Intangible Hydrodynamic Cloaks For Convective Flows

Although studies of hydrodynamic cloaking have attracted considerable attention, most pioneering studies have so far focused on creeping flows, in which nonlinear convective terms are neglected and cloaks are fabricated with inhomogeneous or anisotropic metamaterials. Here we discover that intangible uniform-viscosity hydrodynamic cloaks, which are capable of hiding obstacles immersed in narrow-gap Navier-Stokes flows with non-negligible convection, can be possibly designed. Via the convection diffusion-balance method and the realizable thermally controlled tactic, the diffusion effect exerted by the obstacle surface can be balanced by the convection counterpart exerted by the manipulation of temperature-dependent viscosity inside the intangible cloak. This analysis has been validated by finite element computational simulations that tackle cloaked-cylinder flows for Reynolds numbers in the laminar regime. The proposed study may lay the foundation for attempts to further explore hydrodynamic cloaks and possibly other metamaterial-related devices.