Title:

Hydrodynamic Instabilities in Droplet Breakup at Extreme Conditions

Speaker:

Prof. Jacob McFarland

Affiliation:

Texas A&M University

When:

Thursday, September 26, 2024 at 3:00:00 PM   Add to Calendar

Where:

MRDC Building, Room 4211

Host:

Ellen Mazumdar
ellen.mazumdar@gatech.edu

Abstract

Droplet breakup is a complex process involving interfacial instability and transport across a wide range of length and time scales. Fundamental studies of shock-droplet interaction provide valuable insight into the physical processes behind droplet breakup at high Weber and Reynolds numbers. Many high-speed applications such as liquid-fueled detonations and hypersonic hydrometeor impacts involve small droplets under high Weber numbers and unsteady conditions. Kevin-Helmholtz, Rayleigh-Taylor, and other hydrodynamic instabilities evolve through temporally varying conditions to break down the droplet rapidly. Droplet breakup reduces the equilibration time and is closely coupled to evaporation rates. These effects challenge our current computational capabilities, as they require additional models, simulation methods, and experimental validation. The ability to predict these systems, though, is essential to our national defense, and to enhancing our understanding of our universe. This talk will explore the deformation and hydrodynamics leading to breakup for small droplets (< 200 micrometers) at high Weber numbers (> 1000). High-speed (> 1 MHz) shadowgraphy provides measurement of the droplet deformation rate, acceleration, and breakup timing. The deformation rates, acceleration, and breakup times are compared with existing models, and new models for unsteady breakup conditions.

Biography

Jacob McFarland is an associate professor in the J. Mike Walker Department of Mechanical Engineering at Texas A&M University. He has worked with Lawrence Livermore, and Los Alamos National Laboratories, as well as with the Air Force Research Laboratory and Naval Research Laboratory on shock-driven multiphase flow modeling. He received an NSF CAREER award in 2019 for his work on shock-driven multiphase instabilities and a Young Investigator Award from the ONR in 2020 to study droplet breakup in multiphase detonations. His current research interests are in shock-driven multiphase mixing, droplet breakup, multiphase detonations, and ejecta reaction modeling.