Numerical investigation of flow and heat transfer behind a two-dimensional backward-facing step equipped with a semi-porous baffle

Abstract

The backward-facing step is a critical problem existing in many engineering and industrial applications. In this study, a semi-porous baffle (the root of the baffle is a porous medium and the tip is solid) is placed behind the step. The effects of the length of the porous part, and the baffle location on the energy transfer and pressure drop are studied in different Reynolds numbers (Re=100, 200, 300, 400, 500). The effect of the Darcy number of the porous medium on the aforementioned parameters is also investigated. Both the local maximum and average relative Nusselt numbers (divided by the Nusselt of the base case with no baffle at the same Reynolds) and relative pressure drop (calculated as the relative Nusselt number) are reported. The results show that by adoption of the proper length of the porous medium, the average relative and maximum local Nusselt numbers could be enhanced by 20% and 90%, respectively. Low permeable porous media give better energy transfer. For example, porous media with Da=10⁻⁵ give 30% better maximum local Nusselt number and about 7% higher average Nusselt number with respect to the same case with Da=10⁻².

Keywords

porous media / enhanced heat transfer / baffle / backward-facing step / two-dimensional channel

References

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