11,336 research outputs found
Deflection of jets induced by jet-cloud & jet-galaxy interactions
The model first introduced by Raga & Canto (1996) in which astrophysical jets
are deflected on passing through an isothermal high density region is
generalised by taking into account gravitational effects on the motion of the
jet as it crosses the high density cloud. The problem is also generalised for
relativistic jets in which gravitational effects induced by the cloud are
neglected. Two further cases, classical and relativistic, are discussed for the
cases in which the jet is deflected on passing through the interstellar gas of
a galaxy in which a dark matter halo dominates the gravitational potential.
The criteria for the stability of jets due to the formation of internal
shocks are discussed.Comment: 8 pages, 5 figures, Accepted for publication in MNRA
Short-lived lattice quasiparticles for strongly interacting fluids
It is shown that lattice kinetic theory based on short-lived quasiparticles
proves very effective in simulating the complex dynamics of strongly
interacting fluids (SIF). In particular, it is pointed out that the shear
viscosity of lattice fluids is the sum of two contributions, one due to the
usual interactions between particles (collision viscosity) and the other due to
the interaction with the discrete lattice (propagation viscosity). Since the
latter is {\it negative}, the sum may turn out to be orders of magnitude
smaller than each of the two contributions separately, thus providing a
mechanism to access SIF regimes at ordinary values of the collisional
viscosity. This concept, as applied to quantum superfluids in one-dimensional
optical lattices, is shown to reproduce shear viscosities consistent with the
AdS-CFT holographic bound on the viscosity/entropy ratio. This shows that
lattice kinetic theory continues to hold for strongly coupled hydrodynamic
regimes where continuum kinetic theory may no longer be applicable.Comment: 10 pages, 2 figure
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Out of the musical box
The present paper explores the correlations of music and architecture through a design studio project carried out by second year students of the Architecture programme at Nottingham Trent University in the United Kingdom. In addition the paper looks into some of the most representative architects and composers who have materialized this connectivity between space and music. Last but not least this appraisal intends to illustrate how the studentsâ creative process and spatial understanding may be influenced by introducing music as an analogue to understand architecture
Hydrodynamic Model for Conductivity in Graphene
Based on the recently developed picture of an electronic ideal relativistic
fluid at the Dirac point, we present an analytical model for the conductivity
in graphene that is able to describe the linear dependence on the carrier
density and the existence of a minimum conductivity. The model treats
impurities as submerged rigid obstacles, forming a disordered medium through
which graphene electrons flow, in close analogy with classical fluid dynamics.
To describe the minimum conductivity, we take into account the additional
carrier density induced by the impurities in the sample. The model, which
predicts the conductivity as a function of the impurity fraction of the sample,
is supported by extensive simulations for different values of , the
dimensionless strength of the electric field, and provides excellent agreement
with experimental data.Comment: 19 pages, 4 figure
Towards a unified lattice kinetic scheme for relativistic hydrodynamics
We present a systematic derivation of relativistic lattice kinetic equations
for finite-mass particles, reaching close to the zero-mass ultra-relativistic
regime treated in the previous literature. Starting from an expansion of the
Maxwell-Juettner distribution on orthogonal polynomials, we perform a
Gauss-type quadrature procedure and discretize the relativistic Boltzmann
equation on space-filling Cartesian lattices. The model is validated through
numerical comparison with standard benchmark tests and solvers in relativistic
fluid dynamics such as Boltzmann approach multiparton scattering (BAMPS) and
previous relativistic lattice Boltzmann models. This work provides a
significant step towards the formulation of a unified relativistic lattice
kinetic scheme, covering both massive and near-massless particles regimes
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