Stringari

The flow of quantized vortex lines in superfluid 3He-B is laminar at high temperatures, but below 0.6 Tc turbulence becomes possible, owing to the rapidly decreasing mutual friction damping. In the turbulent regime a vortex evolving in…

Soft Condensed Matter · Physics 2011-02-23 R. Hanninen , V. B. Eltsov , A. P. Finne , R. de Graaf , J. Kopu , M. Krusius , R. E. Solntsev

The reionization of the second electron of helium shapes the physical state of intergalactic gas at redshifts between 2 < z < 5. Because performing full in situ radiative transfer in hydrodynamic simulations is computationally expensive for…

Cosmology and Nongalactic Astrophysics · Physics 2020-07-22 Phoebe Upton Sanderbeck , Simeon Bird

We study the effect of density fluctuations induced by turbulence on the HI/H$_2$ structure in photodissociation regions (PDRs) both analytically and numerically. We perform magnetohydrodynamic numerical simulations for both subsonic and…

Astrophysics of Galaxies · Physics 2017-07-26 Shmuel Bialy , Blakesley Burkhart , Amiel Sternberg