Search results for "Quantized vortice"

showing 4 items of 14 documents

Thermodynamic approach to vortex production and diffusion in inhomogeneous superfluid turbulence

2014

In this paper, we use a non-equilibrium thermodynamic framework to generalize a previous nonlocal model of counterflow superfluid turbulence to incorporate some new coupled terms which may be relevant in the evolution of inhomogeneous vortex tangles. The theory chooses as fundamental fields the energy density, the heat flux, and the averaged vortex line length per unit volume. The constitutive quantities are assumed to depend on the fundamental fields and on their first spatial derivatives, allowing us to describe thermal dissipation, vortex diffusion and a new contribution to vortex formation. The restrictions on the constitutive relations are deduced from the entropy principle, using the …

Statistics and ProbabilityPhysicsTurbulenceQuantum turbulenceCondensed Matter PhysicsQuantum turbulence quantized vortices heat transfer inhomogeneous vortex tangle vortex diffusion entropy fluxVortexSuperfluidityEntropy (classical thermodynamics)symbols.namesakeClassical mechanicsHeat fluxLagrange multiplierHeat transfersymbolsSettore MAT/07 - Fisica Matematica
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Inhomogeneous vortex tangles in counterflow superfluid turbulence: flow in convergent channels

2016

Abstract We investigate the evolution equation for the average vortex length per unit volume L of superfluid turbulence in inhomogeneous flows. Inhomogeneities in line density L andincounterflowvelocity V may contribute to vortex diffusion, vortex formation and vortex destruction. We explore two different families of contributions: those arising from asecondorder expansionofthe Vinenequationitself, andthose whichare notrelated to the original Vinen equation but must be stated by adding to it second-order terms obtained from dimensional analysis or other physical arguments.

T57-57.97Applied mathematics. Quantitative methodsTurbulenceApplied MathematicsQuantum turbulenceQuantum turbulence quantized vortices heat transfer inhomogeneous vortex tangle vortex diffusion.Quantized vorticesquantum turbulencevortex diffusion01 natural sciencesIndustrial and Manufacturing Engineering010305 fluids & plasmasVortexSuperfluidityClassical mechanicsCondensed Matter::Superconductivity0103 physical sciencesHeat transferheat transferinhomogeneous vortex tangle010306 general physicsSettore MAT/07 - Fisica Matematicaquantized vorticesCommunications in Applied and Industrial Mathematics
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Refrigeration of an array of cylindrical nanosystems by superfluid helium counterflow

2017

Abstract Motivated by the challenge of computer refrigeration, we study the limits set by the transition to quantum turbulence on the cooling of an array of heat-producing cylindrical nanosystems by means of superfluid-helium counterflow. The effective thermal conductivity in laminar counterflow superfluid helium is obtained in channels with rectangular cross section, through arrays of mutually parallel cylinders and in the combined situation of arrays of orthogonal cylinders inside the rectangular channel. The maximum cooling capacity is analyzed on the condition that turbulence is avoided and that the highest temperature does not exceed the lambda temperature.

Thermal conductivity Liquid helium Quantum turbulence Micropores Quantized vortices Computer refrigerationQuantum turbulenceCooling capacity01 natural sciences010305 fluids & plasmaslaw.inventionPhysics::Fluid DynamicsThermal conductivitylaw0103 physical sciencesthermal conductivity010306 general physicsSettore MAT/07 - Fisica Matematicathermal conductivity; liquid helium; quantum turbulence; micropores; quantized vortices; computer refrigerationquantized vorticesCondensed Matter::Quantum GasesFluid Flow and Transfer ProcessesPhysicsCondensed matter physicsliquid heliumTurbulenceLiquid heliumMechanical Engineeringcomputer refrigerationRefrigerationquantum turbulenceLaminar flowMechanicsCondensed Matter PhysicsmicroporesSuperfluid helium-4
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Wave propagation in anisotropic turbulent superfluids

2013

In this work, a hydrodynamical model of Superfluid Turbulence previously formulated is applied to study how the presence of a non-isotropic turbulent vortex tangle modifies the propagation of waves. Two cases are considered: wave front parallel and orthogonal to the heat flux. Using a perturbation method, the first-order corrections due to the presence of the vortex tangle to the speeds and to the amplitudes of the first and second sound are determined. It is seen that the presence of the quantized vortices couples first and second sound, and the attenuation of second sound is proportional to the line density L if the wave propagates orthogonal to the heat flux, while it is proportional to …

WavefrontPhysicsAnisotropic superfluid turbulence Quantized vortices Wave propagation Second sound Perturbation method.TurbulenceWave propagationApplied MathematicsGeneral MathematicsAttenuationGeneral Physics and AstronomyMechanicsSuperfluidityAmplitudeClassical mechanicsHeat fluxSecond soundSettore MAT/07 - Fisica Matematica
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