Drag reduction in spatially developing turbulent boundary layers by blowing at constant mass-flux

Yukinori Kametani, Ramis Orlii, Koji Fukagata, Philipp Schlatter

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Abstract

A series of large-eddy simulations of spatially developing turbulent boundary layers with uniform blowing at moderate Reynolds numbers (based on free-stream velocity, U and momentum thickness, θ) up to Reθ ∼ 2500 were performed with the special focus on the effect of intermittent (separated in streamwise direction) blowing sections. The number of blowing sections, N, investigated is set to be 3, 6, 20, 30 and compared to N = 1, which constitutes the reference case, while the total wall-mass flux is constrained to be the same for all considered cases, corresponding to a blowing amplitude of 0.1% of U for the reference case. Results indicate that the reference case provides a net-energy saving rate of around 18%, which initially decreases at most 2 percentage points for N = 3 but recovers with increasing N. The initial reduction of the drag reduction is due to the shorter streamwise length of intermittent blowing sections. The physical decomposition of the skin friction drag through the FIK identity (Fukagata et at, 2002), shows that the distribution of all components over each blowing section has similar trends, resulting in similar averaged values over the whole control region.

Original languageEnglish
Title of host publication9th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2015
PublisherTSFP-9
Volume1
ISBN (Electronic)9780000000002
Publication statusPublished - 2015 Jan 1
Event9th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2015 - Melbourne, Australia
Duration: 2015 Jun 302015 Jul 3

Other

Other9th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2015
CountryAustralia
CityMelbourne
Period15/6/3015/7/3

ASJC Scopus subject areas

  • Fluid Flow and Transfer Processes

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  • Cite this

    Kametani, Y., Orlii, R., Fukagata, K., & Schlatter, P. (2015). Drag reduction in spatially developing turbulent boundary layers by blowing at constant mass-flux. In 9th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2015 (Vol. 1). TSFP-9.