Numerical investigation of heat transfer enhancement in a backward-facing step channel using jet injection and Al₂O₃/CMC nanofluids

Authors

https://doi.org/10.48314/nna.vi.65

Abstract

This study numerically investigates heat transfer enhancement in a Backward-Facing Step (BFS) channel subjected to jet injection using a non-Newtonian Aluminum Oxide/Carboxymethyl Cellulose (Al₂O₃/CMC) nanofluid. The flow is assumed to be steady, laminar, incompressible, and two-dimensional. The rheological behavior of the CMC solution is modeled using the power-law model, while the governing equations of mass, momentum, and energy are solved using the Finite Volume Method (FVM). The effects of Reynolds number, jet injection angle, jet momentum ratio, nanoparticle volume fraction, and fluid rheology on flow structure and thermal performance are systematically analyzed. The numerical model is first validated against previously published experimental and numerical data, showing good agreement. The results indicate that increasing the Reynolds number significantly enhances convective heat transfer due to stronger recirculation and thinner thermal boundary layers. The use of a non-Newtonian CMC solution improves thermal performance compared with Newtonian water, while the addition of Al₂O₃ nanoparticles further increases the heat transfer rate because of enhanced effective thermal conductivity. The jet injection parameters strongly affect the flow field and thermal characteristics. Appropriate jet injection angles and momentum ratios intensify fluid mixing near the heated wall and lead to substantial heat transfer enhancement. The thermal-hydraulic Performance Evaluation Criterion (PEC) demonstrates that the combined use of jet injection and Al₂O₃/CMC nanofluids can provide superior overall performance compared with conventional cooling configurations. The findings confirm the potential of jet-assisted non-Newtonian nanofluids for improving thermal management in BFS channels and similar engineering systems.           

Keywords:

Carboxymethyl cellulose, Nanofluid, Jet injection, Reynolds number, Heat transfer enhancement, Nusselt number

References

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Published

2026-06-15

Issue

Vol. 1 No. 2 (2026): Nano Nexus & Applications (NNA)

Section

Articles

How to Cite

Bozorgimanesh, A. . (2026). Numerical investigation of heat transfer enhancement in a backward-facing step channel using jet injection and Al₂O₃/CMC nanofluids. Nano Nexus & Applications, 1(2), 127-143. https://doi.org/10.48314/nna.vi.65