Enhanced heat transfer and flow analysis in a backward-facing step using a porous baffle

The backward-facing step or the sudden expansion in internal flows is an important problem in different areas. In this study, a porous baffle is mounted on the opposite wall of a sudden expansion to enhance heat transfer near the step. Unlike the solid baffle, which is extensively studied in the literature, the porous baffle has a lower pressure drop, and its properties can be tuned to reach the optimal prospected performance. Effects of different porous baffle geometrical parameters including its normalized height (H_b = 0.5, 1.0, 1.5, 1.75), width (W_b = 0.5, 1, 1.5, 2.0, 2.5), porous baffle-step relative distance (D = 1, 2, 3, 4), Darcy number (10⁻², 10⁻³, 10⁻⁴, 10⁻⁶), and Reynolds number (100, 200, 300, 400, 500) on the heat transfer and pressure drop are investigated. The simulation indicates that higher Reynolds numbers enhance more the heat transfer (35% improvement at Re = 500 with respect to 10% at Re = 100). Also, longer baffles can lead to higher heat transfer rates (5% improvement in H_b = 0.5 with respect to 32% at H_b = 1.5).