Abstract: The coupled dynamics of fluids, particles, and solutes due to their nonlinear interactions can result in unexpected behaviors in engineering and physiological flows that can inspire the design of new applications for particle manipulation in fluid systems. Such applications can include the separation, detection, and concentration of particles and biomaterials, the design of novel chemical reactors, or even the development of techniques to enhance the efficacy of pharmaceuticals and cosmetics. In this talk, I present recent developments in two such confined flow systems that demonstrate surprising coupled fluid, solute, and particle dynamics. First, I use simulations and experiments to demonstrate the formation of vortex breakdown in simple branching microfluidic channels and show that these features can result in the capture and accumulation of particles and bubbles as well as the rapid shear-induced fusion of lipid vesicles. Furthermore, an analytic approach is used to show that this capture is due to invisible, anchor-shaped flow structures. Second, I use theory, numerics, and experiments to investigate the coupled fluid, solute, and particle dynamics in narrow channel flows and pore structures. In particular, I show how the application of solute concentration gradients can dramatically enhance particle transport in dead-end pores, and I also show how the competition between particle advection and diffusiophoresis in channel flows can result in rapid particle accumulation, the dynamics of which can be tuned by adjusting the flow parameters. These results inform the design of novel techniques for particle manipulation in confined flows.
Bio: Jesse Ault received his BSME from Purdue University in 2012 and his PhD from Princeton University in 2017 under the advising of Professor Howard Stone. He spent two years at the Oak Ridge National Laboratory as an Alvin M. Weinberg Distinguished Fellow in the Computational Sciences and Engineering Division before joining the Fluids and Thermal Sciences Group in the School of Engineering at Brown University in 2019. Jesse's research interests are at the intersection of applied mathematics, high-performance computing, and coupled fluid/particle/solute transport phenomena. His recent research has emphasized the manipulation of such coupled transport dynamics to manipulate suspended colloidal particles and biomaterials.