长江口南支非均匀沙垂向分层的数学模型

A vertical layered mathematical model for nonuniform sediment in south branch of the Yangtze estuary

本文在实测资料分析的基础上提出：河口地区瞬时含沙量的变化主要取决于泥沙沿垂线方向的扩散和沉落．对非恒定垂向二维泥沙扩散模型进行了简化，主要考虑其沿垂线方向的运动．在近底部采用李义天的模型考虑不同水流条件下床沙与床沙质的交换，并根据实测资料给出流速与底部含沙量的关系，通过求解垂向扩散方程给出垂线上各个分层的含沙量和悬沙级配．

This paper,based on the analysis of field data, proposed that the instantaneous variation of sediment concentration in estuarine area is mainly due to the particle diffusion and the settling movement along the vertical direction.By a simplified unsteady and vertically two dimensional diffusion model, the study is focused on the vertical movement of sediment.The model proposed by Li Yitian was adopted to consider the exchange between bed load and the bed material,while the relationship between the flow velocity and the sediment concentration near the bottom was determined by the field data analysis.The sediment concentration and the diameter profile along the vertical line were obtained by the solution of the vertical diffusion eqUations.