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Title: Effective Particle Size From Molecular Dynamics Simulations in Fluids

Abstract

Here, we report molecular dynamics simulations designed to investigate the effective size of colloidal particles suspended in a fluid in the vicinity of a rigid wall where all interactions are defined by smooth atomic potential functions. These simulations are used to assess how the behavior of this system at the atomistic length scale compares to continuum mechanics models. In order to determine the effective size of the particles, we calculate the solvent forces on spherical particles of different radii as a function of different positions near and overlapping with the atomistically defined wall and compare them to continuum models. This procedure also then determines the effective position of the wall. Our analysis is based solely on forces that the particles sense, ensuring self-consistency of the method. The simulations were carried out using both Weeks–Chandler–Andersen and modified Lennard-Jones (LJ) potentials to identify the different contributions of simple repulsion and van der Waals attractive forces. Upon correction for behavior arising the discreteness of the atomic system, the underlying continuum physics analysis appeared to be correct down to much less than the particle radius. For both particle types, the effective radius was found to be ~0.75σ, where σ defines the length scale ofmore » the force interaction (the LJ diameter). The effective “hydrodynamic” radii determined by this means are distinct from commonly assumed values of 0.5σ and 1.0σ, but agree with a value developed from the atomistic analysis of the viscosity of such systems.« less

Authors:
 [1]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [2];  [1]; ORCiD logo [2]
  1. Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Mechanical Engineering
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1411988
Alternate Identifier(s):
OSTI ID: 1415366
Report Number(s):
LA-UR-14-28035
Journal ID: ISSN 0935-4964; TRN: US1800771
Grant/Contract Number:  
AC52-06NA25396
Resource Type:
Journal Article: Published Article
Journal Name:
Theoretical and Computational Fluid Dynamics
Additional Journal Information:
Journal Volume: 32; Journal Issue: 2; Journal ID: ISSN 0935-4964
Publisher:
Springer
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 42 ENGINEERING; Material Science; molecular dynamics, colloids

Citation Formats

Ju, Jianwei, Welch, Paul Michael Jr., Rasmussen, Kim Orskov, Redondo, Antonio, Vorobieff, Peter, and Kober, Edward Martin. Effective Particle Size From Molecular Dynamics Simulations in Fluids. United States: N. p., 2017. Web. doi:10.1007/s00162-017-0450-0.
Ju, Jianwei, Welch, Paul Michael Jr., Rasmussen, Kim Orskov, Redondo, Antonio, Vorobieff, Peter, & Kober, Edward Martin. Effective Particle Size From Molecular Dynamics Simulations in Fluids. United States. doi:10.1007/s00162-017-0450-0.
Ju, Jianwei, Welch, Paul Michael Jr., Rasmussen, Kim Orskov, Redondo, Antonio, Vorobieff, Peter, and Kober, Edward Martin. Fri . "Effective Particle Size From Molecular Dynamics Simulations in Fluids". United States. doi:10.1007/s00162-017-0450-0.
@article{osti_1411988,
title = {Effective Particle Size From Molecular Dynamics Simulations in Fluids},
author = {Ju, Jianwei and Welch, Paul Michael Jr. and Rasmussen, Kim Orskov and Redondo, Antonio and Vorobieff, Peter and Kober, Edward Martin},
abstractNote = {Here, we report molecular dynamics simulations designed to investigate the effective size of colloidal particles suspended in a fluid in the vicinity of a rigid wall where all interactions are defined by smooth atomic potential functions. These simulations are used to assess how the behavior of this system at the atomistic length scale compares to continuum mechanics models. In order to determine the effective size of the particles, we calculate the solvent forces on spherical particles of different radii as a function of different positions near and overlapping with the atomistically defined wall and compare them to continuum models. This procedure also then determines the effective position of the wall. Our analysis is based solely on forces that the particles sense, ensuring self-consistency of the method. The simulations were carried out using both Weeks–Chandler–Andersen and modified Lennard-Jones (LJ) potentials to identify the different contributions of simple repulsion and van der Waals attractive forces. Upon correction for behavior arising the discreteness of the atomic system, the underlying continuum physics analysis appeared to be correct down to much less than the particle radius. For both particle types, the effective radius was found to be ~0.75σ, where σ defines the length scale of the force interaction (the LJ diameter). The effective “hydrodynamic” radii determined by this means are distinct from commonly assumed values of 0.5σ and 1.0σ, but agree with a value developed from the atomistic analysis of the viscosity of such systems.},
doi = {10.1007/s00162-017-0450-0},
journal = {Theoretical and Computational Fluid Dynamics},
number = 2,
volume = 32,
place = {United States},
year = {Fri Dec 08 00:00:00 EST 2017},
month = {Fri Dec 08 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1007/s00162-017-0450-0

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