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Micro/Nano Heat Transfer
Published in Sadık Kakaç, Hongtan Liu, Anchasa Pramuanjaroenkij, Heat Exchangers, 2020
Sadık Kakaç, Hongtan Liu, Anchasa Pramuanjaroenkij
where ψ is the sphericity. Sphericity is the ratio of the surface area of a sphere with a volume equal to that of the particle to the surface area of the particle. Therefore, n = 3 for a sphere and in that case, the Hamilton and Crosser model becomes identical to the Maxwell model.88
Investigation into 3D printing of granular media
Published in Andrew McNamara, Sam Divall, Richard Goodey, Neil Taylor, Sarah Stallebrass, Jignasha Panchal, Physical Modelling in Geotechnics, 2018
O. Adamidis, S. Alber, I. Anastasopoulos
Indices related to the shape of a particle use the concepts of sphericity, aspect ratio, and convexity (Altuhafi et al. 2012). Sphericity indicates the degree of similarity of a particle to a sphere. This approach was introduced by Wadell (1932), who took the sphere as a standard of form. The aspect ratio is the ratio between the length of two axes of a particle. Convexity describes a particle’s compactness. Roundness is another index related to the prominence and angularity of smaller features and is traditionally estimated through visual comparison with graphs (Powers 1953, Krumbein and Sloss 1951). Here, the numerical definitions of roundness proposed by Alshibli et al. (2015) were used. An overview of the morphology indices considered is given in Table 1.
Ballast degradation analysis by Los Angeles Abrasion test and image analysis method
Published in Andreas Loizos, Imad L. Al-Qadi, A. (Tom) Scarpas, Bearing Capacity of Roads, Railways and Airfields, 2017
Using the software, Geomagic Studio, can obtain the volumes and surface areas of ballast particles, which are used to calculate the 3D True Sphericity of each particle. It is proved that 3D True Sphericity value is in the range of 0~1, and the closer this value is to 1, the more spherical particles are (Wadell 1935). Meanwhile, the LAA loss of each ballast particle can also be computed with the software, shown in Table 3. Results indicate that the LAA loss of each particle is in the range of 7%~16% after 1000 totations, and most of them are around 9%. However, the whole LAA loss is 26.6%, larger than every single loss. That is because some other particles are smashed into pieces during the test.
Terminal settling velocity for binary irregularly shaped particle mixture from fluidization study: experiment, empirical correlation, and GA-ANN modeling
Published in Particulate Science and Technology, 2023
Sudipta Let, Nirjhar Bar, Ranjan Kumar Basu, Sudip Kumar Das
Most of the published correlations to predict the terminal settling velocity are based on relationships (Brown and Lawler 2003; Rushd et al. 2019), and very few are based on the relationship (Ganguly 1990). These relationships were cultivated for considering spherical particle only and single-component systems in Newtonian liquid. Figure 5 shows the Cd versus Rep plot. The experimental Cd value was higher than the line, as shown in Figure 5. The line was based on the Newtonian liquid and spherical particles. As the sphericity decreases, the drag coefficient increases compared to the spherical particles of the same diameter, so the flow resistance increases. For this reason, the available correlations have failed to predict a binary mixture of irregularly shaped particles. Hence, considering sphericity with other physical and dynamic variables, which influence TSV can be expressed as,
Exploratory investigation on the use of low-cost alternative media for ultrafine grinding of coal
Published in International Journal of Coal Preparation and Utilization, 2022
Qingqing Huang, Aaron Noble, Deniz Talan
where CR is the unitless circularity ratio, A the area, and P the perimeter. The sphericity is a measure of how closely the shape of an object resembles that of a perfect sphere with the numerical value of 1 corresponding to a perfectly spherical shape. Moreover, the aspect ratio describes the proportional relationship between the width and height of an object. As shown in Figs. 6 and 7, there was no change in the shape parameters measured for all the silica beads regardless of the particle size distribution. The circularity ratio, sphericity, and aspect ratio of all the silica beads was around 0.90, 0.98, and 0.99, respectively, which suggests a nearly perfect sphere. As for granular sand, the changes in the circularity and aspect ratio were minimum, as provided in Fig. 8. However, a noticeable difference was observed for the sphericity with the initial value of approximately 0.61 being increased to a value of 0.62 post grinding, which exceeds the difference that can be explained by the experimental variation or standard deviation (Fig. 8). Therefore, a change in the shape of granular sand was suggested. In addition, a circularity of 0.77 and an aspect ratio of approximately 0.75 indicate a less spherical shape for granular sand in comparison with silica beads, which were confirmed by not only the visual observation but also the subsequent image analyses.
Mathematical analysis of MHD stagnation point flow of Cu-blood nanofluid past an exponential stretchable surface
Published in International Journal for Computational Methods in Engineering Science and Mechanics, 2021
Santosh Chaudhary, Ajay Singh, KM Kanika
The associated thermophysical properties of Cu-blood nanofluid like viscosity, density, electrical conductivity, thermal conductivity and heat capacity are defined as [41] where subscripts f and s represent the thermophysical properties of the base fluid– blood, and nano solid particles– Cu, respectively, is the nanoparticle volume fraction, is the empirical shape factor and ξ is the sphericity of the particles. Sphericity is the ratio of sphere surface area to the particle surface area with equal volumes. The values of the thermophysical properties of used materials are represented by Table 1 [41,42]. Furthermore, the numerical value of sphericity ξ for various shapes of particles is given in Table 2 [43].