Effect of dimple geometry on the heat transfer of a dimpled plate: flow patterns and local heat transfer analysis


Аuthors

Deeb R.

National Research University “Moscow Power Engineering Institute”, 14, Krasnokazarmennaya str., Moscow, 111250 Russia

Abstract

In this study, a comprehensive numerical investigation was conducted to analyze the effect of dimpled surfaces on local flow structures and heat transfer characteristics within a Reynolds number range of 8,5×10³ ≤ Re ≤ 75×10³. The study aims to assess the impact of different dimple geometries, including spherical, elliptical, drop-shaped, and cam-shaped dimples, at attack angles of θ = 0° and 180°, on thermal-hydraulic performance. Advanced computational fluid dynamics simulations were utilized to evaluate local and averaged velocity distributions, temperature fields, turbulent kinetic energy (TKE), and heat transfer coefficients. The analysis of velocity profiles and turbulence characteristics revealed that dimples significantly enhance secondary flows, intensify turbulence, and promote boundary layer disruption, leading to a notable improvement in heat transfer rates. Among the investigated geometries, spherical dimples exhibited the most extensive recirculation zones, resulting in the highest enhancement in convective heat exchange. Elliptical dimples, due to their elongated shape, induced a stronger flow separation, but the region of high turbulence was comparatively smaller than that of spherical dimples. Drop-shaped dimples demonstrated a distinctive behavior: at θ = 180°, they intensified internal recirculation and increased turbulence generation, whereas at θ = 0°, they maintained a smoother flow profile with a moderate rise in heat transfer efficiency. Cam-shaped dimples presented a unique combination of characteristics depending on the angle of attack, exhibiting hybrid properties of both spherical and elliptical configurations. The study also investigated the influence of dimple geometry on turbulent kinetic energy distribution. The results indicated that dimple-induced turbulence was most prominent near the leading and trailing edges of the dimples, which contributed to localized heat transfer augmentation. Moreover, temperature contours and local heat transfer coefficients confirmed that the maximum heat transfer intensification occurred in regions where flow reattachment and turbulence intensification were dominant. Overall, this research provides valuable insights into the role of dimple geometry in optimizing heat exchanger surfaces. The findings highlight the potential of drop-shaped and cam-shaped dimples in achieving superior thermal-hydraulic performance, offering a pathway for improving heat exchanger designs in various industrial applications. The results contribute to the growing knowledge base of passive heat transfer enhancement techniques and emphasize the importance of geometric optimization in fluid-thermal systems.

Keywords:

dimple, cavity, angle of attack, vortices, heat transfer coefficient, heat transfer, efficiency, CFD

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