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In this paper, the forced convection heat transfer of Ag–MgO/water hybrid micropolar nanofluid in a channel is studied numerically which the top wall of channel is smooth and bottom of it is in stairway form. The lattice Boltzmann method (LBM) is used for solving the fluid flow and heat transfer equations. The effects of Reynolds numbers (R e = 1 0 0 –400), volume fraction of nanofluid (ϕ = 0 , 0.01 and 0.02) and stairway aspect ratio (a ∕ H = 0. 1 , 0.2 and 0.3) on the velocity, temperature and local and average Nusselt number profiles are investigated. The results show that by incrementing the Reynolds number and solid volume fraction and decreasing the a / H simultaneously, the average Nusselt number increases. [ABSTRACT FROM AUTHOR]

In this study, lattice Boltzmann method (LBM) simulation is performed to investigate laminar forced convection of nanofluids in a horizontal parallel-plate channel with three rectangular cavities. Two cavities are considered as located on the top wall of the channel and one on the bottom wall. The effects of the Reynolds number (100–400), the cavity aspect ratio (AR = 0.25, 0.5), the various distances of the cavities from each other ( X c ′ ) at different solid volume fractions of nanofluids (ϕ = 0 − 0. 0 5) on the velocity and the temperature profiles of the nanofluids are studied. In addition, the flow patterns, i.e. the deflection and re-circulation zone inside the cavities, and the local and averaged Nusselt numbers on the channel walls are calculated. The results obtained are used to ascertain the validity of the written numerical code, which points to the excellent agreement across the results. The results show that, as the solid volume fraction of nanofluids is enhanced, the transfer of heat to working fluids increases significantly. Further, the results show that the maximum value of the averaged Nusselt number in the channel is obtained at X c ′ = 0. 1 2 0 4 for AR = 0.5 and X c ′ = 0. 1 0 2 4 for AR = 0.25. The interval [0.1224, 0.1304] is the best position for the second cavity. It is concluded that the results of this paper are very useful for designing optimized heat exchangers. [ABSTRACT FROM AUTHOR]

The aim of this paper is investigating the forced convection heat transfer in a channel with transverse rectangular cavities using the lattice Boltzmann method (LBM) which is not available in the literature yet. The effects of the Reynolds number (100-400), cavity aspect ratio (, 0.5, 1.0), distance of cavities from each other () in fixed depth of cavity () on the velocity and temperature profiles are studied. Moreover, the flow patterns such as deflection and re-circulation zone inside the cavities are obtained. The local and averaged Nusselt numbers on the channel walls are achieved. The results show that the channel with cavities achieves heat transfer enhancements relative to the smooth channel. For the constant cavity aspect ratio, the maximum value of averaged Nusselt number in the channel is obtained in the case of . Heat transfer to the working fluids increases significantly by increasing the aspect ratio. The existed results are used to ascertain the validity of the numerical code and excellent agreement between results was found. [ABSTRACT FROM AUTHOR]