Nonlinear mechanisms of wall-bounded turbulent flow
California Institute of Technology
Abstract
In this talk, I will discuss the nonlinear interaction in the self-sustaining process of wall-bounded turbulence. Resolvent analysis is used to identify the principal forcing (nonlinear) mode which produces the maximum amplification in direct numerical simulations of the minimal channel for the buffer layer. The identified mode is then removed from the nonlinear term of the Navier–Stokes equations at each time step from a direct numerical simulation of a minimal channel. The results show that the removal of the principal forcing mode is able to inhibit turbulence in the buffer layer, while the removal of subsequent modes only marginally affects the flow. Analysis of the dyadic interactions in the nonlinear term shows that contributions toward the principal forcing mode come from a limited number of wavenumber interactions. Using conditional averaging, the flow structures that are responsible for generating the principal forcing mode, and thus the nonlinear interaction to self-sustain turbulence, are identified to be spanwise rolls interacting with meandering streaks. Finally, I will introduce an extension to resolvent analysis for non-stationary flow.
About the speaker
Dr. Jane Bae is an Assistant Professor of Aerospace at the Graduate Aerospace Laboratories at Caltech. She received her Ph.D. in Computational and Mathematical Engineering from Stanford University in 2018. She was a postdoctoral fellow in the Graduate Aerospace Laboratories at Caltech and the Institute for Applied Computational Science at Harvard University before joining the Caltech faculty. Her main research focuses on computational fluid mechanics with emphasis on modeling and control of wall-bounded turbulence.
