Hassen Walid, Selimefendigil Fatih, Ben Khedher Nidhal, Kolsi Lioua, Borjini Mohamed Naceur, Alresheedi Faisal
Laboratory of Meteorology and Energy Systems, University of Monastir, 5000 Monastir, Tunisia.
Department of Mechanical Engineering, Celal Bayar University, 45140 Manisa, Turkey.
ACS Omega. 2021 Dec 15;6(51):35607-35618. doi: 10.1021/acsomega.1c05334. eCollection 2021 Dec 28.
In this work, mixed convection and entropy generation analyses in a partitioned porous cavity with double inner rotating cylinders are explored under magnetic field effects. A curved partition shape is considered with identical rotating cylinders and an inclined magnetic field, while the right vertical wall moves with a constant speed in the -direction. Numerical simulations are performed by considering various values of Rayleigh number, Hartman number, Darcy number, inclination of the magnetic field, size of the curved partitions, and rotational speeds of the inner cylinders and their vertical locations with the cavity. Complicated flow field with multicellular structures are observed due to the complex interaction between the natural convection, moving wall, and rotational effects of inner cylinders. Improved heat-transfer performance is obtained with higher values of magnetic field inclination, higher values of permeability/porosity of the medium, and higher rotational speeds of the cylinders. Almost doubling of the average number is obtained by decreasing the value of the Hartmann number from 25 to 0 or varying the magnetic field inclination from 90 to 0. When rotational effects of the cylinders are considered, average heat-transfer improvements by a factor of 5 and 5.9 are obtained for nondimensional rotational speeds of 5 and -5 in comparison with the case of motionless cylinders. An optimum length of the porous layer is achieved for which the best heat-transfer performance is achieved. As the curvature size of the partition is increased, better heat transfer of the hot wall is obtained and up to 138% enhancement is achieved. Significant increments of entropy generation are observed for left and right domains including the rotating cylinders. The magnetic field parameter also affects the entropy generation and contributions of different domains including the curved porous partition.
在这项工作中，研究了在磁场作用下，具有双内旋转圆柱的分隔多孔腔内的混合对流和熵产生分析。考虑了具有相同旋转圆柱和倾斜磁场的弯曲分隔形状，而右垂直壁在负方向上以恒定速度移动。通过考虑瑞利数、哈特曼数、达西数、磁场倾角、弯曲分隔的尺寸、内圆柱的旋转速度及其在腔内的垂直位置的各种值来进行数值模拟。由于自然对流、移动壁和内圆柱的旋转效应之间的复杂相互作用，观察到具有多细胞结构的复杂流场。通过更高的磁场倾角值、更高的介质渗透率/孔隙率值和更高的圆柱旋转速度可获得改善的传热性能。通过将哈特曼数的值从25减小到0或将磁场倾角从90改变到0，平均努塞尔数几乎增加了一倍。当考虑圆柱的旋转效应时，与静止圆柱的情况相比，无量纲旋转速度为5和-5时，平均传热分别提高了5倍和5.9倍。实现了多孔层的最佳长度，在此长度下可实现最佳的传热性能。随着分隔的曲率尺寸增加，热壁的传热得到改善，实现了高达138%的增强。在包括旋转圆柱的左右区域中观察到熵产生的显著增加。磁场参数也影响熵产生以及包括弯曲多孔分隔在内的不同区域的贡献。
