Luneburg cloak with pentamode metafluid

This study proposes a pentamode Luneburg cloak (PMLC) based on the principles of transformation acoustics. By converting the traditional Luneburg lens (LL) into a concentric layered structure and employing discretized pentamode unit cells to achieve graded material properties, the PMLC retains omnidirectional focusing capability while enabling both acoustic wave manipulation and cloaking. Numerical simulations demonstrate that the proposed PMLC exhibits effective broadband performance for both focusing and cloaking within the 5 – 15 kHz frequency range. Analysis of the reflection cross-section reveals that the PMLC maintains low reflectivity over a wide frequency band, with performance comparable to cloaks based on continuous transformation. The PMLC not only enables underwater acoustic cloaking but also supports reverse acoustic localization, offering a novel technological solution for applications involving underwater target concealment and acoustic positioning.