Laboratoire de Mécanique des Fluides et d'Acoustique - UMR 5509

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Accueil > Actualités > Séminaires > Archives 2017

Yohann Duguet - LIMSI, Orsay

Intermittent turbulent structures in wall-bounded shear flows.

Vendredi 16 Juin 2017 - 11h - Bât H10 salle B11 - ECL

Intermittent turbulent structures in wall-bounded shear flows.

The problem of transition to turbulence has continued to puzzle hydrodynamicists, mathematicians and engineers for more than a century. Circular and annular pipes, plane channels as well as some simple boundary layer flows are characterised by a turbulent regime in competition with a linearly stable laminar base flow. The associated hysteresis has a strong impact on the energetic performances.

In this talk I will review the most recent developments on transition to turbulence in a variety of wall-bounded shear flows, based on experimental, theoretical and numerical evidence. 

At the lowest values of the Reynolds number where it can be observed, turbulence spontaneously takes the form of localised patches and sometimes genuine laminar/turbulent patterns. The structure and the dynamics at the laminar/turbulent interfaces depend however on the flow geometry. I will explain how this surprising self-organisation is influenced by large-scale flows generated at these interfaces and suggest a deterministic underlying bifurcation diagram.

PNG - 209.2 ko
Figure : Oblique laminar/turbulent stripes in a plane Couette flow (Direct Numerical Simulation using a spectral method, iso-streamwise velocity at mid-gap, Re=330)


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