Sedimentation of Two Side-by-Side Heavy Particles of Different Density in a Shear-Thinning Fluid with Viscoelastic Properties

Sensen Yang,Fubing Bao,Xianfu Ge,Minglu Dai,Chengxu Tu,Xiaoyan Gao,Rongjun Xu

doi:10.3390/app11157113

Sensen Yang, Fubing Bao + Show 5 more

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https://doi.org/10.3390/app11157113

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Journal: Applied Sciences	Publication Date: Jul 31, 2021
Citations: 5	License type: CC BY 4.0

Affiliation: China Jiliang University, Zhejiang University

Abstract

Particle sedimentation has widely existed in nature and engineering fields, and most carrier fluids are non-Newtonian. Recently, the manipulation of a settling particle in liquid has been a topic of high interest to those involved in engineered processes such as composite materials, pharmaceutical manufacture, chemistry and the petroleum industry. Compared with Newtonian fluid, the viscosity of non-Newtonian fluid is closely related to the shear rate, leading to a single settling particle having different dynamic behaviors. In this article, the trajectories and velocities of two side-by-side particles of different densities (heavy and light) settling in a shear-thinning fluid with viscoelastic property were studied, as well as that for the corresponding single settling particle. Regardless of the difference in the particle density, the results show the two-way coupling interaction between the two side-by-side settling particles. As opposed to a single settling particle, the wake of the heavier particle can clearly attract or rebound the light particle due to the shear-thinning or viscoelastic property of the fluid. Regarding the trajectories of the light particle, three basic path types were found: (i) the light particle is first attracted and then repelled by the wake of the heavy one; (ii) the light particle approaches and then largely traces within the path of the heavy one in the limited field of view; (iii) the light particle is first slightly shifted away from its original position and then returns to this initial position. In addition to this, due to the existence of a corridor of reduced viscosity and negative wake generated by the viscoelastic property, the settling velocity of a light particle can exceed the terminal velocity of a single particle of the same density. On the other hand, the sedimentation of the light particle can induce the distinguishable transverse migration of the heavy one.

Highlights

Particle sedimentation can be found in a wide range of natural and industrial processes, such as river flows, blood flows, microfluidic chips and fluidization etc. [1,2,3,4,5]
Considering the relationship between the Reynolds number (Re) and the mass ratio (m*), three typical sedimentation trajectories of a single particle settling in glycerin-water mixture were found: vertical, oblique and zigzag [8], where (m*) is the relative density of the particle compared to the fluid, a map of regimes of the particle trajectories is presented for Re = 100–12,000 and m* = 0–1.5
We studied the trajectories and velocities of two side-by-side particles of different density settling in a non-Newtonian fluid with shear thinning viscoelastic of different density settling a non-Newtonian fluid particle

Summary

Introduction

Particle sedimentation can be found in a wide range of natural and industrial processes, such as river flows, blood flows, microfluidic chips and fluidization etc. [1,2,3,4,5]. Clift proposed that when the particle Reynolds number is large (750 < Re < 2 × 105 ), the viscous resistance of the particle is negligible compared with the inertial force [5]. Considering the relationship between the Reynolds number (Re) and the mass ratio (m*), three typical sedimentation trajectories of a single particle settling in glycerin-water mixture were found: vertical, oblique and zigzag [8], where (m*) is the relative density of the particle compared to the fluid, a map of regimes of the particle trajectories is presented for Re = 100–12,000 and m* = 0–1.5. Five types of trajectories of a free-settling particle in Newtonian fluids have been found: steady and oblique, oblique and oscillating regime with low frequency, oblique and oscillation regime with high frequency, zigzagging periodic regime and three-dimensional chaotic regime [9]. The settling velocities of dual particles would be larger than a single particle at small Reynolds numbers [10]

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