Energy production and self-sustained turbulence at the Kolmogorov scale in Couette flow
File(s)20170923_JFM_YQ_APW_YH_R2.pdf (4.14 MB)
Accepted version
Author(s)
Yang, Q
Willis, AP
Hwang, Y
Type
Journal Article
Abstract
Several recent studies have reported that there exists a self-similar form of invariant solutions down to the Kolmogorov microscale in the bulk region of turbulent Couette flow. While their role in a fully developed turbulent flow is yet to be identified, here we report that there exists a related mechanism of turbulence production at the Kolmogorov microscale in the bulk region of turbulent Couette flow by performing a set of minimal-span direct numerical simulations up to friction Reynolds number . This mechanism is found to essentially originate from the non-zero mean shear in the bulk region of the Couette flow, and involves eddy turn-over dynamics remarkably similar to the so-called self-sustaining process (SSP) and/or vortex–wave interaction (VWI). A numerical experiment that removes all other motions except in the core region is also performed, which demonstrates that the eddies at a given wall-normal location in the bulk region are sustained in the absence of other motions at different wall-normal locations. It is proposed that the self-sustaining eddies at the Kolmogorov microscale correspond to those in uniform shear turbulence at transitional Reynolds numbers, and a quantitative comparison between the eddies in uniform shear and near-wall turbulence is subsequently made. Finally, it is shown that turbulence production by the self-sustaining eddies at the Kolmogorov microscale is much smaller than that of full-scale simulations, and that the difference between the two increases with Reynolds number.
Date Issued
2017-11-17
Online Publication Date
2018-05-17T06:00:24Z
Date Acceptance
2017-09-21
ISSN
0022-1120
Publisher
Cambridge University Press (CUP)
Start Page
531
End Page
554
Journal / Book Title
Journal of Fluid Mechanics
Volume
834
Copyright Statement
The final publication is available via Cambridge Journals Online at http://dx.doi.org/10.1017/jfm.2017.704
Source Database
manual-entry
Sponsor
Engineering and Physical Sciences Research Council
Engineering & Physical Science Research Council (EPSRC)
Grant Number
EP/N019342/1
EP/N019342/1
Subjects
Science & Technology
Technology
Physical Sciences
Mechanics
Physics, Fluids & Plasmas
Physics
turbulence simulation
turbulence theory
turbulent flows
NEAR-WALL TURBULENCE
DIRECT NUMERICAL-SIMULATION
EXACT COHERENT STRUCTURES
HIGH REYNOLDS-NUMBER
CHANNEL FLOW
PIPE-FLOW
ATTACHED EDDIES
SHEAR FLOWS
STATE-SPACE
TRANSITION
01 Mathematical Sciences
09 Engineering
Fluids & Plasmas
Publication Status
Published