Abstract (Invited)

Advances in Theoretical Nonlinear Acoustics

M.Hamilton, Yu.A.Ilinskii, E.A.Zabolotskaya (Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas, USA)

e-mail: hamilton@mail.utexas.edu

Several modern trends in nonlinear acoustics are selected to highlight a few of the theoretical advances in this field. Recent industrial applications of sound fields in resonators employ pressure oscillations that exceed by far the small perturbations often assumed to derive many of the classical model equations in nonlinear acoustics. New model equations for such resonators are presented that do not rely on the assumption of small acoustic Mach number. Thermoacoustic engines are focusing considerable attention on acoustic streaming, and new approaches are being developed to account for effects of narrow channels and temperature dependence on the dc mass flow. Model equations permitting more efficient direct numerical simulation of acoustic fields in thermoacoustic engines are also described. In the area of biomedical ultrasound, current imaging techniques are motivating analyses of harmonic generation in random media, and high intensity focused ultrasound (HIFU) requires description of shock propagation in time varying media. Appropriate model equations for nonlinear beam propagation in these situations are reviewed. The survey concludes with several recent theoretical models for nonlinear wave propagation in solids. Avenues of research considered include surface waves in elastic media, bulk waves in hysteretic media, and wave phase conjugation in magnetostrictive ferrites.

Section : 1