Irregular Particle Shape

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Colleen M Riley - One of the best experts on this subject based on the ideXlab platform.

  • quantitative Shape measurements of distal volcanic ash
    Journal of Geophysical Research, 2003
    Co-Authors: Colleen M Riley, William I Rose, Gregg J S Bluth
    Abstract:

    [1] Large-scale volcanic eruptions produce fine ash (<200 μm) which has a long atmospheric residence time (1 hour or more) and can be transported great distances from the volcanic source, thus, becoming a hazard to aircraft and public health. Ash Particles have Irregular Shapes, so data on Particle Shape, size, and terminal velocities are needed to understand how the Irregular-Shaped Particles affect transport processes and radiative transfer measurements. In this study, a methodology was developed to characterize Particle Shapes, sizes, and terminal velocities for three ash samples of different compositions. The Shape and size of 2500 Particles from (1) distal fallout (∼100 km) of the 14 October 1974 Fuego eruption (basaltic), (2) the secondary maxima (∼250 km) of the 18 August 1992 Spurr eruption (andesitic), and (3) the Miocene Ash Hollow member, Nebraska (rhyolitic) were measured using image analysis techniques. Samples were sorted into 10 to 19 terminal velocity groups (0.6–59.0 cm/s) using an air elutriation device. Grain-size distributions for the samples were measured using laser diffraction. Aspect ratio, feret diameter, and perimeter measurements were found to be the most useful descriptors of how Particle Shape affects terminal velocity. These measurement values show Particle Shape differs greatly from a sphere (commonly used in models and algorithms). The diameters of ash Particles were 10–120% larger than ideal spheres at the same terminal velocity, indicating that Irregular Particle Shape greatly increases drag. Gas-adsorption derived surface areas are 1 to 2 orders of magnitude higher than calculated surface areas based on measured dimensions and simple geometry, indicating that Particle Shapes are highly Irregular. Correction factors for surface area were derived from the ash sample measurements so that surface areas calculated by assuming spherical Particle Shapes can be corrected to reflect more realistic values.

Gregg J S Bluth - One of the best experts on this subject based on the ideXlab platform.

  • quantitative Shape measurements of distal volcanic ash
    Journal of Geophysical Research, 2003
    Co-Authors: Colleen M Riley, William I Rose, Gregg J S Bluth
    Abstract:

    [1] Large-scale volcanic eruptions produce fine ash (<200 μm) which has a long atmospheric residence time (1 hour or more) and can be transported great distances from the volcanic source, thus, becoming a hazard to aircraft and public health. Ash Particles have Irregular Shapes, so data on Particle Shape, size, and terminal velocities are needed to understand how the Irregular-Shaped Particles affect transport processes and radiative transfer measurements. In this study, a methodology was developed to characterize Particle Shapes, sizes, and terminal velocities for three ash samples of different compositions. The Shape and size of 2500 Particles from (1) distal fallout (∼100 km) of the 14 October 1974 Fuego eruption (basaltic), (2) the secondary maxima (∼250 km) of the 18 August 1992 Spurr eruption (andesitic), and (3) the Miocene Ash Hollow member, Nebraska (rhyolitic) were measured using image analysis techniques. Samples were sorted into 10 to 19 terminal velocity groups (0.6–59.0 cm/s) using an air elutriation device. Grain-size distributions for the samples were measured using laser diffraction. Aspect ratio, feret diameter, and perimeter measurements were found to be the most useful descriptors of how Particle Shape affects terminal velocity. These measurement values show Particle Shape differs greatly from a sphere (commonly used in models and algorithms). The diameters of ash Particles were 10–120% larger than ideal spheres at the same terminal velocity, indicating that Irregular Particle Shape greatly increases drag. Gas-adsorption derived surface areas are 1 to 2 orders of magnitude higher than calculated surface areas based on measured dimensions and simple geometry, indicating that Particle Shapes are highly Irregular. Correction factors for surface area were derived from the ash sample measurements so that surface areas calculated by assuming spherical Particle Shapes can be corrected to reflect more realistic values.

Karri Muinonen - One of the best experts on this subject based on the ideXlab platform.

  • scattering and absorption in dense discrete random media of Irregular Particles
    Optics Letters, 2018
    Co-Authors: Johannes Markkanen, Timo Vaisanen, Antti Penttila, Karri Muinonen
    Abstract:

    We present an approximate numerical solution for the multiple scattering problem involving densely packed arbitrarily Shaped small Particles. We define incoherent volume elements that describe the statistics of the random medium and formulate an order-of-scattering solution for the entire random medium. We apply the T-matrix formalism to compute the incoherent interactions of Irregular Particles in the sequence of scattering events in the Monte Carlo radiative transfer algorithm. The T-matrices for the volume elements of arbitrarily Shaped Particles are computed by the volume-integral-equation (VIE)-based T-matrix method. We show that the approximate solution is in agreement with the numerically exact VIE solution for a small spherical random medium. Finally, we demonstrate the importance of applying Irregular Particle Shape models in the analysis of multiple scattering by a large random medium of non-spherical Particles.

Fehmi Nair - One of the best experts on this subject based on the ideXlab platform.

  • simulated and actual micro structure models on the indentation behaviors of Particle reinforced metal matrix composites
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2014
    Co-Authors: Recep Ekici, Kemal M Apalak, Mustafa Yildirim, Fehmi Nair
    Abstract:

    Abstract This study investigates effects of Particle volume fraction and size on the indentation behavior of Al 1080/SiC Particle reinforced metal matrix composites based on both 2D simulated and actual micro-structure models using the non-linear finite element method. A simulated micro-structure model assumes randomly distributed square-Shaped reinforcements through a matrix while the actual micro-structure model has a reinforcement distribution similar to an actual micro-structure taken from the section of a produced specimen. The equivalent stress and strain distributions as well as the indentation depths were compared based on both micro-structure models and experiments. Simulated and actual micro-structure models exhibited different stress and strain distributions, especially underneath the indenter. The actual micro-structure resulted in discontinuous equivalent stress and strain distributions underneath the indenter whereas the simulated micro-structure exhibited more continuous distributions. Experimental and predicted indentation depths exhibit similar trends. However, the actual micro-structure model provided an apparent improvement to predict indentation depths by decreasing differences between the experimental and predicted indentation depths as both size and especially volume fraction of the reinforced Particles were increased. In general, the indentation depth was increased with decreasing volume fraction of reinforcement and increasing reinforcement Particle size. The randomness of reinforcement distribution and actual micro-structure affected permanent indentation surface profiles and depths. The actual micro-structure indicated that Irregular Particle Shape and size and randomness of Particle distribution were effective parameters for predicting and understanding the indentation behavior of Particle reinforced metal matrix composites.

Waldir Antonio Bizzo - One of the best experts on this subject based on the ideXlab platform.

  • characterization of sugarcane bagasse Particles separated by elutriation for energy generation
    Renewable Energy, 2020
    Co-Authors: Paulo Cesar Lenco, Deyber Alexander Ramirezquintero, Waldir Antonio Bizzo
    Abstract:

    Abstract Bagasse Particle is used in energy generation, and the usual method for determining their size distribution is sieving. Traditional methods for measuring the bagasse Particle size distribution, such as sieving, do not evaluate the effect of the Irregular Particle Shape, producing results that are not always applicable to the prediction of fluid dynamic behavior. This work determined size distribution of bagasse Particles considering their aerodynamic behavior. Physical-chemical characterization was performed in different Particle sizes of the bagasse. A particulate elutriation and settling system was developed to determine the terminal velocity distribution of Particles. Drag coefficients and terminal velocities measured were compared with literature correlations. Almost all the correlations analyzed showed significant deviations from the values obtained experimentally. Haider and Levenspiel’s correlation showed the smallest average deviation. Two types of Particles were observed in bagasse: fibers and spongy pith. The apparent density of the Particles depends on the Particle size, and the ash concentration in smaller fractions is 3 times larger than the average. The method of aerodynamic separation for the characterization of bagasse Particle allowed to obtain information that cannot be found by the traditional method of separation by sieving.