Time-domain finite element formulation of porous sound absorbers based on an equivalent fluid model

摘要

Time-domain wave-based room acoustic modeling has attracted considerable interest in recent years. Among the various room acoustic solvers, the authors have been developing an efficient room acoustic solver using time-domain finite element method (TD-FEM) [1,2], which is extremely attractive for modeling room acoustics because of its inherent capability in dealing with complex geometry. Fundamentally, the acoustic TD-FEM uses a locally reacting equivalent impedance model for treating sound absorption effects at boundaries because of its easy implementation with a low associated computational cost. However, the model uses constant real-valued surface impedance at the frequency of interest where the frequency-dependence and incidenceangle-dependence of absorption characteristics of materials are neglected. Therefore, constructing an adequate extendedreacting sound absorber model is an extremely important topic for enhancing the accuracy of room acoustic prediction. Although earlier studies [3,4] have incorporated an extendedreaction model of permeable membrane absorbers into the TD-FEM, it remains an unsolved issue for other sound absorbers such as porous absorbers. The analyses described herein are undertaken to construct a time-domain finite element (FE) model of the extended-reacting porous absorbers based on an equivalent fluid model [5,6].