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Attached eddies in turbulent channel flow: scale interactions and spectral energy transfer

Event Type: 
Date and Time: 
Friday, October 25, 2019 - 16:30
Location: 
CTR Conference Room 103
Event Sponsor: 
Parviz Moin, Director of Center for Turbulence Research
Speaker(s): 
Dr. Hyun Ji (Jane) Bae

The resolvent formulation of McKeon & Sharma (2010) is applied to supersonic turbulent boundary layer flows in order to study the validity of Morkovin’s hypothesis, which postulates that high-speed turbulence structure in zero pressure-gradient turbulent boundary layers remains largely the same as its incompressible counterpart. The resolvent analysis highlights two distinct regions of the supersonic turbulent boundary layer in the wave parameter space: the relatively supersonic region and the relatively subsonic region. The relatively supersonic region, where the flow is supersonic relative to the freestream, contains resolvent modes that display structures consistent with the eddy Mach wave radiation that are absent in the incompressible regime. In the relatively subsonic region, the low-rank approximation of the resolvent operator is effective and the model exhibits a universal and geometrically self-similar behavior via a transformation given by the semi-local scaling. Moreover, with the semi-local scaling, the resolvent modes follow the same scaling law as its incompressible counterparts in this region, which has implications for modeling and the prediction of turbulent high-speed wall-bounded flows.

Bio: 
Dr. Hyun Ji Bae is a postdoctoral scholar at the Department of Aerospace at Caltech. She received her Ph.D. from Stanford University in 2018 in Computational and Mathematical Engineering. Her main research focuses on computational fluid mechanics, in particular on modeling, understanding, and control of wall-bounded turbulence using reduced order modeling.