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| 1 | Numerical simulation of phosphorus release from resuspended sediment显示文摘One of the main issues in environmental hydraulics is pollutant release from sediments.For instance,the strong affinity between phosphorus and sediment permits most of the phosphorus to be adsorbed on the surface of the sediment particles in rivers or lakes.Post sediment resuspension,phosphorus is desorbed from the sediment to the overlying water.The release of phosphorus from the resuspended sediment is an important process in the secondary pollution of water.Herein,a coupled mechanical model of the overlying water,sediment,and pollutant was established based on the experimentally gathered data.Two types of sediment with different adsorption and desorption characteristics were selected to simulate the process of sediment resuspension and phosphorus release under different hydrodynamic conditions.The simulation results were subsequently used to analyze the relationship between the flow field characteristics and phosphorus concentration,from which the relationships between velocity,particle volume fraction,turbulent kinetic energy,total phosphorus concentration,desorbed phosphorus concentration,and time were elucidated.Based on the results,phosphorus is rapidly released into the overlying water from the resuspended sediment,and it reaches a peak value in a short duration.Unlike the release process of non-adsorption pollutants,hydrodynamic conditions and sediment properties play a crucial role in the phosphorus release process.The turbulent kinetic energy rapidly increases with the flow velocity,whereas the desorbed phosphorus concentration exhibits a certain relationship with the particle volume fraction and turbulent kinetic energy.In particular,the turbulent kinetic energy increases the desorbed phosphorus concentration per unit time.Additionally,the time taken by the total phosphorus concentration to attain its peak value is closely related to the characteristics of the flow field,whereas the amount of phosphorus is closely related to sediment properties.Post sediment resuspension,the release of phosphorus shows the characteristics of a centralized and massive release,which suggests that the total phosphorus concentration in the overlying water would change in a short duration and cause secondary pollution in the water environment. | Pengda Cheng Xinquan Wang Chun Feng | 2020 | Acta Mechanica Sinica2020，36，6： | 3 |
| 2 | 再悬浮底泥中非吸附性污染物释放的数值模拟显示文摘环境水动力学中,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. | 程鹏达 朱心广 冯春 王晓亮 | 2020 | 力学学报2020，52，3： | 3 |
| 3 | Empirical model for estimating vertical concentration profiles of re-suspended, sediment-associated contaminants显示文摘Vertical distribution processes of sediment contaminants in water were studied by flume experiments.Experimental results show that settling velocity of sediment particles and turbulence characteristics are the major hydrodynamic factors impacting distribution of pollutants,especially near the bottom where particle diameter is similar in size to vortex structure. Sediment distribution was uniform along the distance, while contaminant distribution slightly lagged behind the sediment. The smaller the initial sediment concentration was, the more time it took to achieve a uniform concentration distribution for suspended sediment. A contaminants transportation equation was established depending on mass conservation equations. Two mathematical estimation models of pollutant distribution in the overlying water considering adsorption and desorption were devised based on vertical distribution of suspended sediment: equilibrium partition model and dynamic micro-diffusion model. The ratio of time scale between the sediment movement and sorption can be used as the index of the models. When this ratio was large, the equilibrium assumption was reasonable, but when it was small, it might require dynamic micro-diffusion model. | H.W.Zhu P.D.Cheng W.Li J.H.Chen Y.Pang D.Z.Wang | 2017 | Acta Mechanica Sinica2017，33，5： | 3 |
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