Nonlinear ultrasound wave propagation in thermoviscous fluids

Mads Peter Sørensen (Invited author)

    Research output: Contribution to conferencePaperResearch

    Abstract

    Traditional ultrasound theory is based on linear theory, however, for strongly focused sound beams, the pressure levels are sufficiently high to generate nonlinear waves. In thermoviscous fluids nonlinearity arises as a result of a nonlinear equation of state together with nonlinear advection. Furthermore, dissipation and dispersion is included in a combined third order term in the velocity potential. We shall report on solitary pulse propagation with generation of higher harmonics of the emitted carrier wave frequency. The envelopes of the carrier wave and its first higher harmonics satisfy two coupled nonlinear partial differential equations, which resembles those of optical chi-2 materials. We think this result makes a remarkable link between nonlinear acoustics and nonlinear optics. Finally our analysis reveal an exact kink solution to the nonlinear acoustic problem. This kink solution is interpreted as a shock wave formation, similar in nature to those of the simple Burgers equation. The results are relevant for medical ultrasound imaging.
    Original languageEnglish
    Publication date2004
    Publication statusPublished - 2004
    Event13th European Conference on Mathematics for Industry - Eindhoven, Netherlands
    Duration: 21 Jun 200425 Jun 2004
    Conference number: 13
    http://www.ecmi2004.tue.nl/

    Conference

    Conference13th European Conference on Mathematics for Industry
    Number13
    CountryNetherlands
    CityEindhoven
    Period21/06/200425/06/2004
    Internet address

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