Effect of rounded edged dimple arrays on the boundary layer development

Hatsari Mitsudharmadi*, C. M.J. Tay, H. M. Tsai

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

The effect of a turbulent boundary layer subjected to a series of rounded edged shallow dimple arrays with dimple depth ratios, d/D of 4%, 8% and 12% were experimentally studied. Measurements show the existence of a higher flow speed region at the center of each dimple. The spanwise distribution of the mean wall shear stress immediately downstream of the centers of the last row of dimples does not vary with dimple depth, and is about 45% over that without the dimple array. Turbulence measurements and surface flow visualization shows that the flow over the shallowest dimple differs from the deeper dimples. Flow separation observed with the deeper rounded edged dimples produce similar flow structures as those from sharp edged dimples reported in the literature. However flow separation is not observed when d/D = 4% but instead two other higher speed regions either side accompany the central flow. The effects of the dimples are rapidly suppressed by the flat surfaces between of the dimples, and the flow rapidly reverts back to an unmanipulated flat boundary layer flow in these areas.

Original languageEnglish (US)
Pages (from-to)17-25
Number of pages9
JournalJournal of Visualization
Volume12
Issue number1
DOIs
StatePublished - Jan 1 2009

Keywords

  • Flow control
  • Shallow dimple
  • Smooth edge dimple
  • Turbulent flow
  • Wall shear stress

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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