When
Thursday, November 5, 2026, at 4:00 p.m.
Jacob McFarland
Associate Professor
Department of Mechanical Engineering
Texas A&M University
"Modeling Droplet Breakup for Hypersonic Hydrometeor Impacts"
AME S212 | Zoom link
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. Hypersonic vehicles encounter atmospheric droplets which can result in damage and disrupt vehicle aerodynamics. The vehicle bow shock helps to breakup and evaporate these droplets before impact, but predicting these processes is complicated by the highly unsteady conditions. Breakup occurs through Kevin-Helmholtz, Rayleigh-Taylor, and other hydrodynamic instabilities which evolve through temporally varying conditions. Droplet breakup reduces the equilibration time and accelerates 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 for high-speed aviation and to enhancing our understanding of our universe.
This talk will explore the breakup for droplets at high Weber numbers 1000) from a complex (shock and expansion wave) acceleration. High-speed (>100kHz) shadowgraphy and laser induced fluorescence (LIF) imaging provide measurements of the droplet deformation rate, acceleration and growth of hydrodynamic modes. The deformation rates and acceleration are compared between measurement techniques and with existing models. Hydrodynamic features are measured from LIF imaging and compared with available theories. A new model for hydrodynamic breakup in unsteady accelerations is presented.
Bio: Jacob McFarland is an associate professor and J. Mike Walker '66 Faculty Fellow in the 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 and Naval Research Laboratories 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. He received the Joint Center for Resilient National Security Faculty Fellowship in 2022. His current research interests are in shock-driven reactive mixing, droplet breakup, multiphase detonations and ejecta modeling.