Journal of the Society of Powder Technology, Japan
Online ISSN : 1883-7239
Print ISSN : 0386-6157
ISSN-L : 0386-6157
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Volume 47, Issue 8
Displaying 1-5 of 5 articles from this issue
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  • Numerical Simulation of Cohesive Particles in a Fluidized Bed by the DEM Coarse Grain Model
    Mikio Sakai, Yoshinori Yamada, Yusuke Shigeto
    2010 Volume 47 Issue 8 Pages 522-530
    Published: August 10, 2010
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.4164/sptj.47.522
    JOURNAL FREE ACCESS
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    The Discrete Element Method (DEM) is widely used in computational granular dynamics. The DEM is a Lagrangian approach where individual particle is calculated based on the Newton's second law of motion. Hence, the DEM enables us to investigate the granular flow characteristics at the particle level. On the other hand, the DEM has a difficulty to be used in large-scale powder systems because the calculation cost becomes too expensive when the number of particles is huge. Consequently, we have developed a coarse grain modeling as a large scale model of the DEM. The coarse grain particle represents a group of original particles. The coarse grain model was applied in typical gas-solid and solid-liquid two phase flows. The cohesive force like the van der Waals force was not considered in these simulations. In the present study, the coarse grain model is evolved to simulate the cohesive particles by considering the interparticle van der Waals force. The adequacy of the coarse grain model is proved by comparing the simulation results of original particle system. It is shown that the coarse grain model considering the interparticle force can simulate the original particle behavior precisely.
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  • Development of a Particle Method for an Elastic Body Considering Random Packing of Powder
    Masahiro Kondo, Yoshinori Yamada, Mikio Sakai, Seiichi Koshizuka
    2010 Volume 47 Issue 8 Pages 531-538
    Published: August 10, 2010
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.4164/sptj.47.531
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    In elastic body calculations using particles, non-structural particle distribution and non-uniform particle size are adopted. A result of Discrete Element Method (DEM) is used to create initial particle coordinates for the elastic analysis. Oscillation cycle of a beam is compared to the theoretical value. Convergence of the present method with respect to particle size is shown.
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  • A Study on Optimizing Dough Plasticity for Manufacturing Insulators
    Takatoshi Kimura, Koichiro Nakaushiro, Hiroshi Kariya, Takamasa Mori, ...
    2010 Volume 47 Issue 8 Pages 539-544
    Published: August 10, 2010
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.4164/sptj.47.539
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    Three types of slurry were prepared. One was the actual process slurry sampled from the production line. The others were dispersed and agglomerated model slurry prepared by adding water glass or MgCl2 to the actual process slurry. The dispersed and agglomerated dough were made from the model slurries. The measured dough hardness and moisture content has a good linear correlation in model dough. The data of hardness and moisture content of the actual process dough are plotted between the two regression lines of model dough. Based on the two regression lines, the agglomeration index was defined and the hardness was expressed as a function of the moisture content and agglomeration index. By using the derived correlation function, the dough hardness can be optimized explicitly not only moisture content but also agglomeration state in slurry.
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Review
  • Flowability Tests for Powders
    Shuji Matsusaka
    2010 Volume 47 Issue 8 Pages 545-553
    Published: August 10, 2010
    Released on J-STAGE: February 03, 2017
    DOIhttps://doi.org/10.4164/sptj.47.545
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    Powder flowability is affected by many factors, such as particle diameter, shape, adhesion, and friction ; thus, it is difficult to theoretically estimate the flowability. To accurately estimate the flowability, powders should be tested. In this review, the test methods are categorized based on the mechanism of measurement, and their systems and procedures are explained. In addition, experimental results obtained by a vibrating tube method that was developed to evaluate the flowability in more detail are presented.

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Review: Frontier Research Series
  • Spatiotemporal Structures of Precipitation Bands with Dissolution Reaction
    Takahiko Ban
    2010 Volume 47 Issue 8 Pages 554-560
    Published: August 10, 2010
    Released on J-STAGE: February 03, 2017
    DOIhttps://doi.org/10.4164/sptj.47.554
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    When the aqueous solution containing an electrolyte contacts the gel containing another electrolyte, particles can precipitate and form stripe patterns in the gel, which is well known as the Liesegang phenomenon. The patterns are static and stationary in the sense that the formed precipitation objects stay at the given position. Precipitation patterns can move if the complex formation of precipitate is possible. In this report, spatial and temporal change in pattern formation of precipitate and the effect of the electrolyte concentration and temperature on dynamic pattern formation of precipitate were discussed.

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