Simulation and Optimization of Underwater Acoustic Alberich Absorbers with Cylindrical and Conical Cavities

In order to absorb underwater acoustics waves, special coatings named “Alberich” are used. The mechanism of these coatings is to transform the wave energy to heat by vibration through holes in them. In this study, the performance of a particular type of anechoic absorber called Alberich and made of polyurethane were evaluated by using Comsol software and the impact of various geometrical parameters were investigated, individually. The results showed that the absorption coefficient increases, while the reflection and transmission coefficients decrease, by increasing the height and radius of the air cylinders. Besides, putting cavities in the middle rows with different radii, increases the frequency range and makes the absorber wideband. Finally, the absorber was optimized to maximize the absorption coefficient. In the optimized model the cavities are in the shape of frustums with 5 degree head angle. Their radiuses in the main and middle rows are 0.8 cm and 1.2 cm, respectively. The Parametric study and optimization of the Alberich absorbers were done for the first time in the current research and it can be used by engineers and researchers.