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Sedimentation behavior of a spherical particle in a Giesekus fluid: A CFD–DEM solution
Journal of Non-Newtonian Fluid Mechanics ( IF 3.1 ) Pub Date : 2020-12-30 , DOI: 10.1016/j.jnnfm.2020.104465
Ali Heydari-Beni , Roman J. Shor , Giovanniantonio Natale

The sedimentation of a spherical solid particle in viscoelastic fluids was studied using a Giesekus model by development of a direct numerical simulation solver based on fully-resolved and immersed boundary methods to understand the complex non-Newtonian fluid flow and spherical particle dynamics. Two benchmark problems were modeled to evaluate the accuracy of the developed solver and excellent agreement with prior experimental and simulation results were obtained. In addition, the temporal and spatial order of convergence of the transient and advection discretization schemes were studied. The aim is to provide a clearer picture for the effect of confinement and rheology of the viscoelastic fluid on the sedimentation phenomenon of a spherical particle in a Giesekus fluid. We report that the negative wake occurs at Weissenberg number Wi 2.45 at all blockage ratios aR=0.243, 0.390, 0.464, and 0.538. At Wi=1.00, the negative wake occurs mainly at blockage ratio aR 0.390 when the effect of confinement is enhanced. There is a linear relationship between the sphere overshoot/steady-state velocity and blockage ratio due to shear-thinning effects. The oscillations in the sphere velocity were reported at all Wi for blockage ratios aR 0.464. The sphere velocity oscillations disappear at the highest blockage ratio aR=0.538 except at Wi=0.01 and 1.00. The viscoelastic fluid velocity oscillations were reported at Wi 1.00 at all blockage ratios. The viscoelastic fluid velocity oscillations become more damped with blockage ratio aR which the mutual effects of shear-thinning and wall effects become more dominant.



中文翻译:

Giesekus流体中球形颗粒的沉降行为:CFD–DEM解决方案

利用Giesekus模型,通过基于完全解析和浸入边界方法的直接数值模拟求解器的开发,研究了粘弹性流体中球形固体颗粒的沉降,以了解复杂的非牛顿流体流动和球形颗粒动力学。对两个基准问题进行了建模,以评估开发的求解器的准确性,并与先前的实验和仿真结果取得了很好的一致性。此外,还研究了瞬态和对流离散化方案收敛的时间和空间顺序。目的是为粘弹性流体的约束和流变性对Giesekus流体中球形颗粒的沉降现象的影响提供更清晰的认识。我们报告负唤醒发生在魏森伯格数无线网 在所有阻塞率下为2.45 一个[R=0243,0.390、0.464和0.538。在无线网=1个00,负唤醒主要发生在阻塞率 一个[R增强封闭效果时为0.390。由于剪切变稀效应,球体超调/稳态速度与阻塞率之间存在线性关系。完全报告了球速的振荡无线网 阻塞率 一个[R0.464。球形速度振荡在最高阻塞率下消失一个[R=0538 除了在 无线网=001和1.00。粘弹性流体的速度振荡在无线网在所有阻塞率下均为1.00。粘弹性流体的速度振荡随着阻塞率而变得更加衰减一个[R 剪切稀化和墙效应的相互影响变得更加明显。

更新日期:2020-12-30
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