Dams are an important part of a country's infrastructure. After the dam breaks, the collision force of the water column, if severe enough, would incur a great deal of destruction and damage and needs to be concerned specially. In this work, 3D dam-break flows against various forms of the obstacle are numerically simulated by the smoothed particle hydrodynamics (SPH) method. In order to tackle boundaries of irregular or curved shapes involved in the obstacle, both wall particles and dummy particles are adopted in SPH, in which dummy particles are arranged by a particle packing algorithm which allows the attainment of a regular particle distribution. To validate the SPH method, 3D dam-break flow against a vertical wall is first simulated, and the SPH results are compared with the experiment and those obtained by other numerical methods. Then, we extend the method to 3D dam-break flows against various forms of the obstacle. A number of challenging numerical examples including 3D dam-break flows against a right-angled obstacle, a sloping obstacle with the angle of inclination α = 60°, 45°, and 30°, and an arc obstacle with the arc angle β = 90°, 60°, and 45° are simulated. The time evolutions of the pressure on the obstacle surface are shown in details. It is demonstrated that the proposed SPH method can handle 3D large-deformation flows with any complex boundaries accurately. The arc obstacle with β = 60° may be selected as one of the optimal forms of the obstacle for reducing the collision force of the fluid after the dam breaks. The maximum pressure on this obstacle surface is less than ~40% of a right-angled obstacle.

大坝是一个国家基础设施的重要组成部分。大坝破裂后，水柱的碰撞力如果足够严重，将导致大量破坏和损坏，需要特别注意。在这项工作中，通过平滑粒子流体动力学（SPH）方法对反对各种形式障碍物的3D溃坝流进行了数值模拟。为了解决障碍物中所涉及的不规则形状或弯曲形状的边界，在SPH中同时采用了壁粒子和虚拟粒子，其中虚拟粒子通过粒子填充算法进行排列，从而可以实现规则的粒子分布。为了验证SPH方法，首先模拟了垂直壁上的3D溃坝流，并将SPH结果与实验以及通过其他数值方法获得的结果进行了比较。然后，我们将方法扩展为针对各种形式的障碍物的3D溃坝流。许多具有挑战性的数值示例，包括针对直角障碍物，倾斜角度倾斜的障碍物的3D溃坝流α  = 60°，45°和30°，并且 模拟了弧角β = 90°，60°和45°的弧障碍。详细显示了障碍物表面上压力的时间演变。证明了所提出的SPH方法可以准确地处理具有任何复杂边界的3D大变形流。 可以选择β = 60°的弧形障碍物作为障碍物的最佳形式之一，以减小水坝破裂后流体的碰撞力。此障碍物表面上的最大压力小于直角障碍物的〜40％。