中文摘要：

以COHERENS模型为基础，建立了长江下游感潮河段三维水流及污染物质输运数学模型，该模型通过口坐标变换，使整个水域垂直方向可采用相同的分层。基于模态分裂法，将三维流动分成表面重力波（外模式）和内重力波（内模式）；模型求解技术上采用算子分裂法，使用了superbee限制器TVD格式，减小非物理的数值虚拟震荡。选取长江常熟段为例，模型较好的模拟了感潮河段三维流场及污染带分布特征。该成果对感潮地区污染物输运规律及水污染控制具有指导意义。

英文摘要：

Based on COHERENS model, mathematical model of three-dimensional flow and mass transport in the downstream Yangtze tidal river was established. Through coordinate transformation in the control equations, the same layer grids in vertical direction were used to fit for local topography. Mode-splitting method for surface gravity waves and internal gravity waves was used in the model. The operator splitting method was used to solve the control equations, and TVD scheme with superbee limiter was used to reduce the fictitious numerical oscillations. Three-dimensional flow field and pollutant distribution in Changshu section of the Yangtze River were well simulated by the use of the model. The study is useful for waste pollution control in the tidal river.