894 research outputs found
Lattice-Gas Simulations of Ternary Amphiphilic Fluid Flow in Porous Media
We develop our existing two-dimensional lattice-gas model to simulate the
flow of single-phase, binary-immiscible and ternary-amphiphilic fluids. This
involves the inclusion of fixed obstacles on the lattice, together with the
inclusion of ``no-slip'' boundary conditions. Here we report on preliminary
applications of this model to the flow of such fluids within model porous
media. We also construct fluid invasion boundary conditions, and the effects of
invading aqueous solutions of surfactant on oil-saturated rock during
imbibition and drainage are described.Comment: 9 pages, 6 figures (1 and 6 are in color), RevTeX with epsf and
graphic
Two-dimensional hydrodynamic lattice-gas simulations of binary immiscible and ternary amphiphilic fluid flow through porous media
The behaviour of two dimensional binary and ternary amphiphilic fluids under
flow conditions is investigated using a hydrodynamic lattice gas model. After
the validation of the model in simple cases (Poiseuille flow, Darcy's law for
single component fluids), attention is focussed on the properties of binary
immiscible fluids in porous media. An extension of Darcy's law which explicitly
admits a viscous coupling between the fluids is verified, and evidence of
capillary effects are described. The influence of a third component, namely
surfactant, is studied in the same context. Invasion simulations have also been
performed. The effect of the applied force on the invasion process is reported.
As the forcing level increases, the invasion process becomes faster and the
residual oil saturation decreases. The introduction of surfactant in the
invading phase during imbibition produces new phenomena, including
emulsification and micellisation. At very low fluid forcing levels, this leads
to the production of a low-resistance gel, which then slows down the progress
of the invading fluid. At long times (beyond the water percolation threshold),
the concentration of remaining oil within the porous medium is lowered by the
action of surfactant, thus enhancing oil recovery. On the other hand, the
introduction of surfactant in the invading phase during drainage simulations
slows down the invasion process -- the invading fluid takes a more tortuous
path to invade the porous medium -- and reduces the oil recovery (the residual
oil saturation increases).Comment: 48 pages, 26 figures. Phys. Rev. E (in press
A Labelling Scheme for Higher Dimensional Simplex Equations
We present a succinct way of obtaining all possible higher dimensional
generalization of Quantum Yang-Baxter Equation (QYBE). Using the scheme, we
could generate the two popular three-simplex equations, namely: Zamolodchikov's
tetrahedron equation (ZTE) and Frenkel and Moore equation (FME).Comment: To appear as a Letter to the Editor in J. Phys. A:Math and Ge
Computation of dynamical correlation functions of Heisenberg chains in a field
We compute the momentum- and frequency-dependent longitudinal spin structure
factor for the one-dimensional spin-1/2 Heisenberg spin chain in a
magnetic field, using exact determinant representations for form factors on the
lattice. Multiparticle contributions are computed numerically throughout the
Brillouin zone, yielding saturation of the sum rule to high precision.Comment: 4 pages, 14 figure
A lattice Poisson algebra for the Pohlmeyer reduction of the AdS_5 x S^5 superstring
The Poisson algebra of the Lax matrix associated with the Pohlmeyer reduction
of the AdS_5 x S^5 superstring is computed from first principles. The resulting
non-ultralocality is mild, which enables to write down a corresponding lattice
Poisson algebra.Comment: 5 page
A reduced model for shock and detonation waves. II. The reactive case
We present a mesoscopic model for reactive shock waves, which extends a
previous model proposed in [G. Stoltz, Europhys. Lett. 76 (2006), 849]. A
complex molecule (or a group of molecules) is replaced by a single
mesoparticle, evolving according to some Dissipative Particle Dynamics.
Chemical reactions can be handled in a mean way by considering an additional
variable per particle describing a rate of reaction. The evolution of this rate
is governed by the kinetics of a reversible exothermic reaction. Numerical
results give profiles in qualitative agreement with all-atom studies
On classical q-deformations of integrable sigma-models
JHEP is an open-access journal funded by SCOAP3 and licensed under CC BY 4.0A procedure is developed for constructing deformations of integrable σ-models which are themselves classically integrable. When applied to the principal chiral model on any compact Lie group F, one recovers the Yang-Baxter σ-model introduced a few years ago by C. Klimčík. In the case of the symmetric space σ-model on F/G we obtain a new one-parameter family of integrable σ-models. The actions of these models correspond to a deformation of the target space geometry and include a torsion term. An interesting feature of the construction is the q-deformation of the symmetry corresponding to left multiplication in the original models, which becomes replaced by a classical q-deformed Poisson-Hopf algebra. Another noteworthy aspect of the deformation in the coset σ-model case is that it interpolates between a compact and a non-compact symmetric space. This is exemplified in the case of the SU(2)/U(1) coset σ-model which interpolates all the way to the SU(1, 1)/U(1) coset σ-modelPeer reviewedFinal Published versio
On algebraic structures in supersymmetric principal chiral model
Using the Poisson current algebra of the supersymmetric principal chiral
model, we develop the algebraic canonical structure of the model by evaluating
the fundamental Poisson bracket of the Lax matrices that fits into the rs
matrix formalism of non-ultralocal integrable models. The fundamental Poisson
bracket has been used to compute the Poisson bracket algebra of the monodromy
matrix that gives the conserved quantities in involution
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