Extraction of the solid-liquid friction coefficient between a water-methanol liquid mixture and a non-polar solid crystal surface by Green-Kubo equations

Abstract

Using equilibrium molecular dynamics (EMD), we analyzed the friction between water-methanol liquid mixtures and a non-polar solid wall. Specifically, we calculated the friction coefficient (FC) from the autocorrelation of the shear force exerted on a liquid from a solid wall using two Green-Kubo (GK) equations proposed by Bocquet and Barrat (BB) [Physical Review E, Vol. 49, (1994), 3079], and Huang and Szulfarska (HS) [Physical Review E, Vol. 89 (2014), 032119], and compared these FC values with those obtained in our previous non-equilibrium molecular dynamics (NEMD) work. Both GK equations reproduced the FC dependence on the methanol concentration in the first adsorption layer X MeOH a observed with NEMD, but the BB method gave a better estimate of the NEMD results with a difference of 20 % at largest. The independent molecular FCs of water and methanol, which were only extractable with the HS method from EMD simulations, corresponded qualitatively well with the NEMD results regarding the dependency on X MeOH a . Though certain discrepancies were observed between the EMD and NEMD results, the EMD had a considerable advantage regarding the computational time required to calculate the FC with a comparable error: the EMD computational time was about 20 times shorter than the NEMD time in the present system.

Green-Kubo measurement of liquid-solid friction in finite-size systems

“…For instance, the maximum of the GK integral-or the value of the GK integral at the first zero of the autocorrelation function-has been used to estimate the friction coefficient. 13,[43][44][45][46][47] Alternative equilibrium [18][19][20]22,23,25,42 and nonequilibrium 14,15 methods have been developed. Recently, Español, de la Torre, and Duque-Zumajo 41 have proposed a general solution to the plateau problem within the context of Mori projection operator formulation, which could in principle be applied to the GK measurement of the liquid-solid friction coefficient.…”

Computational Study of the Structure and Transport in Pyrrolidinium-Li-TFSI-Silica Ionogels

“…Later, Huang and Szulfarska proposed an alternative formulation that apparently addressed shortcomings in the Bocquet and Barrat method. Nakaoka et al . applied both the Bocquet and Barrat, and Huang and Szulfarska formulations to a water–methanol system (vs the previous idealized LJ fluid demonstrations) and compared to a direct driven-flow estimate.…”

(Invited) Nanoscale Wetting and Its Connection with Macroscopic Young's Equation

“…By approximating 𝛾 and 𝛾 by 𝛾 and 0, respectively, it follows for 𝛾 − 𝛾 that 𝛾 − 𝛾 ≈ 𝑊 − 𝑊 − 𝛾 [18] Figure 4. Schematic of the systems to extract the works of adhesion of (a) solid-liquid, and (b) solid-vapor interfaces by the thermodynamic route.…”

“…Molecular dynamics (MD) analysis is a powerful tool to investigate and predict wetting from a microscopic point of view, with which various combinations of liquid and solid surface can be tested in silico. We have carried out MD simulations on the liquid behavior especially around the solid surface including static wetting (2)(3)(4)(5)(6)(7)(8)(9)(10)(11), dynamic wetting (12,13), liquid diffusivity (14-16) around the solid, and solid-liquid friction (17)(18)(19)(20)(21)(22)(23), where the fluid-solid pairs ranged from Lennard-Jones fluid to water, methanol, iso-propyl-alcohol and their mixture as fluids and from simple fcc crystal to OH-terminated Silica as the solid surfaces. In this series of studies, we have developed and adopted several methods for the calculation of the solid-related interfacial tensions from mechanical and thermodynamic viewpoints.…”