| Project/Area Number |
21K04265
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 22030:Geotechnical engineering-related
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| Research Institution | Japan Agency for Marine-Earth Science and Technology |
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Principal Investigator |
CHEN JIAN 国立研究開発法人海洋研究開発機構, 付加価値情報創生部門(数理科学・先端技術研究開発センター), 副主任研究員 (20640931)
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| Project Period (FY) |
2021-04-01 – 2025-03-31
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| Project Status |
Granted (Fiscal Year 2023)
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| Budget Amount *help |
¥2,990,000 (Direct Cost: ¥2,300,000、Indirect Cost: ¥690,000)
Fiscal Year 2023: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2022: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2021: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
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| Keywords | clayey particle / plate particle geometry / discrete element method / adhesive contact / clayey particles / plate-like geometry / unit quaternions / particle simulator / non-spherical DEM / house-of-card effect / electro-chemical forces |
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| Outline of Research at the Start |
The purpose of this research project is to develop a simulator for investigating the macroscopic behaviors of clays from particle-scale interactions. To fulfill this purpose, we will first formulate and develop computer code for the kinematics of plate-like particles in 3D settings using unit quaternions. Then we will model the electro-chemical forces between plate-like particles and develop computer code for the dynamics of the particles. Last, we will validate the computer simulator by conducting numerical experiments with respect to actual experimental results.
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| Outline of Annual Research Achievements |
This project aims to develop a particle simulator tailored for realistic clay particles using the Discrete Element Method (DEM) to analyze granular material dynamics via particle-scale interactions. The DEM simulator consists of three essential components: particle geometry and kinematics, interparticle interactions including force models, and neighborhood detection. In FY2023, we refined the JKR model to remove its discontinuity in force and energy evolution and to achieve a continuous model by combining two mathematically sound analytical solutions. Compared with the discontinuous JKR model derived in FY2022, this refined JKR model enables more stable simulations. In addition, we formulated our version of the Van-der-Waals force model and initiated research on contact torque definitions for two interacting plates. This formulation extends the applicability of the conventional formulations for a plate interacting with an infinite plane. Since neighborhood detection directly affects simulation efficiency, we also worked on improving and testing new neighborhood detection algorithms using tree data structures. We were also able to publish the results of this research project in international journals such as "Powder Technology" and "Computers and Geotechnics", representing an advance in our understanding and simulation capabilities for clay particle systems.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The project is progressing well: Over the past year, we have focused on improving the force-displacement model which we derived based on Johnson-Kendall-Roberts (JKR) theory. The JKR-based force model had inherent discontinuities during contact formation and separation. During this fiscal year, the JKR-based model was further refined to ensure continuous transitions. The refined JKR model stabilizes simulations by allowing numerical integration of particle trajectories and velocities from continuous interparticle forces, allowing larger time steps and ensuring energy conservation in simulations. Details can be found in our published paper in “Powder Technology”. We have also addressed a significant limitation of the conventional van der Waals force model for macroscopic bodies originally proposed by Anandarajah and Chen. Our improved analytical solutions now include extreme cases of parallel and orthogonal orientations of two plates, providing a robust alternative to the previous model, which only considered a rectangular box interacting with an infinite plane. For neighborhood detection, we investigated the potential of a tree data structure approach. A manuscript detailing the implementation and performance analysis of the tree data structure is under review. In summary, the force interaction studies have progressed well, and we have also implemented the plan to improve the neighborhood detection algorithm. While the integration of all the components is still pending, we have made efforts to publish and have been successful in publishing research results.
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| Strategy for Future Research Activity |
The next phase of our project involves the comprehensive integration of the three core components of our particle simulator: particle geometry and kinematics, particle interaction model, and neighborhood detection. This integration will form the basis of a fully functional simulator ready for extensive testing through numerical experiments.
Following the integration, we will conduct a series of test runs to validate and refine the capabilities of our simulator. One of the first tests will be a gravitational deposition experiment designed to assess the interplay between inertial, mechanical and surface forces. This experiment will provide insight into the relative strengths and effects of these forces during particle deposition processes. In addition, understanding the pore space characteristics, such as the size distribution among platy particles, is essential for analyzing the "house of cards" structure they form. This requires the development of analytical tools capable of characterizing these unique spatial configurations.
These experiments and analyses are critical to advancing our knowledge of particle dynamics, and will help refine the simulator to provide more accurate predictions and a better understanding of complex granular systems.
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