Migration, mixing and modulation in reactive Brownian systems of arbitrary geometric complexity

Research Project, 2022 – 2025

Hindered diffusion of reactive Brownian particle mixtures is a key step in a wide range of industrial and biological systems. Even so, unresolved conflicting observations challenge our understanding of these phenomena.
Whereas Brownian spheres migrate towards the centerline in a pressure-driven flow, non-spherical particles migrate towards the walls. Random diffusive motion of spheres enhances the mixing of a tracer species due to streamline distortion, but also suppresses mixing via a flattening of the velocity profile due to particle migration. Attractive interactions enhance migration in simulations but create clusters that resist migration in experiments.In this project, we will use a continuum-based multiphase direct numerical simulation (DNS) framework that couples Lagrangian Langevin equations of motion for Brownian particles of arbitrary shape to a Eulerian resolution of the continuous phase. This framework obtains the correct particle mobilities in arbitrary complex configurations on-the-fly. We will study particle migration in Brownian mixtures with different types of particles in complex geometries. We will determine how tracer mixing and heterogeneous mass transfer occurs in these systems. We will also establish the role of attractive interactions in modulating the diffusion characteristics in complex systems.The results obtained may enable a new paradigm in the optimization of surface-based sensors, micro- and nanofluidic reactors and lab-on-a-chip devices.