复杂汊道汛期水力特性的数值模拟分析

Study on the Digital Simulation of Hydraulic Characteristic for Complex Bifurcated Channel during Flood

为研究复杂汊道汛期的水力特性,结合工程实例,采用平面二维数学模型模拟多汊河道的水流,从分流比、水位和流速3个方面计算天然和两种工况下的水力特性参数,同时比较分析两工况对河道水力特性的影响。结果表明:副坝的建设可以显著改善上游复杂汊道的散乱流态,减少分汊数目,但由于分流比大大增加,副坝内导流明渠下游断面的水位和流速有明显增加;两工况在副坝段开设汊口均不会对左汊和中汊行洪造成影响,但工况2增设2#汊口可降低导流明渠的水力特性参数,更有利于行洪安全。

2D mathematical model of an engineering example is utilized to simulate a complex bifurcated channel. Considering three conditions（ natural,case 1 and case2）,we calculated the hydraulic coefficients of split ratio,water level and velocity,and analyzed the influences brought out by these two cases. The results show that the auxiliary dam could simplify the terrible flow state of the bifurcated channel upstream,but raise the water level and velocity in diversion channel. Both two cases can ensure the left and middle channel safe during flood and case 2 is better for diversion channel because 2# bifurcation can reduce the hydraulic coefficients significantly.