245 research outputs found
Electrokinetic Lattice Boltzmann solver coupled to Molecular Dynamics: application to polymer translocation
We develop a theoretical and computational approach to deal with systems that
involve a disparate range of spatio-temporal scales, such as those comprised of
colloidal particles or polymers moving in a fluidic molecular environment. Our
approach is based on a multiscale modeling that combines the slow dynamics of
the large particles with the fast dynamics of the solvent into a unique
framework. The former is numerically solved via Molecular Dynamics and the
latter via a multi-component Lattice Boltzmann. The two techniques are coupled
together to allow for a seamless exchange of information between the
descriptions. Being based on a kinetic multi-component description of the fluid
species, the scheme is flexible in modeling charge flow within complex
geometries and ranging from large to vanishing salt concentration. The details
of the scheme are presented and the method is applied to the problem of
translocation of a charged polymer through a nanopores. In the end, we discuss
the advantages and complexities of the approach
Discrete solution of the electrokinetic equations
We present a robust scheme for solving the electrokinetic equations. This
goal is achieved by combining the lattice-Boltzmann method (LB) with a discrete
solution of the convection-diffusion equation for the different charged and
neutral species that compose the fluid. The method is based on identifying the
elementary fluxes between nodes, which ensures the absence of spurious fluxes
in equilibrium. We show how the model is suitable to study electro-osmotic
flows. As an illustration, we show that, by introducing appropriate dynamic
rules in the presence of solid interfaces, we can compute the sedimentation
velocity (and hence the sedimentation potential) of a charged sphere. Our
approach does not assume linearization of the Poisson-Boltzmann equation and
allows us for a wide variation of the Peclet number.Comment: 24 pages, 7 figure
Introduction to colloidal dispersions in external fields
Progress in the research area of colloidal dispersions in external fields
within the last years is reviewed. Colloidal dispersions play a pivotal role as
model systems for phase transitions in classical statistical mechanics. In
recent years the leading role of colloids to realize model systems has become
evident not only for equilibrium situations but also far away from equilibrium.
By using external fields (such as shear flow, electric, magnetic or
laseroptical fields as well as confinement), a colloidal suspension can be
brought into nonequilibrium in a controlled way. Various kinds of equilibrium
and nonequilibrium phenomena explored by colloidal dispersions are described
providing also a guide and summary to this special issue. Particular emphasis
is put on the comparison of real-space experiments, computer simulations and
statistical theories.Comment: 11 pages, 2 figures, Eur. Phys. J. Special Topics (accepted
The lattice Boltzmann modeling of two-phase electroosmotic flow in microchannels
Technial Session - 2C Multi-phase Flows(1): no. S2C5In this paper, a numerical framework based on the lattice Boltzmann method is presented for modeling two-phase electroosmotic flow within microchannels. In the model, lattice Boltzmann schemes are designed for all the governing equations involved such as Navier-Stokes equations for momentum transport, Nernst-Planck equations for ion transport, the Cahn-Hilliard equation for the immiscible fluid interface motion, and Poisson equation for the electric potential referring the model proposed in Shao’s work [6]. Related boundary schemes are also proposed to modeling the slip effect on the microchannel surfaces. The theoretical analysis shows that the model has second order accuracy.published_or_final_versio
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