(110d) Multiphysics Simulation of Interfacial Phenomena by Fluctuating Hydrodynamics

We develop a novel method to simulate liquid-vapor and liquid-liquid interfaces by using the framework of fluctuating hydrodynamics (FHD), which generalizes the deterministic Navier-Stokes equations by including stochastic stress in the balance of momentum fields. For the first time, we apply the van der Waals gradient theory with FHD to study the thermodynamics and dynamics of interfacial phenomena under a unified framework. We will present simulations describing the formation of drops, bubbles, and interfaces. To enable such studies, we develop a local scaling scheme to avoid the unphysical appearance of negative densities when simulating dilute systems. We demonstrate that this approach accurately reproduces the power spectra of the fluctuations of a liquid-vapor interface, as predicted by capillary wave theory. We then generalize this method to simulate the adsorption and solidification phenomena in a multicomponent system. Results on model systems will be presented to demonstrate its robustness and general applicability. By using a field-theoretic coarse-grained description of the solvent, we attempt to probe the dynamics of macromolecules that are inaccessible by atomistic molecular dynamics simulations. The results of proof-of-principle studies will be presented to illustrate that both the dynamics and solvation thermodynamics of macromolecules can be described by the combined particle-field method.