Efficient Parameterization Strategies for Optimizing Sub-Wavelength Focusing Structures

Abstract

In the field of acoustic topology optimization, recently, there has been growing interest in optimizing macro-structures for focusing devices such as sonic black holes (SBH). This paper contributes to this emerging field by examining various parameterization approaches. We begin with classical topology optimization (SIMP), where practically each finite element mesh cell is a variable, and compare it to the contemporary feature mapping model, where high-level geometrical objects play the role of parameters. Here we compare a classical feature mapping approach with linked rounded bars against a shape optimization variant. The optimization algorithms implemented in the open source software openCFS are applied to application-oriented example problems to assess their computational effort. The resulting optimized structures are analyzed through numerical simulations, considering key factors such as performance and manufacturability. Based on these findings, we provide recommendations for optimizing sub-wavelength focusing devices.