New directions for metamaterial optimization including viscous and thermal acoustic losses

Structural optimization methods, such as shape and topology optimization, hold significant promise for enhancing the design of acoustic metamaterials. Prior research emphasizes the necessity of incorporating viscous and thermal losses into the optimization process for resonator-based acoustic metamaterials. While acoustic losses can be integrated into boundary element and finite element frameworks, shape optimization often lacks the design flexibility required for complex metamaterial structures. Consequently, topology optimization is frequently preferred due to its greater design freedom. Resent research has demonstrated that density-based topology optimization can include acoustic losses using an indicator function combined with the boundary layer impedance condition. As an alternative to density-based topology optimization, this presentation will discuss implementation aspects of a cut-elements and level-set based topology optimization approach including viscous and thermal losses. The cut-elements method offers advantages over traditional density-based approaches by providing a clear interface between acoustic and rigid domains, ensuring that each design iteration accurately reflects the underlying physical behavior.