Phonons and Phononic Gaps in Continuous Inhomogeneous Media

Abstract

Sound wave propagation in continuous inhomogeneous media plays an important role in various physical phenomena (e.g. earthquakes [1]) as well as in technological applications (such as oil exploration [2], non-destructive evaluation [3], ultrasound in medicine [4], underwater acoustics [5], etc). The relatively large number of material parameters (mass density, ρ, and velocities of the longitudinal, c ₁, and transverse, c _t, components of the sound wave) and the full vector character of the wave give a rich physics.