Open Access

ARTICLE

Basic Study on Heat Transfer Enhancement in Straight Fins by Pulsating Flow

Tomoya Kazumi^1,2, Kota Fujisawa¹, Kenta Emori², Takashi Fukue^1,*, Yasuhiro Sugimoto¹
1 Department of Mechanical Engineering, Kanazawa Institute of Technology, Ishikawa, Japan
2 Advanced Materials and Components Laboratory, Research Division, Nissan Motor Co., Ltd., Kanagawa, Japan
* Corresponding Author: Takashi Fukue. Email:

Frontiers in Heat and Mass Transfer https://doi.org/10.32604/fhmt.2026.088763

Received 09 July 2026; Accepted 03 September 2026; Published online 10 September 2026

Abstract

Efficient thermal management is essential for high-heat-flux electronic devices, where increasing power density and compact packaging impose strict requirements on cooling performance with minimal pressure drop. Pulsating flow has been proposed as a technique to enhance heat transfer; however, its effects on practical heat sink geometries remain insufficiently understood. This study investigates the thermal-hydraulic characteristics of pulsating flow in a multi-straight-fin heat sink operating in the laminar and transitional flow regimes (Re = 480–2400) through a combination of heat transfer experiments and three-dimensional Computational Fluid Dynamics (CFD) analyses. The effects of pulsation frequency, amplitude, and Reynolds number on heat-transfer and pressure-drop characteristics were evaluated using the mean Stanton number, friction coefficient, and performance evaluation criteria (PEC). The CFD model was validated against experimental measurements and used to analyze phase-resolved velocity and temperature fields. The results showed that pulsating flow can either enhance or deteriorate thermal performance depending on the pulsation conditions. Higher pulsation frequencies improved both the mean Stanton number and PEC, whereas lower frequencies reduced overall performance. The enhancement was most pronounced at an intermediate Reynolds number of approximately Re = 960. Increasing pulsation amplitude increased both heat transfer and pressure drop, resulting in little variation in PEC. Local heat-transfer evaluations demonstrated that the enhancement effect became more significant in the downstream region. CFD analyses revealed that periodic disturbances of the thermal boundary layer caused by unsteady near-wall flow were responsible for the enhanced heat transfer. These findings provide fundamental insights into the thermal-hydraulic characteristics and enhancement mechanisms of pulsating flow and support its application to compact liquid-cooled heat sinks for high-heat-flux electronic devices.

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Keywords

Heat transfer; pulsating flow; straight fin; CFD analysis; experiment

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