• français
    • English
    français
  • Login
Help
View Item 
  •   Home
  • Dynamique des Fluides (DynFluid)
  • View Item
  • Home
  • Dynamique des Fluides (DynFluid)
  • View Item
JavaScript is disabled for your browser. Some features of this site may not work without it.

Nonlinear optimal perturbation of turbulent channel flow as a precursor of extreme events

Article dans une revue avec comité de lecture
Author
ccCIOLA, Nicola
134975 Laboratoire de Dynamique des Fluides [DynFluid]
ccDE PALMA, Paul
ccROBINET, Jean-Christophe
134975 Laboratoire de Dynamique des Fluides [DynFluid]
CHERUBINI, Stefania

URI
http://hdl.handle.net/10985/24141
DOI
10.1017/jfm.2023.601
Date
2023-08
Journal
Journal of Fluid Mechanics

Abstract

This work aims at studying the mechanisms behind the occurrence of extreme dissipation events in a channel flow, identifying nonlinear optimal perturbations as potential precursors of these events. Nonlinear optimal perturbations with respect to a generic turbulent instantaneous snapshot are computed for the first time using a direct-adjoint algorithm in the channel flow at $Re_{\tau }\approx 180$ . The resulting initial perturbation displays the upstream tilting characteristic of Orr's mechanism and is positioned along the interfaces between two opposite-sign velocity streaks of the pre-existing turbulent field. Such a perturbation induces a sudden breakdown of the pre-existing structures and a heavier tail in the dissipation probability density function distribution. Different mechanisms are at play during this process: the high shear present at the interface between coherent low- and high-momentum regions is exploited to break down the larger structures and drive energy to small scales. This energy cascade is fed by an enhanced lift-up effect that produces intense streaks near the wall. It is found that the optimal perturbation grows exponentially during the first phase of its evolution reflecting the existence of a secondary modal instability of the streaks. To corroborate the results, the conditional spatiotemporal proper orthogonal decomposition (POD) analysis of Hack & Schimdt (J. Fluid Mech., vol. 907, 2021, A9) is performed both in the perturbed and in the unperturbed flow, showing a clear agreement between the two cases and with the reference study. Thus, the optimal perturbation at initial time can be considered as a precursor of extreme events.

Files in this item

Name:
DYNFLUID_JFM_2023_CIOLA.pdf
Size:
5.979Mb
Format:
PDF
Description:
Nonlinear optimal perturbation ...
Embargoed until:
2024-03-01
View/Open

Collections

  • Dynamique des Fluides (DynFluid)

Related items

Showing items related by title, author, creator and subject.

  • Minimal energy thresholds for sustained turbulent bands in channel flow 
    Article dans une revue avec comité de lecture
    ccPARENTE, Enza; ccROBINET, Jean-Christophe; ccDE PALMA, Paul; CHERUBINI, Stefania (Cambridge University Press (CUP), 2022-05)
    In this work, nonlinear variational optimization is used for obtaining minimal seeds for the formation of turbulent bands in channel flow. Using nonlinear optimization together with energy bisection, we have found that the ...
  • Nonlinear control of unsteady finite-amplitude perturbations in the Blasius boundary-layer flow 
    Article dans une revue avec comité de lecture
    CHERUBINI, Stefania; DE PALMA, Pietro; ccROBINET, Jean-Christophe (Cambridge University Press (CUP), 2013)
    The present work provides an optimal control strategy, based on the nonlinear Navier–Stokes equations, aimed at hampering the rapid growth of unsteady finite-amplitude perturbations in a Blasius boundary-layer flow. A ...
  • The onset of three-dimensional centrifugal global modes and their nonlinear development in a recirculating flow over a flat surface 
    Article dans une revue avec comité de lecture
    CHERUBINI, Stefania; DE PALMA, Pietro; ALIZARD, Frédéric; ccROBINET, Jean-Christophe (American Institute of Physics, 2010)
    The three-dimensional stability dynamics of a separation bubble over a flat plate has been studied in both linear and nonlinear conditions. Using a global eigenvalue analysis, two centrifugal global modes are identified: ...
  • Rapid path to transition via nonlinear localized optimal perturbations in a boundary-layer flow 
    Article dans une revue avec comité de lecture
    CHERUBINI, Stefania; DE PALMA, Pietro; BOTTARO, Alessandro; ccROBINET, Jean-Christophe (American Physical Society (APS), 2010)
    Recent studies have suggested that in some cases transition can be triggered by some purely nonlinear mechanisms. Here we aim at verifying such an hypothesis, looking for a localized perturbation able to lead a boundary-layer ...
  • Numerical Study of the Effect of Freestream Turbulence on by-pass Transition in a Boundary Layer 
    Article dans une revue avec comité de lecture
    CHERUBINI, Stefania; DE PALMA, Pietro; ccROBINET, Jean-Christophe (Elsevier, 2014)
    We use direct numerical simulations in the presence of free-stream turbulence having different values of intensity, T u, and integral length scale, L, in order to determine which kind of structures are involved in the path ...

Browse

All SAMCommunities & CollectionsAuthorsIssue DateCenter / InstitutionThis CollectionAuthorsIssue DateCenter / Institution

Newsletter

Latest newsletterPrevious newsletters

Statistics

Most Popular ItemsStatistics by CountryMost Popular Authors

ÉCOLE NATIONALE SUPERIEURE D'ARTS ET METIERS

  • Contact
  • Mentions légales

ÉCOLE NATIONALE SUPERIEURE D'ARTS ET METIERS

  • Contact
  • Mentions légales