When a massive star runs out of fuel, it collapses under its own weight. The ensuing explosion, called a supernova, sends shock waves through the layers of the dying star. On a much smaller scale, similar shocks are used to compress layers of hydrogen to initiate a nuclear reaction in inertial confinement fusion. These shocks stimulate the formation of vortices, regions of rapid rotation, between layers. Vortex rings, vortices that form a closed loop, can then emerge, transporting mass, momentum, and energy from one layer deep into another. This transport governs the composition of galaxies following supernovae and its mitigation is critical to inertial fusion. Our approach combines theory, simulations, and experiments to determine how these vortex rings form and behave.

Supernova 1987A is the first supernova visible to the naked eye since Kepler's Supernova in 1604. Its recency and proximity to Earth make it one of the most important astrophysical systems shaping our understanding of stellar evolution. Many outstanding mysteries surround Supernova 1987A, including the clumpy ring of gas surrounding the location of the blast. We are working to understand the initial formation of the clumps using the same fluid mechanics that emerge in the wakes of airplanes. Other astrophysical systems, including our early solar system, may be governed by similar dynamics which lead to the formation of planets.

Vortices, interconnected regions in a fluid where rotation plays a significant dynamical role, are fundamental building blocks of complex flows. Understanding the practically intractable number of interactions between vortices in flows spanning a wide range of spatial scales is among the most fundamental goals of fluid mechanics. For the long-foreseeable future, directly calculating all of these interactions is infeasible, and engineering applications therefore rely on models to capture the fundamental behavior of small-scale vortices. To study these flow physics, we focus on isolating the mechanisms governing just two interacting vortices, known as a vortex pair. This framework enables the generation of arbitrary systems of vortex pairs in both experiments and computation, providing previously unattainable measurements of specific instability mechanisms.

Whenever pressure and density gradients are misaligned at fluid interfaces, mixing ensues. This scenario emerges naturally in astrophysical applications, including supernovae, and in many engineering contexts, where the mixing can either be beneficial, like enhanced reactant mixing in hypersonic combustion engines, or detrimental, like the mixing of fusion fuel with cold material that quenches thermonuclear burn. Either way, a deep understanding of this mixing is essential for understanding nature and advancing engineering. Our approach is to leverage knowledge from classical fluid mechanics, including vortex dynamics, to better characterize and ultimately control the interfacial mixing that sets the pace for progress in hypersonic flight and nuclear fusion.