UTA Department of Mathematics

Applied Mathematics Seminar

Date/Time/Room: Friday (10/17/2003) at 2:00pm in 304 Pickard Hall

Speaker: Meelan Choudhari, NASA Langley Research Center, Hampton, VA

"Integrated Transition Prediction: A Case Study in Supersonic Laminar Flow Control"

Abstract: Laminar flow control (LFC) is one of the key enabling technologies for quiet and efficient supersonic aircraft. A novel concept for passive LFC on cross-flow dominated flow configurations (developed recently by researchers at the Arizona State University) employs distributed leading-edge roughness to limit the growth of naturally dominant instabilities that would otherwise lead to an earlier onset of transition. LFC technology development under DARPA's Quiet Supersonic Platform (QSP) and NASA's Supersonic Vehicle Technology (SVT) programs includes wind tunnel and flight experiments that are aimed at further development of this concept at close to full-scale Reynolds numbers. Companion theoretical studies at NASA Langley Research Center seek to provide the physical understanding necessary to optimize roughness based LFC, and to develop physics based transition prediction capability for this and other LFC configurations. An overview of these studies is presented, with particular emphasis on a pair of swept-airfoil configurations derived from wind-tunnel experiments at low through intermediate Reynolds numbers. The findings are used to advocate a holistic approach for transition prediction, which accounts for all major stages within transition (namely, receptivity, linear growth, nonlinear interactions and secondary instability) in an integrated manner. We will also discuss intrinsic challenges in the practical implementation of this holistic approach and potential ways to overcome those challenges.