Lattice Boltzmann simulation of temperature jump effect on the nanofluid heat transfer in an annulus microchannel

Abstract

In this study, laminar forced convection heat transfer of water-alumina nanofluid flow inside an annular microchannel in slip flow regime is investigated by lattice Boltzmann method. Uniform velocity and temperature distributions are assumed at the microchannel inlet. Internal wall is insulated and outer wall is heated uniformly with constant heat flux. In both models that are used to express the kinematic viscosity and thermal conductivity of the nanofluid, the effects of nanoparticles size and Brownian motion are considered. A lattice-Boltzmann computer code is developed and the results are compared with the existing analytical solutions in the literature. In this paper, the effect of various parameters such as nanoparticles volume fraction (0–0.05), diameter (10–100 nm), microchannel radius ratio (0.2–0.8), Reynolds number (5, 10 and 50) and the slip factor (0.005–0.1) on the flow and temperature field are studied. Furthermore, variations of slip velocity, temperature jump, friction factor and Nusselt number along the walls are provided. Results indicate that higher slip factor, radius ratio, Re and volume fractions and also smaller particle diameters, increases the Nusselt number. Also slip velocity and temperature jump increases with slip factor. Nanoparticles volume fraction doesn't have significant effect on slip velocity, while increases the temperature jump.