| 夏军强,王光谦,Lin Binliang,谈广鸣.动床条件下溃坝水流的二维水沙耦合模型[J].水利学报,2011,42(3): |
| 动床条件下溃坝水流的二维水沙耦合模型 |
| 2D morphodynamic modelling of dam-break flows over erodible beds |
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| DOI： |
| 中文关键词: 溃坝水流 泥沙输移 河床变形 二维模型 有限体积算法 耦合解法 |
| 英文关键词: dam-break flows sediment transport bed deformation 2D morphodynamic model finite vol?
ume method coupled solution |
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| 中文摘要: |
| 现有大部分溃坝水流模型仅适用于模拟定床条件下的水流演进，但溃坝水流经常是在动床条件下演进。因此非常有必要同时模拟溃坝洪水演进时的水沙输移及床面冲淤过程。本文首先建立了动床条件下溃坝水流的二维水沙耦合模型。该模型主要由二维浑水控制方程、非均匀沙不平衡输移方程及河床冲淤方程组成，采用水沙耦合解法以及基于无结构三角网格下的有限体积法离散。同时利用Roe-MUSCL方法以及时间方向的预估-校正格式，使模型在时空方向具有二阶计算精度。然后采用已有算例及水槽试验资料对模型进行了初步验证。最后采用该模型研究了均匀沙及非均匀沙床面对典型溃坝水流演进的影响。模拟结果表明溃坝水流在定床及动床条件下的演进过程明显不同。溃坝水流因流速大，床面变形较快，且床面冲淤速率可与水流变化速率相当，故需要采用浑水控制方程及耦合解法。 |
| 英文摘要: |
| The majority of existing models for simulating dam-break flows are usually applicable to
non-erodible or fixed beds. However，dam-break flows usually propagate over erodible beds in alluvial rivers or channels. Therefore it is necessary to simulate the interactive processes between the flow movement，sediment transport and morphological changes caused by dam-break flows. A 2D morphodynamic model to simulate dam-break flows over erodible beds is proposed in this paper. The governing equations included in the model comprise the 2D shallow turbid water equations，the non-equilibrium transport equations for graded sediments and the equation of bed evolution. A coupled solution method is used to predict simultaneously the hydrodynamic processes，the sediment concentrations and the morphological changes. The developed model uses an unstructured finite volume algorithm and employs an approximate Riemann solver，based on the Roe-MUSCL method. The predictor-corrector method is used in time stepping，leading to second-order accuracy in both time and space. In addition，the model can take account of the adjustment process of bed material composition during the morphological evolution process. The model was firstly verified against the results from existing numerical models and laboratory experimental data documented in the literature. The model was then used to investigate the influence of different bed-material compositions on the hydrodnamics and the morphology of a channel bed caused by dam-break flows. Model studies were also undertaken to investigate the difference in the speed of flood wave propagation and the morphological changes over fixed and erodible beds. Simulated results indicate that there is a great difference between dam-break flow simulations over fixed and erodible beds，and it is necessary to adopt the governing equations in turbid water to simulate the morphodynamic processes caused by dam-break flows as the rate of bed evolution is comparable to changes in the flow. |
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