GALCIT Colloquium
Guggenheim 133 (Lees-Kubota Lecture Hall)
Microscale "Turbulence" induced by Electrochemical Interfaces
Ali Mani,
Assistant Professor of Mechanical Engineering,
Stanford,
Electrochemical interfaces, e.g., the interface of an aqueous electrolyte with a charge selective surface such as an electrode or a membrane, are host to a range of physical phenomena involving ion-‐transport, electrostatic interactions, and fluid flow. The equations governing these disciplines are the Nernst-‐Plank, Poisson, and Navier-‐Stokes, which have been well-‐established for more than a century. Analytical solutions to these equations have contributed to the understanding of various interfacial phenomena such as electric double layers, electro-‐osmosis, and diffusion boundary layers. However, only very recently direct numerical solutions to these equations became available. Such simulations allow investigation of nonlinear modes of transport, and have revealed a wide range of highly complex dynamical responses.
In this presentation, we consider voltage-‐driven ion transport from an aqueous electrolyte to an ion-‐selective membrane as a canonical setting to study fluid dynamic effects induced by ion transport near electrochemical interfaces. We will present results from our numerical
simulations demonstrating that beyond a threshold voltage such interfaces trigger hydrodynamic chaos with features similar to turbulent boundary layers despite their low Reynolds number. Structures with scales from sub-‐millimeter down to tens of nanometers can be formed
as a natural result of these hydrodynamic effects. These flow structures are shown to impact mixing and enhance net ion transport well beyond nominal diffusion-‐controlled processes.
While predictions of these simulations are consistent with recent experimental observations, simulations allow for non-‐intrusive capture of fine spatiotemporal details in these flows. We will demonstrate the need for the development of specialized algorithms for computation of
these systems similar to the tools that have been traditionally used for the simulations of turbulent flows. Such calculations require resolving a wide range of scales using unsteady solvers and often demand massively parallel computational resources. By presenting various
examples, we will discuss how the development of high-‐fidelity computational tools can lead to fundamental understanding of complex effects in electrochemical interfaces and facilitate their design and optimization.
For more information, please contact Mallory Neet by phone at 626-395-8026 or by email at [email protected].
Event Series
GALCIT Colloquium Series