Cloaking waveguide defects using local wall deformations

We present a novel approach to achieve the invisibility effect in a water waveguide with parallel walls. By introducing localised wall deformations near a surface-piercing vertical cylinder, we significantly suppress wave scattering from the defect. Our method reduces the reflection coefficient by more than an order of magnitude compared to a standard parallel waveguide, and the effect persists over a broad frequency range. Laboratory experiments confirm the effectiveness of this cloaking strategy, demonstrating a reduction in backscattered energy by factors ranging from 100 to 5000. These results highlight the potential of passive geometrical modifications for wave control in hydrodynamic systems.