Mechanical and Civil Engineering Seminar

Mechanical and Civil Engineering Seminar Series

Title: "Compression-Driven Gas-Liquid Displacement"

Abstract: The gas-driven displacement of a viscous liquid from a confined geometry is a classical class of problems in interfacial fluid dynamics. This process also features in a variety of practical applications, including the operation of a fuel cell, the subsurface storage of carbon dioxide or hydrogen, and even the squeezing of ketchup out of a bottle. In all of these scenarios, the compression of the gas provides the driving force and the viscosity of the liquid provides the resistance. However, both the amount of compression and the amount of resistance are typically coupled to the amount of liquid that has been displaced. Here, we show that the tight coupling of these basic mechanical ingredients leads to surprising behavior, even in the simplest of settings. We study the impact of gas compression on gas-liquid displacement in capillary tubes and Hele-Shaw cells using laboratory experiments, minimal mathematical models, linear stability analysis, and fully nonlinear numerical simulations. We show that a steady rate of squeezing can generate a strongly unsteady flow and we identify a new dimensionless parameter, the compressibility number, that controls the evolution of the flow. We show that increasing the compressibility number can trigger a sudden flow transition in a capillary tube and can systematically delay the onset -- and decrease the ultimate severity -- of viscous fingering in a Hele-Shaw cell.

Bio: Chris is a Professor of Engineering Science at the University of Oxford. He is an engineer and applied scientist with an interest in physical mathematics, fluid and solid mechanics, and interfacial phenomena. His research group -- the Poromechanics Lab -- is an interdisciplinary team of engineers, physicists, mathematicians, and geoscientists who use modelling, simulation, and multi-scale experiments to study flow, transport, and deformation in porous media and other multiphase systems. Their work has applications in subsurface science and engineering, soft materials, and biology and medicine. Prior to joining Oxford in 2013, Chris earned his PhD in Mechanical Engineering from MIT and was then a Postdoctoral Fellow at Yale University.

NOTE: At this time, in-person Mechanical and Civil Engineering Lectures are open to all Caltech students/staff/faculty/visitors.