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 D01: Nonlinear Dynamics: Coherent Structures I
2:30 PM–4:27 PM,
Sunday, November 18, 2018
Georgia World Congress Center
Room: B201
Chair: Rich Kerswell, University of Cambridge
Abstract ID: BAPS.2018.DFD.D01.4
Abstract: D01.00004 : Uniform shear flow: the state space of near-wall turbulence as Reτ tends to ∞
3:09 PM–3:22 PM
Presenter:
Patrick Doohan
(Imperial College London)
Authors:
Patrick Doohan
(Imperial College London)
Ashley P Willis
(University of Sheffield)
Yongyun Hwang
(Imperial College London)
There is a growing body of evidence that self-similar coherent structures in the form of Townsend's attached eddies exist. Each of these structures bears a self-sustaining process remarkably similar to that of the near-wall region. To model this universal feature of wall-bounded turbulence, we have designed a shear flow model of near-wall turbulence applicable to various parallel shear flows as Reτ tends to ∞. As a first step, we consider the minimal unit of near-wall turbulence: the governing equations are rescaled in inner units, while a constant shear stress is imposed as the top boundary condition of the domain located at y+≈90. The model is validated against Couette flow, the near-wall region of which is independent of Reynolds number, and there is excellent agreement between velocity statistics & spectra for y+<60. Thirteen relative equilibrium solutions are presented, the first discovered for this flow configuration. Through continuation in the spanwise width Lz+, the bifurcation behaviour of the equilibria over domain size is examined. The physical properties of the equilibria are also explored through state space projection. Finally, the asymptotic behaviour of the equilibria is studied and three lower-branch solutions are found to scale consistently with VWI theory.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2018.DFD.D01.4
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