中文摘要：

基于雷诺方程和有限体积法建立了描述弯道水流运动的三维数学模型,用室内物理模型试验进行验证,结果表明,该模型能够较好地模拟弯道内水流流速分布以及湍流特征。随后用该模型模拟了若干典型平面形态和床面形态的弯道水流运动。模拟结果表明：弯道中浅滩和深槽相间的地形起伏加剧了断面流速分布的不均匀性,同时使得水流动力轴线更加偏向凹岸,流速的沿程变化也较平整床面更为复杂;另外,与对称型河湾（正弦派生曲线型）相比,非对称河湾（Kinoshita派生曲线型）中在两弯顶中间存在较多的低流速区,有利于泥沙落淤,而对岸流速一般较大,形成河岸的快速崩退,这能够从一个侧面解释非对称河湾向下游方向整体的快速迁移。

英文摘要：

A three-dimensional numerical model was established for bended open channel flow based on Reynolds Equations and Finite Volume Method. The model was validated with laboratory experiments in two physical models. Verification shows that the numerical model can well simulate the flow distribution and turbulent feature in river bends. Then the validated model was used as a tool to carry out numerical test on flow in river bend with various planar shapes and bed topographies. Results show that the alternative pool-bar topography in river meanders increases the unevenness of cross section flow distribution. It shifts the dynamic flow axis more close to the concave bank and complicates the streamwise fluctuation of flow components. Besides, asymmetric meanders （Kinoshita-generated） show more zones with low flow velocities compared with symmetric meanders （sine-generated）, which is favorable for sediment deposit. While the velocity near the opposite bank is relatively large causing fast bank retreat, which may interpret the fast downstream migration of asymmetric river bends.