Propagation of Intense Acoustic Waves in Sonic Crystals

The propagation of intense acoustic waves in a periodic medium (sonic crystal) is numerically studied. The medium consists in a structured fluid, formed by a periodic array of fluid layers with alternating linear acoustic properties and quadratic nonlinearity coefficient. The spacing between layers is of the order of the wavelength; therefore Bragg effects such as band gaps appear. We show that the interplay between strong dispersion and nonlinearity influences wave propagation. The classical waveform distortion process typical of intense acoustic waves in homogeneous media can be strongly altered when nonlinearly generated harmonics lie inside or close to band gaps.