2026/07/27 by Masashi Sode, Gianmarco Pinton
paper · doi:10.1088/1361-6560/ae9116
Abstract Large-scale acoustic simulation is essential for ultrasound imaging and therapy but faces computational bottlenecks when modeling nonlinearity, frequency-dependent attenuation, and absorbing boundaries in heterogeneous media. To address this, we present Fullwave 2, a unified time-domain formulation that integrates power-law tissue attenuation and Perfectly Matched Layers (PMLs) via complex coordinate stretching. This framework preserves the structure of the d'Alembertian operator, enabling the use of high-order staggered-grid finite difference stencils optimized for long distance propagation. Since the attenuation in the interior of the domain uses the same formulation as the boundaries, sophisticated implementations of the PMLs are easily implementable and do not add any computational burden. Here a two-stage Convolutional Perfectly Matched Layer (C-PML) with a transition region is demonstrated to be highly stable. The PML attains high absorption efficiency, achieving reflection coefficients below -50dB with a compact 4λ footprint. The domain-wide multiple relaxation mechanisms achieve