The influence of dimple geometry on the heat transfer effectiveness of a dimpled plate: averaged characteristics and predictive correlations


Аuthors

Deeb R. 1, 2*, Dudolin А. А.1, Orlov A. A.1, Burakov I. A.1, Krylova E. V.1

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

*e-mail: e.rawad.deeb@yandex.com, DeebR@mpei.ru

Abstract

This study investigates the influence of various dimple geometries (spherical, elliptical, cam-shaped, and drop-shaped) at attack angles of 0° and 180° on the heat transfer characteristics and thermal-aerodynamic efficiency of dimpled surfaces. The numerical simulations were conducted in ANSYS Fluent using the SST k–ω turbulence model across a Reynolds number range of 8,5×10³ ≤ Re ≤ 75×10³. The primary goal of the research was to evaluate the effect of dimple geometry on the en-hancement of heat transfer while considering the associated aerodynamic resistance. The results demonstrate that different dimple shapes lead to varying flow structures, turbulence characteristics, and thermal performance. The drop-shaped dimples at an attack angle of 0° exhibited the highest thermal-aerodynamic efficiency due to their streamlined geometry, which promotes smoother reat-tachment of the flow and reduces aerodynamic resistance. In contrast, spherical dimples generated more extensive recirculation zones, which enhanced heat transfer but also led to higher pressure loss-es. Elliptical dimples exhibited moderate heat transfer enhancement, whereas cam-shaped dimples displayed characteristics combining those of both spherical and elliptical shapes, depending on the at-tack angle. Further analysis revealed that the heat transfer augmentation was strongly influenced by the presence of secondary vortices and Kelvin-Helmholtz instabilities, which were more pronounced in spherical dimples. Meanwhile, drop-shaped dimples, particularly at 0° attack angle, facilitated more uniform heat transfer distribution with reduced turbulence intensity, thereby offering a favorable bal-ance between heat transfer enhancement and pressure drop minimization. The results also indicated that cam-shaped dimples at 180° attack angle demonstrated improved thermal performance compared to other dimple shapes at the same angle due to the formation of effective secondary vortices that in-tensified local heat transfer. Based on the findings, empirical correlations for the Nusselt number and overall thermal efficiency were developed to provide predictive tools for engineers and designers. These correlations account for dimple geometry and Reynolds number effects, offering practical guidance for optimizing dimpled surfaces in thermal management applications. Overall, this study highlights the importance of dimple geometry selection in achieving optimal thermal efficiency and proposes drop-shaped dimples at 0° attack angle as the most effective configuration for heat transfer enhancement with minimal aerodynamic losses.

Keywords:

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

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