Method for establishing fluctuation-vibration nonlinear sound field in bubble-containing water medium

Abstract

The invention relates to a method for establishing a fluctuation-vibration nonlinear sound field in a bubble-containing water medium. The method comprises the following steps: establishing a 'wave-bubble volume three-order vibration'equation; setting initial conditions and boundary conditions; determining a time length Tt and a spatial distance T1, and setting a step length division grid; the differential items are rewritten into a differential form; a sound source item is coupled with a wave-bubble volume three-order vibration equation to obtain a difference equation set; setting sound pressure and bubble volume variation initial values; calculating a time node nt bubble volume change value and a sound pressure value, and then adding 1 to nt; when nt is smaller than or equal to Nt, repeating the previous step, calculating to the last point Nt of the time domain, and when nt is equal to Nt, resetting nt to be equal to 3; calculating a sound pressure value nt on the last node Ns in thespatial domain by using the initial parameter and adding 1; and when nt is less than or equal to Nt, repeating the previous step, and calculating to the final point Nt of the time domain. According tothe method, coupling is carried out through sound pressure excitation items, numerical coupling calculation is carried out on the fluctuation-vibration nonlinear equation, and meanwhile the nonlinearsound field characteristic and the bubble nonlinear dynamic characteristic in the bubble-containing water medium are obtained.

Description

technical field [0001] The invention relates to a method for establishing a nonlinear sound field, in particular to a method for establishing a wave-vibration nonlinear sound field in a bubble-containing water medium. Background technique [0002] Due to the disturbance of waves and wind, there are a large number of tiny bubbles on the ocean surface to form the bubble water medium. These bubbles are very stable and have a long existence period; The air is brought into the seawater to form a water medium containing air bubbles, which leads to significant changes in some acoustic properties of the medium and affects the propagation of sound waves. In recent years, with the application of large-amplitude underwater sound waves more and more widely, some nonlinear acoustic characteristics of water media with bubbles have attracted more and more attention. In fact, the bubble-containing water medium itself is a kind of heterogeneous medium, and the bubble-containing water medium...

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Problems solved by technology

[0003] Van Wijingaarden first proposed the acoustic wave equation of the bubble-containing medium based on the mixed medium; Commander and Prosperitti further developed the mixed-medium theory of the bubble-containing medium, and discussed the propagation of linear acoustic waves in the bubble-containing water medium (1Commander K W ,Prosperetti A.Linear pressure waves in bubbly liquids: Comparison between theory and experiments[J].Journal of the Acoustical Society of America,1998,85(21):9383-9391.), but for the influence of nonlinear vibration of bubbles on the acoustic field It was not discussed; Zabolotskaya based on a single bubble vibration equation—Rayleigh-Plesset equation, rewritten the change of bubble radius with time as the change of bubble volume with time, and studied the dynamic characteristics of bubbles (2Zabolotskaya E A. Emission of harmonic and combination-frequency waves by air bubbles[J].Sov.phys.acoust,1973,18.); the above theories did not consider the interaction between the sound field and the nonlinear vibration of bubbles in the water medium containing bubbles

Christian Vanhulle first proposed the idea that the wave equation and the bubble vibration equation can be coupled to calculate, and then solve the sound field characteristics in the bubbly water medium and the bubble vibration characteristics (3Nolinear ultrasonic propagation in bubbly liquids: A numerical model), but for There are few studies on nonlinear sound field characteristics, and the bubble volume vibration model in this paper only considers the second-order nonlinear effect, so it is impossible to analyze the change of sound field characteristics caused by higher-order bubble nonlinear vibration

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