Effect of selective absorption on nonlinear interactions in high intensity acoustic beams.

The effect of second harmonic selective absorption on nonlinear interactions in high intensity acoustic beams is studied. Diffraction and focusing phenomena are taken into account in addition to nonlinearity and selective absorption. The results are compared with those obtained for one-dimensional plane waves in a selective absorption medium and for the focused beams in a medium without absorption. It is shown that selective absorption of the second harmonic does not prevent shock formation, but results in specific waveform distortion, less asymmetry of the waveform in case of the beam, less amplitude of the shock and corresponding nonlinear attenuation. [ABSTRACT FROM AUTHOR]