Abstract

Fluid flow and heat transfer characteristics past four elliptic cylinders arranged in square configuration are numerically investigated in this study. An in-house finite element method code based on streamline upwind Petrov - Galerkin algorithm has been used for simulations of two-dimensional, incompressible and laminar flow of air. Analyses are carried out by changing geometric parameters such as spacing ratio, axis ratio and incident angle. Results in terms of vorticity and temperature contours, Strouhal number, drag and lift coefficients and Nusselt number are studied for all cases. These results show that fluid flow patterns are strongly influenced by geometric parameters, based on which flow can be categorized into different types. A critical spacing ratio is found for some of the configurations, where a steep increase in drag coefficient is encountered. From this study, it is observed that incident angle 22.5 degree gives a higher heat transfer rate compared to the other two configurations (0 and 45 degree). Also, elliptic cylinders (axis ratio of 0.8 and 0.5) have similar Nusselt number value with less drag force compared to circular cylinders (axis ratio of 1.0) which justifies the utilization of elliptic cylinders as an alternative for circular ones.

摘要

在这项研究中，通过以方形配置排列的四个椭圆圆柱体的流体流动和传热特性进行了数值研究。基于流线逆风 Petrov-Galerkin 算法的内部有限元方法代码已用于模拟二维不可压缩空气层流。通过改变间距比、轴比和入射角等几何参数进行分析。在所有情况下都研究了涡度和温度等高线、斯特劳哈尔数、阻力和升力系数以及努塞尔特数方面的结果。这些结果表明流体流动模式受到几何参数的强烈影响，根据几何参数可以将流动分为不同的类型。发现了一些配置的临界间距比，遇到阻力系数急剧增加的情况。从这项研究中可以看出，与其他两种配置（0 度和 45 度）相比，22.5 度的入射角提供了更高的传热率。此外，椭圆柱体（轴比为 0.8 和 0.5）具有相似的努塞尔特数值，与圆柱体（轴比为 1.0）相比阻力更小，这证明使用椭圆柱体作为圆形柱体的替代品是合理的。