Numerical Simulation of Nanoscale Flow: A Molecular Dynamics Study of Drag

Abstract

The design of pathogen biosensors may soon incorporate beads having a nanoscale diameter, thus making the drag force on a nanoscale sphere an important engineering problem. Flows at this small of a scale begin to appear â grainyâ and may not always behave as a continuous fluid. Molecular dynamics provides an approach to determine drag forces in those nanoscale flows which cannot be described with continuum (Navier-Stokes) theory. This thesis uses a molecular dynamics approach to find the drag forces acting on a sphere and a wall under several different conditions. The results are compared with approximations from a Navier-Stokes treatment and found to be within an order of magnitude despite the uncertainties involved in both the atomic interactions of the molecular dynamics simulation and the appropriate boundary conditions in the Navier-Stokes solution.