Numerical Study of the Triple Line Behavior for a Two-Phase Flow in a Rectangular Microchannel

The present study investigates the behavior of the contact line for a two-phase flow inside a rectangular microchannel. It invokes the displacement of a wetting fluid by another non-wetting fluid to analyze the dynamics of the triple line created by the contact of two immiscible fluids and the channel wall. We consider a horizontal rectangular duct of 0.5, 1, and 2 mm in height and 12 mm in length initially containing the wetting fluid at rest. The non-wetting fluid is injected with a uniform axial velocity of 0.04 m/s. Both fluids are considered Newtonian and incompressible in a transient state. The open-source code, OpenFOAM, is employed with a single-fluid model to solve the continuity and momentum equations along with the volume of fluid (VOF) method for interface tracking to obtain the flow field. The analysis of the influence of several factors on the interface evolution, the fluids displacement, and the dynamics of the contact line is carried out. The numerical results show that the dynamics of the triple line are substantially influenced by the nature of the fluids, the magnitude of the surface tension, the dimensions of the channel, and the static contact angle.