Ballistic-diffusive phonon heat transport across grain boundaries

File

2017-XiongLiming-BallisticDiffusive.pdf (2.15 MB)

Date

2017-09-01

Authors

Xiong, Liming
Li, Weixuan
Xiong, Liming
Li, Yang
Yang, Shengfeng
Zheng, Zexi
McDowell, David L.
Chen, Youping

Publisher

Elsevier Ltd.

Altmetrics

Authors

Xiong, Liming

Person

Associate Professor

Organizational Units

Aerospace Engineering

Organizational Unit

Department

Aerospace Engineering

Abstract

The propagation of a heat pulse in a single crystal and across grain boundaries (GBs) is simulated using a concurrent atomistic-continuum method furnished with a coherent phonon pulse model. With a heat pulse constructed based on a Bose-Einstein distribution of phonons, this work has reproduced the phenomenon of phonon focusing in single and polycrystalline materials. Simulation results provide visual evidence that the propagation of a heat pulse in crystalline solids with or without GBs is partially ballistic and partially diffusive, i.e., there is a co-existence of ballistic and diffusive thermal transport, with the long-wavelength phonons traveling ballistically while the short-wavelength phonons scatter with each other and travel diffusively. To gain a quantitative understanding of GB thermal resistance, the kinetic energy transmitted across GBs is monitored on the fly and the time-dependent energy transmission for each specimen is measured; the contributions of coherent and incoherent phonon transport to the energy transmission are estimated. Simulation results reveal that the presence of GBs modifies the nature of thermal transport, with the coherent long-wavelength phonons dominating the heat conduction in materials with GBs. In addition, it is found that phonon-GB interactions can result in reconstruction of GBs.

Comments

This is a manuscript of an article published as Chen, Xiang, Weixuan Li, Liming Xiong, Yang Li, Shengfeng Yang, Zexi Zheng, David L. McDowell, and Youping Chen. "Ballistic-diffusive phonon heat transport across grain boundaries." Acta Materialia 136 (2017): 355-365. DOI: 10.1016/j.actamat.2017.06.054. Copyright 2017 Acta Materialia Inc. Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0). Posted with permission.

Keywords

DegreeDisciplines::Engineering::Aerospace Engineering::Structures and Materials, DegreeDisciplines::Physical Sciences and Mathematics::Physics::Engineering Physics