Asymmetry enhances thermal transport in porous metamaterials at low temperature

Abstract Introducing porosity with different degrees of disorder has been widely used to regulate thermal properties of materials, which generally result in the decrease of thermal conductivity. In this paper, we investigate the thermal conductivity of porous metamaterials in the ballistic transport region through Lorentz gas model. It is found that the introduction of asymmetry and Gaussian disorder into porous metamaterials can lead to a strong enhancement in thermal conductivity. By dividing the transport process into ballistic transport, non-ballistic transport and unsuccessful transport processes, we found that the enhancement in thermal conductivity originates from the significant increase of ratio for ballistic transport. The findings here enhance the understanding of ballistic thermal transport in porous materials and may facilitate the design of high-performance porous thermal metamaterials.