A Novel Boundary Layer Modeling Framework for Modeling Interfacial Mass Transport in Multiphase Flows

We present a new subgrid scale modeling framework for simulating interfacial mass transport in multi-phase flows. In the problem considered, the large Schmidt number leads to the formation of a thin concentration boundary layer at the interface potentially orders of magnitude smaller than the smallest hydrodynamic length scales. As such, fully resolving both hydrodynamic and mass transfer length scales results in prohibitive computational costs. Our framework developed in the Free Software library Basilisk performs a Direct Numerical Simulation of the flow field coupled with a subgrid model to simulate the transport of a concentration field. We use a concentration profile derived from the dominating terms in the transport equation to describe the distribution of mass in interfacial cells, consequently developing correction terms for advective and diffusive fluxes. The framework is profile-agnostic and can be used to model problems with a combination of dynamics present such as chemical reactions or phase change by applying an appropriate profile. Lastly we demonstrate how a shallow neural network can be used to approximate a boundary layer profile given by an equation or a dataset, simplifying the integration of new profiles in the framework.