A multiscale theory to determine thermodynamic properties of confined fluids

Motevaselian, Mohammad Hossein

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https://hdl.handle.net/2142/88082 Copy

Description

Title

A multiscale theory to determine thermodynamic properties of confined fluids

Author(s)

Motevaselian, Mohammad Hossein

Issue Date

2015-07-21

Director of Research (if dissertation) or Advisor (if thesis)

Aluru, Narayana R.

Department of Study

Mechanical Science & Engineering

Discipline

Mechanical Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• confined nanofluids
• Empirical potential-based quasi-continuum theory (EQT)
• classical density functional theory (cDFT)
• molecular dynamics (MD)
• confined mixture
• thermodynamic properties

Abstract

Empirical potential-based quasi-continuum theory (EQT) provides a route to incorporate atomistic detail into a continuum framework such as the Nernst- Planck equation. EQT is a simple and fast approach to predict inhomogeneous density and potential profiles of confined fluids. EQT potentials can be used to construct a grand potential functional for classical density functional theory (cDFT). The combination of EQT and cDFT provides a robust and accurate approach to predict the structure and thermodynamic properties of confined fluids at multiple length-scales, ranging from few Angstroms to macro meters. In this work, first, we demonstrate the EQT-cDFT approach by simulating sin- gle component Lennard-Jones (LJ) fluids, namely, methane and argon, confined inside slit-like channels of graphene. For these systems, we show that the EQT- cDFT can accurately predict the structure and thermodynamic properties, such as density profiles, adsorption, local pressure tensor, surface tension, and solva- tion force of confined fluids as compared to the MD simulation results. Next, we extend the EQT-cDFT approach to confined fluid mixtures and demonstrate it by simulating a mixture of methane and hydrogen inside slit-like channels of graphene. We show that the EQT-cDFT predictions for the structure of the confined fluid mixture compare well with the MD simulations results. In addi- tion, our results show that graphene slit nanopores exhibit a selective adsorption of methane over hydrogen.

Graduation Semester

2015-8

Type of Resource

text

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http://hdl.handle.net/2142/88082

Copyright and License Information

Copyright 2015 Mohammad Hossein Motevaselian

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