Auto-generation in wall turbulence by the interaction of weak eddies

Manu Goudar Vishwanathappa, Wim-Paul Breugem, Gerrit Elsinga

Research output: Contribution to conferenceAbstractScientific

Abstract

For channel flow, we explore how commonly found weak eddies can still auto-generate and produce new eddies. Before, only strong eddies (above a threshold strength) were considered to auto-generate. Such strong eddies are rarely observed in actual turbulent flows however. Here, the evolution of two weak conditional eddies aligned in stream-wise direction is studied. The numerical procedure followed is similar to Zhou et al. (1999). The two eddies are found to merge into a single stronger eddy when the initial upstream eddy is taller than the downstream eddy, which further auto-generates when the initial stream-wise separation is small (<120 wall units). It is also observed that non-merging cases with small initial stream-wise separation auto-generated. The rapid lift-up of an eddy by ejection events is found to play a role in the onset of auto-generation. This lead to a modified interpretation at the later stages of auto-generation mechanism where blockage of mean flow and shear layer deformation are considered instead of vortex dynamics.
Original languageEnglish
Number of pages1
Publication statusPublished - 2016
EventPhysics@FOM 2016 - Veldhoven, Netherlands
Duration: 19 Jan 201620 Jan 2016
https://www.eventure-online.com/eventure/public/showPublic.form?congressId=9720

Conference

ConferencePhysics@FOM 2016
CountryNetherlands
CityVeldhoven
Period19/01/1620/01/16
Internet address

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