2017/03/15 by Pauline Simonnin, Simonnin, Pauline, B. Nœtinger +7 · 1 citation
Chemistry · Engineering · Materials Science · #Computational Physics (physics.comp-ph) #Electrostatics and Colloid Interactions #FOS: Physical sciences #Material Dynamics and Properties #Nanopore and Nanochannel Transport Studies #Soft Condensed Matter (cond-mat.soft)
paper · pdf · doi:10.48550/arxiv.1703.05261
openalex publication_date 2017/03/15 · openalex created_date 2022/10/02 · openalex updated_date 2026/07/28
We investigate finite-size effects on diffusion in confined fluids using\nmolecular dynamics simulations and hydrodynamic calculations. Specifically, we\nconsider a Lennard-Jones fluid in slit pores without slip at the interface and\nshow that the use of periodic boundary conditions in the directions along the\nsurfaces results in dramatic finite-size effects, in addition to that of the\nphysically relevant confining length. As in the simulation of bulk fluids,\nthese effects arise from spurious hydrodynamic interactions between periodic\nimages and from the constraint of total momentum conservation. We derive\nanalytical expressions for the correction to the diffusion coefficient in the\nlimits of both elongated and flat systems, which are in excellent agreement\nwith the molecular simulation results except for the narrowest pores, where the\ndiscreteness of the fluid particles starts to play a role. The present work\nimplies that the diffusion coefficients for wide nanopores computed using\nelongated boxes suffer from finite-size artifacts which had not been previously\nappreciated. In addition, our analytical expression provides the correction to\nbe applied to the simulation results for finite (possibly small) systems. It\napplies not only to molecular but also to all mesoscopic hydrodynamic\nsimulations, including Lattice-Boltzmann, Multi-Particle Collision Dynamics or\nDissipative Particle Dynamics, which are often used to investigate confined\nsoft matter involving colloidal particles and polymers.\n