A perspective on the hydrodynamic phonon transport in two-dimensional materials

Abstract

Thermal transport in two-dimensional (2D) materials has attracted great attention since the discovery of high thermal conductivity in graphene, which is closely related to the hydrodynamic phonon transport. In this Perspective, we briefly summarize the recent progresses in studying hydrodynamic phonon transport in 2D materials, including both theoretical and experimental works. First, the criterion and numerical methods for studying hydrodynamic phonon transport are reviewed. We then discuss the physical mechanism and peculiar phenomena related to hydrodynamic phonon transport in 2D materials and finally present the challenge for future studies. This Perspective aims to provide the physical understanding of the hydrodynamic phonon transport, which might be beneficial to the exploration of novel thermal transport behaviors in 2D materials.

Modeling of second sound in carbon nanostructures

“…As can be seen from Fig. 9, at the profile period Z = 2 11 , damped periodic fluctuations of the temperature profile occur in the nanoribbon at low temperature T = 100K. Such behavior corresponds to the hydrodynamic regime of heat transfer.…”

“…11. As can be seen from the figure, when the profile period is Z = 2 11 and the temperature is T = 100K, slowly attenuating periodic profile oscillations occur in the nanotube. This behavior corresponds to the hydrodynamic regime of heat transfer.…”

“…In three-dimensional materials, second sound was previously observed experimentally only at cryogenic temperatures [6][7][8][9][10], as a reaction of a material to an applied temperature pulse. Discovered later, exceptionally high thermal conductivities of low-dimensional materials (such as carbon nanotubes and nanoribbons, graphene, and boron nitride) occur due to a ballistic flow of longwave acoustic phonons supported by such systems [2,[11][12][13][14][15]. Second sound, or hydrodynamic phonon transfer, is observed between ballistic and diffusion regimes of heat transfer.…”

“…To describe the hydrodynamic regime of phonon transfer in low-dimensional materials, several theoretical models were proposed [11,15,18,[20][21][22][23][24]. In particular, a 3D model of a periodically modulated graphene structure that behaves like a crystal for temperature waves was proposed in Ref.…”

“…11:Relaxation of initial periodic thermal profile (temperature lattice) in the CNT(6,6) for temperature (a) T = 100K (∆T = 50K) and (b) T = 300K (∆T = 150K). The period of the profile Z = 211 , nanoribbon length N = 213 . The temperature change on three periods of the profile is shown.…”