波流耦合下保守污染物迁移扩散的模拟研究

Numerical simulation and study of the conservative pollutant migration under wave-current coupling action

基于三维潮流和谱波浪模型,以及输移扩散模型和拉格朗日粒子追踪模型,构建了波流耦合下保守污染物的迁移扩散模型。模型基于非结构化网格,对近岸复杂岸线有很好的拟合,可用于大范围波流耦合计算。运用所建的耦合模型研究了旅顺港内外的潮流变化、波生流场、保守污染物输移、粒子运动、以及新水道对湾内污染物迁移的影响,模拟的潮流场与实测数据吻合较好。结果表明:潮流会在湾内近湾口处形成一逆时针涡,波浪对湾内影响较小,但波生流会改变湾口流场分布;在湾内处于涡中的水体潮流自净能力较强,而湾中及湾底则较弱,SE向波浪会降低湾内水体的自净能力;新潮流通道的开挖,会显著改善水体的自净能力,尤其对湾底浅水区域作用明显。

Based on the three-dimensional hydrodynamic model, coupled with spectrum wave module, the Lagrangian particle tracking model and convection-diffusion model, a coupled model is established to simulate conservative pollutant migration under coexisting wave-current. The usage of unstructured grid provides great flexibility for simulating the tide,wave and pollutant transport in the area with complex geometries, and the model can simulate the wave-current coupling process in the large-scale area. The tidal current field, wave-induced current, conservative pollutant migration, particle motion and the influence of a new waterway on pollutant migration are simulated and researched by the coupled model. By verification, the results of present model agreed well with the field observed data. The results show that a tidally-induced vortex exists behind the bay mouth, and the wave has little impact in the bay, but wave-induced current will make the flow field change outside the mouth; the self-purification capacity of conservative pollutants in the vortex is better than that in the middle and bottom of the bay, and the water self-purification capacity will be decreased by SE wave action in the bay; the new waterway will strengthen the water self-purification capacity, especially in the bottom of bay.