For the adiabatic boundary condition, the gradient

of the dependent variable normal to the boundary should be zero, i.e., ∂ φ/∂ y = 0. The distribution functions are found to be in the following form [15]: (11) A second-order extrapolation similar to the one given in [17] is used to obtain the values of the unknown distribution functions for the right-hand side boundary (channel outlet) as follows: (12) The local selleck chemicals llc Nusselt number (Nu x ) is computed using the following equation: (13) where L c is the characteristic length and ϕ wall is the wall constant temperature. The mean temperature ϕ m is given by: (14) The GSK872 ic50 effective density of the nanofluid is (15)where ϕ is the solid volume fraction. The effective dynamic viscosity of the nanofluid given by Brinkman [18] is (16) The thermal diffusivity of the nanofluid is (17) The heat capacitance of the nanofluid is (18) k eff is the effective thermal conductivity of the nanofluid and is determined using the model proposed by Patel et al.

[19]. For the two-component entity of spherical particle suspension, the model gives: (19) where k s and k f are the thermal conductivities of dispersed Al2O3 nanoparticles and pure water. (20) where u s is the Brownian motion velocity of the nanoparticles given by: (21) where k b = 1.3087×10−23JK−1 is the Boltzmann GSK126 constant. Results and discussion Code validation and computational results For the purpose to ensure that the obtained results are proper and that the code is free of errors, a flow of cold air in a two-dimensional heated channel was taken as a benchmark test. Both upper and lower walls were heated. The comparisons were carried up between the dimensionless velocity and temperature fields at different locations in the channel as shown

in Figures  3 and 4. The obtained results were found to be identical to the results of [20]. Figure 3 Velocity and profiles at different cross sections. Figure 4 Temperature profiles at different cross sections. Figure 5 shows the effect of Reynolds on the temperature profiles at the same cross sections for Re = 10, 50, and 100. The figures depicted that the many temperature profiles are less sensitive to the change in Reynolds compared to the velocity profiles. Figure 5 Velocity and temperature profiles at different Re. The effects of the Reynolds number and the solid volume fraction on the heat transfer, isotherms, and streamlines are studied. Figure 6 presents the streamlines and the isotherms for the Al2O3-water nanofluid (ϕ = 0.05) and pure water at different Reynolds number (Re = 10, 50, and 100). Figure 6 Streamlines and isotherms for the Al 2 O 3 -water nanofluid and pure water at different Reynolds number. (A) Streamline plots at (a) Re = 10, (b) Re = 50, and (c) Re = 100. (B) Isotherm plots at Re = 10 and (a) φ = 0.0 and (b) φ = 0.05. (C) Isotherm plots at Re = 50 and (a) φ = 0.