弯道水流三维数值模拟研究

Three dimensional numerical simulation of bend flow

通过引入可减小凹凸岸冲刷及弯顶顶冲作用的对称基本型、非对称A型及非对称B型三种具有缓变曲线的弯道型式,在清水冲刷工况下,利用MIKE 3软件流场模型（Flow Model FM）中的泥沙输移模块（ST）,通过模拟单曲线弯道和三种新型弯道型式下的弯道河床冲淤变形,甄选能够减轻水流对河床、堤身及堤脚冲蚀破坏的最优弯道型式。经过数值模拟得出：插有缓变曲线的三种弯道冲深均明显浅于单曲线弯道;且插有缓变曲线弯道可滞后顶冲点位置、缩短凹岸冲刷长度,其中对称基本型弯道的效果最为明显;从冲淤趋势及水面形态上看,各种弯道对于改善水面形态、减小冲刷程度的效果依次为：对称基本型弯道〉非对称A型弯道〉非对称B型弯道〉单曲线弯道。

Three kinds of curves： basic symmetric bend,asymmetric A bend and asymmetric B bend were introduced to decrease the scour depth and top rush. To study the optimal bend to prevent scour along the river bed,dike and feet of the dike,a three dimensional numerical simulation under the condition of clear water scour had been conducted,and the ST module in Flow Model FM of MIKE 3 software were used to analyze the river bed processes among three types of bends. Results are concluded by numerical analysis as： the deep groove of three inserted with graded curves is obviously shallower than that of the round bend; three bends with inserting curves could delay the location of scour point,shorten the erosion length of concave bank. The prediction results of water surface show that the sorting of improving the topography of water surface,and decreasing the degree of scouring and silt from large to small was as basic symmetric bend 〉 asymmetric A bend 〉asymmetric B bend 〉 round bend.