659 research outputs found
Dynamics and Rheology of Vesicle Suspensions in Wall-Bounded Shear Flow
The dynamics and rheology of suspensions of fluid vesicles or red blood cells
is investigated by a combination of molecular dynamics and mesoscale
hydrodynamics simulations in two dimensions. The vesicle suspension is confined
between two no-slip walls, which are driven externally to generate a shear flow
with shear rate . The flow behavior is studied as a function of
, the volume fraction of vesicles, and the viscosity contrast
between inside and outside fluids. Results are obtained for the encounter and
interactions of two vesicles, the intrinsic viscosity of the suspension, and
the cell-free layer near the walls.Comment: In press in EP
Rheological properties of sheared vesicle and cell suspensions
Numerical simulations of vesicle suspensions are performed in two dimensions
to study their dynamical and rheological properties. An hybrid method is
adopted, which combines a mesoscopic approach for the solvent with a
curvature-elasticity model for the membrane. Shear flow is induced by two
counter-sliding parallel walls, which generate a linear flow profile. The flow
behavior is studied for various vesicle concentrations and viscosity ratios
between the internal and the external fluid. Both the intrinsic viscosity and
the thickness of depletion layers near the walls are found to increase with
increasing viscosity ratio.Comment: To be published in the DynaCaps 2014 Conference Proceedings (Procedia
IUTAM
Phase-ordering dynamics of binary mixtures with field-dependent mobility in shear flow
The effect of shear flow on the phase-ordering dynamics of a binary mixture
with field-dependent mobility is investigated. The problem is addressed in the
context of the time-dependent Ginzburg-Landau equation with an external
velocity term, studied in self-consistent approximation. Assuming a scaling
ansatz for the structure factor, the asymptotic behavior of the observables in
the scaling regime can be analytically calculated. All the observables show
log-time periodic oscillations which we interpret as due to a cyclical
mechanism of stretching and break-up of domains. These oscillations are dumped
as consequence of the vanishing of the mobility in the bulk phase.Comment: 9 pages, 4 figures, EPJ styl
A lattice Boltzmann study of phase separation in liquid-vapor systems with gravity
Phase separation of a two-dimensional van der Waals fluid subject to a
gravitational force is studied by numerical simulations based on lattice
Boltzmann methods (LBM) implemented with a finite difference scheme. A growth
exponent is measured in the direction of the external force.Comment: To appear in Communications in Computational Physics (CiCP
Hybrid lattice Boltzmann model for binary fluid mixtures
A hybrid lattice Boltzmann method (LBM) for binary mixtures based on the
free-energy approach is proposed. Non-ideal terms of the pressure tensor are
included as a body force in the LBM kinetic equations, used to simulate the
continuity and Navier-Stokes equations. The convection-diffusion equation is
studied by finite difference methods. Differential operators are discretized in
order to reduce the magnitude of spurious velocities. The algorithm has been
shown to be stable and reproducing the correct equilibrium behavior in simple
test configurations and to be Galilean invariant. Spurious velocities can be
reduced of about an order of magnitude with respect to standard discretization
procedure.Comment: Final version, to appear in Phys. Rev.
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