1 0 0 0 OA 格子ボルツマン法による物体を含む自由界面流れの大規模シミュレーション
- 著者
- 渡辺 勢也 青木 尊之 長谷川 雄太 河原 淳 橋本 博公
- 出版者
- 日本混相流学会
- 雑誌
- 混相流 (ISSN:09142843)
- 巻号頁・発行日
- vol.33, no.1, pp.55-62, 2019-03-15 (Released:2019-04-08)
- 参考文献数
- 21
- 被引用文献数
- 1
Numerical simulations are powerful tools to study tsunami impacts on building structures. We have developed a CFD code for free-surface flows interacting with floating debris by using Lattice Boltzmann Method (LBM) and Discrete Element Method (DEM). Both methods are suitable for GPU computing and large-scale simulations because they are explicit time-integration schemes. In order to improve the accuracy and the stability of flow computation, the cumulant LBM model has been employed and coupled with the conservative Allen-Cahn equation for the purpose of free-surface capturing. A moving boundary approach based on the interpolated bounce-back scheme is utilized at liquid-solid interfaces. Rigid body dynamics of floating debris is computed by using DEM. A model constructed by multiple small spheres represents complex shapes of debris. We measure the weak scalability on multiple GPUs of the TSUBAME3.0 supercomputer, and the code achieved 83.4% parallel efficiency when scaled 16 to 256 GPUs. As a test case, we demonstrate a tsunami flow with driftwoods using 200×600×3000 lattice nodes and 24 GPUs Tesla P100, and the simulation has completed within 24 hours. The impact force of the driftwoods acting on the wall is about 15 times larger than only water. It shows that effects of driftwoods are important to evaluate the tsunami damage on building structures.
1 0 0 0 OA 無人航行制御技術の最前線
- 著者
- 松田 秋彦 橋本 博公 谷口 裕樹 寺田 大介 三好 潤 溝口 弘泰 長谷川 勝男 世良 亘
- 出版者
- 海洋理工学会
- 雑誌
- 海洋理工学会誌 (ISSN:13412752)
- 巻号頁・発行日
- vol.23, no.1, pp.47-51, 2017 (Released:2017-07-07)
- 参考文献数
- 12
As seaborne trade has greatly increased in recent years, it becomes more difficult to secure crew of ships. Therefore, it is an important issue how to realize unmanned robot ships which can automatically navigate without collisions even in congested waters. Although Rolls-Royce is planning to build a remotely controlled ship in 2020, standard control technology for unmanned ships has not been developed yet. Therefore an automatic collision avoidance system is discussed by carrying out not only computer simulations but also model experiments prior to the tests using actual vessels. For this purpose, the authors built an experimental system for the validation of automatic collision avoidance algorithm. In this paper, model experiments using multiple ships conducted at Marine Dynamics Basin at National Research Institute of Fisheries Engineering are introduced. Through comparisons with numerical simulations which the same algorithm for collision avoidance is implemented, it is found that there is a discrepancy in occurrence of collision in extremely congested situation.