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首页> 外文期刊>International journal of numerical methods for heat & fluid flow >MHD mixed convection of nanofluid in a three-dimensional vented cavity with surface corrugation and inner rotating cylinder
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MHD mixed convection of nanofluid in a three-dimensional vented cavity with surface corrugation and inner rotating cylinder

机译：用表面波纹和内部旋转圆筒在三维排气腔中纳米流体混合对流

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摘要

Purpose - This study aims to numerically examine mixed convection of CuO-water nanofluid in a three-dimensional (3D) vented cavity with inlet and outlet ports under the influence of an inner rotating circular cylinder, homogeneous magnetic field and surface corrugation effects. In practical applications, it is possible to encounter some of the considered configurations in a vented cavity such as magnetic field, rotating cylinder and it is also possible to specially add some of the active and passive control means to control the convection inside the cavity such as adding nanoparticles, corrugating the surfaces. The complicated physics with nanofluid under the effects of magnetic field and inclusion of complex 3D geometry make it possible to use the results of this numerical investigation for the design, control and optimization of many thermal engineering systems as mentioned above. Design/methodology/approach - The bottom surface is corrugated with a rectangular wave shape, and the rotating cylinder surface and cavity bottom surface were kept at constant hot temperatures while the cold fluid enters the inlet port with uniform velocity. The complicated interaction between the forced convection and buoyancy-driven convection coupled with corrugated and rotating surfaces in 3D configuration with magnetic field, which covers a wide range of thermal engineering applications, are numerically simulated with finite element method. Effects of various pertinent parameters such as Richardson number (between 0.01 and 100), Hartmann number (between 0 and 1,000), angular rotational speed of the cylinder (between -30 and 30), solid nanoparticle volume fraction (between 0 and 0.04), corrugation height (between 0 and 0.18H) and number (between 1 and 20) on the convective heat transfer performance are numerically analyzed. Findings - It was observed that the magnetic field suppresses the recirculation zone obtained in the lower part of the inlet port and enhances the average heat transfer rate, which is 10.77 per cent for water and 6.86 per cent for nanofluid at the highest strength. Due to the thermal and electrical conductivity enhancement of nanofluid, there is 5 per cent discrepancy in the Nusselt number augmentation with the nanoadditive inclusion in the absence and presence of magnetic field. The average heat transfer rate of the corrugated surface enhances by about 9.5 per cent for counter-clockwise rotation at angular rotational speed of 30 rad/s as compared to motionless cylinder case Convective heat transfer characteristics are influenced by introducing the corrugation waves. As compared to number of waves, the height of the corrugation has a slight effect on the heat transfer variation. When the number of rectangular waves increases from N = 1 to N = 20, approximately 59 per cent of the average heat transfer reduction is achieved. Originality/value - In this study, mixed convection of CuO-water nanofluid in a 3D vented cavity with inlet and outlet ports is numerically examined under the influence of an inner rotating circular cylinder, homogeneous magnetic field and surface corrugation effects. To the best of authors knowledge such a study has never been performed. In practical applications, it is possible to encounter some of the considered configurations in a vented cavity such as magnetic field, rotating cylinder and it is also possible to specially add some of the active and passive control means to control the convection inside the cavity such as adding nanoparticies, corrugating the surfaces. The complicated physics with nanofluid under the effects of magnetic field and inclusion of complex 3D geometry make it possible to use the results of this numerical investigation for the design, control and optimization of many thermal engineering systems as mentioned above.
机译：目的 - 本研究旨在在内旋转圆筒，均匀磁场和表面波纹效应的影响下用入口和出口在三维（3D）排气腔中的Cuo水纳米流体中的混合对流。在实际应用中，可以在诸如磁场，旋转圆筒的排气腔中遇到一些被认为的配置，并且还可以特别地添加一些主动和被动控制装置以控制诸如的腔内的对流添加纳米颗粒，使表面瓦楞。在磁场的影响下，具有纳米流体的复杂物理和复合3D几何形状的含量使得可以利用该数值研究的结果，以了解如上所述许多热工程系统的设计，控制和优化。设计/方法/方法 - 用矩形波形波纹底表面，旋转圆筒表面和腔底表面保持在恒定的热温度下，同时冷流体进入具有均匀速度的入口。用有限元方法进行数值模拟具有磁场的强制对流和浮动驱动对流与磁场中的3D旋转表面的强制对流和旋转表面的复杂相互作用。各种相关参数（如0.01和100），Hartmann号（0和1,000之间），圆柱的角度转速（在-30和30之间），固体纳米颗粒体积分数（0和0.04之间），对流传热性能的波纹高度（0和0.18h）和数量（在1和20之间）进行了数值分析。结果 - 观察到磁场抑制了入口端口下部获得的再循环区域，并增强了水平的平均传热速率，其水为10.77％，纳米流体处的最高强度为10.77％。由于纳米流体的热电导和导电性增强，在没有磁场的情况下，纳米载物夹杂物中的氮含量增加了5％的差异。与一系列动态的气缸壳体对流传热特性相比，波纹表面的平均传热速率以逆时针旋转以30 rad / s的逆时针旋转增强约9.5％，通过引入波纹波来影响。与波的数量相比，波纹的高度对传热变化具有轻微影响。当矩形波的数量从n = 1增加到n = 20时，实现了大约59％的平均传热减少。原创性/值 - 在该研究中，在内旋转圆筒，均匀磁场和表面波纹效应的影响下，用入口和出口的3D排出腔中Cuo水纳米流体的混合对流。据知识知识从未表演过这样的研究。在实际应用中，可以在诸如磁场，旋转圆筒的排气腔中遇到一些被认为的配置，并且还可以特别地添加一些主动和被动控制装置以控制诸如的腔内的对流添加纳米颗粒，瓦楞曲面。在磁场的影响下，具有纳米流体的复杂物理和复合3D几何形状的含量使得可以利用该数值研究的结果，以了解如上所述许多热工程系统的设计，控制和优化。

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