Direct simulation of second sound in graphene by solving the phonon Boltzmann equation via a multiscale scheme

Abstract

The direct simulation of the dynamics of second sound in graphitic materials remains a challenging task due to lack of methodology for solving the phonon Boltzmann equation in such a stiff hydrodynamic regime. In this work, we aim to tackle this challenge by developing a multiscale numerical scheme for the transient phonon Boltzmann equation under Callaway's dual relaxation model which captures well the collective phonon kinetics. Comparing to traditional numerical methods, the present multiscale scheme is efficient, accurate and stable in all transport regimes attributed to avoiding the use of time and spatial steps smaller than the relaxation time and mean free path of phonons. The formation, propagation and composition of ballistic pulses and second sound in graphene ribbon in two classical paradigms for experimental detection are investigated via the multiscale scheme. The second sound is declared to be mainly contributed by ZA phonon modes, whereas the ballistic pulses are mainly contributed by LA and TA phonon modes. The influence of temperature, isotope abundance and ribbon size on the second sound propagation is also explored. The speed of second sound in the observation window is found to be at most 20 percentages smaller than the theoretical value in hydrodynamic limit due to the finite umklapp, isotope and edge resistive scattering. The present study will contribute to not only the solution methodology of phonon Boltzmann equation, but also the physics of transient hydrodynamic phonon transport as guidance for future experimental detection.

arXiv comment44pages,11 figures

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Cited by in corpus (8)

• Phonon hydrodynamics in crystalline materials
• A unified theory of second sound in two dimensional materials
• A fast-converging scheme for the Phonon Boltzmann equation with dual relaxation times
• On the emergence of heat waves in the transient thermal grating geometry
• Analytical Green's Function of Multidimensional Boltzmann Transport Equation for Modeling Hydrodynamic Second Sound
• Thermal response functions and second sound in single-layer hexagonal boron nitride
• Modeling of second sound in carbon nanostructures
• A novel transient heat conduction phenomenon to distinguish the hydrodynamic and (quasi) ballistic phonon transport