Numerical prediction method for multi-phase coupled disasters focused on elementary processes

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K11920
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 60100:Computational science-related
• Research Institution: Kyoto University
• Principal Investigator: Ushijima Satoru 京都大学, 学術情報メディアセンター, 教授 (70324655)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 流体固体連成計算 / マルチフェイズモデル / 固気液多相場 / 粒子層内部流動化 / 間隙水圧 / 浸透流 / 並列計算 / マルチグリッド法

Outline of Final Research Achievements

The aim of this study is to develop a computational methods that can accurately calculate micro-scale fluid-solid interactions (MFSI), such as the mechanical interactions between water flow and soil particles, or liquid flows and superabsorbent polymer particles, by implementing the elementary physical processes in the methods. The following results were obtained in this study:
(1) The processes of internal fluidization and breakdown of a saturated particle layer due to an upward flow of water entering from the bottom were calculated with large-scale parallel computations using the MFSI computational method. As a result, it was confirmed that the effects of particle shapes on particle motions and the unsteady variation of pore water pressure are reasonably calculated.
(2) Since the MFSI computational method requires a large computational load, a multi-grid preprocessing method is introduced to solve the pressure Poisson equations.

Free Research Field

計算科学

Academic Significance and Societal Importance of the Research Achievements

土粒子層の浸透破壊や内部流動化現象などを対象とする計算手法では、これまで粒子スケールの現象、すなわち各粒子の運動や局所的な間隙水圧を正確に扱う手法はほとんどなく、対象領域全体を連続体などとして扱う手法が多かった。本研究では、流体固体連成現象の素過程に着目し、これを計算手法に組み込み、大規模並列計算を利用することにより、多相場が連成する災害現象の基本的な部分をある程度正確に評価できる計算手法を構築した。実験との比較により、粒子形状の影響や間隙水圧の変化が再現できることが示された。また、マルチグリッド前処理法を圧力計算に組み込むことにより、大規模並列計算をより効率的に行うことを可能にした。