Binary mixture flow with free energy lattice Boltzmann methods

TL;DR

This paper demonstrates the use of free energy lattice Boltzmann methods to simulate binary mixture flows, capturing deformation and breakup phenomena in shear and extensional flows with good agreement to analytical and reference results.

Contribution

It applies and evaluates free energy lattice Boltzmann methods for complex binary mixture flows in 2D and 3D, including implementation in an open-source framework.

Findings

Characteristic deformations and breakup mechanisms are captured.

Good agreement with analytical predictions and reference results.

Mass leakage observed for small droplet ratios, but manageable with suitable mesh sizes.

Abstract

We use free energy lattice Boltzmann methods (FRE LBM) to simulate shear and extensional flow of a binary mixture in two and three dimensions. To this end, two classical configurations are digitally twinned, namely a parallel-band device for binary shear flow and a four-roller apparatus for binary extensional flow. The FRE LBM and the test cases are implemented in the open-source C++ framework OpenLB and evaluated for several non-dimensional numbers. Characteristic deformations are captured, where breakup mechanisms occur for critical capillary regimes. Though the known mass leakage for small droplet-domain ratios is observed, suitable mesh sizes show good agreement to analytical predictions and reference results.