Events Calendar

Laufer Lecture Series

Speaker: Patrick Huerre, Professor of Mechanical Polytechnic, Director of Research at the National Centre for Scientific Research, and Head of the Laboratory of Hydrodynamics (LadHyX), UMR CNRS-School Polytechnic

Talk Title: AMPLIFIERS AND OSCILLATORS: A HYDRODYNAMIC STABILITY PERSPECTIVE

Series: Laufer Lecture Series

Abstract: Complex flows of interest in aeronautical applications may often be considered as involving a combination of simpler prototypical free shear flows such as mixing layers, wakes, jets, etc. which prevail in different spatial subdomains. Such archetypical shear flows are in a turbulent state but they are known to exhibit large-scale vortical structures which dominate the dynamics up to very large Reynolds numbers. Experimental observations indicate that some flows are extrinsic amplifiers of external noise while others are intrinsic oscillators which beat at a specific frequency. In this lecture, such structures will be described as instablity waves living on a suitable mean flow. Hydrodynamic stability concepts such as convective/absolute instability, local/ global instability, will then be shown to account for the extrinsic or intrinsic spatio-temporal dynamics of coherent structures in several shear flows. The classical locally parallel asymptotic analyses and the more recently developed fully non-parallel numerical approaches will be critically assessed.

Biography: Professor Patrick Huerre received his Ingénieur’s degree from Ecole Centrale Paris in 1970 and his PhD in Aeronautical Sciences from Stanford University in 1976. After postdoctoral work at the University of Leeds with the late Professor David Crighton, he joined the faculty of the department of Aerospace Engineering at the University of Southern California (USC) in 1978. In 1989 he was appointed Professor of Mechanics at Ecole Polytechnique. Since 1991, he has also been Director of Research at the French National Center for Scientific Research (CNRS). Patrick Huerre was the founder and director of the Hydrodynamics Laboratory (LadHyX) at Ecole Polytechnique in the period 1990-2008. Patrick Huerre is President of the European Mechanics Society. He was Associate-Editor of the Journal of Fluid Mechanics (1999-2009). He has served on several committees and panels in Europe and in the United States.
Patrick Huerre is a member of the Académie des Sciences and a Fellow of the American Physical Society. He is Chevalier de la Légion d’Honneur. His research areas of interest cover a wide variety of hydrodynamic instabilities and transition phenomena in shear flows. His main research achievements include the effective use of absolute/convective instability concepts to rigorously distinguish between amplifiers and oscillators in fluid mechanics, the introduction of the notions of linear and nonlinear global mode and associated frequency selection criteria to account for the dynamics of oscillators and the identification of super-directivity as a key mechanism for the production of sound in shear flows.

Host: Dr. Geoff Spedding

More Info: http://ae-www.usc.edu/seminars/11-14-12-huerre.shtml

Location: Edward L. Doheny Jr. Memorial Library (DML) - Room 240

Audiences: Everyone Is Invited

Contact: April Mundy

Event Link: http://ae-www.usc.edu/seminars/11-14-12-huerre.shtml