Diffraction of high-intensity field in focal region as dynamics of nonlinear system with low-frequency dispersion
2015 (English)In: Acoustical Physics, ISSN 1063-7710, E-ISSN 1562-6865, Vol. 61, no 1, 28-36 p.Article in journal (Refereed) Published
The stationary profile in the focal region of a focused nonlinear acoustic wave is described. Three models following from the Khokhlov-Zabolotskaya (KZ) equation with three independent variables are used: (i) the simplified one-dimensional Ostrovsky-Vakhnenko equation, (ii) the system of equations for paraxial series expansion of the acoustic field in powers of transverse coordinates, and (iii) the KZ equation reduced to two independent variables. The structure of the last equation is analogous to the Westervelt equation. Linearization through the Legendre transformation and reduction to the well-studied Euler-Tricomi equation is shown. At high intensities the stationary profiles are periodic sequences of arc sections having singularities of derivative in their matching points. The occurrence of arc profiles was pointed out by Makov. These appear in different nonlinear systems with low-frequency dispersion. Profiles containing discontinuities (shock fronts) change their form while passing through the focal region and are non-stationary waves. The numerical estimations of maximum pressure and intensity in the focus agree with computer calculations and experimental measurements. Â© 2015, Pleiades Publishing, Ltd.
Place, publisher, year, edition, pages
2015. Vol. 61, no 1, 28-36 p.
Acoustic fields; Acoustic waves; Acoustics; Dispersion (waves); Focusing; Nonlinear systems; One dimensional; Shock waves, HIFU; High-intensity fields; Independent variables; Legendre transformations; Limiting fields; Low-frequency dispersions; nonlinearity; Transverse coordinate, Control nonlinearities
Fluid Mechanics and Acoustics
IdentifiersURN: urn:nbn:se:bth-726DOI: 10.1134/S1063771015010091ISI: 000348299600004ScopusID: 2-s2.0-84921869594OAI: oai:DiVA.org:bth-726DiVA: diva2:815572