Investigation of particle lateral migration in sample-sheath flow of viscoelastic fluid and Newtonian fluid

2016 ◽  
Vol 37 (15-16) ◽  
pp. 2147-2155 ◽  
Author(s):  
Dan Yuan ◽  
Jun Zhang ◽  
Sheng Yan ◽  
Gangrou Peng ◽  
Qianbin Zhao ◽  
...  
Keyword(s):  
Newtonian Fluid ◽  
Viscoelastic Fluid ◽  
Lateral Migration ◽  
Sheath Flow

An implicit scheme for simulation of free surface non-Newtonian fluid flows on dynamically adapted grids

2021 ◽  
Vol 36 (3) ◽  
pp. 165-176
Author(s):  
Kirill Nikitin ◽  
Yuri Vassilevski ◽  
Ruslan Yanbarisov
Keyword(s):  
Free Surface ◽  
Numerical Model ◽  
Newtonian Fluid ◽  
Viscoelastic Fluid ◽  
Fluid Flows ◽  
Numerical Results ◽  
Implicit Scheme ◽  
New Approach

Abstract This work presents a new approach to modelling of free surface non-Newtonian (viscoplastic or viscoelastic) fluid flows on dynamically adapted octree grids. The numerical model is based on the implicit formulation and the staggered location of governing variables. We verify our model by comparing simulations with experimental and numerical results known from the literature.

Analysis of the Motion and Deformation of a Bubble Rising in a Viscoelastic Fluid

2006 ◽  
Author(s):  
Shriram Pillapakkam ◽  
Pushpendra Singh ◽  
Denis L. Blackmore ◽  
Nadine Aubry
Keyword(s):  
Velocity Field ◽  
Newtonian Fluid ◽  
Viscoelastic Fluid ◽  
Bubble Radius ◽  
Polymer Concentration ◽  
Deborah Number ◽  
Two Phase ◽  
Bubble Volume ◽  
Recirculation Zones ◽  
Bubble Rising

A finite element code based on the level set method is developed for performing two and three dimensional direct numerical simulations (DNS) of viscoelastic two-phase flow problems. The Oldroyd-B constitutive equation is used to model the viscoelastic liquid and both transient and steady state shapes of bubbles in viscoelastic buoyancy driven flows are studied. The influence of the governing dimensionless parameters, namely the Capillary number (Ca), the Deborah Number (De) and the polymer concentration parameter c, on the deformation of the bubble is also analyzed. Our simulations demonstrate that the rise velocity oscillates before reaching a steady value. The shape of the bubble, the magnitude of velocity overshoot and the amount of damping depend mainly on the parameter c and the bubble radius. Simulations also show that there is a critical bubble volume at which there is a sharp increase in the bubble terminal velocity as the increasing bubble volume increases, similar to the behavior observed in experiments. The structure of the wake of a bubble rising in a Newtonian fluid is strikingly different from that of a bubble rising in a viscoelastic fluid. In addition to the two recirculation zones at the equator of the bubble rising in a Newtonian fluid, two more recirculation zones exist in the wake of a bubble rising in viscoelastic fluids which influence the shape of a rising bubble. Interestingly, the direction of motion of the fluid a short distance below the trailing edge of a bubble rising in a viscoelastic fluid is in the opposite direction to the direction of the motion of the bubble, thus creating a “negative wake”. In this paper, the velocity field in the wake of the bubble, the effect of the parameters on the velocity field and their influence on the shape of the bubble are also investigated.

Effect of Viscoelasticity on the Turbulence Kinetic Energy Budget of the Non-Newtonian Fluid Turbulent Flow Accompanied by Drag Reduction

2007 ◽  
Author(s):  
Y. Kagawa ◽  
B. Yu ◽  
Y. Kawaguchi
Keyword(s):  
Kinetic Energy ◽  
Turbulent Flow ◽  
Drag Reduction ◽  
Turbulent Kinetic Energy ◽  
Newtonian Fluid ◽  
Viscoelastic Fluid ◽  
Energy Budget ◽  
Rheological Parameters ◽  
Fluid Turbulence ◽  
Kinetic Energy Budget

For the purpose of elucidating the mechanism of drag reduction by additives and finding a way to judge optimum drag-reducing additives through a simple rheological test, we performed DNS analysis of viscoelastic fluid turbulent flow in a two-dimensional channel. In this calculation, we employed the Giesekus constitutive equation to model the interaction between water-soluble polymer, or the elastic micellar network structure, and solvent. We calculated the fluid flow by varying the rheological parameters of the model. We examined the turbulent kinetic energy budget and studied the “viscoelastic contribution” term in the budget equation for turbulent intensity, which is not apparent in normal Newtonian fluid turbulence. Viscoelastic contribution has a characteristic effect on viscoelastic fluid turbulence. We concluded that the viscoelastic contribution plays a major role in turbulent frictional drag reduction. Dissipation and viscoelastic contribution serve as a key factor of turbulent kinetic energy loss in most areas of the channel. From the visualization of local and instantaneous eddy behavior, we discussed the relationship between viscoelastic contribution, elastic energy and turbulent production. We found that viscoelastic contribution serves as a direct local source of turbulent production, and that energy is stored in the elasticity.

Lateral migration of a rigid sphere in torsional flow of a viscoelastic fluid

AIChE Journal ◽  
1984 ◽  
Vol 30 (4) ◽  
pp. 631-636 ◽  
Author(s):  
T. E. Karis ◽  
D. C. Prieve ◽  
S. L. Rosen
Keyword(s):  
Viscoelastic Fluid ◽  
Rigid Sphere ◽  
Lateral Migration ◽  
Torsional Flow

scholarly journals Investigation on Inertial Sorter Coupled with Magnetophoretic Effect for Nonmagnetic Microparticles

Micromachines ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 566 ◽  
Author(s):  
Jiayou Du ◽  
Long Li ◽  
Qiuyi Zhuo ◽  
Ruijin Wang ◽  
Zefei Zhu
Keyword(s):  
Magnetic Field ◽  
Structural Parameters ◽  
Expansion Ratio ◽  
Numerical Results ◽  
Lateral Migration ◽  
Sheath Flow ◽  
Micro Particles ◽  
Micro Piv ◽  
Sorting Efficiency ◽  
Good Agreement

The sizes of most prokaryotic cells are several microns. It is very difficult to separate cells with similar sizes. A sorter with a contraction–expansion microchannel and applied magnetic field is designed to sort microparticles with diameters of 3, 4 and 5 microns. To evaluate the sorting efficiency of the designed sorter, numerical simulations for calculating the distributions of microparticles with similar sizes were carried out for various magnetic fields, inlet velocities, sheath flow ratios and structural parameters. The numerical results indicate that micro-particles with diameters of 3, 4 and 5 microns can be sorted efficiently in such a sorter within appropriate parameters. Furthermore, it is shown that a bigger particle size and more powerful magnetic field can result in a greater lateral migration of microparticles. The sorting efficiency of microparticles promotes a lower inlet velocity and greater sheath flow ratios. A smaller contraction–expansion ratio can induce a greater space between particle-bands. Finally, the micro particle image velocity (micro-PIV) experiments were conducted to obtain the bandwidths and spaces between particle-bands. The comparisons between the numerical and experimental results show a good agreement and make the validity of the numerical results certain.

scholarly journals Three-Dimensional Numerical Simulation of Particle Focusing and Separation in Viscoelastic Fluids

Micromachines ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 908
Author(s):  
Chen Ni ◽  
Di Jiang
Keyword(s):  
Viscoelastic Fluid ◽  
Rectangular Channel ◽  
Particle Interaction ◽  
Three Dimensional ◽  
Viscoelastic Fluids ◽  
Lateral Migration ◽  
Square Channel ◽  
Particle Focusing ◽  
Aspect Ratios ◽  
Large Particles

Particle focusing and separation using viscoelastic microfluidic technology have attracted lots of attention in many applications. In this paper, a three-dimensional lattice Boltzmann method (LBM) coupled with the immersed boundary method (IBM) is employed to study the focusing and separation of particles in viscoelastic fluid. In this method, the viscoelastic fluid is simulated by the LBM with two sets of distribution functions and the fluid–particle interaction is calculated by the IBM. The performance of particle focusing under different microchannel aspect ratios (AR) is explored and the focusing equilibrium positions of the particles with various elasticity numbers and particle diameters are compared to illustrate the mechanism of particle focusing and separation in viscoelastic fluids. The results indicate that, for particle focusing in the square channel (AR = 1), the centerline single focusing becomes a bistable focusing at the centerline and corners as El increases. In the rectangular channels (AR < 1), particles with different diameters have different equilibrium positions. The equilibrium position of large particles is closer to the wall, and large particles have a faster lateral migration speed and few large particles migrate towards the channel center. Compared with the square channel, the rectangular channel is a better design for particle separation.

Anomalous Lateral Migration of a Rigid Sphere in Torsional Flow of a Viscoelastic Fluid

1984 ◽  
Vol 28 (4) ◽  
pp. 381-392 ◽  
Author(s):  
T. E. Karis ◽  
D. C. Prieve ◽  
S. L. Rosen
Keyword(s):  
Viscoelastic Fluid ◽  
Rigid Sphere ◽  
Lateral Migration ◽  
Torsional Flow
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