Convective Thermal Metamaterials: Exploring High-Efficiency, Directional, and Wave-Like Heat Transfer

Convective thermal metamaterials are artificial structures where convection dominates in the thermal process. Due to the field coupling between velocity and temperature, convection provides a new knob for controlling heat transfer beyond pure conduction, thus allowing active and robust thermal modulations. With the introduced convective effects, the original parabolic Fourier heat equation for pure conduction can be transformed to hyperbolic. Therefore, the hybrid diffusive system can be interpreted in a wave-like fashion, reviving many wave phenomena in dissipative diffusion. Here, recent advancements in convective thermal metamaterials are reviewed and the state-of-the-art discoveries are classified into the following four aspects, enhancing heat transfer, porous-media-based thermal effects, nonreciprocal heat transfer, and non-Hermitian phenomena. Finally, a prospect is cast on convective thermal metamaterials from two aspects. One is to utilize the convective parameter space to explore topological thermal effects. The other is to further broaden the convective parameter space with spatiotemporal modulation and multi-physical effects.

Automated summary

Convective thermal metamaterials are innovative structures that utilize convection to control heat transfer beyond pure conduction, resulting in active and stable thermal modulations. By introducing convective effects, the traditional parabolic Fourier heat equation for conduction is transformed into a hyperbolic equation, enabling wave-like phenomena in dissipative diffusion. This review summarizes recent advancements and discoveries in convective thermal metamaterials, including enhanced heat transfer, porous-media-based thermal effects, nonreciprocal heat transfer, and non-Hermitian phenomena. Future prospects for convective thermal metamaterials are discussed, including exploring topological thermal effects within the convective parameter space and expanding the parameter space through spatiotemporal modulation and multi-physical effects.