Broadband cloaking in stratified seas.

Area of Science:

• Fluid dynamics
• Wave physics
• Acoustic and optical metamaterials

Background:

• Invisibility cloaking typically relies on transformation-based methods.
• Existing cloaking techniques are often limited to specific frequencies or wave types.
• Cloaking objects in fluids presents unique challenges due to wave propagation characteristics.

Purpose of the Study:

• To demonstrate broadband invisibility cloaking for floating objects in stratified fluids.
• To investigate a nonlinear resonance concept for wave manipulation.
• To present a surface-noninvasive cloaking solution using bottom corrugations.

Main Methods:

• Utilizing nonlinear resonance between surface and internal waves.
• Designing specific bottom corrugation architectures to mediate wave interaction.
• Analyzing the bending and recovery of wave rays around a cloaked object.

Main Results:

• Achieved broadband cloaking of gravity waves for floating objects.
• Demonstrated that bottom corrugations can effectively bend wave rays.
• Showcased wave recovery downstream without diffraction or scattering, confirming cloaking.
• The cloak is solely dependent on bottom topography, being surface noninvasive.

Conclusions:

• A nonlinear resonance approach enables effective broadband wave cloaking.
• Bottom corrugation design offers a practical, surface-noninvasive method for fluid cloaking.
• This nonlinear scheme provides an alternative to transformation-based cloaking for dispersive waves.