Size effect on phonon hydrodynamics in graphite microstructures and nanostructures Article - Août 2021

Yangyu Guo, Zhongwei Zhang, Marc Bescond, Shiyun Xiong, Moran Wang, Masahiro Nomura, Sebastian Volz

Yangyu Guo, Zhongwei Zhang, Marc Bescond, Shiyun Xiong, Moran Wang, Masahiro Nomura, Sebastian Volz, « Size effect on phonon hydrodynamics in graphite microstructures and nanostructures  », Physical Review B, août 2021. ISSN 2469-9950

Abstract

The understanding of hydrodynamic heat transport in finite-sized graphitic materials remains elusive due to the lack of an efficient methodology. In this paper, we develop a computational framework enabling an accurate description of heat transport in anisotropic graphite ribbons by a kinetic theory approach with full quantum mechanical first-principles input. A unified analysis of the size scaling of the thermal conductivity in the longitudinal and transverse directions of the system is made within the computational framework complemented with a macroscopic hydrodynamic approach. As a result, we demonstrate a strong end effect on the phonon Knudsen minimum, as a hallmark of the transition from ballistic to hydrodynamic heat transports, along a rectangular graphite ribbon with finite length and width. The phonon Knudsen minimum is found to take place only when the ribbon length is ∼5-10 times the upper limit of the width range in the hydrodynamic regime. This paper contributes to a unique methodology with high efficiency and a deeper understanding of the size effect on phonon hydrodynamics, which would open opportunities for its theoretical and experimental investigation in graphitic micro-and nanostructures.

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