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- Title
Interaction between inner and outer layer in drag-reduced turbulent flows.
- Authors
Cormier, Marion; Gatti, Davide; Frohnapfel, Bettina
- Abstract
Effects of wall-based skin-friction drag reduction strategies on the statistical properties of large-scale motions in moderate Reynolds number turbulent flows have been investigated by exploiting Direct Numerical Simulation of turbulent channels. To educe large scales, a new efficient parallel distributed memory algorithm has been implemented which delivers data-driven modes of increasing characteristic lengthscales: the Fast and Adaptive Bidimensional Empirical Mode Decomposition (FABEMD). The influence of wall-based skin friction reduction on large scales is studied by comparing single point statistics, such as r.m.s. fluctuations, and two-point statistics, as cross-correlation functions in controlled and uncontrolled channel flow fields at constant friction Reynolds number. The traditional way of observing large-scale footprinting at the wall, as cross-correlation of the streamwise velocity components at different wall distances, has been found to be unreliable when comparing drag-reduced flows, due to the arbitrary choice of a reference plane in the logarithmic layer. A more sound way of observing the footprinting via the correlation of the streamwise velocity with the friction velocity is addressed and shows an increase of the footprinting in drag-reduced flows. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)
- Subjects
SKIN friction (Aerodynamics); REYNOLDS number; TURBULENT flow; ALGORITHMS; FLUCTUATIONS (Physics); VELOCITY
- Publication
PAMM: Proceedings in Applied Mathematics & Mechanics, 2016, Vol 16, Issue 1, p633
- ISSN
1617-7061
- Publication type
Article
- DOI
10.1002/pamm.201610305