Purpose

The purpose of this paper is to address various works on mixed convection and proposes 10 unified models (Models 1–10) based on various thermal and kinematic conditions of the boundary walls, thermal conditions and/ or kinematics of objects embedded in the cavities and kinematics of external flow field through the ventilation ports. Experimental works on mixed convection have also been addressed.

Design/methodology/approach

This review is based on 10 unified models on mixed convection within cavities. Models 1–5 involve mixed convection based on the movement of single or double walls subjected to various temperature boundary conditions. Model 6 elucidates mixed convection due to the movement of single or double walls of cavities containing discrete heaters at the stationary wall(s). Model 7A focuses mixed convection based on the movement of wall(s) for cavities containing stationary solid obstacles (hot or cold or adiabatic) whereas Model 7B elucidates mixed convection based on the rotation of solid cylinders (hot or conductive or adiabatic) within the cavities enclosed by stationary or moving wall(s). Model 8 is based on mixed convection due to the flow of air through ventilation ports of cavities (with or without adiabatic baffles) subjected to hot and adiabatic walls. Models 9 and 10 elucidate mixed convection due to flow of air through ventilation ports of cavities involving discrete heaters and/or solid obstacles (conductive or hot) at various locations within cavities.

Findings

Mixed convection plays an important role for various processes based on convection pattern and heat transfer rate. An important dimensionless number, Richardson number (Ri) identifies various convection regimes (forced, mixed and natural convection). Generalized models also depict the role of “aiding” and “opposing” flow and combination of both on mixed convection processes. Aiding flow (interaction of buoyancy and inertial forces in the same direction) may result in the augmentation of the heat transfer rate whereas opposing flow (interaction of buoyancy and inertial forces in the opposite directions) may result in decrease of the heat transfer rate. Works involving fluid media, porous media and nanofluids (with magnetohydrodynamics) have been highlighted. Various numerical and experimental works on mixed convection have been elucidated. Flow and thermal maps associated with the heat transfer rate for a few representative cases of unified models [Models 1–10] have been elucidated involving specific dimensionless numbers.

Originality/value

This review paper will provide guidelines for optimal design/operation involving mixed convection processing applications.

中文翻译：

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空腔内各种运动学和热诱导情景的混合对流综合综述

目的

本文的目的是解决混合对流的各种工作，并基于边界壁的各种热和运动学条件、嵌入空腔和运动学的物体的热学条件和/或运动学提出 10 个统一模型（模型 1-10）通过通风口的外部流场。还讨论了混合对流的实验工作。

设计/方法/方法

本评论基于 10 个关于空腔内混合对流的统一模型。模型 1-5 涉及基于受各种温度边界条件影响的单壁或双壁运动的混合对流。模型 6 阐明了由于在固定壁上包含离散加热器的空腔的单壁或双壁的运动而产生的混合对流。模型 7A 基于壁运动的混合对流，用于包含静止固体障碍物（热或冷或绝热）的空腔，而模型 7B 基于空腔内固体圆柱体（热或导电或绝热）的旋转阐明混合对流由静止或移动的墙壁包围。模型 8 基于混合对流，这是由于空气流过受热壁和绝热壁影响的腔体（有或没有绝热挡板）的通风口。模型 9 和 10 阐明了由于空气流过空腔的通风口而产生的混合对流，这些空腔涉及空腔内不同位置的离散加热器和/或固体障碍物（导电或热的）。

发现

混合对流在基于对流模式和传热速率的各种过程中起着重要作用。一个重要的无量纲数，理查森数 (Ri) 确定了各种对流机制（强制对流、混合对流和自然对流）。广义模型还描述了“辅助”和“反对”流动以及两者在混合对流过程中的组合的作用。辅助流（同方向的浮力和惯性力的相互作用）可能会导致传热率的增加，而反向流（相反方向的浮力和惯性力的相互作用）可能会导致传热率的降低。涉及流体介质、多孔介质和纳米流体（具有磁流体动力学）的工作已被突出显示。已经阐明了关于混合对流的各种数值和实验工作。

原创性/价值

这篇评论论文将为涉及混合对流处理应用的优化设计/操作提供指导。