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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 nanometer-scale 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 Single-Wall Carbon Nanotubes, Journal of Heat Transfer, Vol. 129, pp. 705-716. (Second most downloaded article in Journal of Heat Transfer, June 2007)
H. Zhong and J. R. Lukes, 2004, Thermal Conductivity of Single-Wall Carbon Nanotubes, Proceedings of the 2004 International Mechanical Engineering Congress and Exposition, November 13-20, 2004, Anaheim, California, IMECE2004-61665.
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 13-18, 2006, Sydney, Australia, NAN-29.
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. 1129-1137.
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 17-22, 2005, San Francisco, California, HT2005-72377.

© Nanoscale Engineering Laboratory Lukes Research Group