### 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 language | English |
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Title of host publication | 9th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2015 |

Publisher | TSFP-9 |

Volume | 1 |

ISBN (Electronic) | 9780000000002 |

Publication status | Published - 2015 Jan 1 |

Event | 9th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2015 - Melbourne, Australia Duration: 2015 Jun 30 → 2015 Jul 3 |

### Other

Other | 9th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2015 |
---|---|

Country | Australia |

City | Melbourne |

Period | 15/6/30 → 15/7/3 |

### Fingerprint

### ASJC Scopus subject areas

- Fluid Flow and Transfer Processes

### Cite this

*9th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2015*(Vol. 1). TSFP-9.

**Drag reduction in spatially developing turbulent boundary layers by blowing at constant mass-flux.** / Kametani, Yukinori; Orlii, Ramis; Fukagata, Koji; Schlatter, Philipp.

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

*9th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2015.*vol. 1, TSFP-9, 9th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2015, Melbourne, Australia, 15/6/30.

}

TY - GEN

T1 - Drag reduction in spatially developing turbulent boundary layers by blowing at constant mass-flux

AU - Kametani, Yukinori

AU - Orlii, Ramis

AU - Fukagata, Koji

AU - Schlatter, Philipp

PY - 2015/1/1

Y1 - 2015/1/1

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=85034441023&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85034441023&partnerID=8YFLogxK

M3 - Conference contribution

AN - SCOPUS:85034441023

VL - 1

BT - 9th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2015

PB - TSFP-9

ER -