Convective Heat Transfer and Resistance Characteristics of Nanofluids with Cylindrical Particles

Numerical research on convective heat transfer and resistance characteristics of TiO2/water nanofluids with cylindrical particles in laminar channel flow are performed by solving the governing equations of fluid flow with the additional term of cylindrical nanoparticles, the equation of probability density functions for cylindrical nanoparticle orientation, and general dynamics equation for nanoparticle volume concentration. The nonuniformity of nanoparticle distribution is considered and the effects of both particle volume concentration and Reynolds number on friction factor and local Nusselt number are mainly analyzed. The results show that the friction factor of nanofluid flow increases with an increase in particle volume concentration. And the friction factor decreases with increasing Reynolds number and is not dependent on the volume concentration at high Reynolds numbers. The Nusselt number declines when the Reynolds number decreases, and finally approaches an asymptotic value after the Reynolds number falls to a certain value. The Nusselt number is higher in the entrance region than at the downstream locations, and will become steady at somewhere downstream when the flow is thermally and hydraulically developed.