Link Atomistic to Continuum
CG Simulation of Dislocations
Multiscale Thermal Transport
Materials under Irradiations
High-pressure Phase Transitions
Phonon-mediated thermal transport is inherently multiscale, for example , the phonon wave length (λ) is at nanometer scale, the typical phonon wave packet size (η) is tens of nanometers, and the phonon mean free path (Λ) can be microns. To simulate the multiscale thermal transport behavior in materials, we further developed the coarse-grained (CG) atomistic model to reproduce a complete phonon spectrum (figures above), and in turn, to predict the thermal conductivity of polyatomic materials as following.
Thermal transport in materials with microstructure complexity becomes even more complicated. For example, the recent atomistic simulation of heat transfer in bi-crystalline silicon demonstrates that ∑19 tilt grain boundaries (GBs) presents a significantly higher resistance to phonon transport than ∑3 does (figures as shown below). To incorporate the realistic material microstructure across multiple length scales into one computer model, the concurrent atomistic-continuum (CAC) model, which has a fully atomistic resolution at the GB and coarse resolution away from the GB, for thermal transport in nanostructured materials was under further development. The preliminary results show that CAC is capable to simulate the phonon-GBs scattering in heterogeneous materials from the atomic to the microscale (the movie as shown below).
- Chen, X., Chernatynskiy, A., Xiong, L., and Chen, Y., 2015. A coherent phonon pulse model for transient phonon thermal transport, Computer Physics Communications, 195, 112-116. doi:10.1016/j.cpc.2015.05.008
- Xiong, L., Chen, X., Zhang, N., McDowell, D.L., and Chen, Y., 2014. Prediction of phonon properties of 1D polyatomic systems using concurrent atomistic-continuum simulation, Archive of Applied Mechanics, 84: 1665. doi:10.1007/s00419-014-0880-8
- Zheng, Z., Chen, X., Deng, B., Chernatynskiy, A., Yang, S., Xiong, L., and Chen, Y., 2014. Phonon transport through tilt grain boundaries in strontium titanate, Journal of Applied Physics, 116, 073706. http://dx.doi.org/10.1063/1.4893648