### Abstract

We have performed Large-Eddy Simulation of turbulent boundary layer over simplified urban like roughness. Totally six types of arrays are adopted with several roughness densities and roughness aspect ratios. The turbulent flow fields at a pedestrian level are investigated to identify probability characteristics of unsteady flows. Conclusions are summarized as follows. First, the probability density functions of wind speeds at a pedestrian level show long-tail shape with positive skewness for all arrays and well explained by dimensionless probability variable defined by the mean and standard deviation of wind speeds. On the other hands, the discrepancies of the probability between arrays become considerable for events with wind speeds larger than triple of the standard deviations. Second, such events with large wind speed rarely happen; the cumulative probability shows approximately 1%. Lastly, linear relationships are confirmed between the mean and percentile wind speeds. These findings will help the understanding of the unsteadiness nature of turbulent flow in urban boundary layer especially when evaluating very rare events such as gusts or extreme low winds.

Original language | English |
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Pages (from-to) | 1-8 |

Number of pages | 8 |

Journal | Journal of Wind Engineering |

Volume | 42 |

Issue number | 1 |

DOIs | |

Publication status | Published - Jan 2017 |

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### All Science Journal Classification (ASJC) codes

- Renewable Energy, Sustainability and the Environment

### Cite this

**Statistical analysis of wind speeds at a pedestrian level of urban-like roughness.** / Ikegaya, Naoki; Ikeda, Yasuaki; Hagishima, Aya; Tanimoto, Jun.

Research output: Contribution to journal › Article

*Journal of Wind Engineering*, vol. 42, no. 1, pp. 1-8. https://doi.org/10.5359/jwe.42.1

}

TY - JOUR

T1 - Statistical analysis of wind speeds at a pedestrian level of urban-like roughness

AU - Ikegaya, Naoki

AU - Ikeda, Yasuaki

AU - Hagishima, Aya

AU - Tanimoto, Jun

PY - 2017/1

Y1 - 2017/1

N2 - We have performed Large-Eddy Simulation of turbulent boundary layer over simplified urban like roughness. Totally six types of arrays are adopted with several roughness densities and roughness aspect ratios. The turbulent flow fields at a pedestrian level are investigated to identify probability characteristics of unsteady flows. Conclusions are summarized as follows. First, the probability density functions of wind speeds at a pedestrian level show long-tail shape with positive skewness for all arrays and well explained by dimensionless probability variable defined by the mean and standard deviation of wind speeds. On the other hands, the discrepancies of the probability between arrays become considerable for events with wind speeds larger than triple of the standard deviations. Second, such events with large wind speed rarely happen; the cumulative probability shows approximately 1%. Lastly, linear relationships are confirmed between the mean and percentile wind speeds. These findings will help the understanding of the unsteadiness nature of turbulent flow in urban boundary layer especially when evaluating very rare events such as gusts or extreme low winds.

AB - We have performed Large-Eddy Simulation of turbulent boundary layer over simplified urban like roughness. Totally six types of arrays are adopted with several roughness densities and roughness aspect ratios. The turbulent flow fields at a pedestrian level are investigated to identify probability characteristics of unsteady flows. Conclusions are summarized as follows. First, the probability density functions of wind speeds at a pedestrian level show long-tail shape with positive skewness for all arrays and well explained by dimensionless probability variable defined by the mean and standard deviation of wind speeds. On the other hands, the discrepancies of the probability between arrays become considerable for events with wind speeds larger than triple of the standard deviations. Second, such events with large wind speed rarely happen; the cumulative probability shows approximately 1%. Lastly, linear relationships are confirmed between the mean and percentile wind speeds. These findings will help the understanding of the unsteadiness nature of turbulent flow in urban boundary layer especially when evaluating very rare events such as gusts or extreme low winds.

UR - http://www.scopus.com/inward/record.url?scp=85019201323&partnerID=8YFLogxK

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U2 - 10.5359/jwe.42.1

DO - 10.5359/jwe.42.1

M3 - Article

AN - SCOPUS:85019201323

VL - 42

SP - 1

EP - 8

JO - Journal of Wind Engineering

JF - Journal of Wind Engineering

SN - 1349-3507

IS - 1

ER -