Contact line dynamics of pulsatile fluid interfaces modulated by patterned substrates

Abstract

We study the dynamics of microfluidic fronts driven by pulsatile pressures in the presence of patches of hydrophilic wetting on the walls of the confining media. To do so, we use a recently developed phase-field model that takes inertia into account. We track the interface position in channels with different spacing between the patches and observe that the smaller the spacing, the faster the advancement of the front. We find that the wetting patterning induces a modulating dynamics of the contact line that causes an effective wetting, which in turn determines the modulation of the interface velocity. We characterize the modulation frequency in terms of wetting pattern, inertia, and surface tension, via the capillary pressure, viscosity, and confinement.