Abstract Disastrous floods result in severe loss of human lives and intense destruction to the infrastructure and economic activities. Furthermore, it leads to environmental and ecological damages located at the downstream area of the dam. The present study aims at investigating experimentally and numerically the sediment transport and morphological evolution of the erodible bed induced by dam-break flows. Experimental runs were conducted in a flume, specially designed for dam-break flow process, equipped with a thin vertical gate at its middle. Based upon an initial plane bed, the effect of three different compaction rates of the bed at both up-and downstream of the dam was investigated. The experimental data consistently suggested that increasing the bed compaction rate resulted in decreasing the scouring and sedimentation depth, as well as the sediment transport rate. Further, increasing the bed compaction rate led to increasing the wave-front celerity, reducing the scouring rate and the erosion depth. Both the experimental and numerical outputs highlighted the process of air entrainment at the leading edge of the wave-front. The numerical results showed that the maximum void fraction was associated with the maximum flow velocity at the zone of wave-front. Comparisons were made between the experimental results and those are provided from a numerical study using standard volume of fluid VOF method, where three different turbulence closure schemes; RNG, k-e and k-ω, and three bed load sediment transport approaches, Van Rijn, Meyer-Peter-Muller and Nielson, were applied. Accordingly, by considering the error values in predicting the free surface height and the bed deformation, the k-ω closure model showed the highest accuracy in capturing the turbulence features while the Mayer Peter-Muller formula had the highest performance in predicting the bed deformation in non-compacted (NC) bed. Besides, the RNG closure model and Nielsen bed load formula revealed the highest accuracy in predicting the aforementioned features in a semi-compacted (SC) bed. The k-ɛ closure model and Mayer Peter-Muller formula showed the highest accuracy in reproducing the turbulence characteristics and bed profile in a fully-compacted (FC) bed.

中文翻译：

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河床压实对可蚀河床溃坝流的影响 实验和数值建模

摘要 灾难性的洪水造成严重的人员伤亡和对基础设施和经济活动的严重破坏。此外，它还会导致大坝下游地区的环境和生态破坏。本研究旨在通过实验和数值研究由溃坝流引起的可蚀床的沉积物输送和形态演变。实验运行在一个专门为破坝流过程设计的水槽中进行，中间装有一个薄的垂直闸门。以初始平面河床为基础，研究了坝体上下游三种不同压实率对河床的影响。实验数据一致表明，增加床层压实率会降低冲刷和沉降深度，以及泥沙输运速率。此外，增加床层压实率导致增加波前速度，降低冲刷率和侵蚀深度。实验和数值输出都强调了波前前沿的空气夹带过程。数值结果表明，最大空隙率与波前区的最大流速有关。对实验结果与使用标准体积流体 VOF 方法的数值研究提供的结果进行了比较，其中三种不同的湍流闭合方案；应用了 RNG、ke 和 k-ω，以及三种床载沉积物输送方法，Van Rijn、Meyer-Peter-Muller 和 Nielson。因此，通过考虑预测自由表面高度和床层变形的误差值，k-ω闭合模型在捕捉湍流特征方面表现出最高的准确度，而Mayer Peter-Muller公式在预测非压实 (NC) 床。此外，RNG 闭合模型和 Nielsen 床荷载公式显示了在半压实 (SC) 床中预测上述特征的最高准确度。k-ɛ 闭合模型和 Mayer Peter-Muller 公式显示了在完全压实 (FC) 床中再现湍流特征和床剖面的最高准确度。此外，RNG 闭合模型和 Nielsen 床荷载公式显示了在半压实 (SC) 床中预测上述特征的最高准确度。k-ɛ 闭合模型和 Mayer Peter-Muller 公式显示了在完全压实 (FC) 床中再现湍流特征和床剖面的最高准确度。此外，RNG 闭合模型和 Nielsen 床荷载公式显示了在半压实 (SC) 床中预测上述特征的最高准确度。k-ɛ 闭合模型和 Mayer Peter-Muller 公式显示了在完全压实 (FC) 床中再现湍流特征和床剖面的最高准确度。