中文摘要：

明渠横向分流是一种常见的水流形态,分流时易产生漩涡,会产生较大的水头损失。以往的研究主要关注于固定形态河槽、小比降的分流问题。本文采用Mike21数学模拟手段,模拟干流不同断面形态（矩形、梯形、三角形）的水流分流状态,研究分流口门处的局部水头损失,并提出不同断面形态下弗劳德数和局部水头损失系数的变化关系。结果表明：同一断面形态下,随着进口流量的增大,分流口门处产生的局部水头损失逐渐增大;同一流量,三角形断面局部水头损失最大,梯形次之,矩形最小;明流缓流情况下,随着弗劳德数的增加,局部水头损失系数逐渐减小。研究成果既丰富了水力学学科内容,又为类似工程提供技术支撑。

英文摘要：

Lateral diversion from an open channel is a common flow regime that usually produces a larger head loss due to the vortices caused by the diversion. However, most previous studies focused on flow diversion from the channels of fixed cross-sectional shapes and small bottom slopes. In this work, channels of different cross-sectional shapes （rectangle, trapezoid and triangle） and their local head losses around the diverting mouth were studied using numerical simulations based on Mike21, a code for plane-2D flows. A relationship of local head loss coefficient versus Froude number was constructed for different cross-sectional shapes of the channel. The results show that with a fixed channel shape, this minor loss grows gradually with the increasing channel flow rate; under a fixed flow rate, it takes the largest, second largest and smallest values in the cases of triangular, trapezoidal and rectangular cross sections. Under subcritical flow conditions, the minor loss coefficient decreases gradually with the Froude number.