Abstract Steady free-surface flows around buildings occurring during flood or tsunami events can produce major damages and a quantification of the post-peak forces is essential for safety and resilience of coastal structures. The loading process is highly affected by the flow Froude number and the drag coefficient, commonly defined for highly subcritical flows, while field observations of tsunami flows reported Froude numbers close to one, visually appearing as a choked regime. The present experimental study addresses the hydrodynamic forces on emerging buildings in a subcritical choked regime, focusing on the effect of openings and orientation. Laboratory experiments indicated a substantial difference in flow depths between the up- and downstream side of the building for increasing Froude numbers. The presence of openings induced a flow through the building lowering the difference in flow depth, limiting the effect of the hydrostatic component of the loading process. The formulation of an empirical resistance coefficient CR allowed a combination of both form drag and hydrostatic forces. Whilst for impervious buildings CR was consistent with reference studies, for buildings with openings CR was directly dependent upon porosity. Contrarily to the unsteady flow conditions, results showed that the sidewalls also played a role in the loading process. Buildings with a rotated orientation resulted in slightly larger surfaces exposed to the flow and larger horizontal forces. Nevertheless, these were applied at lower cantilever arms, thus reducing the tilting moment. Altogether, this study provides experimentally-derived parameters that will support hydraulic engineers in the design of coastal structures.

中文翻译：

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在稳定的海啸后自由表面流中对具有开口和方向的建筑物施加的力

摘要 在洪水或海啸事件期间发生在建筑物周围的稳定的自由表面流动会产生重大破坏，峰值后力的量化对于沿海结构的安全性和恢复力至关重要。加载过程受流动 Froude 数和阻力系数的影响很大，通常为高度亚临界流定义，而海啸流的现场观察报告 Froude 数接近 1，在视觉上表现为阻塞状态。本实验研究解决了在亚临界阻塞状态下新兴建筑物上的水动力，重点是开口和方向的影响。实验室实验表明，随着弗劳德数的增加，建筑物上游和下游之间的流动深度存在显着差异。开口的存在引起了穿过建筑物的流动，降低了流动深度的差异，限制了加载过程中静水分量的影响。经验阻力系数 CR 的公式允许形式阻力和流体静力的组合。虽然对于不透水建筑物的 CR 与参考研究一致，但对于有开口的建筑物，CR 直接取决于孔隙率。与不稳定的流动条件相反，结果表明侧壁也在加载过程中发挥了作用。具有旋转方向的建筑物会导致暴露在流动和更大的水平力中的表面稍大。然而，这些应用在较低的悬臂上，从而减少了倾斜力矩。共，