Modelling of single-grain and floc settling

An analytical model of time-dependent settling in a suspension of finite depth is presented. The model correctly predicts the decrease in total concentration of three suspensions of fine sediments undergoing single-grain settling. The changes in grain-size spectra, in which decrease in concentration occurs mainly in sizes larger than the modal size, are also predicted. The model is used with data from the settling of flocculated suspensions to show that the rate of flocculation is approximately proportional to the second power of the concentration.

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Experiments on the significance of flocculation in the settling of fine-grained sediment in still water

Canadian Journal of Earth Sciences ◽

10.1139/e80-159 ◽

1980 ◽

Vol 17 (11) ◽

pp. 1517-1526 ◽

Cited By ~ 77

Author(s):

Kate Kranck

Keyword(s):

Grain Size ◽

Salt Water ◽

Total Concentration ◽

Relative Effectiveness ◽

Size Distributions ◽

Fine Grained ◽

Rate Dependent ◽

Clastic Sediments ◽

Single Grain ◽

Sandy Sediments

The changes in grain size and concentration with time were studied in relatively dilute settling suspensions of varying initial concentration and constituent grain size and composition. During single grain settling in distilled water and dispersant solution, i.e., in the absence of flocculation, a narrow range of sizes at a time were lost from suspension at a rate dependent on the initial size distribution. In salt water the importance of single grain settling relative to floe settling decreased with increase in concentration. The decrease in total concentration with time due to floe settling was proportional to the minus four-thirds power of the time. The overall sorting of the sediment had some effect on the flocculation rate but the effect of grain mineralogy appeared to be minor. Comparison between the size distributions of the settled sediment and textures of recent clastic sediments and experimental turbidites indicates that the relative effectiveness of single grain and floe settling largely determines the sorting of most fine-grained as well as many sandy sediments.

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Performance and Time-dependent Degradation in a Single Grain-size Pentacene TFTs

10.7567/ssdm.2002.c-3-3 ◽

2002 ◽

Author(s):

T. Komoda ◽

K. Kita ◽

K. Kyuno ◽

A. Toriumi

Keyword(s):

Grain Size ◽

Time Dependent ◽

Single Grain

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WEAK PLIOCENE BOTTOM CURRENTS IN THE JANE BASIN, NW WEDDELL SEA BASED ON MULTIVARIATE ANALYSIS OF GRAIN SIZE SPECTRA

10.1130/abs/2017am-301941 ◽

2017 ◽

Author(s):

Melissa R. Luna ◽

◽

Suzanne O'Connell ◽

Joseph D. Ortiz ◽

Michael C. Wizevich

Keyword(s):

Grain Size ◽

Multivariate Analysis ◽

Weddell Sea ◽

Size Spectra ◽

Bottom Currents

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Rip current evidence by hydrodynamic simulations, bathymetric surveys and UAV observation

10.5194/nhess-2017-53 ◽

2017 ◽

Cited By ~ 1

Author(s):

Guido Benassai ◽

Pietro Aucelli ◽

Giorgio Budillon ◽

Massimo De Stefano ◽

Diana Di Luccio ◽

...

Keyword(s):

Grain Size ◽

High Resolution ◽

Numerical Simulations ◽

Current System ◽

Current Evidence ◽

Rip Current ◽

Rip Currents ◽

Transport Pathways ◽

Fine Sediments ◽

Scientific Challenge

Abstract. The prediction of the formation, spacing and location of rip currents is a scientific challenge that can be achieved by means of different complementary methods. In this paper the analysis of numerical and experimental data, including UAV observation, allowed to detect the presence of rip currents and rip channels at the mouth of Sele river, in the Gulf of Salerno, southern Italy. The dataset used to analyze these phenomena consisted of two different bathymetric surveys, a detailed sediment 5 analysis and a set of high-resolution wave numerical simulations, completed with satellite and UAV observation. The grain size trend analysis and the numerical simulations allowed to identify the rip current system, forced by topographically constrained channels incised on the seabed, which were detected by high resolution bathymetric surveys. The study evidenced that on the coastal area of the Sele mouth grain-size trends are controlled by the contribution of fine sediments, which exhibit suspended transport pathways due to rip currents and longshore currents. The results obtained were confirmed by satellite and UAV 10 observations in different years.

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Turning Force Prediction of AISI 4130 Considering Dynamic Recrystallization

Volume 1: Processes ◽

10.1115/msec2017-3049 ◽

2017 ◽

Cited By ~ 6

Author(s):

Zhipeng Pan ◽

Yixuan Feng ◽

Xia Ji ◽

Steven Y. Liang

Keyword(s):

Grain Size ◽

Flow Stress ◽

Dynamic Recrystallization ◽

Analytical Model ◽

Cutting Forces ◽

Material Flow ◽

Explicit Calculation ◽

Material Microstructure ◽

Machining Forces ◽

Aisi 4130

Thermal mechanical loadings in machining process would promote material microstructure changes. The material microstructure evolution, such as grain size evolution and phase transformation could significantly influence the material flow stress behavior, which will directly affect the machining forces. An analytical model is proposed to predict cutting forces during the turning of AISI 4130 steel. The material dynamic recrystallization is considered through Johnson-Mehl-Avrami-Kolmogorov (JMAK) model. The explicit calculation of average grain size is provided in an analytical model. The grain size effect on the material flow stress is considered by introducing the Hall-Petch relation into a modified Johnson-Cook model. The cutting forces prediction are based on Oxley’s contact mechanics with consideration of mechanical and thermal loads. The model is validated by comparing the predicted machining forces with experimental measurements.

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Refinement of Size Distributions for Primary Crystallizations

MRS Proceedings ◽

10.1557/proc-481-213 ◽

1997 ◽

Vol 481 ◽

Author(s):

E. Pineda ◽

T. Pradell ◽

D. Crespo ◽

N. Clavaguera ◽

J. ZHU ◽

...

Keyword(s):

Grain Size ◽

Metastable Phase ◽

Primary Crystallization ◽

Controlled Growth ◽

Diffusion Controlled ◽

Average Grain Size ◽

Soft Impingement ◽

Single Grain ◽

Kinetics Of ◽

And Diffusion

ABSTRACTThe microstructure developed in primary crystallizations is studied under realistic conditions. The primary crystallization of an amorphous alloy is modeled by considering the thermodynamics of a metastable phase transition and the kinetics of nucleation and crystal growth under isothermal annealing. A realistic growth rate, including an interface controlled growth at the beginning of the growth of each single grain and diffusion controlled growth process with soft impingement afterwards is considered. The reduction in the nucleation rate due to the compositional change in the remaining amorphous matrix is also taken into account. The microstructures developed during the transformation are obtained by using the Populational KJMA method, from the above thermodynamic and kinetic factors. Experimental data of transformed fraction, grain density, average grain size, grain size distribution and other related parameters obtained from annealed metallic glasses are modeled.

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Unsteady deformations of a free liquid surface caused by radiation pressure

Journal of Fluid Mechanics ◽

10.1017/jfm.2011.236 ◽

2011 ◽

Vol 682 ◽

pp. 460-490 ◽

Cited By ~ 13

Author(s):

B. ISSENMANN ◽

R. WUNENBURGER ◽

H. CHRAIBI ◽

M. GANDIL ◽

J.-P. DELVILLE

Keyword(s):

Analytical Model ◽

Radiation Pressure ◽

Liquid Surface ◽

Acoustic Pulse ◽

Free Liquid Surface ◽

Time Dependent ◽

Surface Dynamics ◽

Fluid Interface ◽

Numerical Predictions ◽

Strongly Damped

We present an analytical model of the time-dependent, small-amplitude deformation of a free liquid surface caused by a spatially localized, axisymmetric, pulsed or continuous, acoustic or electromagnetic radiation pressure exerted on the surface. By exactly solving the unsteady Stokes equation, we predict the surface dynamics in all dynamic regimes, namely inertial, intermediate and strongly damped regimes. We demonstrate the validity of this model in all dynamic regimes by comparing its prediction to experiments consisting of optically measuring the time-dependent curvature of the tip of a hump created at a liquid surface by the radiation pressure of an acoustic pulse. Finally, we present a numerical scheme simulating the behaviour of a fluid–fluid interface subjected to a time-dependent radiation pressure and show its accuracy by comparing the numerical predictions with the analytical model in the intermediate and strongly damped regimes.

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Soil preparation and nutrient losses by erosion in the culture cucumber

Scientia Agricola ◽

10.1590/s0103-90162005000600010 ◽

2005 ◽

Vol 62 (6) ◽

pp. 572-577 ◽

Cited By ~ 1

Author(s):

Nelson Moura Brasil do Amaral Sobrinho ◽

Nelson Mazur

Keyword(s):

Crop Residues ◽

Total Concentration ◽

Organic Matter Content ◽

Soil Surface ◽

Crop Productivity ◽

Matter Content ◽

Nutrient Losses ◽

Cucumis Sativus L ◽

Minimum Tillage ◽

Fine Sediments

Minimum tillage reportedly reduce erosion, avoid soil degradation and improve crop productivity. This study aimed to determine how tillage operations may affect either nutrient accumulation or nutrient losses by erosion. The study was, carried out from December, 2000 to March, 2001, in the watershed of the Caetés River, in Rio de Janeiro State, Brazil (22º25'43"S, 43º25'07"W). The experiment was set up in sandy clay Kandiudult soil, 60% slope, under cucumber (Cucumis sativus L.) crop. Soil samples were collected before planting and after harvest, on 22.0 X 4.0 m Greeoff plots. After each rainfall, fine sediments carried by runoff were deposited into two collecting tanks in a row, installed at the end of each plot, and were later dried, weighed and stored for analyses. Treatments (n = 4) were characterized by different tillage systems: (i) downhill plowing followed by the burning of crop residues (DPB); (ii) downhill plowing with no burning of the crop residues (DPNB); (iii) animal traction contour plowing, with strips of guinea grass planted at a spacing of 7.0 m (AT); and (iv) minimum tillage (MT). Samples of the soil-plowed layer were collected before planting and after harvest, between the rows and from the plants. Total concentration of Ca, Mg, K and P were determined after extraction with nitric perchloride digestion. Labile P and exchangeable K were extracted with the Mehlich 1 extractant solution. The MT system reduced losses of both exchangeable bases (15%) and P (8%), and affected the distribution of labile and organic P. Crop residues left on soil surface in the MT system, resulted in increased organic matter content. Downhill plowing, the most used tillage operation in the region, resulted in the greatest losses of Ca, Mg, K, and P.

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