Experimental study of short- and long-time diffusion regimes of spherical particles in carboxymethylcellulose solutions

2005 ◽  
Vol 41 (8) ◽  
pp. 1772-1780 ◽  
Author(s):  
Ines Delfino ◽  
Chiara Piccolo ◽  
Maria Lepore
Keyword(s):  
Experimental Study ◽  
Spherical Particles ◽  
Long Time

Self-diffusion of bimodal suspensions of hydrodynamically interacting spherical particles in shearing flow

1994 ◽  
Vol 281 ◽  
pp. 51-80 ◽  
Author(s):  
Chingyi Chang ◽  
Robert L. Powell
Keyword(s):  
Diffusion Coefficients ◽  
Cluster Size ◽  
Near Field ◽  
Spherical Particles ◽  
Random Structure ◽  
Shearing Flow ◽  
Self Diffusion ◽  
Long Time ◽  
Mobility Matrix ◽  
Many Body Interactions

We study the average mobilities and long-time self-diffusion coefficients of a suspension of bimodally distributed spherical particles. Stokesian dynamics is used to calculate the particle trajectories for a monolayer of bimodal-sized spheres. Hydrodynamic forces only are considered and they are calculated using the inverse of the grand mobility matrix for far-field many-body interactions and lubrication formulae for near-field effects. We determine both the detailed microstructure (e.g. the pair-connectedness function and cluster formation) and the macroscopic properties (e.g. viscosity and self-diffusion coefficients). The flow of an ‘infinite’ suspension is simulated by considering 25, 49, 64 and 100 particles to be one ‘cell’ of a periodic array. Effects of both the size ratio and the relative fractions of the different-sized particles are examined. For the microstructures, the pair-connectedness function shows that the particles form clusters in simple shearing flow due to lubrication forces. The nearly symmetric angular structures imply the absence of normal stress differences for a suspension with purely hydrodynamic interactions between spheres. For average mobilities at infinite Péclet number, Ds0, our simulation results suggest that the reduction of Ds0 as concentration increases is directly linked to the influence of particle size distribution on the average cluster size. For long-time self-diffusion coefficients, Ds∞, we found good agreement between simulation and experiment (Leighton & Acrovos 1987 a; Phan and Leighton 1993) for monodispersed suspensions. For bimodal suspensions, the magnitude of Ds∞, and the time to reach the asymptotic diffusive behaviour depend on the cluster size formed in the system, or the viscosity of the suspension. We also consider the effect of the initial configuration by letting the spheres be both organized (size segregated) and randomly placed. We find that it takes a longer time for a suspension with an initially organized structure to achieve steady state than one with a random structure.

Experimental study of low-temperature long-time relaxation in epoxy resin

1987 ◽  
Vol 68 (3-4) ◽  
pp. 285-299 ◽  
Author(s):  
M. Koláč ◽  
B. S. Neganov ◽  
A. Sahling ◽  
S. Sahling
Keyword(s):  
Experimental Study ◽  
Low Temperature ◽  
Epoxy Resin ◽  
Time Relaxation ◽  
Long Time

Experimental Study on Restoration of Deteriorated Timber due to Termites by Resin Filling

2022 ◽  
Author(s):  
Takashi Yajima ◽  
Kei-ichi Imamoto ◽  
Chizuru Kiyohara ◽  
Mikako Yamada
Keyword(s):  
Experimental Study ◽  
Injection Pressure ◽  
Theoretical Formula ◽  
Internal Cavity ◽  
Strength Recovery ◽  
The World ◽  
Stable Manner ◽  
Long Time ◽  
Filling Method ◽  
Very High

There are many valuable wooden buildings in the world, because timber has been used all over the world as a building material for a long time. However, there is an issue that timber deteriorates due to various factors. Therefore, in order to preserve these valuable wooden buildings, it is necessary to appropriately repair or reinforce treatment. One of the treatments is the resin filling method. In this method, filling the resin in order to restore the strength into an internal cavity caused by deterioration. It has become clear that it is possible to recover the strength using this method, however, we are still conducting construction based on the rule of thumb. Therefore, authors examined the resin characteristics in order to inject the resin in stable manner and ensure strength recovery. Authors focused on deteriorated timber due to termites, because Japan has a very high amount of such type of timber. Authors reports the following four aspects of the characteristics of resin filling into timber. 1. The Area velocity is determined by the injection pressure, width of the gap, and viscosity of the resin. 2. The resin spreads concentrically in the gap of wood, but there is no regularity in the random gap like deteriorated timber due to termites. 3. Authors proposed a new coefficient for the application, of a theoretical formula to deteriorated timber due to termites. 4. Authors proposed a flowchart of resin filling method to perform stable construction.

An Experimental Study of Acid Exposed Fibre Reinforced Plastic Gratings

2011 ◽  
Author(s):  
Firoz Alam ◽  
Reza N. Jazar
Keyword(s):  
Experimental Study ◽  
High Temperature ◽  
Service Life ◽  
Industrial Plants ◽  
Reinforced Plastics ◽  
Industrial Manufacturing ◽  
Reinforced Plastic ◽  
Fluosilicic Acid ◽  
Long Time ◽  
Adverse Environmental Conditions

Fibre Reinforced Plastics (FRPs) generally have greater advantages over conventional materials for their structural properties. However, the service life can significantly be shortened if the fibre reinforced plastics are exposed to adverse environmental conditions especially acid vapour, humidity and high temperature. In many chemical industrial plants in Australia and elsewhere fibre reinforced plastic gratings are used as structural components of stairs and passages where they are subjected to varying degrees of fluosilicic acid, a byproduct of the industrial manufacturing process. As currently no experimental data on the effects of fluosilicic acid on FRPs is available in the public domain, it is difficult to predict the service life of FRPs with some certainty. In order to understand the structural strength of fluosilicic acid exposed FRPs, an experimental study was undertaken. A series of specimens from various locations of a chemical plan in Australia were acquired and studied. Some new specimens (not exposed to acid, humidity and high temperature) were also studied to provide a benchmark for the comparison. The results indicated that the long time exposure to harsh environment and acid vapour can significantly deteriorate the flexural strength and service life of FRPs.

Settling behavior of non-spherical particles in power-law fluids: Experimental study and model development

Particuology ◽  
2019 ◽  
Vol 46 ◽  
pp. 30-39 ◽  
Author(s):  
Zhengming Xu ◽  
Xianzhi Song ◽  
Gensheng Li ◽  
Zhaoyu Pang ◽  
Zhaopeng Zhu
Keyword(s):  
Experimental Study ◽  
Power Law ◽  
Model Development ◽  
Spherical Particles ◽  
Power Law Fluids ◽  
Settling Behavior

Experimental Study on Stabilization of Chromium Contaminated Soil

2011 ◽  
Vol 414 ◽  
pp. 273-279
Author(s):  
Ji Da Chen ◽  
Li Liu ◽  
Li Wei Zhang ◽  
Shi Guo Liao ◽  
Yong Ting Song ◽  
...  
Keyword(s):  
Experimental Study ◽  
Contaminated Soil ◽  
Critical Value ◽  
Polluted Soil ◽  
Pyrrolidine Dithiocarbamate ◽  
Stabilization Method ◽  
Toxicity Assay ◽  
Long Time ◽  
Stabilization Effect ◽  
Ammonium Pyrrolidine Dithiocarbamate

To develope a practicable stabilization method for remediation chromium contaminated soil, reductant and chelate reagent were investigated for stabilization artificical chromium contaminated soil, and the stabilization effect was tested through extraction toxicity assay after stablized soil was oxidized at pH 12. The experimental results showed that the composition of sodium bisulfite & ammonium pyrrolidine dithiocarbamate was an ideal stabilizer of chromium in soil, and the extraction toxicity was much less than that of classical stabilized chromium polluted soil with only reductant or the maximum critical value in GB16889-2008, which suggested that the composition of reductant & compound of dithiocarbamate might be practically appllied for remediation chromium contaminated soil because it was likely to remain chromium much more stable in soil for a long time and significantly decrease Cr mobility.

Equilibrium radial positions of neutrally buoyant spherical particles over the circular cross-section in Poiseuille flow

2017 ◽  
Vol 813 ◽  
pp. 750-767 ◽  
Author(s):  
Yusuke Morita ◽  
Tomoaki Itano ◽  
Masako Sugihara-Seki
Keyword(s):  
Experimental Study ◽  
Cross Section ◽  
Poiseuille Flow ◽  
Equilibrium Position ◽  
Probability Function ◽  
Circular Cross Section ◽  
Spherical Particles ◽  
Inertial Migration ◽  
Entry Length ◽  
Neutrally Buoyant

An experimental study of the inertial migration of neutrally buoyant spherical particles suspended in the Poiseuille flow through circular tubes has been conducted at Reynolds numbers $(Re)$ from 100 to 1100 for particle-to-tube diameter ratios of ${\sim}$0.1. The distributions of particles in the tube cross-section were measured at various distances from the tube inlet and the radial probability function of particles was calculated. At relatively high $Re$, the radial probability function was found to have two peaks, corresponding to the so-called Segre–Silberberg annulus and the inner annulus, the latter of which was first reported experimentally by Matas et al. (J. Fluid Mech. vol. 515, 2004, pp. 171–195) to represent accumulation of particles at smaller radial positions than the Segre–Silberberg annulus. They assumed that the inner annulus would be an equilibrium position of particles, where the resultant lateral force on the particles disappears, similar to the Segre–Silberberg annulus. The present experimental study showed that the fraction of particles observed on the Segre–Silberberg annulus increased and the fraction on the inner annulus decreased further downstream, accompanying an outward shift of the inner annulus towards the Segre–Silberberg annulus and a decrease in its width. These results suggested that if the tubes were long enough, the inner annulus would disappear such that all particles would be focused on the Segre–Silberberg annulus for $Re<1000$. At the cross-section nearest to the tube inlet, particles were absent in the peripheral region close to the tube wall including the expected Segre–Silberberg annulus position for $Re>700$. In addition, the entry length after which radial migration has fully developed was found to increase with increasing $Re$, in contrast to the conventional estimate. These results may be related to the developing flow in the tube entrance region where the radial force profile would be different from that of the fully developed Poiseuille flow and there may not be an equilibrium position corresponding to the Segre–Silberberg annulus.

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