TY - CONF
T1 - Modal analysis of coherent structures in a self-similar turbulent boundary layer with adverse pressure gradient
AU - Müller, Jens S.
AU - Oberleithner, Kilian
AU - Sekimoto, Atsushi
AU - Eisfelder, Michael P.
AU - Buchner, Abel John
AU - Kitsios, Vassili
AU - Atkinson, Callum
AU - Soria, Julio
N1 - Funding Information:
The authors would like to acknowledge the research funding by the Australian Government through the Australian Research Council and the Australia-Germany Joint Research Cooperation Scheme, an initiative of Universities Australia and the German Academic Exchange Service (DAAD).
Publisher Copyright:
© 2019 International Symposium on Turbulence and Shear Flow Phenomena, TSFP. All rights reserved.
PY - 2019
Y1 - 2019
N2 - Local linear stability analysis as well as Fourier transform and proper orthogonal decomposition are applied to a self-similar turbulent boundary layer on a flat plate with strong adverse pressure gradient to identify coherent structures. The modal analysis is based on data from direct numerical simulations. Coherent structures are identified at the wall-normal position that coincides with an inflection point in the streamwise mean velocity profile. It is found that these coherent structures are governed by broadband Kelvin–Helmholtz instabilities, which are linearly unstable for a certain self-similar frequency range, leading to spatial amplification in streamwise direction before they decay downstream. A very particular challenge is faced due to the limited time length of the dataset compared to the characteristic timescales of interest. Likewise, the spatial extent in streamwise direction limits the large observable wavelengths of interest. This issue is coped with by applying a Fourier transform in time combined with subsequent proper orthogonal decompositions in streamwise and spanwise direction to extract the statistically most correlated and coherent modes in the turbulent boundary layer.
AB - Local linear stability analysis as well as Fourier transform and proper orthogonal decomposition are applied to a self-similar turbulent boundary layer on a flat plate with strong adverse pressure gradient to identify coherent structures. The modal analysis is based on data from direct numerical simulations. Coherent structures are identified at the wall-normal position that coincides with an inflection point in the streamwise mean velocity profile. It is found that these coherent structures are governed by broadband Kelvin–Helmholtz instabilities, which are linearly unstable for a certain self-similar frequency range, leading to spatial amplification in streamwise direction before they decay downstream. A very particular challenge is faced due to the limited time length of the dataset compared to the characteristic timescales of interest. Likewise, the spatial extent in streamwise direction limits the large observable wavelengths of interest. This issue is coped with by applying a Fourier transform in time combined with subsequent proper orthogonal decompositions in streamwise and spanwise direction to extract the statistically most correlated and coherent modes in the turbulent boundary layer.
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M3 - Paper
AN - SCOPUS:85084022579
T2 - 11th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2019
Y2 - 30 July 2019 through 2 August 2019
ER -