2021 Fiscal Year Final Research Report

A unified theory for water movement in porous media under microgravity to hypergravity conditions

Research Project

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Project/Area Number	20K20300
Project/Area Number (Other)	17H06251 (2017-2019)
Research Category	Grant-in-Aid for Challenging Research (Pioneering)
Allocation Type	Multi-year Fund (2020) Single-year Grants (2017-2019)
Research Field	Agricultural economics and rural sociology, Agricultural Engineering, and related fields
Research Institution	Meiji University
Principal Investigator	Noborio Kosuke 明治大学, 農学部, 専任教授 (60311544)
Co-Investigator(Kenkyū-buntansha)	溝口勝東京大学, 大学院農学生命科学研究科(農学部), 教授 (00181917) 加藤雅彦明治大学, 農学部, 専任准教授 (00578312) 小島悠揮岐阜大学, 工学部, 准教授 (70767475) 森也寸志岡山大学, 環境生命科学研究科, 教授 (80252899)
Project Period (FY)	2017-06-30 – 2022-03-31
Keywords	微小重力 / 過重力 / 多孔質体 / 放物線飛行実験 / 落下塔実験 / 水分浸潤 / 毛管上昇 / 水分拡散係数
Outline of Final Research Achievements	The applicability of Darcy's equation from microgravity to hypergravity was experimentally demonstrated. In the case of densely packed porous media, the water flux density in unsaturated porous media is independent of gravity. Under microgravity, in a space as small as the pore space in the porous media, "air supplementation in the pore" did not occur because the water wetted the entire pore space. Furthermore, two types of "infiltration in pore extensions," on a single particle and pore extensions formed at the boundary of particle layers, temporarily inhibited infiltration regardless of the presence or absence of gravity. The intrinsic permeability, which constitutes the hydraulic conductivity, was found to be independent of gravity. It was also experimentally confirmed that the physical properties of water are also independent of gravity.
Free Research Field	農業農村工学・土壌物理学
Academic Significance and Societal Importance of the Research Achievements	1990年代から続いている微小重力下における多孔質体中の水分移動速度が低下するか否かの論争に終止符を打った画期的な研究である。ダルシー・バッキンガム式の重力依存項に対して重力の影響がないことを１つずつ丁寧に実験的に明らかにした。従来報告されている微小重力下で水分移動速度が低下した原因は、微小重力下では粒子が移動することによって粒子間結合が疎になって水分移動が抑制されたためであることを明らかにした。宇宙農業を実施する際の理論的裏付けとして意義ある研究成果が得られた。