Abstract
Heat flux concentrators have important potential applications in thermoelectric generators. In this study, we demonstrated the heat flux concentration characteristic in nanophononic metamaterials using molecular dynamics simulations. The ratio of heat flux (RHF) is used to evaluate the concentration performance, the RHF can reach 1.62. The performance is optimized by varying the height of the nanopillar and the atomic mass of the atoms in the nanopillar. Increasing the atomic mass of the atoms in the nanopillars yields better performance. We found that the main mechanism for concentration is phonon localization in the nanopillar region. Furthermore, when the distance from the surface increases, the low-frequency peak of phonon density of states (PDOS) decreases, the high-frequency peak increases, and the mode participation rate (MPR) transforms from localized to delocalized. This work provides a new design of heat flux concentrator based on nanophononic metamaterials for regulating thermal conduction.