Drag reduction in flow over a two-dimensional bluff body with a blunt trailing edge using a new passive device

Hyungmin Park, Dongkon Lee, Woo Pyung Jeon, Seonghyeon Hahn, Jeonglae Kim, Jungwoo Kim, Jin Choi, Haecheon Choi

Research output: Contribution to journalArticlepeer-review

104 Scopus citations

Abstract

In this paper, we present a new passive control device for form-drag reduction in flow over a two-dimensional bluff body with a blunt trailing edge. The device consists of small tabs attached to the upper and lower trailing edges of a bluff body to effectively perturb a two-dimensional wake. Both a wind-tunnel experiment and large-eddy simulation are carried out to examine its drag-reduction performance. Extensive parametric studies are performed experimentally by varying the height and width of the tab and the spanwise spacing between the adjacent tabs at three Reynolds numbers of Re = uh/v = 20 000, 40 000 and 80 000, wher u is the free-stream velocity and h is the body height. For a wide parameter range, the base pressure increases (i.e. drag reduces) at all three Reynolds numbers. Furthermore, a significant increase in the base pressure by more than 30% is obtained for the optimum tab configuration. Numerical simulations are performed at much lower Reynolds numbers of Re = 320 and 4200 to investigate the mechanism responsible for the base-pressure increase by the tab. Results from the velocity measurement and numerical simulations show that the tab introduces the spanwise mismatch in the vortex-shedding process, resulting in a substantial reduction of the vortical strength in the wake and significant increases in the vortex formation length and wake width.

Original languageEnglish (US)
Pages (from-to)389-414
Number of pages26
Journaljournal of fluid mechanics
Volume563
DOIs
StatePublished - Sep 25 2006
Externally publishedYes

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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