Purpose

A porous cavity flow field generates entropy owing to energy and momentum exchange within the fluid and at solid barriers. The heat transport and viscosity effects on fluid and solid walls irreversibly generate entropy. This numerical study aims to investigate convective heat transfer together with entropy generation in a partially heated wavy porous cavity filled with a hybrid nanofluid.

Design/methodology/approach

The governing equations are nondimensionalized and the domain is transformed into a unit square. A second-order finite difference method is used to have numerical solutions to nondimensional unknowns such as stream function and temperature. This numerical computation is conducted to explore a wide range of regulating parameters, e.g. hybrid nano-particle volume fraction (σ = 0.1%, 0.33%, 0.75%, 1%, 2%), Rayleigh–Darcy number (Ra = 10, 10², 10³), dimensionless length of the heat source (ϵ = 0.25, 0.50,1.0) and amplitude of the wave (a = 0.05, 0.10, 0.15) for a number of undulations (N = 1, 3) per unit length.

Findings

A thorough analysis is conducted to analyze the effect of multiple factors such as thermal convective forces, heat source, surface corrugation factors, nanofluid volume fraction and other parameters on entropy generation. The flow and temperature fields are studied through streamlines and isotherms. The average Bejan number suggested that entropy generation is entirely dominated by irreversibility due to heat transport at Ra = 10, and the irreversibility due to the viscosity effect is severe at Ra = 10³, but the increment in s augments irreversibility due to the viscosity effect over the heat transport at Ra = 10².

Originality/value

To the best of the authors’ knowledge, this numerical study, for the first time, analyzes the influence of surface corrugation on the entropy generation related to the cooling of a partial heat source by the convection of a hybrid nanofluid.

中文翻译：

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部分加热的混合纳米流体饱和波状多孔腔中的熵产生

目的

由于流体内和固体屏障处的能量和动量交换，多孔腔流场产生熵。热传输和粘度对流体和固体壁的影响不可逆地产生熵。这项数值研究旨在研究填充混合纳米流体的部分加热的波状多孔腔中的对流传热和熵产生。

设计/方法论/途径

控制方程是无量纲的，并且域被变换为单位正方形。二阶有限差分法用于对流函数和温度等无量纲未知数进行数值求解。该数值计算旨在探索各种调节参数，例如混合纳米颗粒体积分数（σ = 0.1%、0.33%、0.75%、1%、2%）、瑞利-达西数（Ra = 10、10）² , 10 ³ )，热源的无量纲长度 ( ϵ = 0.25, 0.50,1.0) 和每单位长度的多个波动 (N = 1, 3) 的波幅 (a = 0.05, 0.10, 0.15 )。

发现

深入分析了热对流力、热源、表面波纹因素、纳米流体体积分数等多种因素对熵产生的影响。通过流线和等温线研究流场和温度场。平均贝让数表明，在 Ra = 10 时，熵的产生完全由热传输导致的不可逆性主导，而在 Ra = 10 ^{3时，由于粘度效应导致的不可逆性很严重，但}s的增量增强了由于粘度效应导致的不可逆性Ra = 10 ²时的热传输。

原创性/价值

据作者所知，这项数值研究首次分析了表面波纹对与混合纳米流体对流冷却部分热源相关的熵产生的影响。