Numerical simulation of thermal conductivity of aqueous nanofluids containing graphene nanosheets using molecular dynamics simulation

Abstract

In this work, The Equilibrium Molecular Dynamics (EMD) is applied for computing the thermal conductivity of aqueous nanofluids containing graphene nanosheets (aqueous GNFs), through Green-Kubo framework and studying the effects of concentration and temperature on thermal conductivity enhancement of aqueous GNFs. The SPC/E water model was chosen and the interactions for water molecules have been modelled by the Lennard-Jones (L-J) potential combined with Coulomb potential, as well as a simple body (L-J) potential is used to model the interactions between graphene atoms. The numerical calculations of thermal conductivity are performed in the temperature range of 293-343K and for graphene nanosheets volume fraction 0.175%, 0.190%, 0.306%, 0.521% and 0.722%. Firstly, the molecular dynamics code and the Green-Kubo framework are validated by comparing the thermal conductivity with the previous experimental studies. The results have showed that the thermal conductivity enhancement increases with increasing volume concentration and is substantial even at lower concentrations. However, this enhancement has been not predicted by the classical Maxwell's model. Furthermore, the enhancement depends on temperature, especially, the thermal conductivity of aqueous nanofluids containing graphene nanosheets (aqueous GNFs) increases with increasing system temperature.

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