SOFIA is part of the Mechanical & Aerospace Engineering Department at the University of California, Los Angeles. We are interested in exploring a wide variety of phenomena that occur in fluid flows in nature and technology. The members of our group are investigating such topics as

• The aerodynamics of insect flight.
• Novel techniques for aerodynamic control in next-generation aircraft.
• Fundamental processes of sound generation in jet exhausts.
• Strategies for control of an unstable gas turbine combustor for cleaner and more efficient energy conversion.

Though these topics are superficially diverse, they have an essential unifying principle: they are all unsteady flow phenomena. For example, insects generate lift and thrust by the unsteady production of vorticity—the local rotation of the fluid—at the edges of its wings. An insect has an amazing mastery of its medium that we are only beginning to understand. By concentrating on the tools that natural selection has endowed, then perhaps we can develop new ideas for controlling aircraft!

Sound is also an unsteady process—often, an undesirable one—and we are interested in how it is produced (and just as importantly, ways it can be removed) by fluid flows. The exhaust of a jet engine is a highly turbulent flow that is a major culprit in the noise produced by an airplane. By examining the fundamental mechanisms that are responsible for this sound, then we may find new opportunities for making it less of a nuisance. Sound is also responsible for creating large, potentially damaging oscillations in industrial gas turbines because of their coupling with combustion. We are developing innovative ideas to remove acoustic energy from these systems, so that they can operate in the cleanest, most efficient mode possible.

In most of these projects, we primarily rely on computational simulation to provide answers to our questions. However, it is essential to complement this with physical investigations, and for this we build simple proof-of-concept experiments or collaborate with other research groups.