Viscoelasticity-induced pulsatile motion of 2D roll cell in laminar wall-bounded shear flow

Tomohiro Nimura, Takuya Kawata, Takahiro Tsukahara

Research output: Contribution to journalArticle

Abstract

For the clarification of the routes to elasto-inertial turbulence (EIT), it is essential to understand how viscoelasticity modulates coherent flow structures including the longitudinal vortices. We focused on a rotating plane Couette flow that provides two-dimensional (2D) roll cells for the steady laminar Newtonian-fluid case, and we investigated how the steady longitudinal vortices are modulated by viscoelasticity at different Weissenberg numbers. The viscoelasticity was found to induce an unsteady flow state where the 2D roll-cell structure was periodically enhanced and damped with a constant period, keeping the homogeneity in the streamwise direction. This pulsatile motion of the roll cell was caused by a time lag in the response of the viscoelastic force to the vortex development. Both the pulsation period and time lag were found to be scaled by the turnover time of cell rotation rather than by the relaxation time, despite the viscoelasticity-induced instability. We also discuss the counter torque on the roll cell and the net energy balance, considering their relevance to polymer drag reduction and EIT.

Original languageEnglish
Pages (from-to)65-75
Number of pages11
JournalInternational Journal of Heat and Fluid Flow
Volume74
DOIs
Publication statusPublished - 2018 Dec
Externally publishedYes

Keywords

  • DNS
  • Drag reduction
  • Giesekus model
  • Rotating plane Couette flow
  • Viscoelastic fluid
  • Wall turbulence

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes

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