| 研究課題/領域番号 |
21K04265
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| 研究機関 | 国立研究開発法人海洋研究開発機構 |
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研究代表者 |
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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| 研究期間 (年度) |
2021-04-01 – 2024-03-31
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| キーワード | clayey particle / plate particle geometry / discrete element method / adhesive contact |
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| 研究実績の概要 |
The purpose of this project is to develop a particle simulator for realistic clayey particles. The Discrete Element Method (DEM) is widely recognized as a powerful tool for investigating the complex dynamics of granular materials from particle-scale interactions. In FY2021, we developed the framework using an extruded 3D polygon as the particle shape and solving unit-quaternion-based particle rotation in the body-fixed reference system. Based on this work, we gave an invited talk at an international conference in FY2022 and submitted a journal paper currently under review. There are three main components to a DEM approach: 1). Particle geometry and particle kinematics (especially particle rotation); 2) Interparticle interactions (also known as force models); and 3) Neighborhood detection. Since the first component was developed in FY2021, our research focus has been on the second component. For clayey particles, there are interparticle adhesion forces resulting from intermolecular interactions. To model such forces, we have reviewed existing research on adhesive contact and worked on necessary adaptations. We focus on two force models: a macroscopic Johnson-Kendall-Roberts (JKR) theory and microscopic Van-der-Waals force based formulation derived by Anandarajah and Chen. For the JKR theory, we derived a force-displacement relation that can be used for DEM simulations. For the Anandarajah-Chen model, which was derived for tilted cuboid particles interacting with an infinite wall, we investigated the necessary changes to model the forces between finite size particles.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
The project is progressing smoothly as planned for the reasons for the following reasons: For the interparticle interaction, we have developed a force-displacement relation based on the Johnson-Kendall-Roberts (JKR) theory. In addition, we have investigated the necessary adaptation of a Van-der-Waals-force-based formulation. These force models can be used to model the adhesive forces for clayey particles in DEM simulations. Since the particle geometry is plate-like, there will be two types of particle configurations: parallel and tilted. For the parallel condition, either edge parallel to plane or plane parallel to plane, the attractive force can be easily evaluated using the Van-der-Waals force models. For a tilted configuration, the dominant force would be the force between the closest points on the two particles. For such a configuration, the adhesive force for the pair of nearest points can be estimated by the JKR-based force model we have derived. As an alternative, we have also worked on a Van-der-Waals force based formulation derived for titled cuboid particles interacting with an infinite wall geometry. We have worked on approximations that take into account the finite particle size. This approximation can be used in comparison to the aforementioned macroscopic JKR based force model. Although work still remains to implement the derived force models into the DEM prototype code, the derivation and formulation of the adhesive interparticle interactions have progressed as planned.
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| 今後の研究の推進方策 |
The next step is to implement the adhesive force models into the DEM code. For a full contact process, not only the adhesive force exists but also the repulsive forces. We will adapt an overlap-volume-based repulsive force that have been developed for general polyhedral particles. In addition to the particle interactions, a neighborhood algorithm must be implemented to determine the interacting particle pairs. While the algorithms developed for general polyhedral particles can be used, an adaptation is needed to account for the plate-like geometry for better performance. Once the interactions and the neighborhood algorithms are implemented, we will then consider a consolidation experiment to study the influence of the environmental conditions on the compression and recompression of an assembly of plate-like particles. Simulations of other physical tests will also be performed to validate the developed simulator.
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| 次年度使用額が生じた理由 |
Plans to travel to conferences and invite experts were not carried out due to border restrictions caused by Covid19. Also, the main work of the last year was theoretical derivations without urgent need for computing resources, the planned hardware update was postponed.
In the new fiscal year, with the official downgrading of the pandemic severity and the lifting of border controls, academic travel for presentations and discussions will be more active with surplus. An upgrade or a new purchase of workstations for simulation is under consideration.
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