Materials and Energy Research CenterInternational Journal of Engineering1025-2495311020181001Assessment of Particle-size and Temperature Effect of Nanofluid on Heat Transfer Adopting Lattice Boltzmann Model1749175982217ENA.ShahriariDepartment of Mechanical Engineering, University of Zabol, Zabol, IranN.JahantighDepartment of Mechanical Engineering, University of Zabol, Zabol, IranF.RakaniDepartment of Computer Sciences, University of Sistan & Baluchestan, Zahedan, IranJournal Article20171118The investigation of the effect of nanoparticles’ mean diameter and temperature of Al<sub>2</sub>O<sub>3</sub>–water nanoﬂuid on velocity and energy field using the lattice Boltzmann method is the main objective of this study. The temperature of the vertical walls is considered constant at T<sub>c</sub> and T<sub>h</sub>, respectively, while the up and the down horizontal surfaces are smooth and insulated against heat and mass. The inﬂuences of Grashof number (10<sup>3</sup>, 10<sup>4</sup>, 10<sup>5</sup>) Prandtl number (Pr=3.42, 5.83), the various volume fraction of nanoparticles (φ=0, 0.01, 0.03, 0.05) and particle-size (d<sub>p</sub>= 24, 47, 100 nm) were carried out on heat transfer and ﬂow fields. It was concluded that addition of nanoparticles causes a signiﬁcantly affect on temperature and flow fields. The decrement of heat transfer is observed with the increment of solid volume fraction, but it increases when Grashof number and nanoparticles’ mean diameter increase. The decrement of nanoparticles’ mean diameter and Prandtl number have the same effect on Nusselt number. In addition, it was resulted that the thermal conductivity model had insignificantly impact on the mean Nusselt number than the dynamic viscosity model.http://www.ije.ir/article_82217_f1d7eb41785622e5953406d3d0d32ca4.pdf