MAE Affiliate Seminar – Fundamentals and Applications of Diffusiophoresis: Particle Motion Induced by Solute C

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Fundamentals and Applications of Diffusiophoresis: Particle Motion Induced by Solute Concentration Gradients

Thursday, April 6, 2023, at 12:50 pm
Location: In-Person MAE-A, Room 303

Henry C.W. Chu, PhD
Assistant Professor, Department of Chemical Engineering, University of Florida

Abstract
Diffusiophoresis refers to the deterministic motion of particles induced by a surrounding concentration gradient of solute. Diffusiophoresis has received much attention in recent years for its ability to manipulate colloid transport in a wide range of applications, including mixing and separation of colloids, enhanced oil recovery, drug delivery, to water and surface cleaning. In this talk, I present three projects in my group concerning the fundamentals and applications of diffusiophoresis. In the first project, the motivation is an ongoing challenge of predicting the transport of diffusiophoretic colloids in hydrodynamic flows. I present our Taylor-dispersion-like macro transport framework for predicting the transport of a diffusiophoretic colloidal species under a steady pressure-driven flow and transient solute gradient. In addition to its accuracy, our macro transport equation requires O(103) times less computational runtime than the direct numerical solution of the original, two/three-dimensional advection-diffusion equations. In the second project, we examine the unidirectional drying of a colloidal suspension for manufacturing colloidal films, where the role of diffusiophoresis is unexplored to date when coupled with gravity. I present our direct numerical simulations of the advective-diffusive transport of an electrolyte-colloid suspension in a unidirectional drying cell under gravity and diffusiophoresis. Our results show new scalings for the growth of the colloidal layer, where the layer produced with diffusiophoretic colloids could be an order of magnitude thicker than with non-diffusiophoretic colloids. In the third project, recent experiments demonstrated diffusiophoresis in porous media, but existing theories cannot predict colloid motion. We open a new area of research by developing a foundational mathematical model that can predict colloid diffusiophoresis in porous media. A comparison between our model predictions and experiments demonstrates excellent agreement. Our model will motivate future work and could be used to benchmark future experiments.

Biography
Dr. Henry Chu is an Assistant Professor in the Department of Chemical Engineering at the University of Florida (UF). He obtained an M.Phil. in Mechanical Engineering from The University of Hong Kong (HKU) in 2012 under the supervision of Professors Chiu-On Ng and Kwok-Wing Chow. He earned a Ph.D. in Mechanical Engineering from Cornell University in 2017 under the supervision of Professor Roseanna Zia. Following his Ph.D., he was a Postdoctoral Fellow in Chemical Engineering at Carnegie Mellon University, working with Professors Aditya Khair, Robert Tilton, and Stephen Garoff. In 2021, he joined UF. The theme of his research is heterogeneous soft matter transport and design, covering topics such as complex fluid dynamics, colloid, and interface science, electrokinetics, and rheology. His research develops predictive multi-scale computational tools and fundamental theory to address emerging National Academy of Engineering Grand Challenges for Engineering in these research areas, emphasizing close collaboration with experimental groups to translate knowledge into applications. His work has been recognized through several awards, including the Clyde W. Mason Scholarship (Cornell), Research Travel Grant Award (Cornell), Student Member Travel Award (American Institute of Physics), Global Faculty Fellowship (UF), and Soft Matter Emerging Investigator (The Royal Society of Chemistry). Dr. Chu welcomes collaboration with academia, government agencies, and industry sponsors.

MAE Faculty Host: TBD