Molecular Dynamics Study of Energy Transport Mechanism in Nanofluids: Spatial and Component Decompositions of Effective Thermal Conductivity

Nanofluids, which are nanoparticle-suspended fluids, have gathered extensive attention for decades. Yet, the energy transport mechanism of nanofluids has not been comprehensively understood. The present study employs spatial and component decompositions of the effective thermal conductivity (ETC), and numerically investigates the energy transport mechanism of nanofluids, with a focus on influence of liquid layering (i.e., the adsorption layer of the fluid molecules) around nanoparticles. The local ETC of the nearest adsorption layer increases as the nanoparticle wettability improves, but this value has a certain upper limit. Compared with the case of the nearest adsorption layer, the local ETC of the liquid, except for the adsorption layers, gently increases as the nanoparticle wettability improves. However, a main contribution to the ETC component contributed by the liquid is the change in the local ETC of the liquid, except for the adsorption layers, since its volume fraction is relatively large. In conclusion, as a whole, the nanofluid's ETC is mainly determined by the change in the ETC component contributed by the liquid.