### Abstract

In this paper some results are presented on the statistical properties of zero crossings of turbulent velocity fluctuations in boundary layers over a wide range of Reynolds numbers. The earlier Unding that the probability density function (pdf) of the intervals between successive zero crossings of the streamwise velocity fluctuation u can be approximated by two exponentials, each with its own characteristic scale, is confirmed. The cross-stream variation of these characteristic scales is investigated. One of these scales, corresponding to the large zero-crossing intervals, is independent of the Reynolds number, while the other for the viscous-dominated small-scale crossings varies with as Rλ^{-1/2}, where Rλ is the Reynolds number based on the Taylor microscale, λ. The pdf's for the normal velocity component v and the fluctuating part of the Reynolds stress uv are essentially exponential over the whole range of zero-crossing scales, and each possesses just one characteristic scale. The mean and the standard deviation of the zero-crossing scales of u and v, when normalized by their respective Taylor microscales, are roughly unity and essentially independent of the cross-stream position. Similar data are also presented for the Reynolds stress fluctuations. A brief discussion of the results as well as an example of the application of the zero-crossing pdf are given.

Original language | English (US) |
---|---|

Pages (from-to) | 2879-2885 |

Number of pages | 7 |

Journal | Physics of Fluids A |

Volume | 5 |

Issue number | 11 |

State | Published - 1992 |

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### ASJC Scopus subject areas

- Fluid Flow and Transfer Processes
- Engineering(all)
- Computational Mechanics
- Mechanics of Materials
- Physics and Astronomy(all)
- Condensed Matter Physics

### Cite this

*Physics of Fluids A*,

*5*(11), 2879-2885.

**Zero crossings of velocity fluctuations in turbulent boundary layers.** / Kailasnath, P.; Sreenivasan, K. R.

Research output: Contribution to journal › Article

*Physics of Fluids A*, vol. 5, no. 11, pp. 2879-2885.

}

TY - JOUR

T1 - Zero crossings of velocity fluctuations in turbulent boundary layers

AU - Kailasnath, P.

AU - Sreenivasan, K. R.

PY - 1992

Y1 - 1992

N2 - In this paper some results are presented on the statistical properties of zero crossings of turbulent velocity fluctuations in boundary layers over a wide range of Reynolds numbers. The earlier Unding that the probability density function (pdf) of the intervals between successive zero crossings of the streamwise velocity fluctuation u can be approximated by two exponentials, each with its own characteristic scale, is confirmed. The cross-stream variation of these characteristic scales is investigated. One of these scales, corresponding to the large zero-crossing intervals, is independent of the Reynolds number, while the other for the viscous-dominated small-scale crossings varies with as Rλ-1/2, where Rλ is the Reynolds number based on the Taylor microscale, λ. The pdf's for the normal velocity component v and the fluctuating part of the Reynolds stress uv are essentially exponential over the whole range of zero-crossing scales, and each possesses just one characteristic scale. The mean and the standard deviation of the zero-crossing scales of u and v, when normalized by their respective Taylor microscales, are roughly unity and essentially independent of the cross-stream position. Similar data are also presented for the Reynolds stress fluctuations. A brief discussion of the results as well as an example of the application of the zero-crossing pdf are given.

AB - In this paper some results are presented on the statistical properties of zero crossings of turbulent velocity fluctuations in boundary layers over a wide range of Reynolds numbers. The earlier Unding that the probability density function (pdf) of the intervals between successive zero crossings of the streamwise velocity fluctuation u can be approximated by two exponentials, each with its own characteristic scale, is confirmed. The cross-stream variation of these characteristic scales is investigated. One of these scales, corresponding to the large zero-crossing intervals, is independent of the Reynolds number, while the other for the viscous-dominated small-scale crossings varies with as Rλ-1/2, where Rλ is the Reynolds number based on the Taylor microscale, λ. The pdf's for the normal velocity component v and the fluctuating part of the Reynolds stress uv are essentially exponential over the whole range of zero-crossing scales, and each possesses just one characteristic scale. The mean and the standard deviation of the zero-crossing scales of u and v, when normalized by their respective Taylor microscales, are roughly unity and essentially independent of the cross-stream position. Similar data are also presented for the Reynolds stress fluctuations. A brief discussion of the results as well as an example of the application of the zero-crossing pdf are given.

UR - http://www.scopus.com/inward/record.url?scp=0027396822&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0027396822&partnerID=8YFLogxK

M3 - Article

VL - 5

SP - 2879

EP - 2885

JO - Physics of fluids. A, Fluid dynamics

JF - Physics of fluids. A, Fluid dynamics

SN - 0899-8213

IS - 11

ER -