UC Irvine

In this master thesis, we have probed the heat transport in C-S-Hs by both molecular dynamics simulations and phonon eigenvalue analyses. Green-Kubo method is used in molecular dynamics simulations to compute the heat flux and thermal conductivity in C-S-Hs. Noting that C-S-H is relatively amorphous, both propagating modes and nonpropagating modes of phonons are considered in analytical analyses. Bose-Einstein transport equation is used to compute the contribution to the total thermal conductivity from each propagating eigenmode of phonon vibration, while AF theory is applied to investigate the nonpropagating modes of C-S-H. GULP analyses have been performed on C-S-H samples, giving us the eigenfrequencies and eigenvectors of phonons in the system. The participation ratios, group velocities, relaxation times and mode diffusivities of phonons are studied. After comparing our simulation results with analytical analyses, we found that the heat transport phenomenon in amorphous C-S-Hs can be well explained by the combination of BTE equation and AF theory.