Abstract. This study aims to test the capacity of Flow-3D regarding the simulation of a rockslide-generated impulse wave by evaluating the influences of the extent of the computational domain, the grid resolution, and the corresponding computation times on the accuracy of modelling results. A detailed analysis of the Lituya Bay tsunami event (1958, Alaska, maximum recorded run-up of 524 m a.s.l.) is presented. A focus is put on the tsunami formation and run-up in the impact area. Several simulations with a simplified bay geometry are performed in order to test the concept of a “denser fluid”, compared to the seawater in the bay, for the impacting rockslide material. Further, topographic and bathymetric surfaces of the impact area are set up. The observed maximum run-up can be reproduced using a uniform grid resolution of 5 m, where the wave overtops the hill crest facing the slide source and then flows diagonally down the slope. The model is extended along the entire bay to simulate the wave propagation. The tsunami trimline is well recreated when using (a) a uniform mesh size of 20 m or (b) a non-uniform mesh size of 15 m × 15 m × 10 m with a relative roughness of 2 m for the topographic surface. The trimline mainly results from the primary wave, and in some locations it also results from reflected waves. The denser fluid is a suitable and simple concept to recreate a sliding mass impacting a waterbody, in this case with maximum impact speed of ∼93 m s −1 . The tsunami event and the related trimline are well reproduced using the 3D modelling approach with the density evaluation model available in Flow-3D.

中文翻译：

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1958 年利图亚湾海啸——利用计算流体动力学软件 Flow-3D 进行事前测深重建和 3D 数值建模

摘要。本研究旨在通过评估计算域范围、网格分辨率和相应计算时间对建模结果准确性的影响，测试 Flow-3D 在模拟岩崩产生的脉冲波方面的能力。提供了对利图亚湾海啸事件（1958 年，阿拉斯加，记录的最大上升高度为 524 m asl）的详细分析。重点放在影响区域的海啸形成和上升上。为了测试与海湾中的海水相比，撞击岩石滑坡材料的“密度更大的流体”的概念，我们使用简化的海湾几何形状进行了几次模拟。此外，设置了撞击区域的地形和测深表面。观察到的最大爬升可以使用 5 m 的统一网格分辨率再现，波浪越过面向滑坡源的山峰，然后沿斜线向下流动。该模型沿整个海湾延伸以模拟波浪传播。当使用 (a) 20 m 的均匀网格尺寸或 (b) 15 m × 15 m × 10 m 的非均匀网格尺寸以及地形表面的相对粗糙度为 2 m 时，可以很好地重建海啸修剪线。修边线主要由主波产生，在某些地方，它也由反射波产生。密度较大的流体是一种合适且简单的概念，可用于重建撞击水体的滑动质量，在这种情况下，最大撞击速度为 ~93 m s -1 。使用 3D 建模方法和 Flow-3D 中可用的密度评估模型，可以很好地再现海啸事件和相关的修剪线。