Giuseppe Romano1 Aria Hosseini2

1, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
2, University of California, Riverside, Riverside, California, United States

Encompassing diffusive, quasi-ballistic and ballistic regimes, heat conduction is inherently a multiscale problem. At the atomistic level, the phonon mean-free-path (MFP) distribution is typically obtained by density functional theory. On the other side, phonon-boundary interaction is conveniently captured by continuum models, such as the Boltzmann transport equation (BTE). Finally, short-MFP phonons will mostly travel diffusively, so they can be accounted for by a standard diffusive solver. OpenBTE [1] attempts bridging these three regimes. Specifically, the MFP distribution, computed by first-principles, is used as input to the MFP-BTE [2], a recently introduced version of the BTE that uses the phonon MFP as a control variable. Then, using a parameter-free multiscale approach, the BTE solver integrates a modified diffusive model that calculates heat carried by short-MFP phonons. After a brief introduction to the software architecture, we will show example applications, including thin films, nanoporous materials, Graphene nanoribbons, Si serpentines, phonon focusing and large-scale screening of nanostructured materials for thermoelectric applications. Conclusions and final remarks will conclude the talk.
[1] G. Romano and J. C. Grossman. "Heat conduction in nanostructured materials predicted by phonon bulk mean free path distribution." Journal of Heat Transfer, 137.7 (2015): 071302.