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  • The Contribution of Instabi...
    Yudin, M. A.; Kopiev, V. F.; Chernyshev, S. A.; Faranosov, G. A.

    Doklady. a journal of the Russian Academy of Sciences. Physics, 09/2022, Volume: 67, Issue: 9
    Journal Article

    The statistics of the pressure and velocity-field fluctuations in a subsonic turbulent jet is investigated. The data obtained previously in the numerical calculation by the LES method for a round jet with the Mach number M = 0.8 and the Reynolds number Re ~ 750 000 are analyzed. Pulsations are considered both in the potential core of the jet and in the mixing layer. For studying the statistics and identifying the intermittency (the property of statistics to differ from normal), the probability-density function and the flat factor (the ratio of the fourth moment to the square of the second moment) are used. It is shown that, in contrast to the homogeneous isotropic turbulence, where the velocity fluctuations have Gaussian statistics, for a turbulent jet, the velocity field statistics turns out to be intermittent at the boundary of the potential core and at the outer boundary of the mixing layer. An explanation that this difference is related to the contribution of large-scale fluctuations of the mean flow (instability waves), is proposed. It is also shown that the intermittency of the pressure field in the region of the outer boundary of a turbulent jet cannot be associated with large-scale oscillations but is a characteristic of small-scale turbulence, as well as in the case of homogeneous isotropic turbulence.