This paper is concerned with 3D-numerical studies on free convection flow of CuO–water nanofluid in a cubical cavity with porous fins embedded. The two-phase mixture model is employed and the numerical simulations are performed for natural flow of the nanofluid with volume concentrations from 0% to 3% at different Rayleigh (Ra) numbers inside the cavity equipped with 1, 2 and 3 porous fins. Increasing the nanoparticle fraction shows an improvement in heat transfer and Nusselt number. By increment of Ra and domination of convection, the nanofluid flow becomes truly irregular and consequently, the average Nusselt number enhances. For low Ra, isotherms are rather uniform due to weak buoyancy force. While, at higher Rayleigh numbers, augmentation of buoyancy force strongly reduces the isotherms uniformity. In the presence of porous fins, the flow velocity decreases with no significant change in the flow pattern. Also, at low Rayleigh numbers, embedding porous fins results in agitating parallel arrangement of isotherms. The influence of three mentioned variables (i.e., volume fraction, Rayleigh number and number of porous fins) on average Nusselt number is comparatively determined using Taguchi technique and signal to noise ratio according to which nanoparticle loading shows the most principal effect of all.

本文涉及3D数值研究CuO-水纳米流体在嵌入多孔鳍片的立方腔中的自由对流。采用两相混合物模型，并在装有1、2和3个多孔散热片的腔体内，以不同的瑞利（Ra）数对体积浓度为0％至3％的纳米流体的自然流动进行了数值模拟。纳米颗粒分数的增加显示出传热和努塞尔数的改善。通过Ra的增加和对流的控制，纳米流体流真正变得不规则，因此，平均Nusselt数增加。低Ra由于浮力弱，等温线相当均匀。而在较高的瑞利数下，增加浮力会大大降低等温线的均匀性。在存在多孔翅片的情况下，流速降低而流型没有明显变化。同样，在低瑞利数下，嵌入多孔鳍片会引起等温线的平行排列。使用Taguchi技术和信噪比比较确定了三个提到的变量（即体积分数，瑞利数和多孔鳍片的数量）对平均Nusselt数的影响，根据该信噪比，纳米粒子的负载显示出最主要的影响。