FDTD model of acoustic wave interaction with soft targets

Abstract

We have used the finite difference time domain acoustic wave algorithm to study the interaction of a time harmonic acoustic wave with soft acoustic targets. Our interest has been on the character of the acoustic field inside the target and the interaction parameters which influence it. The numerical simulations suggest that for an acoustically denser target the interior field consist of alternate bands of high-(and low-) pressure, though in a narrow cylindrical target the interior is almost completely filled with a high-pressure band. Also, the acoustic field inside the target is influenced by the target aspect ratio, characteristic size and material contrast, such that increasing the aspect ratio and/or characteristic size leads to a significant increase in the interior field magnitude. Provided the aspect ratio is greater than unity and the target is acoustically denser than the exterior medium, the interior acoustic field can attain a magnitude much greater than the amplitude of the incident wave.

Journal of the Nigerian Association of Mathematical Physics Vol. 9 2005: pp. 545-560