Molecular dynamics study of the thermal conductivity in nanofluids

TL;DR

This study uses molecular dynamics simulations to investigate how nanoparticle concentration affects the thermal conductivity of nanofluids, revealing that only low volume fractions enhance conductivity.

Contribution

It introduces a detailed simulation approach combining EMD and NEMD to analyze nanofluid thermal conductivity, considering nanoparticle dispersion and aggregation effects.

Findings

Low volume fractions (2-3%) increase conductivity.

Nanoparticle aggregation does not significantly affect conductivity.

Higher volume fractions do not enhance thermal conductivity.

Abstract

We evaluate the thermal conductivity of a model nanofluid at various volume fractions of nanoparticles with equilibrium (EMD) and non-equilibrium (NEMD) molecular dynamics simulations. The Green-Kubo formalism is used for the EMD simulations while a net heat flux is imposed on the system for the NEMD simulations. The nanoparticle-nanoparticle, fluid-fluid and fluid-nanoparticle interactions are all taken as Lennard-Jones potentials. An empirical parameter is added to the attractive part of the potential to control the hydrophilicity of the nanoparticles, hence controlling how well dispersed are the nanoparticles in the base fluid. The results show that the aggregation of the nanoparticles does not have a measurable effect on the conductivity of the nanofluid. Nanofluids with volume fractions of 2% and 3% show an enhanced conductivity with respect to the bulk fluid. Surprisingly, nanofluids with higher volume fractions did not show any enhancement of the conductivity.