Non-trivial Thermal and Rheological Behaviour of Complex Nanofluids in Bifurcated Micro-confinements

Abstract

The transport properties of nanofluids widely differ contingent on several factors, starting from the base fluid properties to the nanoparticle inclusion-induced rheological behavioural changes of the nanofluids. Inclusion of nanoparticle alter the fluid and flow behaviour, often to an extent of altering the constitutive properties of the fluid including rheology. We unveil the impact non-intuitive rheological properties on the thermal behaviour of nanofluids. We demonstrate that the non-Newtonian nanofluid behaviour can offer superior heat transfer performance compared to base fluid in a bifurcated micro-confinement by suitably tuning the fluid properties. The non-Newtonian behaviour of a nanofluid with a range of concentrations of nanoparticles may portray non-trivial flow behaviour, resulting in a wide variety of thermal outcomes. Our study highlights the significant impact of fluid rheology on improving the heat transfer, for confined flows where pumping cost can be significant at low Reynolds number. We further demonstrate that an increase in the shear-thinning behaviour of fluids can lead to improved heat transfer performance up to a certain threshold. Beyond this threshold, further increases in shear-thinning behaviour may cause a decrease in heat transfer performance involving non-trivial flow asymmetry in a bifurcated channel system. Overall, this research for the first time provides insights into the unique heat transfer properties of non-Newtonian rheology involving nanofluids and highlights their potential as an efficient coolant for bifurcated micro-confinements. The findings could contribute to the advancement effective cooling systems in various industrial applications with the interplay of the effects of nanoparticle inclusion and rheological properties.