Global and Koopman modes analysis of sound generation in mixing layers - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Physics of Fluids Année : 2013

Global and Koopman modes analysis of sound generation in mixing layers

Résumé

It is now well established that linear and nonlinear instability waves play a significant role in the noise generation process for a wide variety of shear flows such as jets or mixing layers. In that context, the problem of acoustic radiation generated by spatially growing instability waves of two-dimensional subsonic and supersonic mixing layers are revisited in a global point of view, i.e., without any assumption about the base flow, in both a linear and a nonlinear framework by using global and Koopman mode decompositions. In that respect, a timestepping technique based on disturbance equations is employed to extract the most dynamically relevant coherent structures for both linear and nonlinear regimes. The present analysis proposes thus a general strategy for analysing the near-field coherent structures which are responsible for the acoustic noise in these configurations. In particular, we illustrate the failure of linear global modes to describe the noise generation mechanism associated with the vortex pairing for the subsonic regime whereas they appropriately explain the Mach wave radiation of instability waves in the supersonic regime. By contrast, the Dynamic Mode Decomposition (DMD) analysis captures both the near-field dynamics and the far-field acoustics with a few number of modes for both configurations. In addition, the combination of DMD and linear global modes analyses provides new insight about the influence on the radiated noise of nonlinear interactions and saturation of instability waves as well as their interaction with the mean flow.
Fichier principal
Vignette du fichier
DYNFLUID_POF_2013_SONG.pdf (12.67 Mo) Télécharger le fichier
Origine : Fichiers produits par l'(les) auteur(s)

Dates et versions

hal-01069675 , version 1 (29-09-2014)

Identifiants

  • HAL Id : hal-01069675 , version 1
  • DOI : 10.1063/1.4834438
  • ENSAM : http://hdl.handle.net/10985/8642

Citer

Ge Song, Frédéric Alizard, Jean-Christophe Robinet, Xavier Gloerfelt. Global and Koopman modes analysis of sound generation in mixing layers. Physics of Fluids, 2013, 25, pp.124101. ⟨10.1063/1.4834438⟩. ⟨hal-01069675⟩
92 Consultations
167 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More