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中文核心期刊

再悬浮底泥中非吸附性污染物释放的数值模拟

NUMERICAL SIMULATION ON THE RELEASE OF NON-ADSORPTION POLLUTANTS DURING THE SEDIMENT RESUSPENDED

  • 摘要: 环境水动力学中, 湖库底泥中污染物释放是人们研究的主要问题之一. 在水动力学条件作用下, 污染底泥再悬浮使大量污染物被重新释放出来, 造成水体的二次污染. 本文基于水槽实验研究提供的大量实测数据, 建立上覆水体-底泥-污染物的耦合力学模型. 在上覆水体不同流速条件下, 数值模拟底泥起动再悬浮过程以及污染物释放过程. 分析流场特性和污染物浓度之间的关系, 得到速度、颗粒体积分数、污染物浓度、湍动能以及时间等参数之间的定量关系. 研究表明, 底泥再悬浮污染物释放过程, 是由上覆水体-底泥-污染物构成的耦合过程. 迅速进入上覆水体的底泥颗粒, 影响了上覆水体流动特性, 进而影响到污染物的释放. 对于非吸附性污染物, 底泥起动后复杂的流场特性是底泥再悬浮污染物释放的主要影响因素. 当流场特性(如雷诺数)改变时, 对流和湍流扩散作用在污染物输运过程贡献不同. 建立上覆水体-底泥-污染物的耦合模型, 研究水动力学条件与底泥污染物释放规律的定量化关系, 可为构建湖库区域水污染模型提供支撑.

     

    Abstract: In environmental hydrodynamics, the release of pollutants from sediments is one of the main problems. Under the condition of hydrodynamics, the resuspension of polluted sediment makes a large number of pollutants released again, resulting in the secondary pollution of water body. Based on a large number of experimental data provided by water channel experiments, a coupled mechanical model of overlying water body, sediment and pollutants is established in this paper. The process of sediment incipient motion and pollutant release are numerically simulated under different velocity of overlying water. The quantitative relationships among velocity, particle volume fraction, pollutant concentration, turbulent kinetic energy and time are obtained by analyzing the relationship between flow field characteristics and pollutant concentration distribution. The results show that the pollutants release process of sediment resuspended is a coupling process composed of overlying water, sediment and pollutants. When the sediment particles are resuspended into the overlying water body, the flow characteristics of overlying water and the release of pollutants are affected rapidly. For the non-adsorption pollutants, the complex characteristics of flow field are the main factors affecting the release of pollutants from resuspended sediment. When the flow field characteristics (Re) change, the contribution of convection diffusion and turbulent diffusion is different to pollutant release process. The coupling model of overlying water body, sediment and pollutants is established, and the quantitative relationship between hydrodynamic conditions and sediment pollutant release is studied, which can provide support for the construction of water pollution model in lake and reservoir area.

     

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