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Investigation of the roughness-induced transition: global stability analyses and direct numerical simulations

Type
Articles dans des revues avec comité de lecture
Auteur
LOISEAU, Jean-Christophe
ROBINET, Jean-Christophe
134975 Laboratoire de Dynamique des Fluides [DynFluid]
CHERUBINI, Stefania
19097 Dipartimento di Ingegneria Meccanica e Gestionale [DIMEG]
134975 Laboratoire de Dynamique des Fluides [DynFluid]
LERICHE, Emmanuel
1252 Laboratoire de Mécanique de Lille - FRE 3723 [LML]

URI
http://hdl.handle.net/10985/8974
DOI
10.1017/jfm.2014.589
Date
2014
Journal
Journal of Fluid Mechanics

Résumé

The linear global instability and resulting transition to turbulence induced by an isolated cylindrical roughness element of height h and diameter d immersed within an incompressible boundary layer flow along a flat plate is investigated using the joint application of direct numerical simulations and fully three-dimensional global stability analyses. For the range of parameters investigated, base flow computations show that the roughness element induces a wake composed of a central low-speed region surrounded by a three-dimensional shear layer and a pair of low- and high-speed streaks on each of its sides. Results from the global stability analyses highlight the unstable nature of the central low-speed region and its crucial importance in the laminar–turbulent transition process. It is able to sustain two different global instabilities: a sinuous and a varicose one. Each of these globally unstable modes is related to a different physical mechanism. While the varicose mode has its root in the instability of the whole three-dimensional shear layer surrounding the central low-speed region, the sinuous instability turns out to be similar to the von Kármán instability in the two-dimensional cylinder wake and has its root in the lateral shear layers of the separated zone. The aspect ratio of the roughness element plays a key role on the selection of the dominant instability: whereas the flow over thin cylindrical roughness elements transitions due to a sinuous instability of the near-wake region, for larger roughness elements the varicose instability of the central low-speed region turns out to be the dominant one. Direct numerical simulations of the flow past an aspect ratio 1 roughness element sustaining only the sinuous instability have revealed that the bifurcation occurring in this particular case is supercritical. Finally, comparison of the transition thresholds predicted by global linear stability analyses with the von Doenhoff–Braslow transition diagram provides qualitatively good agreement

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  • Dynamique des Fluides (DynFluid)

Documents liés

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  • Global Stability Analyses Unraveling Roughness-induced Transition Mechanisms 
    LOISEAU, Jean-Christophe; ROBINET, Jean-Christophe; CHERUBINI, Stefania; LERICHE, Emmanuel (ELSEVIER, 2015)
    The linear global instability and resulting transition to turbulence induced by a cylindrical roughness element of heighth and diameter d=3h immersed within an incompressible boundary layer flow along a flat plate is ...
  • Influence of the Shape on the Roughness-Induced Transition 
    LOISEAU, Jean-Christophe; CHERUBINI, Stefania; ROBINET, Jean-Christophe; LERICHE, Emmanuel (Springer, 2015)
    lobal instability analysis of the three-dimensional flow past two rough- ness elements of different shape, namely a cylinder and a bump, is presented. In both cases, the eigenspectrum is made of modes characterised by a ...
  • Intermittency and transition to chaos in the cubical lid-driven cavity flow 
    LOISEAU, Jean-Christophe; ROBINET, Jean-Christophe; LERICHE, Emmanuel (IOP Publishing, 2016)
    Transition from steady state to intermittent chaos in the cubical lid-driven flow is investigated numerically. Fully three-dimensional stability analyses have revealed that the flow experiences an Andronov-Poincaré-Hopf ...
  • Successive bifurcations in a fully three-dimensional open cavity flow 
    PICELLA, Francesco; LOISEAU, Jean-Christophe; LUSSEYRAN, F; ROBINET, Jean-Christophe; CHERUBINI, Stefania; PASTUR, L (Cambridge University Press, 2018)
    The transition to unsteadiness of a three-dimensional open cavity flow is investigated using the joint application of direct numerical simulations and fully three-dimensional linear stability analyses, providing a clear ...
  • Time-Stepping and Krylov Method for large scale instability problems 
    LOISEAU, Jean-Christophe; BUCCI, Michele Alessandro; CHERUBINI, Stefania; ROBINET, Jean-Christophe (Springer, 2018)
    With the ever increasing computational power available and the development of high-performances computing, investigating the properties of realistic very large-scale nonlinear dynamical systems has become reachable. It ...

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