Work

Slip length of water on graphene: Limitations of non-equilibrium molecular dynamics simulations

Year: 2012

Type: article

Abstract: Data for the flow rate of water in carbon nanopores is widely scattered, both in experiments and simulations. In this work, we aim at precisely quantifying the characteristic large slip length and flow rate of water flowing in a planar graphene nanochannel. First, we quantify the slip length using the intrinsic interfacial friction coefficient between water and graphene, which is found from equilibrium molecular dynamics (EMD) simulations. We then calculate the flow rate and the slip length from the streaming velocity profiles obtained using non-equilibrium molecular dynamics (NEMD) simulations and compare with the predictions from the EMD simulations. The slip length calculated from NEMD simulations is found to be extremely sensitive to the curvature of the velocity profile and it possesses large statistical errors. We therefore pose the question: Can a micrometer range slip length be reliably determined using velocity profiles obtained from NEMD simulations? Our answer is "not practical, if not impossible" based on the analysis given as the results. In the case of high slip systems such as water in carbon nanochannels, the EMD method results are more reliable, accurate, and computationally more efficient compared to the direct NEMD method for predicting the nanofluidic flow rate and hydrodynamic boundary condition.

Source: The Journal of Chemical Physics

DOI: 10.1063/1.3675904

Authors: Sridhar Kumar Kannam, B. D. Todd, J. S. Hansen, Peter J. Daivis

Institutions: Swinburne University of Technology, Roskilde University, RMIT University

Language: English

Topic: Nanopore and Nanochannel Transport Studies

Subfield: Biomedical Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: bronze

Funders: Lundbeckfonden, National Cancer Institute

Award: G2336960465