Parvin Salaika, Roy Nepal Chandra, Saha Litan Kumar
Department of Mathematics, University of Dhaka, Dhaka 1000, Bangladesh.
Department of Applied Mathematics, University of Dhaka, Dhaka 1000, Bangladesh.
Heliyon. 2023 Jun 1;9(6):e16579. doi: 10.1016/j.heliyon.2023.e16579. eCollection 2023 Jun.
A numerical investigation has been carried out in a wavy-shaped enclosure with an elliptical inner cylinder to find out the effect of an inclined magnetic field and a non-Newtonian nanofluid on fluid flow and heat transfer. Here, the dynamic viscosity and thermal conductivity of the nanofluid are also taken into account. These properties change with the temperature and nanoparticle volume fraction. The vertical walls of the enclosure are modeled through complex wavy geometries and are kept at a constant cold temperature. The inner elliptical cylinder is deemed to be heated and the horizontal walls are considered adiabatic. Temperature difference between the wavy walls and the hot cylinder leads to natural convective circulation flow inside the enclosure. The dimensionless set of the governing equations and associated boundary conditions are numerically simulated using the COMSOL Multiphysics software, which is based on finite element methods. Numerical analysis has been scrutinized for varying Rayleigh number (), Hartmann number (), magnetic field inclination angle (), rotation angle of the inner cylinder (), power-law index (), and nanoparticle volume fraction (). The findings demonstrate that the solid volumetric concentration of nanoparticles diminishes the fluid movement at greater values of . The heat transfer rate decreases for larger nanoparticle volume fractions. The flow strength increases with an increasing Rayleigh number resulting in a best possible heat transfer. A higher Hartmann number diminishes the fluid flow but converse behavior is exhibited for magnetic field inclination angle (). The average Nusselt number () values are maximum for = 90°. The power-law index plays a significant role on the heat transfer rate, and results show that the shear-thinning liquid augments the average Nusselt number.
在一个带有椭圆形内圆柱的波浪形封闭腔内进行了数值研究，以探究倾斜磁场和非牛顿纳米流体对流体流动和传热的影响。在此，还考虑了纳米流体的动态粘度和热导率。这些特性会随温度和纳米颗粒体积分数而变化。封闭腔的垂直壁通过复杂的波浪几何形状建模，并保持在恒定的低温。内椭圆形圆柱被视为受热，水平壁被视为绝热。波浪壁和热圆柱之间的温差导致封闭腔内出现自然对流循环流。使用基于有限元方法的COMSOL Multiphysics软件对控制方程和相关边界条件的无量纲集进行了数值模拟。针对不同的瑞利数（）、哈特曼数（）、磁场倾斜角（）、内圆柱的旋转角（）、幂律指数（）和纳米颗粒体积分数（）进行了数值分析审查。研究结果表明，在较大的 值时，纳米颗粒的固体体积浓度会降低流体运动。对于较大的纳米颗粒体积分数，传热速率会降低。流动强度随着瑞利数的增加而增加，从而实现最佳的传热效果。较高的哈特曼数会降低流体流动，但对于磁场倾斜角（）则表现出相反的行为。对于 = 90°，平均努塞尔数（）值最大。幂律指数对传热速率有重要影响，结果表明剪切变稀液体可提高平均努塞尔数。
