Bulletin of the American Physical Society
71st Annual Meeting of the APS Division of Fluid Dynamics
Volume 63, Number 13
Sunday–Tuesday, November 18–20, 2018; Atlanta, Georgia
Session Q29: Turbulent Mixing II
12:50 PM–3:13 PM,
Tuesday, November 20, 2018
Georgia World Congress Center
Room: B401
Chair: Emmanuel Villermaux, Aix-Marseille University
Abstract ID: BAPS.2018.DFD.Q29.4
Abstract: Q29.00004 : Numerical study of turbulent channel flow perturbed by spanwise topographic heterogeneity: amplitude and frequency modulation within low- and high-momentum pathways*
1:29 PM–1:42 PM
Presenter:
William Anderson
(Univ of Texas, Dallas)
Authors:
Ankit Awasthi
(University of Texas at Dallas)
William Anderson
(Univ of Texas, Dallas)
We studied the effects of spanwise heterogeneous, topographically-driven secondary flows on inner-outer interaction in turbulent channel flow. This topography induces domain-scale, counter-rotating vortices. The vortices are anchored to the topography such that prominent upwelling and downwelling occurs above the low and high roughness, respectively. We have quantified the extent to which such secondary flows disrupt the distribution of spectral density across constituent wavelengths throughout the depth of the flow, which has direct implications for amplitude and frequency modulation. The distinct outer peak associated with large-scale motions -- the “modulators” -- is preserved within the upwelling zone, but vanishes in the downwelling zone. Within the downwelling zones, structures are steeper and shorter. Single- and two-point correlations for amplitude and frequency modulation demonstrate insensitivity to resolution across cases. We also show a pronounced crossover between the single- and two-point correlations, a product of modulation quantification based upon Parseval's theorem (i.e., spectral density, not the wavelength at which energy resides, defines the strength of modulation).
*AFOSR Grant # FA9550-14-1-0101 Eugene McDermott Endowed Professorship (WA)
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2018.DFD.Q29.4
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