Computational modeling of a rotary nanopump.

The dynamics of a rotary nanopump, consisting of three coaxial carbon nanotubes and a number of graphene blades, has been simulated via application of the molecular dynamics (MD) method. In this nanopump the inner nanotube, the middle carbon nanotube with together the graphene blades and the outer nanotube are used as the shaft, rotor, and sleeve of the pump, respectively. The rotary motion of the rotor is due to the mechanical rotation of the two first carbon rings of the rotor's carbon nanotube. We found that this pump flow the gas atoms between two sides of the nanopump and it can produce an atomic gradient. Also it is observed that a rotary frequency of the rotor affected on the pump performance for generating the density gradient and the maximum performance is occurred at a special frequency of the rotor. This special rotary frequency can be computed by an analytical formula, for given material and temperatures. Moreover, the results indicate that the number of the rotor's graphene blades do not have a significant effect on the pumping capacity. Our finding provides a potentially useful mechanism for gas purification process.