SonicRadiation : Ghost‐Cell‐Free Hybrid Acoustic Simulation via Consistent Boundary‐Grid Coupling

ABSTRACT Accurate sound radiation simulation remains challenging in the presence of complex and dynamic object boundaries. Existing time‐domain grid solvers, such as ghost‐cell‐based finite‐difference time‐domain (FDTD) methods, approximate boundary conditions through geometric rasterization, often leading to large discretization errors, geometric inconsistencies, and reduced efficiency in complex scenes. We present SonicRadiation, a hybrid time‐domain solver that eliminates the need for ghost cells by introducing a consistent boundary–grid coupling formulation between the time‐domain boundary element method (TDBEM) and FDTD. Instead of approximating boundary conditions through rasterization, we derive a unified representation that directly links Dirichlet and Neumann boundary data with pressure variables in grid cells. This formulation enables a novel boundary–grid synchronization strategy, which achieves stable bidirectional information exchange between boundary elements and grid cells while preserving physical consistency. The resulting hybrid solver inherits the geometric accuracy of TDBEM in the near field and the computational efficiency of FDTD in the far field, yielding a scalable solution for dynamic and geometrically intricate scenes. Extensive experiments, including analytical monopole benchmarks and acoustic transfer tests, demonstrate that our method significantly outperforms ghost‐cell‐based approaches in both numerical accuracy and computational efficiency, particularly for thin structures and dynamically evolving boundaries.