Thermoviscous-acoustic metamaterials to damp acoustic modes in complex shape geometries at low frequencies

This article proposes a hybrid numerical-analytical approach to effectively predict the sound absorption coefficient of complex periodic metamaterials with reasonably low computation time. A variation an existing metamaterial, consisting succession necks and cavities, is also proposed. The design was intended decrease frequencies resonant peaks consists in adding eccentricity neck position. combines thermoviscous-acoustic (TVA) transfer matrix (TM) method. TVA estimates thermoviscous losses acoustic waves unit cell (PUC) metamaterial. TM method used simulate behaviour complete metamaterial from PUC calculated numerically. compared impedance tube measurements on prototypes comparison shows that proposed good agreement measured coefficient. In addition, numerical simulations experiments demonstrate results shift down frequency without deteriorating their performance.