CFD study of obstacle orientation and arrangement effects on thermo-hydraulic performance in turbulent channel flow

This numerical study analyzes the improvement in forced-convection heat transfer in a two-dimensional rectangular channel subjected to turbulent airflow in the presence of detached obstacles. Two distinct parametric tests were conducted to investigate the thermo-hydraulic performance of the channel. Test 1 examines the effect of the orientation of a V-shaped inclined obstacle, considering three configurations: upstream-facing, downstream-facing, and vertical (reference) orientations. Test 2 focuses on the influence of the number of successive vertical obstacles arranged at a constant spacing. This dual approach underscores the novelty of the present study by systematically evaluating the combined effects of geometric orientation and spatial configuration on heat transfer enhancement and pressure drop characteristics. Simulations were performed over a Reynolds number range of 10,000–30,000, using the Reynolds-Averaged Navier-Stokes (RANS) equations coupled with the energy equation, solved by the finite volume method using ANSYS Fluent software. The RNG k–ε turbulence model is adopted to accurately represent the separation, recirculation, and mixing phenomena induced by obstacles. The results show that the orientation of the obstacles in Test 1 significantly alters the flow structure and the intensity of heat transfer. The vertical obstacle generates larger recirculation zones and high velocity gradients, leading to the highest local Nusselt number values, at the cost of increased head loss. Furthermore, at higher Reynolds numbers, Case C achieved a thermal optimization factor approximately 14% greater than that of Case B and 9% greater than that of Case A, demonstrating its superior thermo-hydraulic performance under high-flow-rate conditions. In Test 2, increasing the number of vertical obstacles results in a cumulative intensification of heat transfer, associated with repeated destruction of the thermal boundary layer and an increase in local turbulence. However, this thermal improvement is accompanied by increasing hydraulic penalization, highlighting the existence of a thermo-hydraulic trade-off. This study thus underscores the key role of obstacle geometry and configuration in optimizing heat transfer in turbulent channels.