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首页> 外文期刊>International journal of numerical methods for heat & fluid flow >Unsteady natural convection in a partially porous cavity having a heat-generating source using local thermal non-equilibrium model
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Unsteady natural convection in a partially porous cavity having a heat-generating source using local thermal non-equilibrium model

机译：使用局部热非平衡模型的具有生热源的部分多孔腔体中的不稳定自然对流

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Purpose The purpose of this study is a numerical analysis of transient natural convection in a square partially porous cavity with a heat-generating and heat-conducting element using the local thermal non-equilibrium model under the effect of cooling from the vertical walls. It should be noted that this research deals with a development of passive cooling system for the electronic devices.Design/methodology/approach The domain of interest is a square cavity with a porous layer and a heat-generating element. The vertical walls of the cavity are kept at constant cooling temperature, while the horizontal walls are adiabatic. The heat-generating solid element is located on the bottom wall. A porous layer is placed under the clear fluid layer. The governing equations, formulated in dimensionless stream function, vorticity and temperature variables with corresponding initial and boundary conditions, are solved using implicit finite difference schemes of the second order accuracy. The governing parameters are the Darcy number, viscosity variation parameter, porous layer height and dimensionless time. The effects of varying these parameters on the average total Nusselt number along the heat source surface, the average temperature of the heater, the fluid flow rate inside the cavity and on the streamlines and isotherms are analyzed.Findings The results show that in the case of local thermal non-equilibrium the total average Nusselt number is an increasing function of the interphase heat transfer coefficient and the porous layer thickness, while the average heat source temperature decreases with the Darcy number and viscosity variation parameter.Originality/value An efficient numerical technique has been developed to solve this problem. The originality of this work is to analyze unsteady natural convection within a partially porous cavity using the local thermal non-equilibrium model in the presence of a local heat-generating solid element. The results would benefit scientists and engineers to become familiar with the analysis of convective heat transfer in enclosures with local heat-generating heaters and porous layers, and the way to predict the heat transfer rate in advanced technical systems, in industrial sectors including transportation, power generation, chemical sectors and electronics.
机译：目的本研究的目的是使用局部热非平衡模型，在垂直壁冷却的作用下，对具有生热和导热元件的方形局部多孔空腔中的瞬态自然对流进行数值分析。应该注意的是，这项研究涉及电子设备的被动冷却系统的开发。设计/方法/方法感兴趣的领域是具有多孔层和发热元件的方腔。空腔的垂直壁保持恒定的冷却温度，而水平壁则是绝热的。发热固体元件位于底壁上。将多孔层置于透明流体层下方。使用具有二阶精度的隐式有限差分方案，求解了由无量纲流函数，涡度和温度变量以及相应的初始和边界条件所公式化的控制方程。控制参数是达西数，粘度变化参数，多孔层高度和无量纲时间。分析了这些参数的变化对沿热源表面的平均总Nusselt数，加热器的平均温度，型腔内部的流体流速以及流线和等温线的影响。局部热不平衡，总平均努塞尔数是相间传热系数和多孔层厚度的增加函数，而平均热源温度随达西数和粘度变化参数而降低。被开发来解决这个问题。这项工作的独创性是在存在局部生热固体元素的情况下，使用局部热非平衡模型来分析部分多孔空腔内的不稳定自然对流。该结果将有利于科学家和工程师熟悉具有局部生热加热器和多孔层的机壳中对流传热的分析，以及预测先进技术系统，运输，电力等工业部门中传热率的方法。发电，化工和电子。

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