Molecular dynamics simulation of viscosity and rheology of nanofluids with single wall carbon nanotubes

Novosibirsk State University of Architecture and Civil Engineering (Sibstrin), Leningradskaya, 113, Novosibirsk, 630008, Russia

^* Corresponding author: rafalskaya.ta@yandex.ru

Abstract

The purpose of this work is to study the dependence of the viscosity and rheology of benzene-based nanofluids with carbon nanotubes on their length. The problem is solved by the method of nonequilibrium molecular dynamics; the rheology of nanofluids with single-walled carbon nanotubes with a length from 1.45 to 14.96 nm has been studied. The volume concentration of nanotubes was 2 %. It was established that at low shear rates nanofluids are Newtonian. Their viscosity significantly exceeds the viscosity of benzene, and this excess is not described by classical theories for coarse liquids. In addition, the viscosity of nanofluids significantly depends on the length of the carbon tubes and increases with their growth. Starting from a certain shear rate, nanofluids change rheology and become pseudoplastic. Thus, the change in rheology is a threshold phenomenon and the corresponding critical shear rates depend on the length of the nanotubes. At high shear rates, the differences between the viscosities of nanofluids with different nanotube lengths decrease monotonically. A correlation has been obtained that makes it possible to predict the viscosity of the nanofluid and the trend of its change depending on the shear rate and the length of the nanotubes.