Large effect of lateral box size in molecular dynamics simulations of liquid-solid friction

Koshun Ogawa (1) , Haruki Oga (1) , Hiroki Kusudo (1) , Yasutaka Yamaguchi (1, 2) , Takeshi Omori (1) , Samy Merabia (3) , Laurent Joly (3)

1 Osaka University [Osaka]
2 Tokyo University of Science [Tokyo]
3 iLM - MMCI - iLM - Modélisation de la matière condensée et des interfaces

Molecular dynamics simulations are a powerful tool to characterize liquid-solid friction. A slab configuration with periodic boundary conditions in the lateral dimensions is commonly used, where the measured friction coefficient could be affected by the finite lateral size of the simulation box. Here we show that for a very wetting liquid close to its melting temperature, strong finite size effects can persist up to large box sizes along the flow direction, typically ∼30 particle diameters. We relate the observed decrease of friction in small boxes to changes in the structure of the first adsorbed layer, which becomes less commensurable with the wall structure. Although these effects disappear for lower wetting cases or at higher temperatures, we suggest that the possible effect of the finite lateral box size on the friction coefficient should not be automatically set aside when exploring unknown systems.

Mots clés: Friction; Interfacial flows; Nanofluidics; Shear flows; Liquid-solid interfaces; Microfluidics; Molecular dynamics

Domaines: Physique [physics]

Koshun Ogawa, Haruki Oga, Hiroki Kusudo, Yasutaka Yamaguchi, Takeshi Omori, et al.. Large effect of lateral box size in molecular dynamics simulations of liquid-solid friction. Physical Review E , 2019, 100 (2), pp.054502. ⟨10.1103/PhysRevE.100.023101⟩. ⟨hal-02391337⟩