Terminal fall velocity: the legacy of Stokes from the perspective of fluvial hydraulics

Dey, Subhasish; Ali, Sk Zeeshan; Padhi, Ellora

doi:10.1098/rspa.2019.0277

Cited by 73 publications

(69 citation statements)

References 98 publications

(165 reference statements)

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“…During the experiments, 2 % bentonite suspension was used (quarry sample, Cherkasy deposit, Ukraine). Sedimentation analysis of the suspension by the method of continuous weighing of the sediment using a torsion balance [10].…”

Section: Materials and Methods Of Researchmentioning

confidence: 99%

Mathematical modeling of the sedimentation process for determining the fractional composition of suspensions

Chumak

Maksymiuk

Косенко

et al. 2021

EEJET

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Exceptional prospects for use in science, technology and industry are opened by highly dispersed powders (ultradispersed diamonds, nanoceramics, medicinal powders) and materials based on them. The properties of such materials depend on the particle size determined by sedimentation analysis. An equation is proposed for processing sedimentation analysis data, which does not depend on the size distribution law of polydisperse system particles, and is used to describe the distribution functions of particles with radii for clay suspensions. A program in the Microsoft Visual Basic for Applications (VBA) language has been created for calculating the fractional composition of suspensions according to the proposed equation; the correctness of its operation on a model system has been checked and confirmed. Experimental research has confirmed that the use of the developed program and the "Search for a solution" add-on for the MS Excel environment makes it possible to determine the fractional composition of suspensions. It has been proven that the proposed method can be used to analyze polydisperse systems. It has been found that for the suspensions under consideration, as containing 25 fractions, it is possible to determine the integral curve of the distribution of the masses of the particles of the dispersed phase along the radii. This allows to assert the possibility of using the proposed equation for processing sedimentation analysis data, which does not depend on the law of mass distribution of polydisperse system particles by size. Thus, there is reason to assert about the possibility of a reasonable determination of the fractional composition of any polydisperse systems. It is possible to obtain certain effects from the introduction of sedimentation analysis data processing according to the proposed equation in production, where the fractional composition of dispersed phases is regulated.

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Section: Materials and Methods Of Researchmentioning

confidence: 99%

Mathematical modeling of the sedimentation process for determining the fractional composition of suspensions

Chumak

Maksymiuk

Косенко

et al. 2021

EEJET

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“…Gravitational settling of dust is solved implicitly from top to bottom using a gravitational settling velocity based on the Stokes-Cunningham approximation. As the settling velocity increasingly deviates from Stokes settling for large particles (approximately > 10 µm) and to correct for potential numerical diffusion (Ginoux, 2003) and other unaccounted phenomena (Stout et al, 1995;van der Does et al, 2018;Dey et al, 2019), we successively reduce the settling velocity using bin-wise tuning factors. By default, we use 1, 1, 1, 1, 0.5, 0.3, 0.2, and 0.1 from bins 1 to 8.…”

Section: Dust Transport and Depositionmentioning

confidence: 99%

Mineral dust cycle in the Multiscale Online Nonhydrostatic AtmospheRe CHemistry model (MONARCH) Version 2.0

Klose

Jorba

Gonçalves³

et al. 2021

Geosci. Model Dev.

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Abstract. We present the dust module in the Multiscale Online Non-hydrostatic AtmospheRe CHemistry model (MONARCH) version 2.0, a chemical weather prediction system that can be used for regional and global modeling at a range of resolutions. The representations of dust processes in MONARCH were upgraded with a focus on dust emission (emission parameterizations, entrainment thresholds, considerations of soil moisture and surface cover), lower boundary conditions (roughness, potential dust sources), and dust–radiation interactions. MONARCH now allows modeling of global and regional mineral dust cycles using fundamentally different paradigms, ranging from strongly simplified to physics-based parameterizations. We present a detailed description of these updates along with four global benchmark simulations, which use conceptually different dust emission parameterizations, and we evaluate the simulations against observations of dust optical depth. We determine key dust parameters, such as global annual emission/deposition flux, dust loading, dust optical depth, mass-extinction efficiency, single-scattering albedo, and direct radiative effects. For dust-particle diameters up to 20 µm, the total annual dust emission and deposition fluxes obtained with our four experiments range between about 3500 and 6000 Tg, which largely depend upon differences in the emitted size distribution. Considering ellipsoidal particle shapes and dust refractive indices that account for size-resolved mineralogy, we estimate the global total (longwave and shortwave) dust direct radiative effect (DRE) at the surface to range between about −0.90 and −0.63 W m−2 and at the top of the atmosphere between −0.20 and −0.28 W m−2. Our evaluation demonstrates that MONARCH is able to reproduce key features of the spatiotemporal variability of the global dust cycle with important and insightful differences between the different configurations.

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“…where υ is the kinematic viscosity of the fluid and ε is the dissipation rate per unit mass. Particle engagement also depends on particle size and density, as well as the density of the ambient fluid (Dey et al, 2019). These factors are reflected in particle relaxation time, τ p :…”

Section: Effect Of Size On Turbulent Mixing and Marine Microplastic Entrainmentmentioning

confidence: 99%

Evidence of Microplastic Size Impact on Mobility and Transport in the Marine Environment: A Review and Synthesis of Recent Research

Shamskhany

Patel

et al. 2021

Front. Mar. Sci.

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Marine Microplastics (MPs) exhibit a wide range of properties due to their variable origins and the weathering processes to which they are exposed. MP’s versatile properties are connected to their dispersal, accumulation, and deposition in the marine environment. MP transport and dispersion are often explained by analogy with sediments. For natural sediments, one of the key features linked to transport and marine morphology is particle size. There is, however, no size classification defined for MP particles and MPs constitute all plastic particles sized smaller than the threshold of 5 mm. In this study, based on existing knowledge in hydrodynamics and natural sediment transport, the impact of MP size on turbulent entrainment, particle settling, and resuspension is described. Moreover, by analyzing several quantitative studies that have provided size distribution, size-selective accumulation of MPs in various regions of the marine environment is reported on. The preferential presence of MPs based on their size in different marine compartments is discussed based on the governing hydrodynamic parameters. Furthermore, the linkage between polymer properties and MP shape and size is explored. Despite the evident connection between hydrodynamic transport and MP size presented, classification of MP size presents challenges. MP size, shape, and density appear simultaneously in the definition of many hydrodynamic parameters described in this study. Unlike mineral sediments that possess a narrow range of density and shape, plastics are manufactured in a wide variety of densities and marine MPs are versatile in shape. Classification for MP size should incorporate particle variability in terms of polymer density and shape.

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Terminal fall velocity: the legacy of Stokes from the perspective of fluvial hydraulics

Cited by 73 publications

References 98 publications

Mathematical modeling of the sedimentation process for determining the fractional composition of suspensions

Mathematical modeling of the sedimentation process for determining the fractional composition of suspensions

Mineral dust cycle in the Multiscale Online Nonhydrostatic AtmospheRe CHemistry model (MONARCH) Version 2.0

Evidence of Microplastic Size Impact on Mobility and Transport in the Marine Environment: A Review and Synthesis of Recent Research

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