118th NIA CFD Seminar: Distributed Vortex-Wave Interaction Arrays and Turbulent Shear Flows
Speaker: Philip Hall, NIA Visitor
Date: Monday, August 5, 2019
Location: NIA, Room 137
Host: Mujeeb Malik, NASA/LaRC
High Reynolds number descriptions of nonlinear exact coherent structures in shear flows are discussed using a combination of asymptotic and numerical methods. Such states have been previously shown to describe: a) Bypass transition and b) Near wall streaks in developed and boundary layer turbulent shear flows.
Here we discuss the more general relevance of arrays of vortex-wave interactions to turbulent shear flows. The mean flow associated with such arrays is driven by the local interaction of waves, rolls and streaks and the slow dynamics of the interaction gives equations to determine the mean flow and the variation of the dominant energy-carrying wavenumbers. The approach leads to evolution equations which can be viewed as explicit closure models related to turbulence modeling. The arrays predict many of the classical properties of turbulent shear flows such as uniform momentum zones and self-similarity. The relevance of the approach to Townsend’s attached eddy hypothesis and the law of the wall is discussed.
Philip did his undergraduate and graduate work at Imperial College, London. His research in Applied Mathematics concentrates on nonlinear hydrodynamic stability theory, computational fluid dynamics, boundary layer control, convection, lubrication theory, chaotic fluid motion, geomorphology of rivers, coherent structures in high Reynolds number flows. In 2014, he became Head of the School of Mathematics at Monash University, Melbourne, Australia. And prior to that appointment, he was Professor of Applied Mathematics at Imperial College as well as Head of Mathematics and Director of Institute of Mathematics and Director of LFC-UK during his time there.