Shear-induced particle migration and size segregation in bidisperse suspension flowing through symmetric T-shaped channel

2019 ◽  
Vol 31 (5) ◽  
pp. 053305 ◽  
Author(s):  
M. Mallikarjuna Reddy ◽  
Anugrah Singh
Keyword(s):  
Particle Migration ◽  
Size Segregation ◽  
Bidisperse Suspension

Exploitation of Particle Migration Mechanism to Promote Economy and Ecology in Concrete Technology

2006 ◽  
Vol 302-303 ◽  
pp. 19-25 ◽  
Author(s):  
Piet Stroeven ◽  
J. Hu ◽  
Martijn Stroeven
Keyword(s):  
Computer Simulation ◽  
Simulation Study ◽  
Coarse Aggregate ◽  
Fine Particles ◽  
Local Density ◽  
Fine Sand ◽  
Particle Migration ◽  
Size Segregation ◽  
Concrete Technology ◽  
Computer Simulation Study

The computer simulation study of Portland cement blending confirmed the major mechanism to be size segregation in the Interfacial Transition Zones around the aggregate particles. Fine particles tend to move through the skeleton of larger particles towards the surface of the aggregate grains, improving local density. But the most interesting feature is a disproportionately larger internal bond capacity (based on van der Waals forces between nearby particles). In this contribution, we have isolated the mechanism of internal diffusion capacity of particles, on which blending efficiency relies, for a simulation study on the migration of fine sand articles into the network of coarse aggregate grains. The influences of technical parameters (including gap in size between fine sand and coarse aggregate, as well as the workability conditions) have been investigated on the migration capacity of fine sand particles. This paper will report briefly the outcomes of this computer simulation study on aggregate mix systems.

Shear-Induced Size Segregation Phenomena in Bidisperse Suspensions

1994 ◽  
Vol 47 (6S) ◽  
pp. S236-S239 ◽  
Author(s):  
Gokul P. Krishnan ◽  
David T. Leighton
Keyword(s):  
Reynolds Number ◽  
Parallel Plate ◽  
Migration Velocity ◽  
Particle Migration ◽  
Size Segregation ◽  
Concentrated Suspension ◽  
Colloidal Spheres ◽  
Tracer Particles ◽  
Flow Geometry ◽  
Wide Gap

The behavior of tracer particles in a concentrated suspension of non-colloidal spheres sheared in a parallel plate viscometer at low Reynolds number was investigated. The tracer particles were shown to migrate radially, with the tracer particles larger than those making up the suspension migrating radially outward. The migration velocity of the large tracer particles was measured, and found to be consistent with a shear-induced migration scaling (Leighton and Acrivos, 1987b), however the direction of the migration was the reverse of that suggested by the experiments of Abbot, et al. (1991) in a wide gap Couette device. The particle migration and segregation described here are interpreted in terms of the curvature of the flow geometry.

Depletion of coating color components in the blade coating process circulation

TAPPI Journal ◽  
2011 ◽  
Vol 10 (9) ◽  
pp. 17-23 ◽  
Author(s):  
ANNE RUTANEN ◽  
MARTTI TOIVAKKA
Keyword(s):  
Fine Particles ◽  
Particle Density ◽  
Stable Process ◽  
Size Fraction ◽  
Color Stability ◽  
Strong Interactions ◽  
Coating Process ◽  
Size Segregation ◽  
Coating Color ◽  
Average Size

Coating color stability, as defined by changes in its solid particle fraction, is important for runnability, quality, and costs of a paper coating operation. This study sought to determine whether the size or density of particles is important in size segregation in a pigment coating process. We used a laboratory coater to study changes in coating color composition during coating operations. The results suggest that size segregation occurs for high and low density particles. Regardless of the particle density, the fine particle size fraction (<0.2 μm) was the most prone for depletion, causing an increase in the average size of the particles. Strong interactions between the fine particles and other components also were associated with a low depletion tendency of fine particles. A stable process and improved efficiency of fine particles and binders can be achieved by controlling the depletion of fine particles.

Molecular Dynamics Study of Cohesionless Granular Materials: Size Segregation by Shaking

1993 ◽  
Vol 07 (09n10) ◽  
pp. 1865-1872 ◽  
Author(s):  
Toshiya OHTSUKI ◽  
Yoshikazu TAKEMOTO ◽  
Tatsuo HATA ◽  
Shigeki KAWAI ◽  
Akihisa HAYASHI
Keyword(s):  
Molecular Dynamics ◽  
Steady State ◽  
Specific Gravity ◽  
Pressure Gradient ◽  
Granular Materials ◽  
Buoyancy Force ◽  
Temporal Evolution ◽  
Particle Radius ◽  
Size Segregation ◽  
Increasing Function

The Molecular Dynamics technique is used to investigate size segregation by shaking in cohesionless granular materials. Temporal evolution of the height h of the tagged particle with different size and mass is measured for various values of the particle radius and specific gravity. It becomes evident that h approaches the steady state value h∞ independent of initial positions. There exists a threshold of the specific gravity of the particle. Below the threshold, h∞ is an increasing function of the particle size, whereas above it, h∞ decreases with increasing the particle radius. The relaxation time τ towards the steady state is calculated and its dependence on the particle radius and specific gravity is clarified. The pressure gradient of pure systems is also measured and turned out to be almost constant. This suggests that the buoyancy force due to the pressure gradient is not responsible to h∞.

scholarly journals Surface charge modulation of rifampicin-loaded PLA nanoparticles to improve antibiotic delivery in Staphylococcus aureus biofilms

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
David Da Costa ◽  
Chloé Exbrayat-Héritier ◽  
Basile Rambaud ◽  
Simon Megy ◽  
Raphaël Terreux ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Surface Charge ◽  
Treatment Efficacy ◽  
Particle Migration ◽  
Bacterial Biofilm ◽  
Poly Lactic Acid ◽  
Retention Capacity ◽  
The Impact ◽  
Positively Charged ◽  
Antibiotic Delivery

Abstract Background After the golden age of antibiotic discovery, bacterial infections still represent a major challenge for public health worldwide. The biofilm mode of growth is mostly responsible for chronic infections that current therapeutics fail to cure and it is well-established that novel strategies must be investigated. Particulate drug delivery systems are considered as a promising strategy to face issues related to antibiotic treatments in a biofilm context. Particularly, poly-lactic acid (PLA) nanoparticles present a great interest due to their ability to migrate into biofilms thanks to their submicronic size. However, questions still remain unresolved about their mode of action in biofilms depending on their surface properties. In the current study, we have investigated the impact of their surface charge, firstly on their behavior within a bacterial biofilm, and secondly on the antibiotic delivery and the treatment efficacy. Results Rifampicin-loaded PLA nanoparticles were synthetized by nanoprecipitation and characterized. A high and superficial loading of rifampicin, confirmed by an in silico simulation, enabled to deliver effective antibiotic doses with a two-phase release, appropriate for biofilm-associated treatments. These nanoparticles were functionalized with poly-l-lysine, a cationic peptide, by surface coating inducing charge reversal without altering the other physicochemical properties of these particles. Positively charged nanoparticles were able to interact stronger than negative ones with Staphylococcus aureus, under planktonic and biofilm modes of growth, leading to a slowed particle migration in the biofilm thickness and to an improved retention of these cationic particles in biofilms. While rifampicin was totally ineffective in biofilms after washing, the increased retention capacity of poly-l-lysine-coated rifampicin-loaded PLA nanoparticles has been associated with a better antibiotic efficacy than uncoated negatively charged ones. Conclusions Correlating the carrier retention capacity in biofilms with the treatment efficacy, positively charged rifampicin-loaded PLA nanoparticles are therefore proposed as an adapted and promising approach to improve antibiotic delivery in S. aureus biofilms.

scholarly journals Combined electrokinetic and shear flows control colloidal particle distribution across microchannel cross-sections

Soft Matter ◽  
2021 ◽  
Author(s):  
Varun Lochab ◽  
Shaurya Prakash
Keyword(s):  
Shear Flow ◽  
Cross Sections ◽  
Lift Force ◽  
Shear Flows ◽  
Colloidal Particle ◽  
Particle Distribution ◽  
Particle Migration ◽  
Flow Parameters

We quantify and investigate the effects of flow parameters on the extent of colloidal particle migration and the corresponding electrophoresis-induced lift force under combined electrokinetic and shear flow.

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