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Experimental Investigation Of The Travel-Time Variance Of An Acoustic Wave Propagating Through The Grid-Generated Turbulence, Tatiana A. Andreeva, William W. Durgin
Experimental Investigation Of The Travel-Time Variance Of An Acoustic Wave Propagating Through The Grid-Generated Turbulence, Tatiana A. Andreeva, William W. Durgin
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An experimental technique for the investigation of the behaviour of acoustic wave propagation through a turbulent medium is discussed. The present study utilizes the ultrasonic travel-time technique to diagnose a grid-generated turbulence. Travel-time variance is studied versus mean flow velocity, travel distance and outer turbulence scale. The effect of thermal fluctuations, which result in fluctuations of sound speed, is studied using a heated-grid experiment. Experimental data obtained using ultrasonic technique confirm numerical and theoretical predictions of nonlinear increase of the travel-time variance with propagation distance, which could be connected to the occurrence of caustics. The effect of turbulent intensity on …
Effect Of Chaos And Stochastics Induced By Internal Waves On Acoustic Wave Propagation, Tatiana A. Andreeva, William W. Durgin
Effect Of Chaos And Stochastics Induced By Internal Waves On Acoustic Wave Propagation, Tatiana A. Andreeva, William W. Durgin
Office of the Provost Scholarship
In the present paper the eikonal equation is considered in the form of a second order, nonlinear ordinary differential equation with harmonic excitation due to internal wave. The harmonic excitation is taken imperfect, i.e. there is a random phase modulation due to Gaussian white noise. The amplitude and wavelength of the acoustic wave are used as the principle signal characteristics in bifurcation analysis. The regions of instability, identified using the bifurcation diagrams, examined through phase diagrams and Poincare maps. The effect of stochastic nature in addition to chaotic one of internal waves is demonstrated by means of comparison of the …