Segregation of granular media: Mechanizm of spatio-tempral structure of dissipative multi-particle systems

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K03463
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 13010:Mathematical physics and fundamental theory of condensed matter physics-related
• Research Institution: Kyushu University
• Principal Investigator: Inagaki Shio 九州大学, 理学研究院, 准教授 (20452261)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 非平衡物理学 / 粉粒体物理学 / 非平衡散逸系 / 物性実験 / 相分離

Outline of Final Research Achievements

When you add milk to coffee or ink to water, it almost mixes by itself. This is called the diffusion phenomenon, and it can be seen everywhere in our daily lives. On the other hand, it is known that powders and granules made of macroscopic particles tend to separate more easily the more you try to mix them when you shake different types of particles. In this study, in order to clarify the basic principle of the mixing and segregation mechanism of granular materials, we conducted experiments on the segregation phenomenon in which particles of different types are placed in a cylindrical container and form a stripe pattern when the container is rotated, systematically changing the specific gravity and size of the particles. We experimentally found the conditions under which segregation occurs.

Free Research Field

非平衡散逸系物理学

Academic Significance and Societal Importance of the Research Achievements

工業的には、原材料の 75%、製品の 50%が粉粒体からなるといわれるように、工業プロセスのほとんどで粉粒体が関わっていますが、粉粒体製造に消費される電力は全体の 1.3％に上ります。これまでは経験則に頼ることがほとんどでしたが、その効率的な扱いを根本的な原理から明らかにすることで、製造業におけるエネルギー消費を抑えることもできると期待されます。そのためにも、基礎科学的な側面から、粉粒体の分離・混合メカニズムの原理を明らかにし、具体的な物理量によって現象を記述する基礎方程式を確立することで、定量的に混合・分離の制御ができるようになる必要があります。