Role of solid-liquid interaction energy on anomalous thermal conductivity enhancement in well-dispersed dilute nanofluids studied by equilibrium molecular dynamics

In this study, Green-Kubo formulism was employed to quantitatively assess thermal conductivity of nanofluids with different solid-liquid interaction energy. Anomalous thermal conductivity enhancement was observed in well-dispersed dilute nanofluids with strong solid-liquid interaction energy. The simulation results indicated that solid-liquid interaction is the key factor for the understanding of the heat conduction mechanism in nanofluids. Green-Kubo theory and Brownian motion were studied in detail to derive the physical origin of thermal conductivity enhancement. The results suggested that the phonons across the solid-liquid interface or micro-convection induced by Brownian motion of nanoparticles is responsible for thermal conductivity enhancement. In addition, a wide range of thermal conductivity enhancement and nonlinear increasing with volume fraction was observed, which is consistent with experiment investigations. The effect of solid-liquid interaction energy on the viscosity of nanofluids was also studied and was found to be an insignificant factor. Our results indicated that the nanofluids with strong solid-liquid interaction energy should have more significant application potential.