Physics Department - University of Alaska



J O U R N AL CLUB

 

Atomistic Flows in Nano Tubes: New Dynamics in Nanoscale Systems

by

David Newman
Dept. of Physics, UAF

 

ABSTRACT

In nature the interaction between fluid flows and surfaces and the resultant transport due to the flows is both ubiquitous and of fundamental importance. Because of the fundamental nature of this problem, an enormous amount of attention has been given to these systems and much progress has been made in the modeling and understanding of the dynamics of these continuous fluid flows (CFD) using the Navier-Stokes equations. However, with the ever increasing interest in smaller sizes (for example, in MEMS applications) and with the push to develope true nanotechnology, an interesting new regime is encountered. This is the regime in which the distance between surfaces becomes comparable to the atomic or molecular sizes of the flowing material. Typically the effective viscosity is expected to be high--unless, perhaps, the flow "channel" is very regular and smooth (inside a carbon nanotube, for example). The "fluid" dynamics of flows on this scale, in the smooth walled case, have not yet been extensively studied. Flows in nanoscale structures are, for reasonable "fluid" densities, atomistic in nature. Molecular dynamics calculations of such an atomistic, forced flow of a helium fluid through a carbon nanotube exhibit characteristics of a transition analogous to the transition from laminar to turbulent flow in a continuous fluid. This occurs through thermalization of the atomistic flow velocity by helium fluid-carbon nanotube wall interactions above a transition threshold velocity. The demonstration of dynamics with transitions within the tube suggests altogether new uses for atomistic flows. These dynamics and the appenent transition will be discussed.

 

 

Friday, Oct. 5, 2001
Room 401, IARC Bldg.
3:45 pm