Abstract

The financial and environmental cost of turbulence is staggering: manage to quell turbulence in the thin boundary layers on the surface of a commercial airliner and you could almost halve the total aerodynamic drag, dramatically cutting fuel burn, emissions and cost of operation. Yet systems-level tools to model scale interactions or control turbulence remain relatively under-developed. Resolvent analysis for turbulent flow provides a simple, but rigorous, approach by which to deconstruct the full turbulence field into a linear combination of modes which interact through the nonlinear term. In this talk, resolvent analysis is used to explore the influence of passive and active control techniques on turbulence structure.  Model results obtained using desktop computing power are compared with direct numerical simulation and complex experiments, highlighting the utility of resolvent analysis as a design tool for schemes to control wall turbulence, and the dramatic reduction in complexity associated with sparsity and low-rank behavior in the resolvent. We close with a brief discussion of the potential to exploit these findings to create turbulence with specified, or “designer” properties.

The support of the U.S. Air Force Office of Scientific Research under grant FA 9550-16-1-0361 and the U.S. Office of Naval Research under grant N00014-17-1-2307 is gratefully acknowledged.

Beverley McKeon is Theodore von Karman Professor of Aeronautics at the Graduate Aerospace Laboratories at Caltech (GALCIT). Her research interests include interdisciplinary approaches to manipulation of boundary layer flows using morphing surfaces, fundamental investigations of wall turbulence at high Reynolds number, the development of resolvent analysis for modeling turbulent flows, and assimilation of experimental data for efficient low-order flow modeling. She was the recipient of a Vannevar Bush Faculty Fellowship from the DoD in 2017, the Presidential Early Career Award (PECASE) in 2009 and an NSF CAREER Award in 2008, and is an APS Fellow and AIAA Associate Fellow. She is the past editor-in-chief of Experimental Thermal and Fluid Science and currently serves as an associate editor of Physical Review Fluids, and on the editorial boards of the AIAA J., Annual Review of Fluid Mechanics and Experiments in Fluids. She is the APS representative and Vice Chair of the US National Committee on Theoretical and Applied Mechanics.