Dependence of the viscosity of nanofluids on nanoparticle size and material

•The viscosity of nanofluids is modeled and analyzed.•The nanofluid viscosity coefficient depends on the nanoparticle size.•The viscosity of the nanofluid increases with decreasing nanoparticle size.•The viscosity of the nanofluid depends on the nanoparticle material.

The viscosity of nanofluids as a function of nanoparticle size and material is modeled and analyzed. Dependences of the viscosity of nanofluids based on liquid argon with aluminum and lithium nanoparticles are obtained. The nanoparticle size ranges from 1 to 4 nm. The volume concentration of nanoparticles is varied from 1% to 12%. It is shown that the viscosity of the nanofluid increases with decreasing nanoparticle size and, in addition, depends on the nanoparticle material.