Computer Science Colloquium

Aeroelastic systems are those that involve the coupled interaction between a convecting fluid and a flexible elastic structure. The nonlinear dynamical response of such systems is of great current interest.Currently operational aircraft are known to encounter limit cycle oscillations (LCO) in certain flight regimes and relatively simple experimental wind tunnel models have been designed to exhibit LCO as well. The LCO may either be favorable or dangerous for the safety of the aircraft.The results of several wind tunnel experiments are discussed along with comparable results from mathematical models.The physical models include (1) an airfoil with a control including free-play; (2) a delta wing with elastic geometrical nonlinearities due to plate-like deformations and (3) a high aspect ratio wing with geometrical nonlinearities due to coupling among torsional twist, transverse bending and fore-and-aft bending. The advantages of representing the unsteady aerodynamic flow field in terms of global modes for the theoretical studies are emphasized. A recent theoretical result for modeling the nonlinear effects of large shock motions in the transonic flow around an oscillating airfoil is presented to illustrate the advantages of this approach.

Earl Dowell, a leading authority in the fields of aeroelasticity and structural dynamics, is a recipient of the major research award in his field, the American Institute of Aeronautics and Astronautics Structures, Structural Dynamics and Materials Award. He is a Fellow of the American Academy of Mechanics, the American Institute of Aeronautics and Astronautics, and the American Society of Mechanical Engineers. He has also served as Vice President, Publications and member of the Executive Committee of the Board of Directors of the AIAA, as a member of the United States Air Force Scientific Advisory Board, the Office of Naval Research Board of Visitors, and as a member of the AGARD (NATO) advisory panel for aerospace engineering. He is an elected member of the National Academy of Engineering.

In addition to being author of over two hundred research articles, Dr. Dowell is the author or co-author of three books, "Aeroelasticity of Plates and Shells", "A Modern Course in Aeroelasticity", and "Studies in Nonlinear Aeroelasticity". His teaching and research interests span the component disciplines of acoustics, aerodynamics and structural dynamics. He has been a consultant to local, state and federal government and industry.

A native of Illinois, Dr. Dowell received his B.S. degree from the University of Illinois and his S.M. and Sc.D. degrees from the Massachusetts Institute of Technology. Before coming to Duke as Dean of the School of Engineering, he taught at M.I.T. and Princeton. He has also worked with the Boeing Company.