88 research outputs found
Navier-Stokes Equations for Generalized Thermostatistics
Tsallis has proposed a generalization of Boltzmann-Gibbs thermostatistics by
introducing a family of generalized nonextensive entropy functionals with a
single parameter . These reduce to the extensive Boltzmann-Gibbs form for
, but a remarkable number of statistical and thermodynamic properties have
been shown to be -invariant -- that is, valid for any . In this paper, we
address the question of whether or not the value of for a given viscous,
incompressible fluid can be ascertained solely by measurement of the fluid's
hydrodynamic properties. We find that the hydrodynamic equations expressing
conservation of mass and momentum are -invariant, but that for conservation
of energy is not. Moreover, we find that ratios of transport coefficients may
also be -dependent. These dependences may therefore be exploited to measure
experimentally.Comment: RevTeX and epsf macros required, 19 pages, 8 figure
A Particulate Basis for an Immiscible Lattice-Gas Model
We show that a phenomenological hydrodynamic lattice-gas model of two-phase
flow, developed by Rothman and Keller in 1988 and used extensively for
numerical simulations since then, can be derived from an underlying model of
particle interactions. From this result, we elucidate the nature of the
hydrodynamic limit of the Rothman-Keller model.Comment: 11 pages. Accepted for publication in Computer Physics Communication
From Dirac to Diffusion: Decoherence in Quantum Lattice Gases
We describe a model for the interaction of the internal (spin) degree of
freedom of a quantum lattice-gas particle with an environmental bath. We impose
the constraints that the particle-bath interaction be fixed, while the state of
the bath is random, and that the effect of the particle-bath interaction be
parity invariant. The condition of parity invariance defines a subgroup of the
unitary group of actions on the spin degree of freedom and the bath. We derive
a general constraint on the Lie algebra of the unitary group which defines this
subgroup, and hence guarantees parity invariance of the particle-bath
interaction. We show that generalizing the quantum lattice gas in this way
produces a model having both classical and quantum discrete random walks as
different limits. We present preliminary simulation results illustrating the
intermediate behavior in the presence of weak quantum noise.Comment: To appear in QI
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