Abstract The bulk motion of fluid and diffusive transport within fluid are two processes during natural or forced convection. The complexity of the convective heat flow is realized since last few decades and the analysis of the heat flow as well as thermal characteristics gradually becomes cumbersome. Although earlier researchers studied convective heat flow via velocity profiles, streamlines and isotherms, these tools were not enough for the efficient visualization of the unique features of convection heat flow. An efficient tool, termed as ‘heatline’ (mathematically represented as heatfunction) was first proposed by Kimura and Bejan in 1983 for the heat flow visualization during convective heat flow. The aim of this article is to review existing works on ‘heatline’ involving various physical systems. The mathematical implications of heatfunctions based on derivations of governing equations and boundary conditions for heatfunctions are presented in detail. The non-homogeneous boundary conditions for heatfunctions arise due to hot or cold or adiabatic walls as well as the junction between the walls and these conditions vary with the location of the reference or datum of the heatfunction. The physics on the heat flow via ‘heatlines’ are found to be invariant with the locations of the reference value of the heatfunction. The heat flow visualization is analyzed for various test cases from simple one dimensional boundary layer problem to convection in two dimensional complex cavities. The detailed explanations of earlier works on ‘heatlines’ during one dimensional flow involving forced or natural convection with various applications are discussed. Further, applications of ‘heatlines’ during convective heat flow within enclosed cavities involving uniform or non uniform heating of walls, discrete heating or cooling, conjugate convection and mixed convection are discussed and ‘heatlines’ are found to be successful to demonstrate various complex heat flow paths and multiple heat flow circulation cells. Overall, the analysis of convective heat flow from simple to complicated geometries via ‘heatline’ is crucial for the visualization of the thermal transport, mixing and efficient thermal management.

中文翻译：

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Heatlines：建模、可视化、混合和热管理

摘要 流体的整体运动和流体内的扩散输送是自然对流或强制对流的两个过程。对流热流的复杂性在最近几十年才得以实现，对热流和热特性的分析逐渐变得繁琐。尽管早期的研究人员通过速度剖面、流线和等温线研究了对流热流，但这些工具还不足以有效地可视化对流热流的独特特征。Kimura 和 Bejan 于 1983 年首次提出了一种称为“热线”（数学上表示为热函数）的有效工具，用于对流热流期间的热流可视化。本文的目的是回顾现有的涉及各种物理系统的“热线”工作。详细介绍了基于控制方程和热函数边界条件推导的热函数的数学含义。热函数的非均匀边界条件是由于热壁或冷壁或绝热壁以及壁之间的连接而产生的，这些条件随热函数的参考或数据的位置而变化。发现通过“热线”的热流物理与热函数参考值的位置是不变的。从简单的一维边界层问题到二维复杂腔体中的对流，分析了各种测试案例的热流可视化。讨论了在涉及强制或自然对流的一维流动期间的“热线”早期工作的详细解释和各种应用。此外，讨论了“热线”在封闭腔内的对流热流中的应用，涉及壁的均匀或非均匀加热、离散加热或冷却、共轭对流和混合对流，并且发现“热线”成功地证明了各种复杂的热流路径和多个热流循环单元。总体而言，通过“热线”分析从简单几何到复杂几何的对流热流对于热传输、混合和有效热管理的可视化至关重要。讨论了共轭对流和混合对流，发现“热线”成功地展示了各种复杂的热流路径和多个热流循环单元。总体而言，通过“热线”分析从简单几何到复杂几何的对流热流对于热传输、混合和有效热管理的可视化至关重要。讨论了共轭对流和混合对流，发现“热线”成功地展示了各种复杂的热流路径和多个热流循环单元。总的来说，通过“热线”分析从简单几何到复杂几何的对流热流对于热传输、混合和有效热管理的可视化至关重要。