IGM Colloquium: Bursting bubbles and the search for the smallest jet droplet

When a bubble bursts at an interface, the capillary waves create an intriguing cusp, which is responsible for an upward jet that can break into droplets. This jet drop phenomena has been studied for over 60 years and is relevant to a variety of topics including the transport of respiratory pathogens and cloud-forming marine aerosols. Yet, several fundamental questions remain, including the physics that sets the size of the smallest jet droplets.
This talk explores the dynamics of jet drop formation through a combination of experiments and theory.  The first part of this talk addresses how gravity and viscosity can inhibit jet drop production. The dominant role of gravity appears to be its role in the setting the bubble shape. The second part of the talk explores the size of the smallest aerosols produced. Microfluidic experiments, dynamic similitude, and numerical simulations collectively reveal a mechanism in which viscous stresses – both before and after the jet forms – sets the size of these microscopic droplets.

Bio:
James Bird is an Assistant Professor in the Department of Mechanical Engineering at Boston University.  He received his B.S. from Brown University and his Ph.D. from Harvard University, after which he completed an NSF Mathematical Science Postdoctoral Fellowship at MIT.  His research focuses on interfacial fluid dynamics with an emphasis on the dynamics of drops and bubbles.  He is the recipient of a Fulbright Fellowship (2004), an NSF CAREER award (2014), and an ONR YIP award (2016).