Drag reduction by herringbone riblet texture in direct numerical simulations of turbulent channel flow

Henk Benschop, Wim-Paul Breugem

Research output: Contribution to journalArticleScientificpeer-review

25 Citations (Scopus)
141 Downloads (Pure)

Abstract

A bird-feather-inspired herringbone riblet texture was investigated for turbulent drag reduction. The texture consists of blade riblets in a converging/diverging or herringbone pattern with spanwise wavelength Λf. The aim is to quantify the drag change for this texture as compared to a smooth wall and to study the underlying mechanisms. To that purpose, direct numerical simulations of turbulent flow in a channel with height Lz were performed. The Fukagata-Iwamoto-Kasagi identity for drag decomposition was extended to textured walls and was used to study the drag change mechanisms. For Λf/Lz ≳ O(10), the herringbone texture behaves similarly to a conventional parallel-riblet texture in yaw: the suppression of turbulent advective transport results in a slight drag reduction of 2%. For Λf/Lz ≲ O(1), the drag increases strongly with a maximum of 73%. This is attributed to enhanced mean and turbulent advection, which results from the strong secondary flow that forms over regions of riblet convergence/divergence. Hence, the employment of convergent/divergent riblets in the texture seems to be detrimental to turbulent drag reduction.
Original languageEnglish
Pages (from-to)717 - 759
JournalJournal of Turbulence
Volume18
Issue number8
DOIs
Publication statusPublished - 2017

Keywords

  • Drag reduction
  • riblets
  • direct numerical simulations

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