Low frequency fluctuations of laser beam intensity run through the system of cavitation water clusters |
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Authors: | V N Skokov V P Koverda A V Vinogradov and A V Reshetnikov |
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Institution: | 1.Institute of Thermal Physics of Ural Branch RAS,Ekaterinburg,Russia |
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Abstract: | Experiments on water cavitation in ultrasonic field have been carried out. Low frequency fluctuations of the intensity of
laser beam run through the cavitation area have been studied. Experiments have proved presence of low-frequency random fluctuations
with frequency dependence of power spectra, S ∼ 1/f
α
where the exponent α ranged within 0.8 ≤ α ≤ 1.2. From experimental realizations, large-scale low frequency pulsations characterized by scale invariance, which duration
is distributed according to the power law, have been distinguished. The results are explained on the basis of mathematical
model for the rise of scale invariant fluctuations with 1/f
α
power spectrum in the system of two nonlinear stochastic differential equations describing interaction of heterogeneous phase
transitions. Distribution of extreme low frequency emissions obtained from numerical solutions to stochastic equations takes
the power series form. Correlations of dynamic scaling between critical indicators determining frequency dependence of pulsations
power spectra α and distribution functions of extreme low frequency pulsation amplitudes β have been determined. It is shown that both in the experiments on acoustic cavitation of water and in the theoretical model
of interacting phase transitions critical indicators are bound with the correlation α + β = 2. Spectra of fluctuation power are determined in the experiments simpler and more accurately than the function of extreme
amplitudes distribution. In case when only one frequency dependence of fluctuation capacity spectra is known correlations
between indicators serve to obtain information on the distribution of large scale emissions and to estimate critical amplitudes. |
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Keywords: | |
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