Department of Mechanical Engineering, Jeonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju-si, Jeollabuk-do 54896, Republic of Korea.
Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, 842 West Taylor Street, Chicago, IL 60607, USA.
Philos Trans A Math Phys Eng Sci. 2023 May;381(2246):20220126. doi: 10.1098/rsta.2022.0126. Epub 2023 Mar 13.
Taylor-Couette flow of concentrated non-colloidal suspensions with a rotating inner cylinder and a stationary outer one is numerically investigated. We consider suspensions of the bulk particle volume fraction = 0.2, 0.3 with the ratio of annular gap to the particle radius = 60 confined in a cylindrical annulus of the radius ratio (i.e. ratio of inner and outer radii) = 0.877. Numerical simulations are performed by applying suspension-balance model and rheological constitutive laws. To observe flow patterns caused by suspended particles, the Reynolds number of the suspension, based on the bulk particle volume fraction and the rotating velocity of the inner cylinder, is varied up to 180. At high Reynolds number, modulated patterns undiscovered in the flow of a semi-dilute suspension emerge beyond a wavy vortex flow. Thus, a transition occurs from the circular Couette flow via ribbons, spiral vortex flow, wavy spiral vortex flow, wavy vortex flow and modulated wavy vortex flow for the concentrated suspensions. Moreover, friction and torque coefficients for suspensions are estimated. It turns out that suspended particles significantly enhance the torque on the inner cylinder while reducing friction coefficient and the pseudo-Nusselt number. In particular, the coefficients are reduced in the flow of more dense suspensions. This article is part of the theme issue 'Taylor-Couette and related flows on the centennial of Taylor's seminal paper (Part 2)'.
同心环式泰勒流中浓悬浮液的流动特性研究，内筒旋转，外筒固定。我们考虑了体积分数为 0.2 和 0.3 的悬浮液，环形间隙与颗粒半径的比值为 60，颗粒被限制在半径比为 0.877 的圆柱环中。数值模拟通过应用悬浮液平衡模型和流变本构定律来进行。为了观察悬浮颗粒引起的流动模式，基于悬浮体的体积分数和内筒的旋转速度，将悬浮体的雷诺数提高到 180。在高雷诺数下，除了波状涡旋流之外，在半稀悬浮体的流动中还出现了调制模式。因此，对于浓悬浮体，流动从圆型 Couette 流通过带状流、螺旋涡旋流、波状螺旋涡旋流、波状涡旋流和调制波状涡旋流转变。此外，还估计了悬浮液的摩擦和扭矩系数。结果表明，悬浮颗粒显著增大了内筒的扭矩，同时降低了摩擦系数和拟努塞尔数。特别是在更密集的悬浮液流动中，这些系数会减小。本文是主题为“Taylor 开创性论文百年之际的 Taylor-Couette 和相关流动（第 2 部分）”的一部分。
