考虑泥沙冲淤对水流控制方程的改进与模拟

Modification of water continuity equation considering the exchange flux between sediment laden flow and bed

以一维数学模型为例,通过数值实验及渭河实际资料的验证,发现在含沙量较大的情况下,水流连续方程里的浑水与床面的交换项对流量影响是明显的,计算中应予考虑。解释了在像黄河这样的多沙河流中存在的“水变沙”、“沙变水”的现象。由此可见,在模拟含沙量较大河流的水沙数学模型中,应完整考虑水流连续方程的微元河段的水量变化率、进出通量变化及浑水与床面的交换通量这三项。

In the sediment mathematical model, three compossitions of the flow should be included in the the volume flow rate of a control volume, the volume flow rate in and out the control volume and the ex continuity equation ： change flux between sediment laden flow and bed. Now, the exchange term between sediment laden flow and bed is not be considered in the flow continuity equation in most sediments mathematical models. One dimension-mathematlcal model is taken as an example to evaluate the importance of the exchange term with the numerical experiments. Based on the schematic model and the field data of the Weihe River, the research results show that the exchange term has obvious influence on discharge when sediment concentration is high. The phenomenon of the so-called‘change flow into bed material＇ or‘change bed material into flow＇, which often occurs in the sediment-laden river like the Yellow River, can be explained. The conclusion can be made when the sediment concentration is high. The three compositions of the equation of continuity of flow should be synthetically considered in the water and sediment mathematics model.