An overview of the acoustic studies of bone-like porous materials, and the effect of transverse acoustic waves

In this paper, the effects of transverse acoustic waves in characterizing a bone-like, porous medium filled with a viscous fluid are analyzed for the first time. Scattering operators along with stress fields are derived by using the standard Biot-JKD model. A short duration acoustical pulse is applied to one side of a bone-like, porous medium so that both longitudinal and transverse waves travel through the intermediate medium which is filled with a viscous fluid. The reflection and transmission operators along with stresses in the medium are expressed in terms of these waves. The numerical implementation is validated for the longitudinal wave by comparison with the numerical simulation performed by Fellah, Chapelon, Berger, Lauriks, and Depollier (2004). The effects of the transverse waves on the reflection and transmission coefficients as well as the stress field are studied by considering different viscosities and porosities. It is shown that when the fluid viscosity in the medium is relatively high (such as bone marrow), the effect of the transverse wave dominates. However, this effect is negligible when the medium is filled with a relatively low viscous fluid (such as air). Furthermore, it is shown that the role of transverse waves in characterizing bone structures and bone loss is imperative since the acoustical response of such media at specific frequencies can be triggered only by considering the effects of transverse waves. (C) 2019 Elsevier Ltd. All rights reserved.