“河性行曲”力学机理之边壁泥沙的临界起动条件

在借鉴水流紊动相干结构研究成果的基础上,深层次揭示了紊流紊动涡体猝发、喷射、清扫的过程中对边壁泥沙颗粒的抽吸、挖掘的力学机理;系统概括了河道岸壁泥沙颗粒从起动,到进入水体,促使顺直河道发育成犬牙交错的边滩,并逐步演变为弯曲性河道的全过程;进而在对边壁泥沙颗粒受力分析的基础上,运用涡能理论,提出了边壁泥沙起动的临界条件;并根据黄河的实际情况进行了分析,认为河流边界的糙率、水深等数值越大,泥沙越容易起动。

On Incipient Motion Condition of the Sediment Particles on River Side Wall

Based on the relevant research results of the coherent structure,the paper presents the mechanism of sediment transport during the process of turbulent bursting,ejecting and sweeping.Besides,the paper shows the detailed process of how a straight channel,due to the sediment particles moving from side walls into the water channel,changes into ith alternate side bars,and eventually into a meandering channel.Further,the paper presents the proposed critical incipient motion condition of the particles on the side wall by analyzing the forces exerted on the particles and be applying the turbulent eddy theories.The incipient motion condition is applied in Yellow River.The study showes that increasing bed roughness and flow depth are more helpful to the incipient motion of the sediment.