Abstract:In this study, divided into two parts, the effect on a two-dimensional backward-facing step flow (BFSF) of a cylinder placed downstream of the step was numerically investigated. While in Part 1, the numerical simulations carried out without the cylinder were validated using the available literature data, in Part 2 the effect of the cylinder was investigated. In the laminar regime, different Reynolds numbers were considered. In the turbulent regime, the effects on the flow structure of a cylinder placed at diff… Show more
“…Their results suggested an increase in heat transfer and a decrease in reattachment length with the use of non-rotating cylinders. Abdollahpour et al [21] conducted an analysis of the effect of the cylinder on the flow over a backward-facing step channel, finding an increase in the skin friction coefficient in the recirculation zone with the use of a cylinder.…”
This study presents a numerical investigation of laminar forced convective flow through a backward-facing step channel integrated with an oval rib, spanning a Reynolds number range of 200-1000. Two-dimensional governing equations of continuity, momentum, and energy were solved in body-fitted coordinates employing the finite volume approach. The investigation sought to elucidate the effects of rib height, rib location, and the Reynolds number on key parameters including the reattachment length, friction factor, total entropy generation, average Nusselt number, and the hydrothermal performance factor. Results demonstrated that both the average Nusselt number and the total entropy generation exhibited an increase with the augmentation of rib height, and conversely, a decrease with the expansion of the step-to-rib distance. In addition, the friction factor was found to increase in proportion to the distance between the rib and the step, and decrease with the rise in rib height, particularly when the Reynolds number exceeded 400. Furthermore, the reattachment length of the primary vortex was observed to increase with the step-to-rib distance and decrease with the rib height. The study concludes that a backward-facing step channel utilizing an oval rib, with a rib height of 0.3 and a rib-to-step distance of 2, delivers an optimal performance factor around 2.1 at a Reynolds number of 400. Therefore, the implementation of the oval rib in a backward-facing step channel is recommended for high thermal performance and compact heat exchanger design.
“…Their results suggested an increase in heat transfer and a decrease in reattachment length with the use of non-rotating cylinders. Abdollahpour et al [21] conducted an analysis of the effect of the cylinder on the flow over a backward-facing step channel, finding an increase in the skin friction coefficient in the recirculation zone with the use of a cylinder.…”
This study presents a numerical investigation of laminar forced convective flow through a backward-facing step channel integrated with an oval rib, spanning a Reynolds number range of 200-1000. Two-dimensional governing equations of continuity, momentum, and energy were solved in body-fitted coordinates employing the finite volume approach. The investigation sought to elucidate the effects of rib height, rib location, and the Reynolds number on key parameters including the reattachment length, friction factor, total entropy generation, average Nusselt number, and the hydrothermal performance factor. Results demonstrated that both the average Nusselt number and the total entropy generation exhibited an increase with the augmentation of rib height, and conversely, a decrease with the expansion of the step-to-rib distance. In addition, the friction factor was found to increase in proportion to the distance between the rib and the step, and decrease with the rise in rib height, particularly when the Reynolds number exceeded 400. Furthermore, the reattachment length of the primary vortex was observed to increase with the step-to-rib distance and decrease with the rib height. The study concludes that a backward-facing step channel utilizing an oval rib, with a rib height of 0.3 and a rib-to-step distance of 2, delivers an optimal performance factor around 2.1 at a Reynolds number of 400. Therefore, the implementation of the oval rib in a backward-facing step channel is recommended for high thermal performance and compact heat exchanger design.
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