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NASA Ames Research Center
This is an abstract for a talk to be given at the Fifth Foresight Conference on Molecular Nanotechnology.
A number of nanoscale mechanical devices have been proposed. One of our interests is to explore the properteis of carbon nanotube based gears via realistic computer simulations. Our preliminary molecular dynamics (MD) simulation studies (Nanotechnology, Vol.8, No.3, 95, 1997 ), have demonstrated that the molecular gears work well if the gear temperature is below 1000K in a vacuum. In the current work, we study molecular dynamics of the gears in atomspheres.
Simulations show that the gear works well in a 200K He and Ne at <0.5 atm. Gear temperature reaches a maximum of ~400K at first ~500 ps and then decrease to near the gas temperature of 200K. However, the gas impede the gear rotation and reduce rotaion rate from 0.1 to 0.05 revolution per picosecond. At higher gas densities or pressures, these molecular gears do not work as the gear teeth slip.
To our knowledge, it is the first time MD simulations have been used to study heat and momentum transfer on the nanoscale. More importantly, this study reveals the flow and surface phenomena involved. We observe that gear cooling is driven not only by gas flow around the molecular gears but also, possibly, by liquid-like capillary flow of gas atoms inside the carbon nanotubes.
Dr. Jie Han, NASA Ames Research Center, Moffett Field, CA 94035, ph: 415-604-4799 fax: 415-604-3957 email: email@example.com
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