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Volume 44, Issue 3
Displaying 1-15 of 15 articles from this issue
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Junya Kano2007 Volume 44 Issue 3 Pages 161
Published: March 10, 2007
Released on J-STAGE: April 30, 2010
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Jusuke Hidaka, Norichika Katsura2007 Volume 44 Issue 3 Pages 162-172
Published: March 10, 2007
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSA new method for a large-scale simulation of granular flow was developed using cellular automata. The automaton rule consists of the transition rule of constituent paticles and the interaction rule between particles. The interaction rule is further divided into three rules; the collision rule, the static contact rule between particles, and propagation rule of impulsive force through the particle bed. Tha interaction rule was derived quantitatively on the basis of microscopic information on the interactive force between flowing particles under gravity obtained by DEM simulation. The evolution of granular flow with time can be simulated by defining the time equivalent to one step in automaton simulation, and the state variables in granular flow can be obtained by the proposed simulation method. The validity of the proposed powder cellular automaton method was confirmed by comparison of the simulated flow pattern of discharging flow from a hopper with the experimental one. Granular flows in real powder equipments can be simulated with a high speed by the proposed automaton method.View full abstractDownload PDF (2775K) -
Takuya Tsuji, Kazuki Nakamura, Keizo Yabumoto, Toshitsugu Tanaka2007 Volume 44 Issue 3 Pages 173-179
Published: March 10, 2007
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSIn engineering equipment such as fluidized bed and spouted bed, dense particles strongly interact with each other and surrounding carrier flows. The coupling scheme between Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD) is meritorious for the simulation of such flows. However, this approach needs to solve the equations of motion of all individual particles which account for many-body contacts and fluid forces exerting on particles, as well as the simultaneous computation of the motion of fluid flow. Consequently, it requires huge amounts of computation time and hence the applications of this scheme have been restricted to a small-scale system. In this paper, in order to conduct a large-scale simulation, hopefully in actual engineering equipment scale, DEM-CFD coupling scheme is parallelized on a commodity PC-cluster parallel computer. By using 1-D domain decomposition technique, fairly good scalability is obtained. We have succeeded to simulate a system composed of millions of particles.View full abstractDownload PDF (2238K) -
Yuichiro Suzuta, Junya Kano, Fumio Saito2007 Volume 44 Issue 3 Pages 180-185
Published: March 10, 2007
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSMotion of balls during planetary ball milling was simulated with a DEM (Discrete Element Method) in order to predict the power consumption during the milling. Grinding experiment of gibbsite powder was conducted to assess the validity of the prediction method of the power consumption by DEM simulation and to investigate the correlation between the power consumption and the grinding rate constant. The calculated power consumption agreed well with the experimental one for various grinding conditions, such as various ball diameters, ball densities and ball filling ratios. The grinding rate constant is found to be correlated with the calculated power consumption.View full abstractDownload PDF (584K) -
Akira Sato, Junya Kano, Fumio Saito2007 Volume 44 Issue 3 Pages 186-190
Published: March 10, 2007
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSIn order to investigate the abrasion phenomena in a planetary ball mill, we conducted the grinding operation without a powder and sought a correlation between the ball abrasion and the ball impact energy estimated by a Discrete Elemental Method (DEM) simulation. Experimental results showed that the mass of abraded balls increased in proportion to the grinding time in the early stage of grinding up to 75min. The abrasion rate increases quadratically with the mill rotation speed. It decreases with an increase in ball diameter up to 12.7mm and then slightly increases when the diameter is 15.8mm. It also increases with an increase in the ball filling ratio of the mill up to 50%. Similar tendencies are found in the impact energy calculated from the balls motion simulated by DEM. Therefore, it is said that the abrasion rate has a strong correlation to the impact energy of balls under any milling conditions.View full abstractDownload PDF (573K) -
Yasuya Nakayama, Kang Kim, Ryoichi Yamamoto2007 Volume 44 Issue 3 Pages 191-197
Published: March 10, 2007
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSWe developed a simulation scheme called “Smoothed Profile (SP) method” to predict the dynamic behavior of colloidal dispersions. SP method provides a coupling scheme between continuum fluid dynamics and rigid-body dynamics through smoothed profile of colloidal particles. Moreover, SP method can incorporate multi-component fluids, such systems as charged colloids in electrolyte solutions. Numerical results which assess the hydrodynamic interactions of colloidal dispersions are presented to verify SP method. Application of SP method is not restricted to a Newtonian solvent, but any constitutive model can be handled. Henceforth, it is suitable to treat colloidal dispersions in complex fluids where solvent-mediated interaction dominates the dynamical behaviors of colloids.View full abstractDownload PDF (794K) -
Kimiaki Washino, Chih-Hung Hsu, Toshihiro Kawaguchi, Yutaka Tsuji2007 Volume 44 Issue 3 Pages 198-205
Published: March 10, 2007
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSDiscrete Element Method (DEM) is widely applied to the numerical simulations of fluidized beds. However, the computational expense increases explosively as the number of particles increases. This issue hinders DEM from being applied to real-scale simulations. A model particle is sometimes employed in order to overcome this problem, in which real particles are replaced by larger model particles. When the model particle is used, some conditions (e. g., superficial velocity, gas density, gas viscosity, particle density) must be adjusted accordingly. Those are referred to as the ‘similarity conditions.’ In this research the similarity conditions are derived from the equations of change through a dimensionless analysis. Bubble motions are compared between the model particle cases and the real particle case to validate the proposed similarity conditions.View full abstractDownload PDF (1029K) -
Hiroshi Mio, Atsuko Shimosaka, Yoshiyuki Shirakawa, Jusuke Hidaka2007 Volume 44 Issue 3 Pages 206-211
Published: March 10, 2007
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSIn this work, benchmark analyses of DEM program are performed using several types of compilers and processors. The effectiveness of program optimization as well as compiler and processor performance on the calculation time is discussed. As a result, the calculation time is reduced by about 10-18% by using the cache-optimized program when PGI, PathScale, NAG, Compaq or Fujitsu compilers are used. The inline expansion is effective for Intel (ver. 8.1 and 9.1), Fujitsu, PGI or PathScale, and especially works well under the dual-core processor. Since the reduction in calculation time strongly depends on the nature of compilers and processors, proper optimization of program for a given compiler and processor is necessary for a large-scale computation.View full abstractDownload PDF (623K) -
Kyoichi Tsurusaki, Yuichi Furukawa, Atsushi Kawamura, Ryoen Shirasaki2007 Volume 44 Issue 3 Pages 212-216
Published: March 10, 2007
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSIn this paper, the crack patterns of powder solids consisting of adhesive particles are investigated by a computer simulation. We observed various crack patterns due to a difference in adhesion force between particles. The fractal dimensions of crack patterns are estimated by the gyration radius method and the coarse-grain method. As a result, we found that the crack pattern varies with the adhesion force between particles and that there exists a maximum in fractal dimension with respect to the adhesion force.View full abstractDownload PDF (2109K) -
Toward Further Progress in Computer Simulations of Powder Systems Scaling up, Speeding up, Hybrid Modeling and Continuum ModelingRyoichi Yamamoto2007 Volume 44 Issue 3 Pages 217-218
Published: March 10, 2007
Released on J-STAGE: April 30, 2010
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[in Japanese]2007 Volume 44 Issue 3 Pages 219
Published: March 10, 2007
Released on J-STAGE: April 30, 2010
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[in Japanese]2007 Volume 44 Issue 3 Pages 219a-220
Published: March 10, 2007
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSDownload PDF (276K) -
[in Japanese]2007 Volume 44 Issue 3 Pages 220
Published: March 10, 2007
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSDownload PDF (130K) -
2007 Volume 44 Issue 3 Pages 220a
Published: March 10, 2007
Released on J-STAGE: April 30, 2010
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Hiroyuki Asou2007 Volume 44 Issue 3 Pages 221
Published: March 10, 2007
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSDownload PDF (2656K)
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