1204363

What problems of Nonlinear Acoustics seem to be most important and interesting today?

Lev Ostrovsky 1; Oleg Rudenko 2
1Zel Technologies/NOAA ESRL, and University of Colorado at Boulder, Boulder, United States; 2Blekinge Institute of Technology, Mechanical Engineering, Karlskrona, Sweden


The purpose of this presentation is to outline briefly a progress and achievements in the nonlinear acoustics research during the last few years. To answer the question: "What is going on in nonlinear acoustics since the last ISNA-17?" we analyzed results published in journals and delivered at acoustical meetings. Following criteria were used to select most topical problems:

1. Number of papers devoted to a given problem. 2. Activity shown at international meetings (special sessions, symposia and "round table" discussions). 3. Popular scientific papers and public opinion. 4. Number of scientific programs and grants, activity at getting of financial support.

Among the topics which meet these claims are:

1. Phenomena related to the sonic boom (generation and propagation of nonlinear shock waves through inhomogeneous and turbulent atmosphere, fluctuations on the ground). Expert systems for selection the optimum flight regimes and routes.

2. Nonlinear acoustics in geophysical research, including progress in understanding of anomalous behavior of rock (such as hysteresis and slow time), atmospheric effects of earthquakes and tsunamis, including nonlinear effects upon transformation of infrasound from lower atmosphere to ionosphere, etc.

3. Progress in biomedical ultrasound and biomechanics (nonlinear properties of organs and living tissues, nonlinearity in medical diagnostics and therapy, shear wave generation in tissues, acoustically induced destruction of tissues and concretions)

4. "Sonofusion": is thermonuclear fusion reachable in the course of cavitation? Long-term history, ideas, patents, physical results and new hopes.

5. Discussions around an "acoustic maser", "saser", "uaser," etc, including some new ideas and toy experiments. Although this selection of topics would inevitably reflect the authors' preferences, we hope it could be helpful in evaluating the modern trends in nonlinear acoustics.


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