Numerical Investigation of Natural and Forced Convection Effects on the Thermal Performance of a Finned Heat Sink inside a Rectangular Duct

Abstract

Efficient thermal management is essential for electronic systems operating under high power densities and confined conditions. This study presents a three-dimensional numerical investigation of a finned heat sink mounted inside a rectangular duct under different convection modes and operating parameters. Natural and forced convection are examined together with laminar and turbulent flow regimes. The effects of heat dissipation rate (100–150 W) and inlet air temperature (25–50 °C) on thermal performance are systematically analyzed. The steady-state governing equations of mass, momentum, and energy are solved using the finite volume method, with turbulence modeled by the k–ω SST model. Flow structures and temperature fields are evaluated, and maximum and volume-averaged heat sink temperatures are used as performance indicators. The results show that natural convection leads to weak airflow and localized heat accumulation, resulting in the highest heat sink temperatures. Forced convection significantly improves cooling performance, while turbulent flow provides the lowest temperatures and the most uniform thermal distribution. Increasing heat dissipation rate raises heat sink temperature in all cases, whereas higher inlet air temperature degrades cooling effectiveness. Overall, forced turbulent convection is identified as the most effective cooling strategy for duct-based air-cooled electronic systems.

Keywords

• Computational fluid dynamics
• Electronic cooling
• Finned heat sink
• Natural and forced convection
• Laminar and turbulent flow
• Thermal performance

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