(279h) Molecular Simulation of Nanoscale Hydrodynamics In Complex Fluids

Advances in experimental techniques of micro and nanofluidics have led to renewed interest in the hydrodynamics at molecular length scales. Molecular hydrodynamics plays an important role in the phenomena such as collective motion of microorganisms as well as application of nanofluidic devices for manipulation of biological molecules.

In this work, we use molecular dynamics (MD) simulations to study the hydrodynamic interactions in systems containing nanoparticles that are suspended in complex fluids. An explicit, atomistic model is used for the suspending medium in our simulations. The nanoparticles themselves have an internal structure and consist of smaller beads that are connected to each other. All of the particles in the system interact with each other via pairwise additive intermolecular potentials of the Lennard-Jones type. Diffusion and hydrodynamics are thus governed by the intermolecular interactions in our model systems.

We use MD simulations to study the motion of nanoparticles through the medium. The systems studied consist of dilute suspensions of nanoparticles in simple monomeric fluids or in polymeric fluids as well as the concentrated suspensions of the nanoparticles. Molecular simulations are used to deduce the length scale of hydrodynamic interactions in these systems. The coupling between molecular scale structure in the system and hydrodynamics plays an important role in governing particle motion at the nanoscale; this effect is studied in detail. Simulation results are also used to study the effects of particle concentration on the hydrodynamic behavior. The influence of a solid surface on the hydrodynamic interactions is quantified by studying particle motion at different separation distances from a confining solid surface.