The present study was carried out in order to study the effective parameters on the secondary circulation and maximum values of the transverse velocity in river bends using a 3D numerical model. To this end, a total of 569 numerical tests were then performed to investigate the effect of different parameters, namely bed friction, bend angle and channel geometry including relative width (channel width/bend radius, B/R) and relative depth (water depth/bend radius, H/R) on Secondary circulation over a wide range of flow conditions. The results obtained from the numerical model were validated using the collected data sets from three distinct experiments according to which two equations for prediction of the maximum values of transverse velocity at the water surface and near the channel bed of the river bends were proposed. According to the obtained results, the increment of the B/R ratio results in higher transverse velocity both at the water surface (v_ns(max)) and near the channel bed (v_nb(max)). The v_ns(max) near the surface varying with the H/R ratio follows an incremental trend up to a critical relative depth (H/R)_scr, after which the transverse velocity is decreased. Similarly, a critical relative depth (H/R)_bcr exists near the channel bed. However, the v_nb(max) remains almost constant after (H/R)_bcr. According to the obtained results, the greater the relative width, bed friction and bend angle, the higher the critical relative depth in the surface and the bed of the channel.

进行本研究是为了使用3D数值模型研究弯道二次循环的有效参数和横向速度的最大值。为此，总共进行了569次数值测试，以研究不同参数的影响，即床身摩擦力，弯曲角度和通道几何形状，包括相对宽度（通道宽度/弯曲半径，B / R）和相对深度（水深） /弯曲半径，H / R）在各种流量条件下进行二次循环。使用三个不同实验收集的数据集验证了从数值模型获得的结果，并据此提出了两个方程，用于预测水面和河弯河床附近的横向速度最大值。根据获得的结果，B / R比的增加导致水面（v _ns（max））和河床附近（v _nb（max））的横向速度更高。的v_{纳秒（最大）}表面附近与变化的ħ / ř比率遵循递增趋势直到临界相对深度（H / R）_scr，之后横向速度减小。类似地，在通道床附近存在临界相对深度（H / R）_bcr。但是，在（H / R）_bcr之后，v _nb（max）几乎保持恒定。根据获得的结果，相对宽度，床身摩擦力和弯曲角度越大，通道表面和床身中的临界相对深度越高。