Slip length of confined liquid with small roughness of solid-liquid interfaces

TL;DR

This study investigates how small surface roughness and chemical interactions influence the slip length of confined liquids, using analytical and numerical methods to quantify their effects.

Contribution

It introduces a combined analytical and Monte Carlo simulation approach to quantify the impact of surface roughness and chemical interactions on slip length.

Findings

Total slip length is linearly proportional to chemical interaction slip length.

Roughness variance decreases the total slip length.

Correlation length of roughness can significantly enhance slip length to saturation.

Abstract

We have studied the slip length of confined liquid with small roughness of solid-liquid interfaces. Dyadic Green function and perturbation expansion have been applied to get the slip length quantitatively. In the slip length, both effects of the roughness of the interfaces and the chemical interaction between the liquid and the solid surface are involved. For the numerical calculation, Monte Carlo method has been used to simulate the rough interfaces and the physical quantities are obtained statistically over the interfaces. Results show that the total slip length of the system is linearly proportional to the slip length contributed from the chemical interaction. And the roughness of the interfaces plays its role as the proportionality factor. For the roughness, the variance of the roughness decreases the total slip length while the correlation length of the roughness can enhance the slip length dramatically to a saturation value.