Display Settings:

Format

Send to:

Choose Destination
See comment in PubMed Commons below
J Chem Phys. 2012 Jul 21;137(3):034110. doi: 10.1063/1.4732515.

Pair diffusion, hydrodynamic interactions, and available volume in dense fluids.

Author information

  • 1Department of Chemical Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, USA. jeetain@lehigh.edu

Abstract

We calculate the pair diffusion coefficient D(r) as a function of the distance r between two hard sphere particles in a dense monodisperse fluid. The distance-dependent pair diffusion coefficient describes the hydrodynamic interactions between particles in a fluid that are central to theories of polymer and colloid dynamics. We determine D(r) from the propagators (Green's functions) of particle pairs obtained from molecular dynamics simulations. At distances exceeding ~3 molecular diameters, the calculated pair diffusion coefficients are in excellent agreement with predictions from exact macroscopic hydrodynamic theory for large Brownian particles suspended in a solvent bath, as well as the Oseen approximation. However, the asymptotic 1/r distance dependence of D(r) associated with hydrodynamic effects emerges only after the pair distance dynamics has been followed for relatively long times, indicating non-negligible memory effects in the pair diffusion at short times. Deviations of the calculated D(r) from the hydrodynamic models at short distances r reflect the underlying many-body fluid structure, and are found to be correlated to differences in the local available volume. The procedure used here to determine the pair diffusion coefficients can also be used for single-particle diffusion in confinement with spherical symmetry.

PMID:
22830686
[PubMed - indexed for MEDLINE]
PMCID:
PMC3411593
Free PMC Article

Images from this publication.See all images (5)Free text

Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for American Institute of Physics Icon for PubMed Central
    Loading ...
    Write to the Help Desk