长江口北槽丁坝坝田区潮流及污染物迁移扩散特征

为研究长江口深水航道北槽坝田水流结构,基于非结构网格FVM法,建立了长江口大范围二维潮流水质耦合数学模型,在数学模型验证良好的基础上,对北槽涨落潮水流结构及坝田污染物扩散进行了研究。结果表明,北槽中上段北坝田高潮位明显高于主槽,北槽下段,高潮位与主槽相近;南坝田高潮位大都高于主槽,南北坝田低潮位与主槽相近;坝田污染物落潮时释放扩散速度较快,南侧坝田污染物扩散速度比北坝田快,大潮坝田污染物扩散速度比小潮快,坝田外部污染物扩散速度比坝田内部快;坝田释放污染源后,污染物随涨落潮流在坝田与主槽内运动,短时间内污染物进入航道的量较少。

Tidal current and pollutant diffusion characteristics in spur dike field of North Passage in Yangtze Estuary

In order to study the flow structure in a spur dike field of the North Passage in the Yangtze Estuary, a two-dimensional large-scale coupling model for tidal current and water quality was established using the finite volume method(FVM)and unstructured grids. Based on model verification, the flow structure and pollutant diffusion in the spur dike field of the North Passage during flood tides and ebb tides were studied. The following conclusions are drawn: the high tide level in the north spur dike field in the middle-upper reach of the North Passage is significantly higher than that in the main channel, while the high tide level in the lower reach of the North Passage is close to that in the main channel; the high tide level in the south spur dike field is mostly higher than that in the main channel, and the low tide levels in the north and south spur dike fields are close to that in the main channel; the rate of pollutant diffusion in the south spur dike field is higher than that in the north spur dike field, with a relatively high rate of diffusion during ebb tides; the rate of pollutant diffusion in the spur dike field is higher during spring tides than during neap tides, with a relatively high rate of pollutant diffusion outside the spur dike field in contrast to that inside the spur dike field; after release of pollutants in the spur dike field, the pollutants are transported within the spur dike field and the main channel following flood tides and ebb tides, and lesser amounts enter into the waterway in a short period.