TY - GEN

T1 - Stability of a self-similar adverse pressure gradient turbulent boundary layer

AU - Eisfelder, M. P.

AU - Müller, J. S.

AU - Sekimoto, A.

AU - Buchner, A. J.

AU - Kitsios, V.

AU - Atkinson, C.

AU - Oberleithner, K.

AU - Soria, J.

N1 - Funding Information:
The authors would like to acknowledge the research funding by the Australian Government through the Australian Research Council, The Australia-Germany Joint Research Cooperation Scheme an initiative of Universities Australia and the German Academic Exchange Service (DAAD) and the computational resources provided by the Australian National Computational Infrastructure and The Pawsey Supercomputing Centre through the National Computational Merit Allocation Scheme.
Publisher Copyright:
© 2018 Australasian Fluid Mechanics Society. All rights reserved.

PY - 2018

Y1 - 2018

N2 - Linear stability analysis (LSA) of a self-similar adverse pressure gradient (APG) turbulent boundary layer (TBL) is explored in order to identify coherent structures. An eddy viscosity model (EV) is implemented via the Boussinesq hypothesis [8] to model the nonlinear coherent-turbulent interactions. Direct numerical simulations (DNS) by Kitsios et al. [3, 6] are used for the database of this study. A weak APG and strong APG (on the verge of separation) are studied with dimensionless streamwise pressure gradients (β) of 1 and 39 respectively. Their Reynolds numbers based on the momentum thickness (δ2) within their respective regions of interest are 3, 100 − 3, 400 and 10, 000 − 12, 300. For the strong APG, the most unstable eigen-solution produces a wave resembling a Kelvin-Helmholtz (KH) instability located near the displacement thickness (δ1) height. This position coincides with the inflection point (IP) in the mean flow profile. The IP satisfies Rayleigh’s and Fjortoft’s criterion for the existence of an inviscid instability [9]. Positive growth rate is seen for non-dimensional angular frequencies of 0.08 ≤ ω ≤ 0.51, with the maximum growth occurring at ω = 0.26. The weak APG also contains a KH like wave, however for all ω, the growth rates are negative. Spanwise wavenumber kxr and phase velocity ĉr increase monotonically for both β cases. Comparisons with a quasi-laminar analysis are also made.

AB - Linear stability analysis (LSA) of a self-similar adverse pressure gradient (APG) turbulent boundary layer (TBL) is explored in order to identify coherent structures. An eddy viscosity model (EV) is implemented via the Boussinesq hypothesis [8] to model the nonlinear coherent-turbulent interactions. Direct numerical simulations (DNS) by Kitsios et al. [3, 6] are used for the database of this study. A weak APG and strong APG (on the verge of separation) are studied with dimensionless streamwise pressure gradients (β) of 1 and 39 respectively. Their Reynolds numbers based on the momentum thickness (δ2) within their respective regions of interest are 3, 100 − 3, 400 and 10, 000 − 12, 300. For the strong APG, the most unstable eigen-solution produces a wave resembling a Kelvin-Helmholtz (KH) instability located near the displacement thickness (δ1) height. This position coincides with the inflection point (IP) in the mean flow profile. The IP satisfies Rayleigh’s and Fjortoft’s criterion for the existence of an inviscid instability [9]. Positive growth rate is seen for non-dimensional angular frequencies of 0.08 ≤ ω ≤ 0.51, with the maximum growth occurring at ω = 0.26. The weak APG also contains a KH like wave, however for all ω, the growth rates are negative. Spanwise wavenumber kxr and phase velocity ĉr increase monotonically for both β cases. Comparisons with a quasi-laminar analysis are also made.

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M3 - Conference contribution

AN - SCOPUS:85084094751

T3 - Proceedings of the 21st Australasian Fluid Mechanics Conference, AFMC 2018

BT - Proceedings of the 21st Australasian Fluid Mechanics Conference, AFMC 2018

A2 - Lau, Timothy C.W.

A2 - Kelso, Richard M.

PB - Australasian Fluid Mechanics Society

T2 - 21st Australasian Fluid Mechanics Conference, AFMC 2018

Y2 - 10 December 2018 through 13 December 2018

ER -