Laying the groundwork for sophisticated underwater cloaking techniques

Hydrodynamic cloaks allow objects to move through fluids without disturbing the flow. Fish travel in schools, using cloaking to reduce their hydrodynamic trails—trails which can be detected by predatory fish and harbor seals. Minimizing these aquatic disruptions through collaborative behaviors increases the survivability of the fish schools.

Not only is hydrodynamic stealth important in safeguarding natural ecosystems, but it is also crucial in enhancing capabilities of unmanned underwater vehicles and aerial vehicles. Yao et al. developed a theoretical hydrodynamic cloak for objects with an arbitrary distribution of size and object position.

“Our research endeavors to cultivate analogous strategies that can mitigate flow disturbances and enhance the collaborative operations of multiple objects,” said author Bin Wang.

Most hydrodynamic cloak research has focused on cloaking a single object. Using theoretical and numerical validations, these newly proposed hydrodynamic cloaks effectively eliminate flow disturbances generated by collaborative teamwork among objects of different sizes and include symmetric and asymmetric arrangements.

The cloaking effect is primarily achieved through the antagonism between the boundary effect of hydrodynamic perturbations and vorticity magnitudes within the cloaked area. This method of integration treats the various objects in a group as a singular entity while preserving the overall volume of intrusion.

The team’s next projects will focus on experimental validation of these theoretical models using physical prototypes in real-world conditions.

“We also plan to expand our research to include more complex scenarios, such as cloaking objects in non-uniform or turbulent flows and integrating intelligent control systems that can dynamically adjust the cloak’s properties,” said Wang.

Source: “Hydrodynamic cloaks with isotropic and homogeneous viscosity for multi-object in collaborative operations,” by Neng-Zhi Yao, Bin Wang, Hao Wang, Chen-Long Wu, and Xuesheng Wang, Physics of Fluids (2024). This article can be accessed at https://doi.org/10.1063/5.0233315 .