Stochastic Rotation Dynamics simulations of wetting multi-phase flows

TL;DR

This paper extends the Stochastic Rotation Dynamics method to simulate multi-phase flows with wetting properties, enabling detailed studies of emulsion droplets and contact angles in microfluidic environments.

Contribution

The authors develop a modified SRDmc algorithm that incorporates wetting conditions and angular momentum conservation, broadening its application to immiscible two-phase flows with viscosity contrast.

Findings

SRDmc can accurately model bulk properties of mono-phase fluids.

The extended SRDmc+ method effectively simulates wetting and dewetting phenomena.

Simulation results agree with experimental and numerical studies of interfacial morphologies.

Abstract

Multi-color Stochastic Rotation Dynamics (SRDmc) has been introduced by Inoue et al. as a particle based simulation method to study the flow of emulsion droplets in non-wetting microchannels. In this work, we extend the multi-color method to also account for different wetting conditions. This is achieved by assigning the color information not only to fluid particles but also to virtual wall particles that are required to enforce proper no-slip boundary conditions. To extend the scope of the original SRDmc algorithm to e.g. immiscible two-phase flow with viscosity contrast we implement an angular momentum conserving scheme (SRDmc+). We perform extensive benchmark simulations to show that a mono-phase SRDmc fluid exhibits bulk properties identical to a standard SRD fluid and that SRDmc fluids are applicable to a wide range of immiscible two-phase flows. To quantify the adhesion of a SRDmc+ fluid in contact to the walls we measure the apparent contact angle from sessile droplets in mechanical equilibrium. For a further verification of our wettability implementation we compare the dewetting of a liquid film from a wetting stripe to experimental and numerical studies of interfacial morphologies on chemically structured surfaces.