An efficient finite element model for viscothermal acoustics

Standard isentropic acoustic models do not include the dissipative effects of viscous friction and heat conduction. These viscothermal effects can be important, for example in models of small acoustic transducers. Viscothermal acoustics can be modeled in arbitrary geometries with models that contain four or five coupled fields. Therefore, these fully coupled models are computationally costly. On the other hand, efficient approximate viscothermal acoustic models exist, but these are only applicable to certain simplified geometries. A new approximate model is presented which fills the gap between these two extremes. This new model can be used for arbitrary geometries and has a computational efficiency which is higher than the full model and lower than the models with geometrical constraints. The new model is derived and demonstrated on several problems, including acoustic-structure interaction problems