Numerical Simulation of Relatively Wide, Shallow Channels with Erodible Banks
Numerical Simulation of Relatively Wide, Shallow Channels with Erodible Banks
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DOI：
10.1061/(asce)0733-9429(2005)131:7(565
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发表时间：
2005-07
影响因子：
2.4
通讯作者：
C. Jang;Y. Shimizu
中科院分区：
文献类型：
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作者：
C. Jang;Y. Shimizu
建立了一个二维数值模型，用于模拟具有易蚀河床和由分选良好的桑迪材料组成的河岸的相对较宽、较浅的河流。一个移动的边界拟合坐标系被用来计算水流，河床变化，和银行侵蚀。流动计算采用三次插值拟粒子法，该方法几乎不引入数值扩散。在考虑二次流的情况下，采用流线和横向输沙的泥沙输运方程来估计河床和河岸随时间的演变。当河岸的横截面方向的坡度比淹没休止角更陡时，由于河岸附近的床面侵蚀，模拟河岸侵蚀。数值模型较好地再现了中心沙坝的特征，如沙坝生长、沙坝周围水流发散导致的河道加宽、沙坝背风面的冲刷坑以及沙坝尺寸随时间的增大等。这些特征与实验室观测结果一致。再现了辫状河的新河道生成、旧河道废弃、河道分叉汇流、河道侧向迁移等特征。该模型表明，输沙率随时间的波动，在分汊河道观察到的动力学特征之一。
A two-dimensional numerical model was developed to simulate relatively wide, shallow rivers with an erodible bed and banks composed of well-sorted, sandy materials. A moving boundary-fitted coordinate system was used to calculate water flow, bed change, and bank erosion. The cubic interpolated pseudoparticle method was used to calculate flow, which introduced little numerical diffusion. The sediment-transport equation for the streamline and transverse transport was used to estimate bed and bank evolution over time, while considering the secondary flow. Bank erosion was simulated when the gradient in the cross-sectional direction of the banks was steeper than the submerged angle of repose because of bed erosion near the banks. The numerical model reproduced the features of central bars well, such as bar growth, channel widening due to divergence of the flow around the bars, scour holes at the lee of the bars, and the increase of bar size with time. These features were in accordance with the observations for laboratory experiments. It also reproduced the features of braided rivers, such as the generation of new channels and abandonment of old channels, the bifurcation and confluence of channels, and the lateral migration of the channels. The model showed that the sediment discharge rate fluctuated with time, one of the dynamic features observed in braided channels.