Phase-Field Model-Based Simulation of Motions of a Two-Phase Fluid on Solid Surface

Abstract

A preliminary numerical simulation of the microscopic two-phase fluid motion on a solid surface was conducted using an interface-tracking method based on the phase-field model (PFM). Two variations of the lattice Boltzmann method (LBM) based on fictitious particle kinematics are proposed for solving diffuse-interface advection equations which were revised to improve volume-of-fluid conservation in the PFM simulations. The major findings are as follows: (1) the interface-tracking method accurately predicted the capillary force effect on dynamic two-phase fluid systems with a high density ratio between parallel plates; (2) the initial shape and volume of the two-phase fluid were retained adequately in linear translation with the use of the LBMs. These results proved that the PFM-based method and the LBM-based advection schemes can be used for simulating two-phase fluid motions in various macro-and microfluidics problems for devices, machineries and higher-throughput microdevice fabrication processes.

Phase-field model-based simulation of two-phase fluid motion on partially wetted and textured solid surface

“…PFM-based CFD methods for simulating immiscible incompressible isothermal viscous two-phase fluid flows generally adopt the following set of mass and momentum conservation equations with a diffuse-interface advection equation [4,9,[16][17][18]:…”

“…In the PFM-CFD method we previously proposed [17,18], the conservation-modified Allen-Cahn (AC) form [11,16] is adopted for Eq. (3) instead of the CH form with Eqs.…”

“…The contact angle, depending on the energy balance among three types of interfaces, is obtained from the potential of the solid surface through a simple boundary condition of the gradient of the order parameter on the surface [7,8]. As a result, PFM-CFD methods do not necessarily require conventional elaborating algorithms for the advection and reconstruction of interfaces [4,[7][8][9][10][11][12][13][14][15][16][17][18]. The method therefore has an advantage over others, namely the efficient simulation of motions of multiple fluid-fluid interfaces attached to solid bodies with edges and partially wetted textured surfaces.…”

“…The method therefore has an advantage over others, namely the efficient simulation of motions of multiple fluid-fluid interfaces attached to solid bodies with edges and partially wetted textured surfaces. We recently evaluated two types of diffuse-interface advection equations based on PFMs [9,16] in terms of their ability to perform the simulation of two-phase fluid motion on a solid surface [17,18]. In our previous study, the PFM-CFD method we proposed was shown to successfully predict immiscible liquid-liquid slug flow patterns in a rectangular microchannel with a T-junction and flat solid walls in agreement with the experimental data for low Reynolds and capillary numbers [18].…”

“…Our objective in this study is to examine the applicability of the PFM-CFD method [17,18] to simulations of microscopic two-phase fluid motion on textured and partially wetted solid surfaces for evaluating various fluidic devices. This paper is organized as follows.…”