Numerical modeling and simulation of heat transfer and fluid flow in a two-dimensional sudden expansion model using porous insert behind that

A sudden expansion is a classical problem which is happened in different industries such as energy conversion, environmental control, and chemical processing. The current investigation is done to numerically analyze the fluid flow behavior and heat transfer over a sudden expansion when a porous medium is placed right after that. Effect of different parameters including Reynolds number (Re = 100, 200, 300), porous block height (D/H = 0.1, 0.2, 0.3, 0.4, 0.5), porous block length (L/H = 0.5, 1.0, 1.5, 2.0), and solid matrix-fluid thermal conductivity ratio (RK = 1, 10, 10(2), 10(3), and 10(4)) on the heat transfer and pressure drop are examined. Results show that the average Nusselt number and performance number (the ratio of Nusselt number improvement to pressure drop increment) on the heated wall, located after the expansion, enhanced when Reynolds number rises (about 40% in Nusselt number at Re = 300). As well as, the results show that even low-permeable porous media could augment heat transfer at the expense of a little higher pressure drop (PN = 0.94 and about 16% better Nusselt number atL/H = 15,D/H = 0.5, Re = 300). The main achievement of this paper is that if the porous cover permeability is tuned, a good heat transfer enhancement could be achieved.