A note on the variation of nanofluid viscosity with temperature

The variation with temperature of the effective viscosity of a nanofluid, together with the effect of particle size on this quantity, is discussed. The analysis of available experimental correlations suggests that the effect of the particle size is approximately independent of the temperature, and increases the viscosity by an amount that decreases with the increase of size. Physically, we expect that this happens because increased size means fewer particles per unit volume, which results in decreased interference with the rate at which fluid molecules reorganise themselves in groups.