scholarly journals An active particle in a complex fluid

2017 ◽  
Vol 823 ◽  
pp. 675-688 ◽  
Author(s):  
Charu Datt ◽  
Giovanniantonio Natale ◽  
Savvas G. Hatzikiriakos ◽  
Gwynn J. Elfring
Keyword(s):  
Newtonian Fluid ◽  
Slip Velocity ◽  
Shear Thinning ◽  
Reciprocal Theorem ◽  
Janus Particle ◽  
Active Particles ◽  
Complex Fluid ◽  
The Reciprocal Theorem ◽  
Fluid Rheology ◽  
Shear Thinning Fluid

In this work, we study active particles with prescribed surface velocities in non-Newtonian fluids. We employ the reciprocal theorem to obtain the velocity of an active spherical particle with an arbitrary axisymmetric slip velocity in an otherwise quiescent second-order fluid. We then determine how the motion of a diffusiophoretic Janus particle is affected by complex fluid rheology, namely viscoelasticity and shear-thinning viscosity, compared to a Newtonian fluid, assuming a fixed slip velocity. We find that a Janus particle may go faster or slower in a viscoelastic fluid, but is always slower in a shear-thinning fluid as compared to a Newtonian fluid.

Experimental Investigation of Flow-Induced Vibration in Gas/Shear-Thinning Liquid Flows in Vertical Pipe

2020 ◽  
Author(s):  
Ruinan Lin ◽  
Ke Wang ◽  
Qing Li ◽  
Narakorn Srinil ◽  
Fangjun Shi
Keyword(s):  
Newtonian Fluid ◽  
Industrial Process ◽  
Flow Region ◽  
Shear Thinning ◽  
Maximum Energy ◽  
Internal Diameter ◽  
Flow Induced Vibration ◽  
Two Phase ◽  
Liquid Flows ◽  
Shear Thinning Fluid

Abstract The non-Newtonian shear-thinning fluid widely exists in the industrial process and the rheology exerts a significant influence on the flow pattern transition and flow-induced vibration (FIV). However, studies on the rheology effect of the liquid phase in the vertical upward two-phase flows are quite lacking due to the complexity of non-Newtonian fluid properties. In the present study, the vertical upward gas/shear-thinning liquid flows experiments are conducted on a rigid acrylic pipe with an internal diameter of 20 mm. Three different Carboxymethyl Cellulose (CMC) solutions are used as the non-Newtonian fluid, aimed at capturing a two-phase flow regime transition including the vertical slug, churn and annular flows. The results indicate that the maximum energy spectral densities of vibration occur at the slug-to-churn flow transition boundary at low liquid velocities and the annular flow region under high liquid velocities, respectively. The effects of the rheology of the shear-thinning fluid in terms of the flow patterns and FIV are also presented and discussed.

scholarly journals Force moments of an active particle in a complex fluid

2017 ◽  
Vol 829 ◽  
Author(s):  
Gwynn J. Elfring
Keyword(s):  
Hydrodynamic Force ◽  
Newtonian Fluids ◽  
Active Particle ◽  
Reciprocal Theorem ◽  
Background Flow ◽  
Weakly Nonlinear ◽  
Active Particles ◽  
Special Cases ◽  
Complex Fluid

A generalized reciprocal theorem is formulated for the motion and hydrodynamic force moments of an active particle in an arbitrary background flow of a (weakly nonlinear) complex fluid. This formalism includes as special cases a number of previous calculations of the motion of both passive and active particles in Newtonian and non-Newtonian fluids.

The Shear-Driven Fluid Motion Using Oscillating Boundaries

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Md. Shakhawath Hossain ◽  
Nihad E. Daidzic
Keyword(s):  
Newtonian Fluid ◽  
Stokes Equations ◽  
Fluid Motion ◽  
Wall Slip ◽  
Shear Thinning ◽  
Infinite Domain ◽  
Diffusion Type ◽  
Flow Rates ◽  
Finite Differences Method ◽  
Fluid Rheology

A classical Stokes’ second problem has been known for a long time and represents one of the few exact solutions of nonlinear Navier-Stokes equations. However, oscillatory flow in a semi-infinite domain of Newtonian fluid under harmonic boundary excitation only leads to fluid wind-milling back and forth in close wall vicinity. In this study, we are presenting the mathematical model and the numerical simulations of the Newtonian fluid and the shear-thinning non-Newtonian blood-mimicking fluid flow. Positive flow rates were obtained by periodic yet nonharmonic oscillatory motion of one or two infinite boundary flat walls. The oscillatory flows in semi-infinite or finite 2D geometry with sawtooth or periodic rectified-sine boundary conditions are presented. Rheological human blood models used were: Power-Law, Sisko, Carreau, and Herschel-Bulkley. A one-dimensional time-dependent nonlinear coupled conservative diffusion-type boundary layer equations for mass, linear momentum, and energy were solved using the finite-differences method with finite-volume discretization. It was possible to test the accuracy of the in-house developed computational programs with the few isothermal flow analytical solutions and with the celebrated classical Stokes’ first and second problems. Positive flow rates were achieved in various configurations and in absence of the adverse pressure gradients. Body forces, such as gravity, were neglected. The calculations utilizing in-phase sawtooth and rectified-sine wall excitations resulted in respectable net flow which stabilizes and becomes quasi-steady, starting from rest, after three to ten periods depending on the fluid rheology. It was assumed that rapid return stroke of the wall actuator resulted in total wall slip while forward wall motion existed with no-slip boundary condition. Shear “driving” and “driven” fluid regions were identified. The shear-thinning fluid rheology delivered many interesting results, such as pluglike flow. Constructive interference of diffusive penetration layers from multiple flat surfaces could be used as practical pumping mechanism in micro-scales.

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

2021 ◽  
Vol 11 (15) ◽  
pp. 7113
Author(s):  
Sensen Yang ◽  
Chengxu Tu ◽  
Minglu Dai ◽  
Xianfu Ge ◽  
Rongjun Xu ◽  
...  
Keyword(s):  
Newtonian Fluid ◽  
Viscoelastic Property ◽  
Particle Density ◽  
Petroleum Industry ◽  
Shear Thinning ◽  
Light Particle ◽  
Original Position ◽  
Particle Sedimentation ◽  
Settling Particle ◽  
Shear Thinning Fluid

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.

scholarly journals Numerical Modeling of Sperm Swimming

Fluids ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 73
Author(s):  
Fang-Bao Tian ◽  
Li Wang
Keyword(s):  
Sperm Quality ◽  
Computational Studies ◽  
Theoretical Methods ◽  
Structure Interaction ◽  
Sperm Density ◽  
Fluid Environment ◽  
Complex Fluid ◽  
Fluid Rheology ◽  
Wall Interactions ◽  
Open Issues

Due to rising human infertility, sperm motility has been an important subject. Among the hundreds of millions of sperms on the journey up the oviducts, only a few excellent travelers will reach the eggs. This journey is affected by many factors, some of which include sperm quality, sperm density, fluid rheology and chemotaxis. In addition, the sperm swimming through different body tracks and fluids involves complex sperm flagellar, complex fluid environment, and multi-sperm and sperm-wall interactions. Therefore, this topic has generated substantial research interest. In this paper, we present a review of computational studies on sperm swimming from an engineering perspective with focus on both simplified theoretical methods and fluid–structure interaction methods. Several open issues in this field are highlighted.

scholarly journals Soft Matter Emerging Investigators Issue 2021 - "Propulsion of an elastic filament in a shear-thinning fluid at low Reynolds numbers"

Soft Matter ◽  
2021 ◽  
Author(s):  
Ke Qin ◽  
Zhiwei Peng ◽  
Ye Chen ◽  
Herve Nganguia ◽  
Lailai Zhu ◽  
...  
Keyword(s):  
Soft Matter ◽  
Reynolds Numbers ◽  
Shear Thinning ◽  
Low Reynolds Numbers ◽  
Elastic Filament ◽  
Low Reynolds ◽  
Micro Organisms ◽  
Surrounding Fluid ◽  
Shear Thinning Fluid ◽  
Flexible Appendages

Some micro-organisms and artificial micro-swimmers propel at low Reynolds numbers (Re) via the interaction of their flexible appendages with the surrounding fluid. While their locomotion have been extensively studied with...

scholarly journals Swimming efficiency in a shear-thinning fluid

2017 ◽  
Vol 96 (6) ◽  
Author(s):  
Herve Nganguia ◽  
Kyle Pietrzyk ◽  
On Shun Pak
Keyword(s):  
Shear Thinning ◽  
Swimming Efficiency ◽  
Shear Thinning Fluid
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