Size Dependent Thermal Transport in Nanostructures
(Funding: Office
of Naval Research )
One of our group's research interests is to apply atomistic
and mesoscale computational methods to understand how
nanometerscale characteristic dimensions affect the thermal
properties of materials. Work in this area includes
the following projects:

Thermal Conductivity of Carbon Nanotubes 

We have investigated the length dependence of (10,10) carbon
nanotube thermal conductivity using molecular dynamics
simulations. This work has made several important
contributions, including 1) the first quantum correction of
molecular dynamics thermal conductivity results for carbon
nanotubes, which is essential for modeling the thermal
conductivity temperature dependence appropriately; 2) a new
technique for determining whether transport is ballistic or
diffusive, based on heat current autocorrelation decay times;
3) a new, simple technique for estimating average speed of
sound from molecular dynamics without the need for
complicated dispersion relation calculations; and 4) a new
method for eliminating size effects from molecular dynamics
thermal conductivity calculations even for domain sizes much
smaller than the bulk phonon mean free path.



Thermal Conductivity of Silicon Nanowires


We have investigated the diameter dependence of the thermal
conductivity of silicon nanowires using Monte Carlo
simulations. We have observed that thermal conductivity
decreases as nanowire diameter decreases. By comparison to
experimental measurements, we have also
found that confinement effects on the dispersion
relation of silicon nanowires are important at diameters
smaller than 100 nanometers.



Relevant Publications


J. R. Lukes and H. Zhong, 2007,
Thermal Conductivity of Individual SingleWall Carbon
Nanotubes, Journal of Heat Transfer,
Vol. 129, pp. 705716. (Second most downloaded
article in Journal of Heat Transfer, June 2007)


H. Zhong and J. R. Lukes, 2004,
Thermal Conductivity of SingleWall Carbon
Nanotubes,
Proceedings of the 2004 International Mechanical
Engineering Congress and Exposition, November 1320,
2004, Anaheim,
California, IMECE200461665.


J. R. Lukes and H. Zhong, 2006,
Thermal Conductivity of Single Wall Carbon
Nanotubes: A Comparison of Molecular Dynamics
Simulation Approaches, Proceedings of the 13th
International Heat Transfer Conference, August 1318,
2006, Sydney, Australia, NAN29.


Y. Chen, D. Li, J. R. Lukes, and
A. Majumdar, 2005,
Monte Carlo Simulation of Silicon Nanowire Thermal
Conductivity, Journal of Heat Transfer, Vol. 127,
pp. 11291137.


Y. Chen, D. Li, J. R. Lukes, and
Z. Ni, 2005,
Monte Carlo Simulation of Thermal Conductivities of
Silicon Nanowires, Proceedings of the 2005 Summer
Heat Transfer Conference, July 1722, 2005, San
Francisco, California, HT200572377.


