Mixed Convection of an Ag/Water Nanofluid in a Ventilated Square Cavity Containing Cold Blocks of Different Shapes

This research presents the results of a numerical study on mixed convection in a ventilated cavity with a central cold block of varying shapes. The direction of the forced flow of Ag/water nanofluid is perpendicular to the transverse axis (y) of the central cold block. Mixed convection is induced by cooling at the entrance of the ventilated cavity and uniformly heating its bottom wall. The governing equations for the flow of an incompressible Newtonian nanofluid are assumed to be two-dimensional, steady, and laminar. The finite volume method is employed for numerical simulations. A series of calculations are conducted to investigate the effects of key influencing factors: Reynolds number (Re = 100), Richardson number (Ri = 1), and nanoparticle volume fractions (0 ≤ ∅ ≤ 8%) on the enhancement of heat transfer. The impact of four different geometric shapes of the cold obstacle (circular, square, triangular, and elliptical) on fluid flow and heat transfer rate is also explored. The results indicate that an increase in nanoparticle volume fraction enhances the heat exchange rate in the cavity only when the geometric shape of the cold obstacle is circular. This is followed by square and triangular shapes, which approximately yield concordant results, and then the elliptical shape.