Modeling thermal conductivity and collective effects in a simple nanofluid

Molecular dynamics simulations are used to simulate the thermal properties of a model fluid containing nanoparticles (nanofluid). The flexibility of molecular simulation allows us to consider the effects of particle mass, particle-particle and particle-fluid interaction and the spatial distribution of the particles on the thermal conductivity. We show that the heat conductivity of a well dispersed nanofluid is well described by the classical Maxwell Garnet equation model. In the case of particle clustering and strong inter particle interaction the conductivity can be again described by effective medium calculation taking into account the aspect ratio of the cluster. Heat transfer is increased with particle alignment in the temperature gradient direction. This kind of collective effects can explain the observed substantial increase in the conductivity observed by experiment.