J. Phys. II France
Volume 7, Numéro 5, May 1997
Page(s) 801 - 812
DOI: 10.1051/jp2:1997152
J. Phys. II France 7 (1997) 801-812

Sound Scattering on a Turbulent, Weakly Heated Jet

A. Petrossian1, 2 and J.-F. Pinton1

1  Laboratoire de Physique, École Normale Supérieure de Lyon CNRS URA 1325, 69364 Lyon France
2  Physics Department, Yerevan State University, 1 Manoukian street, 375049 Yerevan, Armenia

(Received 28 October 1996, revised 22 January 1997, accepted 13 February 1997)

We report an experimental study of the scattering of ultrasonic plane waves on a turbulent jet in air (Pr = 0.7). The jet is weakly heated so that the temperature fluctuations act as a passive scalar. In the backscattering geometry one measures the Fourier components of the temperature field $\tilde{T}(q, t)$. The time averaged characteristics are analyzed in detail; in particular we observe a Kolmogorov "-5/3" power law behavior for the passive scalar spectrum in the inertial range of scales. The study of the time fluctuations shows that the histograms of $\tilde{T}(q, t)$ remain close to a Gaussian at all scales.

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