Time-domain modelling: Combining ESM and FDTD methods for acoustic wave propagation

Time-domain modelling of acoustic wave propagation is computationally expensive, escpecially in applications with large differences in length scales, such as thermoacoustic devices. Thus, there is a need for efficient modelling solutions. One possibility is to combine the established time-domain methods with more efficient methods. The aim of this paper has been to develop a time-domain model combining the equivalent source method (ESM) and the finite-difference time-domain (FDTD) method. The idea was to model the complex acoustic fields using FDTD method and the less complex fields using ESM. These methods were coupled by ensuring continuity of volume velocity and pressure at the boundary between them. Simulations with the combination of the methods were compared to analytical and experimental results, and shown to be accurate and numerically stable for 1-D energy flow, including viscous attenuation. Furthermore, the combination proved significantly quicker than using only the FDTD method. Combining ESM and FDTD has potential as a computationally efficient alternative compared to the latter alone