Tunable-slip boundaries for coarse-grained simulations of fluid flow

TL;DR

This paper introduces a systematic method to implement tunable partial-slip boundary conditions in coarse-grained fluid simulations, accurately capturing slip behavior from full-slip to no-slip conditions.

Contribution

A new approach to model arbitrary slip lengths in simulations by representing microscopic interfaces with a spatially varying viscous force.

Findings

Analytical expression for slip length derived for planar and curved surfaces.

Method validated against DPD simulations across slip regimes.

Accurate modeling of slip behavior in micro- and nanoscale flows.

Abstract

On the micro- and nanoscale, classical hydrodynamic boundary conditions such as the no-slip condition no longer apply. Instead, the flow profiles exhibit ``slip`` at the surface, which is characterized by a finite slip length (partial slip). We present a new, systematic way of implementing partial-slip boundary conditions with arbitrary slip length in coarse-grained computer simulations. The main idea is to represent the complex microscopic interface structure by a spatially varying effective viscous force. An analytical equation for the resulting slip length can be derived for planar and for curved surfaces. The comparison with computer simulations of a DPD (dissipative particle dynamics) fluid shows that this expression is valid from full-slip to no-slip.