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Heat and Mass Transfer

, Volume 54, Issue 3, pp 785–791 | Cite as

A molecular dynamics study of liquid layering and thermal conductivity enhancement in nanoparticle suspensions

  • J. Paul
  • A. K. Madhu
  • U. B. Jayadeep
  • C. B. Sobhan
  • G. P. Peterson
Original
  • 206 Downloads

Abstract

Liquid layering is considered to be one of the factors contributing to the often anomalous enhancement in thermal conductivity of nanoparticle suspensions. The extent of this layering was found to be significant at lower particle sizes, as reported in an earlier work by the authors. In continuation to that work, an investigation was conducted to better understand the fundamental parameters impacting the reported anomalous enhancement in thermal conductivity of nanoparticle suspensions (nanofluids), utilizing equilibrium molecular dynamics simulations in a copper-argon system. Nanofluids containing nanoparticles of size less than 6 nm were investigated and studied analytically. The heat current auto-correlation function in the Green-Kubo formulation for thermal conductivity was decomposed into self-correlations and cross-correlations of different species and the kinetic, potential, collision and enthalpy terms of the dominant portion of the heat current vector. The presence of liquid layering around the nanoparticle was firmly established through simulations that show the dominant contribution of Ar-Ar self-correlation and the trend displayed by the kinetic-potential cross-correlation within the argon species.

Nomenclature

U

Interatomic potential

k

Thermal conductivity

V

Volume

T

Temperature

kB

Boltzmann constant

J

Heat current vector

Ei

Total energy of atom i

h

Partial enthalpy of the system

N

Total number of atoms

rij

Distance between atoms i and j

Fij

Force exerted on atom i by j

vi

Velocity of i th atom

t

Time

Greek letters

ε

Depth of the potential well

σ

Finite distance at which U = 0

α, β

Different species in the system

Subscripts

i,j

The atom’s indices

s

Solid

l

Liquid

sl

Solid - liquid

Superscripts

*

Reduced units

k, l

Number of atoms in a species

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Copyright information

© Springer-Verlag GmbH Germany 2017

Authors and Affiliations

  • J. Paul
    • 1
  • A. K. Madhu
    • 1
    • 2
  • U. B. Jayadeep
    • 3
  • C. B. Sobhan
    • 1
  • G. P. Peterson
    • 4
  1. 1.School of Nano Science and TechnologyNational Institute of TechnologyCalicutIndia
  2. 2.Department of Mechanical EngineeringCollege of EngineeringAdoorIndia
  3. 3.Department of Mechanical EngineeringNational Institute of TechnologyCalicutIndia
  4. 4.School of Mechanical EngineeringGeorgia Institute of TechnologyAtlantaUSA

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