Purpose

This paper aims to study, experimentally validate and select the main physical and numerical parameters of influence in computational numerical simulations to evaluate mean heat flux by natural convection on square flat plates.

Design/methodology/approach

Several numerical models were built to study the influence of physical and numerical parameters about the predictions of the natural convection heat transfer rates on the surface of a flat plate with aspect ratio = 1, in isothermal conditions, turbulent regime and using the free and open-source software OpenFOAM®. The studied parameters were: boundary conditions (using or not using wall functions in properties ε, κ, ν_t and ω), degree of mesh refinement, refinement layers and turbulence models [κ – ε and κ – ω Shear Stress Transport (SST)]. From the comparison of the values of the mean Nusselt number, obtained from numerical simulations and literature experimental results, the authors evaluated the precision of the studied parameters, validating and selecting the most appropriate to the analyzed problem situation.

Findings

The validation and agreement of the numerical results could be proven with excellent precision from experimental references of the technical scientific literature. More refined meshes with refinement layers were not suitable for the studies developed. The κ – ε and κ – ω SST turbulence models, in meshes without refinement layers, proved to be equivalent. Whether or not to use wall functions in turbulent boundary conditions proved to be irrelevant as to the accuracy of results for the problem situation studied.

Practical implications

Use of the physical and numerical parameters is studied and validated for various applications in natural convection heat transfer of technology and industry areas.

Social implications

Use of free and open-source software as a research tool in the Computational Fluid Dynamics (CFD) area, especially in conditions without large financial resources or state-of-the-art infrastructure.

Originality/value

To the best of the authors’ knowledge, this work is yet not available in existing literature.

中文翻译：

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三维方形板上自然对流湍流模拟中的物理-数值参数

目的

本文旨在研究、实验验证和选择影响计算数值模拟的主要物理和数值参数，以评估方形平板上自然对流的平均热通量。

设计/方法/方法

建立了几个数值模型来研究物理和数值参数对纵横比 = 1 的平板表面自然对流换热率预测的影响，在等温条件下，湍流状态，并使用自由和开放-源软件 OpenFOAM®。研究的参数是：边界条件（在属性ε、κ、ν _t和ω 中使用或不使用壁面函数）、网格细化程度、细化层和湍流模型 [ κ - ε和κ - ω 剪切应力传递（SST)]。通过比较从数值模拟和文献实验结果获得的平均努塞尔数的值，作者评估了研究参数的精度，验证并选择最适合分析问题情况的参数。

发现

数值结果的验证和一致性可以从技术科学文献的实验参考中以极好的精度证明。带有细化层的更细化的网格不适合开发的研究。该κ  - ε和κ  - ωSST湍流模型，在无网格细化层，被证明是等价的。事实证明，在湍流边界条件下是否使用壁面函数与所研究问题情况的结果准确性无关。

实际影响

对物理和数值参数的使用进行了研究和验证，用于技术和工业领域自然对流热传递的各种应用。

社会影响

使用免费和开源软件作为计算流体动力学 (CFD) 领域的研究工具，尤其是在没有大量财务资源或最先进基础设施的情况下。

原创性/价值

据作者所知，这项工作在现有文献中尚不可用。