63 research outputs found
Pulsating flow and boundary layers in viscous electronic hydrodynamics
Motivated by experiments on a hydrodynamic regime in electron transport, we
study the effect of an oscillating electric field in such a setting. We
consider a long two-dimensional channel of width , whose geometrical
simplicity allows an analytical study as well as hopefully permitting
experimental realisation. The response depends on viscosity , driving
frequency, and ohmic heating coefficient via the
dimensionless complex variable . While at small , we recover the static solution, a new regime
appears at large with the emergence of a boundary layer. This includes
a splitting of the location of maximal flow velocity from the centre towards
the edges of the boundary layer, an an increasingly reactive nature of the
response, with the phase shift of the response varying across the channel. The
scaling of the total optical conductance with differs between the two
regimes, while its frequency dependence resembles a Drude form throughout, even
in the complete absence of ohmic heating, against which, at the same time, our
results are stable. Current estimates for transport coefficients in graphene
and delafossites suggest that the boundary layer regime should be
experimentally accessible.Comment: 5 pages, 3 figures, the title has been changed, the manuscript has
been substantially modified and references update
One-loop effective actions and 2D hydrodynamics with anomalies
We revisit the study of a 2D quantum field theory in the hydrodynamic regime
and develop a formalism based on Euclidean one-loop partition functions that is
suitable to analyze transport properties due to gauge and gravitational
anomalies. To do so, we generalize the method of a modified Dirac operator
developed for zero-temperature anomalies to finite temperature, chemical
potentials and rotations.Comment: 5 page
Boundary condition and geometry engineering in electronic hydrodynamics
We analyze the role of boundary geometry in viscous electronic hydrodynamics.
We address the twin questions of how boundary geometry impacts flow profiles,
and how one can engineer boundary conditions -- in particular the effective
slip parameter -- to manipulate the flow in a controlled way. We first propose
a micropatterned geometry involving finned barriers, for which we show by an
explicit solution that one can obtain effectively no-slip boundary conditions
regardless of the detailed microscopic nature of the channel surface. Next we
analyse the role of mesoscopic boundary curvature on the effective slip length,
in particular its impact on the Gurzhi effect. Finally we investigate a
hydrodynamic flow through a circular junction, providing a solution, which
suggests an experimental set-up for determining the slip parameter. We find
that its transport properties differ qualitatively from the case of ballistic
conduction, and thus presents a promising setting for distinguishing the two.Comment: 9 pages, 15 figures, 5 appendice
A New Approach to Non-Abelian Hydrodynamics
We present a new approach to describe hydrodynamics carrying non-Abelian
macroscopic degrees of freedom. Based on the Kaluza-Klein compactification of a
higher-dimensional neutral dissipative fluid on a group manifold, we obtain a
d=4 colored dissipative fluid coupled to Yang-Mills gauge field. We calculate
the transport coefficients of the new fluid, which show the non-Abelian
character of the gauge group. In particular, we obtain group-valued terms in
the gradient expansions and response quantities such as the conductivity matrix
and the chemical potentials. While using SU(2) for simplicity, this approach is
applicable to any gauge group. Resulting a robust description of non-Abelian
hydrodynamics, we discuss some links between this system and quark-gluon plasma
and fluid/gravity duality.Comment: 41 pages (31 + appendices), 1 figure. V2: Minor modifications, some
typos fixed and references adde
Nieperturbacyjne aspekty fizyki plazmy w supersymetrycznej teorii cechowania : metody teoriostrunowe
Molecular modelling of odd viscoelastic fluids
We consider an active, stochastic microscopic model of particles suspended in
a fluid and show that the coarse-grained description of this model renders odd
viscoelasticity. The model is made up of odd dumbbells, each featuring a
robotic device as the bead, which exhibits a particular torque response. We
analytically compute the stress-stress correlator and corroborate the results
using molecular dynamics simulations. We also provide a unified analytical
framework for several experimental and numerical setups designed to elucidate
odd effects in fluids.Comment: 17 pages, 7 figure
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