scholarly journals DEPOSITIONAL BEHAVIOR OF FINE SEDIMENT IN A TURBULENT FLUID MOTION

1966 ◽  
Vol 1 (10) ◽  
pp. 40 ◽  
Author(s):  
Emmanuel Partheniadis ◽  
John F. Kennedy
Keyword(s):  
Initial Period ◽  
Fluid Motion ◽  
Particle Diameter ◽  
Equilibrium Concentration ◽  
Annular Channel ◽  
Sediment Concentration ◽  
Parent Material ◽  
Silty Clay ◽  
Initial Concentration ◽  
Average Shear

An experimental investigation, utilizing an apparatus consisting of a counterrotating annular channel and ring, of the depositional characteristics of fine, cohesive sediment revealed that after an initial period of rapid deposition, the sediment concentration approaches asymptotically an equilibrium value. The ratio of this equilibrium concentration to the initial concentration is nearly independent of initial concentration and for a given sediment and environment depends only on the flow conditions. For the three water depths investigated, the ratio of equilibrium to initial concentration was found to he a single function of an average shear stress around the channel-section perimeter. A comparison of the size distributions of the parent material with the material retained in suspension when equilibrium was achieved indicated that the greatest losses occur in the clay-size fractions, suggesting that the deposition is controlled predominantly by flocculation, and that the strength and size of the floes exert a stronger influence on the deposition than does the particle weight. A silty-clay sediment with a mean particle diameter of 0.0009 mm was used in all experiments.

The mechanism of the anionic coordination polymerization of isoprene

1980 ◽  
Vol 45 (9) ◽  
pp. 2391-2399 ◽  
Author(s):  
Miroslav Kašpar ◽  
Jiří Trekoval
Keyword(s):  
Chromatographic Method ◽  
Initial Period ◽  
Reaction Scheme ◽  
Polymerization Kinetics ◽  
Coordination Polymerization ◽  
Initial Concentration ◽  
The Cross ◽  
Gas Chromatographic Method ◽  
Kinetics Of

The polymerization kinetics of isoprene (2-methyl-1,3-butadiene) in benzene with butyllithium as the initiator was investigated by the gas chromatographic method. After completion of the initial period of the reaction, its order with respect to the initial concentration of initiator is negative at the concentrations of the latter between 0.01 and 0.25 mol/l, and positive at higher concentrations. A reaction scheme has been suggested with respect to the "cross" association of butyllithium and of the "living" oligoisoprene.

Interface Movement and Microstructure Evolution of Interdiffusion in the Binary Alloy Diffusion Couples

2011 ◽  
Vol 689 ◽  
pp. 123-129
Author(s):  
Yong Sheng Li ◽  
Yan Zhou Yu ◽  
Xiao Lin Cheng ◽  
Guang Chen
Keyword(s):  
Single Phase ◽  
Relative Concentration ◽  
Equilibrium Concentration ◽  
Diffusion Couples ◽  
Binary Diffusion ◽  
Two Phase ◽  
Concentration Difference ◽  
Initial Concentration ◽  
Interdiffusion Flux ◽  
Interface Movement

The phase field simulation of interface movement and interdiffusion microstructure in a binary diffusion couples was developed. The diffusion couples with nonequilibrium concentration for single phase or single phase and two-phase including the temperature and mobility effects were studied. It’s shown that the interface movement and the atoms diffusion direction were determined by the magnitude of relative concentration difference between the initial concentration and the equilibrium concentration, the distance of interface movement and interdiffusion flux increases as the temperature or the mobility increasing, and the large mobility makes the particles coarsening faster.

scholarly journals CFD analysis of the fluid motion in the isolation rooms

2021 ◽  
Vol 850 (1) ◽  
pp. 012025
Author(s):  
P Tamil Selvan ◽  
K Abhiram ◽  
Ch Anu Raghava ◽  
V Naveen Sai
Keyword(s):  
World Health Organization ◽  
Atmospheric Pressure ◽  
Pressure Difference ◽  
Fluid Motion ◽  
Particle Diameter ◽  
World Health ◽  
Cfd Analysis ◽  
Cfd Simulations ◽  
The World ◽  
Health Organization

Abstract COVID-19 is declared as a pandemic by WHO (world health organization) which has led to many deaths all over the world. This study deals with the fluid motion in the isolation rooms with 12 or more ACH (air changes per hour) and maintaining a minimum pressure difference of 2.5 Pascal that can help in reducing the transmission of the virus from affected people. ANSI/ASHRAE guidelines are considered for the analysis. These Isolation rooms help in eradicating the spread of the contaminated particles to the surroundings by creating a pressure less than the atmospheric pressure in in the room. CFD simulations are carried to study the fluid motion of the particles emitted by the patient inside the room. The Analysis is carried out with various human cough velocities of different particle diameters and we observed from the results that the time taken by the particles to reach the exhaust increases with increase in particle diameter, and the flow inside the room increases with increase in human cough velocity.

Application of dimensional analysis in removal prediction of 2-[4-(dimethylamino) styryl]-1-methylpyridinium iodide dye using humic acid coated magnetic nanoparticle

2021 ◽  
Author(s):  
Anahita Esmaeilian ◽  
Kevin E. O'Shea
Keyword(s):  
Humic Acid ◽  
Dimensional Analysis ◽  
Concentration Ratio ◽  
Magnetic Nanoparticle ◽  
Equilibrium Concentration ◽  
Sorption Process ◽  
Dose Ratio ◽  
Initial Concentration ◽  
Liquid Systems ◽  
Isotherm Equations

<p>Numerous factors affect adsorption phenomena in solid–liquid systems. Critical factors are the sorbent dose and initial concentrations of the contaminants in the system. However, the combination of these two factors and their effects on removal prediction are largely unexplored. In this study, batch experiments were conducted to examine such effects on the adsorption of 2-[4-(dimethylamino) styryl]-1-methylpyridinium iodide cationic dye (2-ASP) in contaminated water to humic acid coated magnetic nanoparticles (HA-MNPs). Dimensional analysis and Buckingham’s π theorem were subsequently used to assess the relationship between the sorbent dose, initial concentration, and percent removal. Results of dimensional analysis along with experimental data suggest that sorbent dose and sorbate concentration ratio are the main variables controlling sorption of dye on HA-MNPs. In conventional isothermal studies, the isotherm equations are developed based on experiments of one sorbent dose which cannot be generalized for all sorbent doses.  In this study, a power function (Isotherm-like) model was obtained from the dimensional analysis that can describe precisely the sorption process of dye on HA-MNPs as a function of equilibrium concentration and sorbent dose ratio. Moreover, a relation is deduced for prediction of removal percent as a function of sorbent dose and initial concentration ratio with R<sup>2</sup> of 0.98.</p><p><strong>Keywords: Remediation, Dimensional analysis, Isotherm-like model, Magnetic nanoparticle, Styryl pyridinium dyes, Water treatment</strong></p>

Relationship of White Spruce to Lenses of Perennially Frozen Ground, Mount McKinley National Park, Alaska

ARCTIC ◽  
1965 ◽  
Vol 18 (4) ◽  
pp. 262 ◽  
Author(s):  
Leslie A. Viereck
Keyword(s):  
Snow Cover ◽  
National Park ◽  
White Spruce ◽  
Parent Material ◽  
Silty Clay ◽  
Frozen Ground ◽  
Moss Layer ◽  
Individual Trees ◽  
Relationship Of

Reports investigations of perennially frozen mounds beneath individual trees growing in silty clay on a terrace of the McKinley River. Climate, vegetation and parent material of the spruce stand are described. The mounds, 2-4 m in diam, contain a frozen lens-shaped core. The permafrost results from lower temperatures under the trees due to less snow cover and a thicker moss layer. A proposed cycle of development and collapse of the tree mounds is outlined.

Soil erosion processes. I. The relative importance of rainfall detachment and dunoff entrainment

Soil Research ◽  
1991 ◽  
Vol 29 (5) ◽  
pp. 671 ◽  
Author(s):  
APB Proffitt ◽  
CW Rose
Keyword(s):  
Soil Erosion ◽  
Overland Flow ◽  
Water Flux ◽  
Equilibrium Concentration ◽  
Sediment Concentration ◽  
Soil Types ◽  
Relative Importance ◽  
Runoff Water ◽  
Erosion Processes ◽  
Volumetric Flux

Experiments carried out in a simulated-rainfall tilting-flume facility are reported in which sediment concentrations (c) in runoff water resulting from overland flow only, or from a combination of rainfall and overland flow, were measured under controlled conditions using a series of slopes (0.1, 05, 1, 3 and 5%). The mixture of rainfall (of rate 100 mm h-1) and runon of water at the top of the flume were arranged to provide a constant volumetric flux (1.0x10-3 m3 m-l s-1) at exit from the 5.8 m long flume. Two contrasting soil types were studied: a cracking clay (black earth or vertisol), and a slightly dispersive sandy clay loam (solonchak or aridisol). Two major processes which can contribute to soil erosion under rainfall are rainfall detachment and runoff entrainment. For both soil types, c was generally highest for the steepest slope and decreased with slope. For constant rainfall and/or runoff conditions, c generally decreased with time until an equilibrium concentration was reached. At this equilibrium, the relative importance of rainfall detachment and entrainment in terms of soil loss was dependent on soil type and streampower which incorporates effects of slope and water flux. For streampowers <0.1 W m-2 for the black earth, and <0.3 W m-2 for the solonchak, the greatest contribution to c was by rainfall detachment, whilst at greater streampowers entrainment was the dominant contributor to c. At any streampower, the contribution by rainfall detachment was greater for the weakly structured solonchak than for the well aggregated black earth. At lower strearnpowers, the interaction between erosion processes was found to give higher c than the sum of both sediment concentrations resulting from the separately occurring processes. At streampowers greater than approximately 0.5 W m-2, rainfall reduced eroded sediment concentration by suppressing rill development. The findings in this study suggest that both runoff entrainment and rainfall detachment can contribute to sediment concentration from 'interrill' areas.

scholarly journals Soil and sediment analysis for agricultural and arctic landscapes

2021 ◽  
Author(s):  
Emily Lemke ◽  
David Atkinson ◽  
Christopher Wellen
Keyword(s):  
Water Quality ◽  
Particle Size ◽  
Grain Size ◽  
Particle Diameter ◽  
Quantitative Measure ◽  
Terrestrial Ecosystems ◽  
Parent Material ◽  
Soil Conditions ◽  
Local Climate ◽  
Local Soil

Soil plays in integral role in our terrestrial ecosystems. It is the membrane between the atmosphere and the biosphere. Soils provide a medium for vegetation, a filtration system for water, and contain the essential minerals and nutrients plants require (ref). Soil is composed of living (biotic) and non-living (abiotic) material. Soil development is a dynamic and ongoing process that depends on local climate, parent material, topography, vegetation, and time. The size of the inorganic mineral particles within a soil is referred to as grain size. Soil grain size is classified as Clay if the particle diameter is <0.002 mm, as silt if it is between 0.002 mm and 0.06 mm, or as sand if it is between 0.06 mm and 2 mm (Figure). The texture of a soil, or the distribution of particle grain size, can be a determining factor on how the soil drains or retains water, and its ability to retain nutrients, and its susceptibility to erosion, all of which can be direct factors in the development of natural vegetation or crop suitability. To classify a particular soils texture the proportions of particle size (% Sand, % Silt, % Clay) of a given sample is required. The use of a standard method is essential in order to compare data obtained at different locations (ref). A well-developed method for determining the quantitative proportions of particle size is the hydrometer method. Additionally, local soil conditions, or infrastructure (Roads) can have a direct impact on the water quality, specifically the turbidity of local water. The quantitative measure of sediment with water is known as Total Suspended Sediment, and can be related to other water quality measures such as conductivity. Total suspended solids is determined by filtering a known volume of water and measuring the mass of the suspended material that is captured on a fine filter.

Erosion mechanisms in combined sewers and the potential for pollutant release to receiving waters and water treatment plants

2002 ◽  
Vol 45 (3) ◽  
pp. 61-69 ◽  
Author(s):  
T.D. Mcllhatton ◽  
R. Sakrabani ◽  
R.M. Ashley ◽  
R. Burrows
Keyword(s):  
Initial Period ◽  
Suspended Sediments ◽  
Field Studies ◽  
Sediment Concentration ◽  
Storm Event ◽  
Receiving Waters ◽  
Using Data ◽  
Erosion Mechanisms ◽  
Maintenance Requirements

The problems associated with solids in sewerage systems result in common difficulties such as blockages and flooding and the subsequent maintenance requirements have been well documented. Concerns regarding pollutant release have also been demonstrated, with the contribution from in-sewer solids to the quality of the flow during a storm event being especially significant. These events known as “foul flushes” in combined sewers typically occur in the initial period of storm flows, when the concentration of suspended sediments and other pollutants are significantly higher than at other times. Traditionally impacts from these events have been related to the suspended solids phase of the flow passing through a CSO structure. It is now apparent that much of the suspended load originates from solids eroded from the bed. The “near bed solids” which are re-entrained into the flow, together with solids eroded from the bulk bed, account for large changes in the suspended sediment concentration under time varying flow conditions. The influence of these eroded solids and their potential impact on receiving waters and treatment plants will be reviewed using data obtained from field studies carried out in the main Dundee interceptor sewer in Scotland. This paper describes some of the methods employed to investigate the characteristics of the pollutants associated with solids erosion in combined sewers.

Effect of application timing on pyrithiobac persistence

Weed Science ◽  
1997 ◽  
Vol 45 (1) ◽  
pp. 179-182 ◽  
Author(s):  
Eric P. Webster ◽  
David R. Shaw
Keyword(s):  
Half Life ◽  
Sandy Loam ◽  
Analysis Of Covariance ◽  
Field Analysis ◽  
Silty Clay ◽  
Soil Slope ◽  
Application Timing ◽  
Initial Concentration ◽  
Greenhouse Study ◽  
Loam Soil

Experiments were conducted in 1993 and 1994 to determine persistence of pyrithiobac as determined by bioavailability following different application times in a silty clay. Pyrithiobac was applied at PPI, PRE, pinhead square (PHS), and first bloom (FB) application timings. Greenhouse studies were also conducted in 1993 and 1994 to determine pyrithiobac persistence under controlled conditions on a sandy loam soil. Slope comparison indicated no difference in degradation patterns in the field for any application timing of pyrithiobac within years; thus, application timings were combined for 1993 and 1994. Slope comparison also indicated no difference in slope between 1993 and 1994; thus, years were combined to determine pyrithiobac persistence. The initial concentration was 30 ηg g−1. The half-life of pyrithiobac was 62 d in the field. Analysis of covariance indicated no difference in slope for the 1993 and 1994 greenhouse studies, and years were combined to determine the half-life. The initial concentration was 43 η g−1. The half-life was 43 d in the greenhouse study.

Depositional Process of Fine Sediments

1982 ◽  
Vol 14 (4-5) ◽  
pp. 175-184 ◽  
Author(s):  
T Kusuda ◽  
T Umita ◽  
K Koga ◽  
H Yorozu ◽  
Y Awaya
Keyword(s):  
Shear Stress ◽  
Particle Diameter ◽  
Critical Diameter ◽  
Sediment Concentration ◽  
Suspended Particles ◽  
Cohesive Sediments ◽  
Fine Sediments ◽  
Annular Flume ◽  
Depositional Process ◽  
Depositional Rate

The main purposes of this study were to investigate the depositional properties of the typical fine less-cohesive sediments in Japanese estuaries and bays and to make it possible to estimate the amount of deposition of the sediments. Suspended fine sediment concentration depends strongly on the shear stress and a critical particle diameter exists corresponding to a certain shear stress. The suspended particles larger than the critical diameter settle down proportionally to the concentration of particles. On the other hand, the suspended particles smaller than the critical diameter are held in water without settling. The depositional properties obtained from experiments make it possible to estimate the depositional rate and amount of the sediments. In the laboratory experiments on deposition, an annular flume with a ring and a channel was used.

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