Numerical Simulation of Laminar and Two-Phase Flow and Heat Transfer of Water-Aluminum Oxide Nanofluid in Microchannel with V-Shaped Ribs

Abstract

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 (phi) = 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 alpha, the wake area increases. By increasing alpha, the vortices and velocity gradients separated from the ribs' surfaces penetrate the central core of the flow. At alpha = 50 degrees, because the fluid collides with the ribs, it is associated with a greater velocity drop and the creation of stronger vortices, so Cf has the highest value. In the ribbed region and for alpha = 40 degrees to alpha = 50 degrees, the changes in local Nusselt number are similar. By increasing phi, the penetration of fluid to the back of the ribs becomes possible; In these diagrams, the minimum amount of Sgen is for alpha = 40 degrees and 50 degrees. In general, the behavior of Sgen is the same as the growth of dimensionless temperature, and at Re= 400, the maximum amount of Sgen is related to alpha = 20 degrees.