Study of particle migration and deposition in mixed convective pipe flow of nanofluids at different inclination angles

Abstract

Mixed convection flow of aluminium-oxide nanoparticles in water through a circular tube was modelled using the discrete phase model and implemented on ANSYS-Fluent 17.0 through customised user-defined functions. The inclination angle was varied to study its effect on the migration and deposition of the nanoparticles. Experimentally determined thermo-physical properties were used in the analysis instead of theoretical or empirical models from the literature. Varying inclination angles were found to significantly affect the migration and deposition of nanoparticles. A critical angle of maximum deposition of approximately 30° was found for volume concentrations 1%, 3% and 5%. The effect of varying inclination angle on the heat transfer coefficient was minimal for low angles of inclination between 0 and 35% and decreased significantly after 40%. The effect of Saffman’s lift, thermophoretic, Magnus and Brownian effects were also investigated, and results show that thermophoretic and Brownian effects were most dominant effects.