Thermodynamically Consistent Phase-Field Cahn-Hilliard Navier-Stokes Models for Aqueous Phase Separating Multiphase Flow Systems

Generation of multicomponent microdroplets is an important step for such applications as development of polymeric nanoparticles for drug delivery and emulsions for cosmetics, where strategies based on phase separation of flowing mixtures are posited to control the droplet creation process. From a theoretical standpoint, such phase separating flows are mediated by the coupled Cahn-Hilliard Navier-Stokes (CHNS) system, for which a variety of models exist that describe the coupling terms between the two equations, depending on the system. In this work, we describe the application of a class of these models which can be formally derived ensuring thermodynamic consistency. After that, we also explore how these thermodynamically consistent models can be applied to understand systems that consist of flows of aqueous solutions in microchannels to understand how diffusive mechanisms associated with phase separation interact with viscous and convective processes associated to hydrodynamic flow. Such an understanding holds the potential to predict phenomena that could inform experimental realizations of phase separating flow systems.