Jie Feng, Department of Chemical and Biological Engineering Princeton University
601 Pao Yue-Kong Library
Bubbles are fundamentally important in many natural processes and in a host of industrial and man-related activities. In particular, bubble-bursting plays a key role in many cross-interface phenomena. Previous studies of bubbles bursting at a water-air interface investigate how the bursting dynamics lead to mass transfer from the lower liquid phase to the upper gas phase. Here we describe the reverse transport process, where submicrometer oil droplets, formed during bubbles bursting at a water-oil-air interface are transported from the upper to the lower phase. The dispersal results from the detachment of an oil spray from the bubble boundary when the bubble collapses, and the droplet size is set by physicochemical interactions between oil and surfactants. The unrecognized role of this dispersal mechanism for environmental remediation processes is demonstrated. This dispersant system provides an energy-efficient platform, with potential upscalability, for applications in nanomaterials engineering. Furthermore, several hydrodynamic questions inspired by such a multi-phase configuration will be discussed. In the observation for dynamics of bubbles bursting at the compound interface, the oil and water films rupture separately. We present a theoretical model for such a two-layer system that provides predictions for the separated or simultaneous rupture. Additionally, we show the dynamics of the oil rim that forms when an oil film dewets in a pseudo-partial wetting state on an aqueous substrate. Remarkably, the rim around the expanding hole displays an instability which leads to the rim break-up into a series of humps, which resembles a garden of “interfacial flowers”. The critical conditions at which humps form are theoretically quantified and validated by experiments.
Jie Feng is a Postdoctoral Research Associate in the Department of Chemical & Biological Engineering at Princeton University. He received his Ph.D. in Mechanical & Aerospace Engineering from Princeton University. Jie’s primary research focuses on the fundamental understandings of interfacial transport phenomena in multi-phase flows, with a goal is to develop innovative platforms of materials engineering for revolutionary solutions in some of today’s most challenging problems, such as the environment and human health. Currently, his research includes interfacial mixing for multi-functional nanocluster assembly, structured microparticle generation and sorting using microfluidics, thin-film dynamics and instability and complex material characterizations using laser spectroscopy. Jie’s research has led to over 14 publications in major scientific journals, such as Nature Physics, Advanced Materials, Journal of Fluid Mechanics, Experiments in Fluids and Langmuir. He has received the Wu Prize for Excellence and Wallace Memorial Honorific Fellowship for displaying highest scholarly excellence from Princeton University.