Numerical simulation of resonances in microtomographic models
M. M. Haney, J. T. Fredrich, Brian J. Zadler, John A. Scales, David F. Aldridge · 2006
To quantitatively assess material properties in porous media and their associated scale dependence, we simulate acoustic wavefield resonances in numerical models derived from microtomographic data gathered for sintered glass bead packs. The 3D wave propagation simulations utilize a staggered-grid finite-difference (FD) formulation of the first order velocity-pressure system of equations. The FD code is capable of modeling both stress-free and periodic boundaries and this flexibility facilitates the modeling of an infinitely-extending “slab” resonator from the microtomographic-based models. We find that the porous materials act as homogeneous effective media at low frequencies and we observe the transition into the regime of strong scattering from the pore structure, where an effective medium description is no longer valid. Future work will focus on simulating viscous loss, elastic wave propagation, and resonances resulting from a cube sample geometry instead of a “slab” in order to reproduce the experimental setup typically used in resonant ultrasound spectroscopy (RUS).