Simulating Moving Contact Lines in Three-Phase Suspensions Using a Front Tracking Method

TL;DR

This paper extends a front tracking method to simulate the motion of three-phase contact lines, including systems with solids, using explicit and implicit strategies that achieve comparable accuracy and are suitable for complex 3D flows.

Contribution

It introduces two strategies for tracking three-phase contact lines, one explicit and one implicit, with the implicit approach being easier to implement for 3D simulations.

Findings

Both approaches achieve similar accuracy.

The implicit approach is easier to implement in 3D.

The virtual interface method effectively models contact lines with solids.

Abstract

Three-phase multiphase flows are found in an extraordinarily large number of applications. Often those involve a liquid phase and a gas phase in addition to a third phase that consists of either liquid drops or solid particles, suspended in the flow. Frequently the third phase is in contact with both the liquid and the gas, resulting in a contact line where all the phases meet. Here, we present an extension of a front tracking method, where the interface between two fluid phases is followed using connected marker points, to simulate the motion of triple contact lines for both three fluids systems and systems containing two fluids and suspended solid particles. We describe two related strategies, one where the contact line is tracked explicitly and one where it is captured implicitly, and show that both approaches achieve comparable accuracy. The second approach is, however, easier to implement, particularly for three-dimensional flows. For both tracked and untracked approaches for solid particles, and for the untracked three fluids case, we use a ``virtual interface,'' where the boundary of a liquid phase is extended into either another fluid or the solid. For three fluids systems the surface tension of the virtual interface is zero, but for systems with solids the surface tension of the virtual interface is the same as that of the physical interface.