Anatol Roshko Lecture in Aerospace

Date: Friday, October 1, 2010 3:00 PM - 4:00 PM
Location: 101 Guggenheim Lab, Lees-Kubota Lecture Hall
Reception to follow in Dabney Gardens
Speaker: Professor Garry Brown, Robert Porter Patterson Professor Mechanical and Aerospace Engineering, Princeton University

This lecture is given in honor of Dr. Anatol Roshko, Theodore von Kármán Professor of Aeronautics, Emeritus, a faculty member of GALCIT from 1952. He made pioneering contributions towards shock-tube technology, bluff-body aerodynamics and organized vortical structure in turbulent shear flows.

The Anatol Roshko Lecture in Aerospace is made possible through a generous gift from Caltech alumni Drs. Jain-Ming (James) Wu (MS'59, PhD'65 Ae) and Ying-Chu Lin (Susan) Wu (PhD'63 Ae) who carried out their doctoral research in GALCIT. Through this lecture they honor a professor who has made significant impact in their lives.

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Structure and Vorticity in Turbulent Shear Flow

Turbulent shear flow has a long history. Leonardo da Vinci (1500) commented “…the small eddies are almost numberless, and large things are rotated by large eddies and not by small ones, and small things are turned by both small eddies and large...”. In the twentieth century Prandtl, Taylor and Karman, who pioneered attempts to predict Reynolds stress in turbulent shear flow, all had ideas about structure and ‘eddies’. Turbulent shear flows separate broadly into free turbulent shear flows and wall–bound turbulent shear flows. The long history of the ‘turbulence problem’ can be partly explained by the central role of structure, or of the unsteady vorticity, and the hope (it now seems unrealizable) for some single universality in the way this structure is connected with the Reynolds stress in these two classes of turbulent shear flow. The lecture traces some of this history including the seminal work that provided observations of structure in the ‘simplest’ flows of both cases. The measurement of the unsteady vorticity field is particularly difficult but advances in CFD have provided new opportunities to illuminate this structure. Experimental and CFD results are discussed which show the quite different characteristics of this vorticity field for the two classes of turbulent shear flow and the very different instabilities that contribute to vorticity transport and Reynolds stress. Advances in ‘understanding’ these characteristics and mechanisms not only answer basic questions but offer opportunity for a measure of control and practical exploitation.

Garry Brown

Princeton University
Garry Brown

Garry Brown is Robert Porter Patterson Professor of Engineering at Princeton University. He received a first class Honors Degree in Engineering from the University of Adelaide in 1964, was awarded a Rhodes scholarship, completed his D.Phil at Oxford and was then a research fellow/senior research fellow at GALCIT. In 1971 he returned to the University of Adelaide and in 1978 returned to Caltech as full professor. He was asked to serve as Director of the Australian Aeronautical Research Laboratory and held this position from 1981-1990 after which he joined the faculty at Princeton, serving as Chair of the Department of Mechanical and Aerospace Engineering from 1990 to 1998. His best known work is in the study of turbulence. Fifty years after the inception of the Journal of Fluid Mechanics, his 1974 paper with Professor Roshko “On density effects and large structure in turbulent mixing layers,” was the most frequently cited paper in the history of the journal. Since joining Princeton he has explored new research horizons while continuing his abiding interest in turbulence. He has also made significant contributions, as a consultant to the American aerospace industry, that include the root cause of failure and redesign of the solid rocket motor for the Titan IV, the cause of early failure and development of the thrust-vectoring system for AIM-9X and the resolution of critical issues for Tactical Tomahawk and for the Standard Missile-3 Programs. He is a Fellow of the Institution of Engineers of Australia, Fellow of the American Physical Society, and a Fellow of the AIAA.