Mourad Abed, Abderrahmane Aissa, Younis Obai, Marzouki Riadh, Alazzam Anas
Laboratoire de Physique Quantique de la Matière et Modélisation Mathématique (LPQ3M), University Mustapha Stambouli of Mascara, Mascara 29000, Algeria.
Department of Mechanical Engineering, College of Engineering at Wadi Addwaser, Prince Sattam Bin Abdulaziz University, Al-Kharj 16278, Saudi Arabia.
Micromachines (Basel). 2022 Jan 26;13(2):182. doi: 10.3390/mi13020182.
The current paper presents a numerical study of the magnetohydrodynamics natural convection and entropy production of Cu-water nanofluid contained in a porous annulus between a heated Koch snowflake and wavy cylinder with lower temperature with respect to the Koch snowflake. The numerical algorithm is based on the Galerkin Finite Element Method. The impacts of Rayleigh number ( = 10, 10, 10, and 10), Hartman number ( = 0, 25, 50, and 100), Darcy number ( = 10, 10, 10, and 10), nanoparticle volumetric fraction ( = 2%, 3%, 4%, and 5%), and the undulations number of the outer wavy cylinder (three cases) on the distributions of isotherms, streamlines, mean Nusselt number (), as well as on total entropy production and Bejan number are thoroughly examined. The computational outcomes disclose that dispersing more Cu nanoparticles in the base fluid and creating a flow with higher intensity inside the annulus by raising the Rayleigh number bring about a boosted natural convective flow in the cavity, which improves the heat transmission rate. In addition, it can be noted that owing to the peculiar form of the heated Koch snowflake, nanofluid gets trapped between the angled parts, resulting in uneven temperature profiles with higher values in these places.
本文对置于加热的科赫雪花与温度低于科赫雪花的波浪形圆柱之间多孔环形空间内的铜 - 水纳米流体的磁流体动力学自然对流和熵产生进行了数值研究。数值算法基于伽辽金有限元法。深入研究了瑞利数（= 10⁴、10⁵、10⁶和10⁷）、哈特曼数（= 0、25、50和100）、达西数（= 10⁻⁶、10⁻⁵、10⁻⁴和10⁻³）、纳米颗粒体积分数（= 2%、3%、4%和5%）以及外波浪形圆柱的起伏数（三种情况）对等温线分布、流线、平均努塞尔数（）以及总熵产生和贝扬数的影响。计算结果表明，在基液中分散更多的铜纳米颗粒以及通过提高瑞利数在环形空间内产生更高强度的流动，会使腔内自然对流增强，从而提高热传递速率。此外，可以注意到，由于加热的科赫雪花的特殊形状，纳米流体被困在成角部分之间，导致这些地方的温度分布不均匀且值更高。
