Jacqueline O'Connor

Professor, Department of Mechanical Engineering
Pennsylvania State University

Use of information networks for understanding hydrodynamic instability on complex wake flows

August 27, 2026

Hydrodynamic instability drives the performance and operability of a number of aerospace systems, including aircraft, rotorcraft, and propulsion systems. Identifying the source of the instability and its dynamics in complex configurations is challenging, particularly in highly turbulent, three-dimensional environments. In this talk, we'll explore the use of information network theory for identifying the critical regions of unstable flows. We apply these methods to wake flows, both single- and multi-wake systems, to explore opportunities for better insight into complex flow behaviors.

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Dr. Jacqueline O'Connor is a professor of mechanical engineering at Penn State and directs the Reacting Flow Dynamics Laboratory. She and her students study issues related to combustor operability, alternative fuels, and high-temperature material durability and heat transfer for power and propulsion applications. She received a B.S. from MIT and an M.S. and Ph.D. from Georgia Tech. She was a post-doctoral researcher at Sandia National Laboratories before starting at Penn State in 2013. She is a fellow of the American Society of Mechanical Engineers and an associate fellow of the American Institute of Aeronautics and Astronautics.

Aditya Nair

Associate Professor, Department of Mechanical Engineering
University of Nevada, Reno

Data-driven approaches for simulation, modeling and control of unsteady fluid flows

September 3, 2026

Unsteady flows are expensive to simulate and hard to control. But their dynamics are rarely spread evenly. The physics that matters concentrates in a few regions of space and a few moments in time. This talk presents a suite of data-driven strategies built on that premise.

In space, dominant balance analysis locates where the governing physics is active. An adaptive mesh refinement framework uses this to allocate resolution where it is needed, cutting cost without sacrificing accuracy. Force and moment partitioning offers the complementary view, attributing unsteady loads to the specific vortical structures that generate them.

In time, spectral POD with triadic interaction mapping reveals how energy transfer between scales is regulated by modal amplitude. Phase-amplitude reductions identify when an oscillatory flow is most receptive to actuation. Cluster-based latent control coarse-grains the dynamics into transitions among representative states, and acts on those states directly in a learned latent space, with no model of the full system required.

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Dr. Aditya G. Nair is an Associate Professor in the Department of Mechanical Engineering at the University of Nevada, Reno. His research interests are in the areas of computational fluid dynamics, high-performance computing, data science, and control theory focused on modeling and control of unsteady fluid flows. He received his M.S. from University of Michigan in 2013 and Ph.D. from Florida State University in 2018. Dr. Nair is the recipient of the Department of Energy Early Career Award in 2022, AFOSR DEPSCoR award in 2023 and is a founding member of the NSF AI institute of Dynamic Systems.

Christoph Brehm

Associate Professor, Department of Aerospace Engineering
University of Maryland, College Park

Hypersonic droplet impact: From aerobreakup to damage

September 10, 2026

High-speed vehicles operating at low altitudes are often exposed to adverse weather conditions such as rain, hail, and snow, giving rise to complex multiphase flow interactions that can compromise structural integrity. Accurate numerical prediction of droplet aerobreakup and impact under hypersonic conditions remains highly challenging because of the broad range of coupled physical phenomena involved, including high Reynolds number and high Weber number breakup, shock–droplet interactions, gas–liquid–solid phase change, dispersed-phase dynamics, and fully-coupled fluid–structure interaction. This presentation highlights recent advances in high-speed multiphase-flow modeling aimed at capturing these mechanisms with improved fidelity and providing deeper physical insight. After introducing key aspects of the numerical methods used in this work, the talk examines several fundamental processes in detail, including droplet aerobreakup in high-speed environments, droplet mass-loss behavior, scaling relations relevant to integrated load predictions, and the role of phase change. In addition, velocity disequilibrium is proposed as a central mechanism underlying the splashing dynamics observed during droplet impingement. The second part of the presentation focuses on fluid–structure interaction modeling for predicting material damage caused by droplet impact. Under hypervelocity impact conditions, strong coupling effects can become significant and must be modeled accurately. Numerical predictions are validated against recent end-to-end experiments, capturing the full droplet history and fully-coupled impact dynamics, and yielding new insight into the mechanisms that drive material damage.

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Dr. Christoph Brehm is an Associate Professor of Aerospace Engineering at the University of Maryland, College Park. Before entering academia, he was a principal developer of NASA's Launch Ascent and Vehicle Aerodynamics framework (LAVA), work that was recognized with multiple NASA individual and group achievement awards. His research focuses on hypersonics, multiphysics modeling, and high-performance scientific computing, with interests spanning laminar–turbulent transition, ramjet and scramjet simulation, ablation and high-temperature aerothermodynamics, multiphase flows, fluid–structure interaction, impact physics, and flow control using metamaterials. He has authored over 150 peer-reviewed journal and conference publications in these areas. Professor Brehm serves on several national working groups on hypersonic transition and turbulence modeling and leads a NATO study group on boundary-layer transition and ablation effects as part of AVT-346 receiving the Panel Excellent Award 2026 awarded by the NATO Science & Technology Board. He is the recipient of both the NSF CAREER Award (2021) and the Office of Naval Research Young Investigator Award (2019). In 2023, he co-founded Whoosh HPC Lab, a startup developing GPU-accelerated digital engineering software ranging from rapid design tools to large-scale, high-fidelity multiphysics simulation.