Micro- and nanoscale fluid flow on chemical channels

Abstract

We study the time evolution and driven motion of thin liquid films lying on top of chemical patterns on a substrate. Lattice-Boltzmann and molecular dynamics methods are used for simulations of the flow of microscopic and nanoscopic films, respectively. Minimization of fluid surface area is used to examine the corresponding equilibrium free energy landscapes. The focus is on motion across patterns containing diverging and converging flow junctions, with an eye towards applications to lab-on-a-chip devices. Both open liquid-vapor systems driven by body forces and confined liquid-liquid systems driven by boundary motion are considered. As in earlier studies of flow on a linear chemical channel, we observe continuous motion of a connected liquid film across repeated copies of the pattern, despite the appearance of pearling instabilities of the interface. Provided that the strength of the driving force and the volume of liquid are not too large, the liquid is confined to the chemical channels and its motion can be directed by small variations in the geometry of the pattern.

A study on the unphysical mass transfer of SCMP pseudopotential LBM

“…where and ̅ denote the corresponding components. Using MCMP models to study multiphase flows involving multi-bubble/droplet systems is more popular than SCMP models, and such studies can be found in reference [29][30][31][32][33][34][35]. However, the MCMP always suffers the limitation of increasing the density ratio and kinematic viscosity ratio [5], which restricts its application to a large extent.…”

Gradient dynamics model for drops spreading on polymer brushes

“…The theoretical description and numerical simulation of wetting processes on micro-, meso-and macroscales is in the case of simple liquids on inert solid substrates quite well developed. The range of approaches includes Molecular Dynamics (MD) simulations [14,18,31], lattice Boltzmann simulations [18], phase-field models [74], classical hydrodynamics (Navier-Stokes equations) [35,36] and asymptotic approaches as mesoscopic thin-film (or long-wave) models [13,45]. Comparative studies, parameter passing approaches and consistency conditions connect these approaches into a multiscale framework [18,35,49,68,70].…”

“…The range of approaches includes Molecular Dynamics (MD) simulations [14,18,31], lattice Boltzmann simulations [18], phase-field models [74], classical hydrodynamics (Navier-Stokes equations) [35,36] and asymptotic approaches as mesoscopic thin-film (or long-wave) models [13,45]. Comparative studies, parameter passing approaches and consistency conditions connect these approaches into a multiscale framework [18,35,49,68,70]. In macroscopic hydrodynamic models, polymer brushes are often considered as flexible (viscoelastic) layers without adaptability [32].…”

Unidirectional transport of water nanodroplets entrapped inside a nonparallel smooth surface: a molecular dynamics simulation study

“…9 Moreover, surfaces with wettability gradients and surfaces with an unsymmetrical structure can usually efficiently aid the unidirectional motion of the liquid. 10,11 However, the transport of the liquid droplet in the above mentioned studies is dependent on an external source or on the surface heterogeneity. 12 In a number of industrial processes, it has been observed that a bridge of liquid is formed between two solid surfaces.…”