A multiscale volume of fluid method with self-consistent boundary conditions derived from molecular dynamics

Hanyi Liu, Jun Zhang, Paolo Capobianchi, Matthew Borg, Yonghao Zhang, Dongsheng Wen

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Abstract

Molecular dynamics (MD) and volume of fluid (VOF) are powerful methods for
the simulation of dynamic wetting at the nanoscale and macroscale, respectively, but the massive computational cost of MD and the sensitivity and uncertainty of boundary conditions in VOF limit their applications to other scales. In this work, we propose a multiscale simulation strategy by enhancing VOF simulations using self-consistent boundary conditions derived from MD. Specifically, the boundary conditions include a particular slip model based on the molecular kinetic theory for the three-phase contact line to account for the interfacial molecular physics, the classical Navier slip model for the remaining part of the liquid-solid interface, and a new source term supplemented to the momentum equation in VOF to replace the convectional dynamic contact angle model. Each slip model has been calibrated by the MD simulations. The simulation results demonstrate that with these new boundary conditions, the enhanced VOF simulations can provide consistent predictions with full MD simulations for the dynamic wetting of nanodroplets on both smooth and pillared surfaces, and its performance is better than those with other VOF models, especially for the pinning-depinning phenomenon. This multiscale simulation strategy is also proved to be capable of simulating dynamic wetting above the nanoscale, where the pure MD simulations are inaccessible due to the computational cost.
Original languageEnglish
Article number062004
Number of pages52
JournalPhysics of Fluids
Volume33
DOIs
Publication statusPublished - 3 Jun 2021

Keywords

  • dynamic wetting
  • volume of fluid (VOF)
  • molecular dynamics (MD) simulation

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