Don Noid and Bobby Sumpter, Oak Ridge National Laboratory
The development of nanotechnology will include building atomic-scale
machines able to move and sort substances molecule by molecule. Many of
these so-called nanomachines will likely contain fluids that flow through
pipes (to and from very small chemical reaction chambers) or fluids
confined to small volumes (inside nano-hydraulic pistons, for example). The
flow of helium (a light, non-reactive gas) through a simple pipe composed
of a graphite-like material has been simulated on a computer through novel
molecular dynamics techniques and the results computer-animated.
close-up of buckyball interrupting
flow of helium atoms in graphite nanotube,
MPEG animation (775 KB)
The animations show a variety of features of fluid flow that are not
readily apparent from the raw computer data. As the fluid atoms, shown in
green, flow through the pipe, they bounce off the pipe wall and cause it to
flex. In some simulations, the helium gas carries along a comparatively
heavy buckyball molecule, which has a cage-like structure. Because of its
tight fit, the buckyball can cause the pipe to bulge as it passes through.
If the pipe flexes or bulges, parts of the nanomachine attached to it may
vibrate. When designing nanomachines, the effects of this vibration must be
accounted for. Inspection of computer animations can illuminate these and
other crucial issues in the design of nanomachines.
