## Abstract

(N + 1)-point conditional averages of the velocity field are the highest order moments that appear in the N-point probability density function equation for turbulence, and their approximation by linear mean square estimation affects a complete closure of the p.d.f. hierarchy up to the N-point level for N 2. The accuracy of such approximations for turbulence has been studied experimentally for two-time conditional averages of scalar quantities. Measurements of the conditional averages are compared with the linear estimates for two different scalars in a turbulent jet: the streamwise fluctuating velocity and the fluctuating static pressure. Favourable agreement is found, and it is also shown that the spectra of the conditional averages possess equilibrium inertial subranges similar to those of the unconditional power spectra. (A)

Original language | English (US) |
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Title of host publication | Unknown Host Publication Title |

Publisher | Am. Phys. Soc |

State | Published - 1976 |

Externally published | Yes |

## ASJC Scopus subject areas

- General Engineering