Particles In non-Newtonian Fluids Research Articles

Transport of nonspherical particles in non-Newtonian fluid: A review

The transport of spherical particles in microchannel flow has been extensively studied owing to its relevance to efficient particle control, particularly in high-throughput cytometry and in single-cell detection and analysis. Despite significant advances in the field of inertial microfluidics, however, there remains a need for a deeper understanding of the migration of nonspherical particles in non-Newtonian fluids, given the diverse shapes of particles found in biological and industrial contexts. In this review, the transport behaviors of both spherical and nonspherical particles in both Newtonian and non-Newtonian fluids are examined. The current state of knowledge, challenges, and potential opportunities in inertial microfluidics are analyzed, with a focus on the underlying physical mechanisms and the development of novel channel designs. The findings presented here will enhance our understanding of the accumulation behavior of rigid particles in non-Newtonian fluid channel flow and may provide insights into efficient particle focusing and control in microfluidic devices.

Computational study on interaction between rotating non-spherical particles and shear-thinning fluids

In this paper, the drag coefficient (Cd), lift coefficient (Cl), and torque coefficient (Ct) of rotating non-spherical particles in shear-thinning non-Newtonian fluids are investigated based on particle-resolved direct numerical simulation. The Carreau model is used to describe the rheological behavior of non-Newtonian fluids, and the numerical model is validated against previously published data. Then, the effects of aspect ratio (Ar), spin number (Spa), flow index (n), and Carreau number (Cu) on Cd, Cl, and Ct of rotating non-spherical particles are investigated at different Reynolds numbers (Re). The numerical results show that the closer the particles are to the spherical shape, the smaller the fluctuations of Cd, Cl, and Ct curves. The peaks and valleys of Cd, Cl, and Ct of oblate and prolate ellipsoidal particles are reversely distributed. The fluctuations of Cd and Cl curves increase with increasing Spa. Cd decreases with increasing Spa at low Re, contrary to Newtonian fluids' results. Cd and Ct decrease with increasing shear-thinning properties, Cl increases with increasing shear-thinning properties, and the effect of shear-thinning properties decreases with increasing Re. The variation of viscosity and pressure is the main reason for the variation of Cd, Cl, and Ct under different variables. Predictive correlations of Cd and Ct are established based on Re, Spa, n, Cu, and α. The findings indicate that particle rotation and shear-thinning properties must be considered when evaluating particle-fluid interactions, which provide important guidance for predicting and controlling the orientation and distribution of non-spherical particles in non-Newtonian fluids.

Wall effect on cluster particle's settling terminal velocity and drag coefficient in Newtonian and non-Newtonian fluid medium

The experimental investigation of the wall effect on the cluster particle settling in the Newtonian and non-Newtonian fluid medium is carried out in three different diameter flow channels. The cluster usually forms during the sedimentation of particles in a fluid medium, so it becomes necessary to study the behavior of the cluster particles. Different cluster particles are considered depending on the number of spheres (N) attached to the cluster and the cluster's shape. The present experiment covers the following range of conditions: 0.05 ≤ deq/D ≤ 0.24, 2 ≤ N ≤ 7, 0.64 ≤ n ≤ 1, and 0.14 ≤ K ≤ 1.81. The results reveal that the terminal velocity varies with the blockage ratio (deq/D), N, and cluster shape. For a particular deq/D ratio and the same N, the terminal velocity of polyhedron particles is high compared to the planar and chain shape particles. The blockage ratio and the Reynolds number affect the wall factor of the cluster particles. However, from the experiment, it is observed that the wall effect also depends on the orientation of the particles. The impact of the wall on the cluster particle is high in Newtonian fluid when compared to cluster particles in non-Newtonian fluid. The present work additionally investigates the influence of drag on cluster particles in the presence and absence of the wall effect. The numerical relationships are developed to predict experimental results in Newtonian and non-Newtonian fluid mediums.

Hindered Settling of Fiber Particles in Viscous Fluids

In the current literature, information can mainly be found about free and hindered settling of isometric particles in Newtonian and non-Newtonian fluids. These conclusions cannot be used to describe the sedimentation of non-isometric particle in non-Newtonian fluids. For this reason, we have carried out systematic experiments and calculated the correlation of the hindered settling velocity of a cloud of non-isometric particles in high-viscosity and pseudoplastic liquid. The experiments were performed in transparent model fluids, namely, glycerine (a Newtonian fluid) and an aqueous solution of carboxylmethylcelulose CMC (a non-Newtonian pseudo-plastic liquid). These fluids have similar rheological properties, for example, the fresh fine-grained cementitious composites HPC/UHPC. The experiments were carried out with steel fibers with a ratio of d/l = 0.3/20. The settling velocity was determined for fiber volumes from 1% to 5%. While it is known from previous studies that for spherical particles the hindered settling velocity is proportional to the porosity of a suspension cloud on exponent 4.8, which was confirmed by our verification experiment, for the studied fiber particles it is proportional to the porosity on exponent 22.1. This great increase in the exponent is an effect of both the shape of the particles and, in particular, a mutual influence that arises from their interweaving and connection in the suspension.

Intensification of suspension of solid particles in non-Newtonian fluids with coaxial mixers

The coaxial mixers intensify the suspension of solids in complex fluids, which is highly desirable for process intensifications in food processing, pharmaceuticals production, and cosmetics manufacturing. The prime aim of this research work was to examine the mixing efficacy of a coaxial mixing system, comprising of a close clearance outer anchor and an inner axial impeller, in intensifying the suspension and dissemination of solid particles in carboxymethyl cellulose (CMC) solutions employing response surface methodology (RSM) and electrical resistance tomography (ERT). RSM was utilized in this research study to examine the impacts of three different numeric factors and one categoric factor on two response variables. The ERT conductivity data were utilized to generate axial as well as radial concentration profiles. The solids distribution quality in CMC solutions was assessed employing three different mixing indexes. The fluid flow patterns generated by the coaxial mixers in suspending and dispersing the solids in CMC solutions was obtained utilizing computational fluid dynamics (CFD) turbulent modeling approach. The influences of various important factors namely outer anchor speed, speed ratio, solids content, CMC concentration, average particle size, inner impeller types, and rotating mode on the slurry suspension and dispersion behaviour were comprehensively analyzed in this study.

Insulator-based dielectrophoretic focusing and trapping of particles in non-Newtonian fluids.

Insulator-based dielectrophoretic (iDEP) microdevices have been limited to work with Newtonian fluids. We report an experimental study of the fluid rheological effects on iDEP focusing and trapping of polystyrene particles in polyethylene oxide, xanthan gum, and polyacrylamide solutions through a constricted microchannel. Particle focusing and trapping in the mildly viscoelastic polyethylene oxide solution are slightly weaker than in the Newtonian buffer. They are, however, significantly improved in the strongly viscoelastic and shear thinning polyacrylamide solution. These observed particle focusing behaviors exhibit a similar trend with respect to electric field, consistent with a revised theoretical analysis for iDEP focusing in non-Newtonian fluids. No apparent focusing of particles is achieved in the xanthan gum solution, though the iDEP trapping can take place under a much larger electric field than the other fluids. This is attributed to the strong shear thinning-induced influences on both the electroosmotic flow and electrokinetic/dielectrophoretic motions.

Dynamics of rigid particles in a confined flow of viscoelastic and strongly shear-thinning fluid at very small Reynolds numbers

Despite growing interest in the focusing and manipulation of particles in non-Newtonian fluids in confined flows, the combined effect of viscoelastic and shear-thinning effects on particle dynamics is not well understood. Herein, we report the dynamics of rigid microparticles in confined flows of strongly shear-thinning viscoelastic (STVE) fluids at very low Reynolds numbers. Our experiments with different STVE fluids reveal five different regimes: original streamline, bimodal, center migration, defocusing, and wall migration (WM), depending upon the fluid properties and flow rates. It is found that the occurrence of the different regimes depends on the STVE parameter (ψ) and average strain rate (γ̇¯). We find that the dynamics of particles in the different regimes is underpinned by the synergy between viscoelastic lift force (FVE) and shear-thinning lift force (FST). Numerical simulation results of strain rate and viscosity profiles at different ψ and γ̇¯ enable estimation of the forces and explaining the dynamics observed. We expect that our study will find relevance in applications involving positioning and manipulation of particles in confined flows of STVE fluids.

Effective viscoelasticity affected by dispersed particles in non-Newtonian fluid under unsteady shear

Effective viscoelasticity affected by dispersed particles in non-Newtonian fluid under unsteady shear

Thermal Radiation Effects on Heat and Mass Transfer of Magnetohydrodynamics Dusty Jeffrey Fluid past an Exponentially Stretching Sheet

The heat and mass transfer of steady magnetohydrodynamics of dusty Jeffrey fluid past an exponentially stretching sheet in the presence of thermal radiation have been investigated. The main purpose of this study is to conduct a detailed analysis of flow behaviour of suspended dust particles in non-Newtonian fluid. The governing equations hav been converted into dimensionless form, and then solved numerically via the Keller-box method. The expression of Sherwood number, Nusselt number and skin friction have been evaluated, and then displayed in tabular forms. Velocity, temperature and concentration profiles are presented graphically. It is observed that large value of dust particles mass concentration parameter has reduced the flow velocity significantly. Increase in radiation parameter enhances the temperature, whereas the increment in Schmidt number parameter reduces the concentration.

Numerical study of shear thickening fluid with distinct particles dispersed in carrier fluid

The Shear Thickening Fluid (STF) is a non- Newtonian fluid which comes under dilatant material, STF undergoes phase transition from a low to high viscosity when shear stress is applied on it. In this paper modelling and simulation tools are used to study the STF fluid interaction when subjected to applied shear stress. The Eulerian description used for the fluid flow and the model considered the Lagrangian description of the rigid particles. The numerical analysis inspects important guideline such as acceleration of the flow, particle dispersion and the base of Non-Newtonian fluid. The fluid particles interrelation of STF showed that the shape, arrangement, volume concentration, and size of the particles had a vital effect on the behavior of STF. By adding sand particles in non-Newtonian fluids and applying high shear strain rates showed improvement in the shear thickening effects.

Determination of the convective mass transfer coefficient in the dissolution of NaCl particles in non-Newtonian fluids

The main objective of this work was to study the dissolution of salt (NaCl) particles in water and in non-Newtonian fluids that contain xanthan gum. In an agitated tank, experimental profiles of salt concentration as a function of time in the liquid phase were obtained. The experimental data were used to evaluate the mass transfer coefficient in different operational conditions and to validate the mathematical model. It was found that the dissolution kinetics of the salt particles was affected by both the fluid's xanthan gum concentration and initial salt concentration. Adding xanthan gum to the fluid decreased the salt dissolution kinetics. The mass transfer coefficient for a system with xanthan gum was smaller than the one for pure water. The values of the mass transfer coefficient for pure water base fluids varied from (0.836 ± 0.003) × 10−4 to (1.110 ± 0.003) × 10−4 m/s, and for xanthan gum solutions from (0.526 ± 0.003) × 10−4 to (0.865 ± 0.003) × 10−4 m/s. The mathematical model based on the mass conservation equations for the liquid and solid phases predicts the salt concentration profiles simulating the dissolution process. In addition, it was proposed an equation to model the decrease in the diameter of the particles due to dissolution. The mathematical model fitted the experimental data with an average relative error of 2.2%.

Enhanced computational performance of the lattice Boltzmann model for simulating micron- and submicron-size particle flows and non-Newtonian fluid flows

Significant improvements in the computational performance of the lattice-Boltzmann (LB) model, coded in FORTRAN90, were achieved through application of enhancement techniques. Applied techniques include optimization of array memory layouts, data structure simplification, random number generation outside the simulation thread(s), code parallelization via OpenMP, and intra- and inter-timestep task pipelining. Effectiveness of these optimization techniques was measured on three benchmark problems: (i) transient flow of multiple particles in a Newtonian fluid in a heterogeneous fractured porous domain, (ii) thermal fluctuation of the fluid at the sub-micron scale and the resultant Brownian motion of a particle, and (iii) non-Newtonian fluid flow in a smooth-walled channel. Application of the aforementioned optimization techniques resulted in an average 21× performance improvement, which could significantly enhance practical uses of the LB models in diverse applications, focusing on the fate and transport of nano-size or micron-size particles in non-Newtonian fluids.

Direct-forcing immersed boundary – non-Newtonian lattice Boltzmann method for transient non-isothermal sedimentation

In this study a direct numerical simulation methodology for investigating the transient non-isothermal sedimentation of circular particles in non-Newtonian fluids was developed. The combined method of direct-forcing immersed boundary and non-Newtonian lattice Boltzmann method (IB-NLBM) with split-forcing algorithm was used for simulating fluid-particle interactions including the thermal effects. The 4-point diffuse interface scheme was used to link the fixed Eulerian nodes of fluids to the moving Lagrangian nodes of immersed boundary. The effects of added mass due to the particle acceleration were also included in the analysis. The accuracy of the method was successfully validated by comparison of the model predictions with experimental data and earlier numerical results for cold and hot falling particles. The effects of non-Newtonian power-law index and temperature-dependent viscosity of shear-thinning and shear-thickening fluids on settling particles at fixed or varying temperatures for different generalized Archimedes and Prandtl numbers were also investigated. The results for shear-thinning fluids indicated that the effect of temperature-dependent viscosity was more noticeable at higher value of non-Newtonian behaviour index. Furthermore, the differences between the cases of constant and varying particle temperature were more noticeable at higher non-Newtonian behaviour index and larger values of generalized Prandtl number.

Hydrodynamic chromatography using flow of a highly concentrated dextran solution through a coiled tube

Separation of colloidal particles in non-Newtonian fluid is important in food engineering. Using hydrodynamic chromatography, colloidal particles and starch granules originating from corn were individually injected into dextran solutions (Mw 2,000,000g/mol) flowing through a coiled tube for efficient size separation. Rheological properties of dextran solutions ranging from 50 to 250g/L were determined, revealing pseudoplastic fluid behavior. Velocity profiles for dextran solution flow in coiled tubes were obtained from rheological power law parameters. Suspensions of colloidal particles of diameters 1.0 and 20μm were individually injected into the dextran flows, demonstrating that dextran solutions at high concentration separated colloidal particles. Starch granules were separated by size using a dextran solution flow (250g/L). Thus, we expect to obtain efficient separation of colloidal particles in foods using highly concentrated dextran solutions.

A FEM-DEM technique for studying the motion of particles in non-Newtonian fluids. Application to the transport of drill cuttings in wellbores

We present a procedure for coupling the finite element method (FEM) and the discrete element method (DEM) for analysis of the motion of particles in non-Newtonian fluids. Particles are assumed to be spherical and immersed in the fluid mesh. A new method for computing the drag force on the particles in a non-Newtonian fluid is presented. A drag force correction for non-spherical particles is proposed. The FEM-DEM coupling procedure is explained for Eulerian and Lagrangian flows, and the basic expressions of the discretized solution algorithm are given. The usefulness of the FEM-DEM technique is demonstrated in its application to the transport of drill cuttings in wellbores.

On Laminar Flow of Non-Newtonian Fluids in Porous Media

Flow of generalized Newtonian fluids in porous media can be modeled as a bundle of capillary tubes or a pore-scale network. In general, both approaches rely on the solution of Hagen–Poiseuille equation using power law to estimate the variations in the fluid viscosity due to the applied shear rate. Despite the effectiveness and simplicity, power law tends to provide unrealistic values for the effective viscosity especially in the limits of zero and infinite shear rates. Here, instead of using power law, Carreau model (bubbles, drops, and particles in non-Newtonian fluids. Taylor & Francis Group, New York, 2007) is used to determine the effective viscosity as a function of the shear strain rate. Carreau model can predict accurately the variation in the viscosity at all shear rates and provide more accurate solution for the flow physics in a single pore. Using the results for a single pore, normalized Fanning friction coefficient has been calculated and plotted as a function of the newly defined Reynolds number based on pressure gradient. For laminar flow, the variation in the friction coefficient with Reynolds number has been plotted and scaled. It is observed that generalized Newtonian fluid flows show Newtonian nature up to a certain Reynolds number. At high Reynolds number, deviation from the Newtonian behavior is observed. The main contribution of this paper is to present a closed-form solution for the flow in a single pore using Carreau model, which allows for fast evaluation of the relationship between flux and pressure gradient in an arbitrary pore diameter. In this way, we believe that our development will open the perspectives for using Carreau models in pore-network simulations at low computational costs to obtain more accurate prediction for generalized Newtonian fluid flows in porous media.

Separation of particles in non-Newtonian fluids flowing in T-shaped microchannels

Background: The flow of suspensions through bifurcations is encountered in several applications. It is known that the partitioning of particles at a bifurcation is different from the partitioning of the suspending fluid, which allows particle separation and fractionation. Previous works have mainly investigated the dynamics of particles sus- pended in Newtonian liquids. Methods: In this work, we study through 2D direct numerical simulations the par- titioning of particles suspended in non-Newtonian fluids flowing in a T-junction. We adopt a flow configuration such that the two outlets are orthogonal, and their flow rates can be tuned. A fictitious domain method combined with a grid deformation procedure is used. The effect of fluid rheology on the partitioning of particles between the two outlets is investigated by selecting different constitutive equations to model the suspending liquid. Specifically, an inelastic shear-thinning (Bird-Carreau) and a viscoelastic shear-thinning (Giesekus) models have been chosen; the results are also compared with the case of a Newtonian suspending liquid. Results: Simulations are carried out by varying the confinement, the inlet flow rate and the relative weight of the two outlet flow rates. For each condition, the fluxes of particles through the two outflow channels are computed. The results show that shear- thinning does not have a relevant effect as compared to the equivalent Newtonian case, i.e., with the same choice of the relative outlet flow rates. On the other hand, fluid elasticity strongly alters the fraction of particles exiting the two outlets as compared to the inlet. Such effect is more pronounced for larger particles and inlet flow rates. Conclusions: The results illustrated here show the feasibility to efficiently separate/ fractionate particles by size, through the use of viscoelastic suspending liquids.

An analytical investigation on unsteady motion of vertically falling spherical particles in non-Newtonian fluid by Collocation Method

Abstract An analytical investigation is applied for unsteady motion of a rigid spherical particle in a quiescent shear-thinning power-law fluid. The results were compared with those obtained from Collocation Method (CM) and the established Numerical Method (Fourth order Runge–Kutta) scheme. It was shown that CM gave accurate results. Collocation Method (CM) and Numerical Method are used to solve the present problem. We obtained that the CM which was used to solve such nonlinear differential equation with fractional power is simpler and more accurate than series method such as HPM which was used in some previous works by others but the new method named Akbari-Ganji’s Method (AGM) is an accurate and simple method which is slower than CM for solving such problems. The terminal settling velocity—that is the velocity at which the net forces on a falling particle eliminate—for three different spherical particles (made of plastic, glass and steel) and three flow behavior index n, in three sets of power-law non-Newtonian fluids was investigated, based on polynomial solution (CM). Analytical results obtained indicated that the time of reaching the terminal velocity in a falling procedure is significantly increased with growing of the particle size that validated with Numerical Method. Further, with approaching flow behavior to Newtonian behavior from shear-thinning properties of flow ( n → 1 ), the transient time to achieving the terminal settling velocity is decreased.

Electrophoretic velocity of spherical particles in Quemada fluids

The biomicrofluidic devices utilizing electrophoresis for sample manipulation are usually encountered with non-Newtonian behavior of working fluids. Hence, developing theoretical models capable of predicting the electrophoretic velocity of colloidal particles in non-Newtonian fluids is of high importance for accurate design and active control of these devices. The present investigation is dealing with the electrophoresis of a spherical particle in a biofluid obeying the Quemada rheological model. The sphere radius is considered to be significantly larger than the Debye length. Moreover, it is assumed that the particle zeta potential is small so that the Debye–Hückel linearization is allowable. An approximate analytical solution is obtained for the particle electrophoretic velocity for the conditions that the deviations of the fluid rheological behavior from the predictions of the Newton's law of viscosity are small. A parametric study along with inspection of some practical examples assuming the blood as the working fluid reveals that the non-Newtonian contribution to the electrophoretic velocity is comparable with the Newtonian part and therefore cannot be neglected. It is observed that the non-Newtonian part of electrophoretic velocity is an increasing function of the hematocrit level and the Deborah number and is independent of the particle size.

Numerical study of shear thickening fluid with discrete particles embedded in a base fluid

The Shear Thickening Fluid (STF) is a dilatant material, which displays non-Newtonian characteristics in its unique ability to transit from a low viscosity fluid to a high viscosity fluid. The research performed investigates the STF behavior by modeling and simulation of the interaction between the base flow and embedded rigid particles when subjected to shear stress. The model considered the Lagrangian description of the rigid particles and the Eulerian description of fluid flow. The numerical analysis investigated key parameters such as applied flow acceleration, particle distribution and arrangement, volume concentration of particles, particle size, shape and their behavior in a Newtonian and non-Newtonian fluid base. The fluid-particle interaction model showed that the arrangement, size, shape and volume concentration of the particles had a significant effect on the behavior of the STF. Although non-conclusive, the addition of particles in non-Newtonian fluids showed a promising trend of improved shear thickening effects at high shear strain rates.