Numerical simulation of laminar and two-phase flow and heat transfer of water-aluminum oxide nanofluid in microchannel with V-shaped ribs

• A rectangular microchannel equipped with V-shaped ribs at the bottom, filled with a solid-liquid suspension of water-aluminum oxide, is evaluated. • The two-phase mixture method is used to simulate the incompressible water-aluminum oxide nanofluid. • Fluid in the areas after the ribs has reverse velocity gradients and by increasing α , the wake area increases. • By increasing α , the vortices and velocity gradients separated from the ribs’ surfaces penetrate the central core of the flow. • In the ribbed region and for α =40° to α =50°, the changes in local Nusselt number are similar. In this study, a rectangular microchannel equipped with V-shaped ribs at the bottom filled with a solid-liquid suspension of water-aluminum oxide is evaluated. To better estimate the movement of solid-liquid phases, the two-phase mixture method simulates the incompressible water-aluminum oxide nanofluid (NF). The results are obtained for different hydrodynamic and heat transfer values and volume fraction of solid nanoparticles (φ) = 0, 2, and 4% and Reynolds number (Re) = 400-1200. The finite volume method (FVM) in three-dimensional (3D) space is used for simulations. The results show that the fluid in the areas after the ribs has reverse velocity gradients and by increasing α, the wake area increases. By increasing α, the vortices and velocity gradients separated from the ribs’ surfaces penetrate the central core of the flow. At α = 50°, because the fluid collides with the ribs, it is associated with a greater velocity drop and the creation of stronger vortices, so C f has the highest value. In the ribbed region and for α = 40° to α = 50°, the changes in local Nusselt number are similar. By increasing φ, the penetration of fluid to the back of the ribs becomes possible; In these diagrams, the minimum amount of S gen is for α = 40° and 50°. In general, the behavior of S gen is the same as the growth of dimensionless temperature, and at Re= 400, the maximum amount of S gen is related to α = 20°.