Advertisement

A Parameter Study of Focused Sound Fields in Active Media

  • L. Bjørnø
  • T. H. Neighbors
Conference paper
Part of the Research Reports in Physics book series (RESREPORTS)

Abstract

Focused sound fields ranging from very low frequencies (infrasound) in the sea to frequencies far into the MHz region, used for medical and industrial purposes, have received particular attention during recent years. Medical applications of focused ultrasound for diagnostic scanning of organs and for therapeutic disintegration of body stones, are of considerable interest to the Industrial Acoustics Laboratory at the Technical university of Denmark. A parameter study has been performed of the KZK-model in order to determine the applicability of this model for computational simulation of focused, nonlinear wave propagation in active media. Some modifications to the KZK-model introduced permit the computation of variations in frequency and time domain responses of axisymmetric nonlinear wave fields with linear focusing gains in the range of 200, e.g shock formation in the focal zone. Parameters considered in the evaluation include the relative influence of parameters describing nonlinear effects (B/A, fundamental frequency, source amplitude, etc.), diffraction effects (geometrical considerations), attenuation effects (absorption and scattering), and linear focusing gains with particular emphasis on wave distortion in and around the focal zone. The computer codes developed have been implemented to run on personal computers.

Keywords

Pulse Repetition Rate Focus Ultrasound Finite Amplitude Source Pressure Focal Zone 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Bjø0rnø, L., “Nonlinear Acoustics”, in ACOUSTICS AND VIBRATION PROGRESS, edited by R.W.B. Stephens and H.G. Leventhall, Chapman & Hall, London, 1976.Google Scholar
  2. 2.
    Trivett, D.G. & Van Buren, A.L., “Propagation of plane, cylindrical and spherical finite amplitude waves”. J. Acoust. Soc. Amer., 69, 943–9 49, 1981.ADSCrossRefGoogle Scholar
  3. 3.
    Haran, M.E. & Cook, B.D., “Distortion of finite amplitude ultrasound in lossy media”, J. Acoust. Soc. Amer., 73, 774–7 79, 1983.ADSCrossRefGoogle Scholar
  4. 4.
    Kuznetsov, V.P., “Equations of nonlinear acoustics”, Sov. Phys. Acoust., 16, 467–4 70, 1971.Google Scholar
  5. 5.
    Tjøta, J.N. & Tjøtta, S., “Nonlinear equations of acoustics, with application to parametric acoustic arrays”. J. Acoust. Soc. Amer., 69, 1644–16 52, 1981.ADSCrossRefGoogle Scholar
  6. 6.
    Aanonsen, A.I., Barkve, T., Tjøtta, S.N. & Tjøtta, S., “Distortion and harmonic generation in the nearfield of a finite amplitude beam”. J.Acoust. Soc. Amer., 75, 749–7 68, 1984.ADSMATHCrossRefGoogle Scholar
  7. 7.
    Sutin, A.M., “Influence of nonlinear effects on the properties of acoustic focusing systems”. Sov. Phys.-Acoust., 24, 334–3 39, 1979.Google Scholar
  8. 8.
    Salto, S., Kim, C. & Muir, T.G., “Second harmonic component of a nonlinearly distorted wave in a focused sound beam”. J. Acoust. Soc.Amer, 82, 621–6 28, 1987.ADSCrossRefGoogle Scholar
  9. 9.
    Hart, T.S., “Numerical investigation of nonlinear effects in focused sound beams”, M.S. Thesis, The University of Texas at Austin, 1987.Google Scholar
  10. 10.
    Aanonsen, S.I., “Numerical computation of the nearfield of a finite amplitude sound beam”, Report No. 73, Department of Mathematics, University of Bergen, Norway, 1983.Google Scholar
  11. 11.
    Hart, T.S. & Hamilton, M.F., “Nonlinear effects in focused sound beams”, Submitted to J. Acoust. Soc. Amer.Google Scholar
  12. 12.
    Ruger, D., “Resolution beyond the diffraction in the acoustic microscope: A nonlinear effect”, J. Appl. Phys., 56, 1338–13 46, 1984.ADSCrossRefGoogle Scholar
  13. 13.
    Zinck, J.P., “Focusing transducer system for disintegration of kidney stones”, Report No. 13, Industrial Acoustics Laboratory, Technical University of Denmark, June 1988. (In Danish)Google Scholar
  14. 14.
    Bjørnø, L. & Lewin, P.A., “Nonlinear focusing effects in ultrasonic imaging”. Proc. IEEE Ultrasonic Symposium 1982, 659–6 62, 1982.Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1989

Authors and Affiliations

  • L. Bjørnø
    • 1
  • T. H. Neighbors
    • 2
  1. 1.Industrial Acoustics LaboratoryTechnical University of DenmarkLyngbyDenmark
  2. 2.Physics DepartmentGeorgetown UniversityWashingtonUSA

Personalised recommendations