MEMS Seminar: Turbulence and Energetic Reactive Flows

The most complex and difficult problems in fluid dynamics involve transitions among what seem to be relatively stable states. In turn, one of the most complex and intriguing sequences of fluid transitions is the series of changes in the behavior of an energetic reactive flow that occurs as a small spark, often ignited quite accidentally, evolves into a powerful supersonic wave, a detonation. These reactive-flow transitions are critical elements in the working of systems ranging from engines for propulsion, to accidental fuel explosions, to explosions of thermonuclear supernova, and arguably to the primal explosion that created the universe. This presentation will use results from a combination of numerical simulations of unsteady, multidimensional, compressible reactive flows, theoretical analyses, laboratory experiments, and even devastating large-scale accidents in an attempt to determine when and how such transitions occur. The emphasis is on interactions of shocks and turbulence when energy is released locally into the fluid system. If time allows, a very different kind of transition will be described, one that proceeds from a fire whirl (a turbulent vortical reacting structure similar to a tornado) to an essentially laminar, newly discovered state, the "blue whirl."
Lunch will be served from 11:30 -am - 12:00 noon. https://mems.duke.edu/about/events/seminars