CIMMS Lunchtime Series: Progress toward efficient viscous simulation of flapping, deforming wings for investigations of flying and swimming

Dr. Jeff D. Eldredge
Mechanical and Aerospace Engineering Department
University of California, Los Angeles

Biological applications of flying and swimming provide lofty and exciting challenges for computational fluid dynamics. A hovering dragonfly, for example, flaps its two pairs of flexible wings in an intricate interplay of three-dimensional kinematics, adding momentum to the surrounding air at just the right rate to keep itself aloft with astounding precision.

This talk will discuss ongoing work with the Viscous Vortex Particle Method for solving problems with moving, deforming boundaries, using the paradigm of insect flight as a measuring stick with which to measure our progress. This Lagrangian numerical method is especially well suited for this class of problems, because complicated moving boundaries present little more difficulty than posed by fixed ones. As Lighthill described, vorticity is diffused from the wing surface into the surrounding fluid in just the right measure to enforce the no-slip condition. Furthermore, by focusing computational resources on vorticity, from the moment of its birth on the wing surface to its shedding into the wake, a physically enlightening and computationally efficient simulation tool is realized.

I will present our results of the two-dimensional flapping of a rigid elliptical wing (both single and in pairs). Then I will discuss the extension to deforming surfaces, and other future directions.