A two-component nanofluid has a third component.
Silver changes the water closest to its surface. Counting that dense nanolayer explains why a conventional mixture rule misses both the fluid’s density and its resistance to flow.
Journal of Molecular Liquids · 2018 · MM Heyhat, A Rajabpour, M Abbasi, S Arabha
The liquid near a particle is a distinct region
Water near a silver nanoparticle forms an ordered interfacial layer. If that layer occupies a meaningful fraction of the fluid, treating a nanofluid as only “particles plus bulk water” can misstate its density and viscosity.
Does explicitly accounting for the interfacial nanolayer improve predictions of silver–water nanofluid properties?
Build the mixture from its molecular structure
Equilibrium molecular dynamics was used to study silver particles dispersed in water. The authors represented the mixture as three components—the nanoparticle, its ordered water nanolayer, and the remaining base fluid—and compared this model with simulation data and conventional mixture relations.
Equilibrium molecular dynamics first checks pure-water density and viscosity against reference data over 25–65 °C. It then measures radial water density around silver particles and evaluates nanofluid density and viscosity. Density comparisons use an initial nanoparticle volume fraction of 0.04. The ternary model is tested with bulk constituent properties and, separately, with constituent values obtained from the same molecular model.
Key findings
Interfacial structure
The water density returns toward bulk over roughly 1 nm, with the strongest change within about 0.3 nm.
Density model
Accounting for particle, nanolayer, and remaining liquid improves the density prediction; consistent constituent inputs improve it further.
Viscosity consequence
Shell-aware viscosity models follow the molecular concentration trend more closely than models without the interfacial layer.
Count the interfacial liquid as part of the mixture
The interfacial water layer is a distinct part of the mixture; including it gives a more faithful route from molecular structure to density and viscosity.
The work provides a molecular basis for revising simple mixture relations. Its practical contribution is a model in which the organized liquid at the particle surface has an explicit role in the fluid’s properties.