基于非恒定流的底泥污染物释放的数值模拟

郑淑君　何百通　郭加宏　徐蕤

【摘 要】当外源污染受到控制后，河流与湖泊底泥中的污染物可能会引起上覆水的再次污染。天然河流和湖泊中的水流，由于各种因素的影响，流速等参数常常是随时间变化的。本文在上覆水流动不致底泥起动悬浮的条件下，数值模拟研究单向非恒定流中污染物通过底泥-上覆水界面的释放规律。采用k-ε湍流模型计算上覆水的流动；采用Darcy定律描述多孔介质中的渗流，耦合计算上覆水和底泥中孔隙水的非恒定流动，在此基础上，计算了污染物溶质在上覆水体和底泥孔隙水中输运过程。数值研究结果表明，与恒定流相比较，非恒定流中上覆水中污染物浓度峰值较大，从而影响上覆水体的水质。

【关键词】底泥-上覆水界面；数值模拟；污染物；非恒定流

中图分类号： X52；X143 文献标识码： A 文章编号： 2095-2457（2018）08-0166-003

Numerical Simulation of Pollutant Release from Sediment Based on Unsteady Flow

ZHENG Shu-jun HE Bai-tong GUO Jia-hong XU Rui

（Luzhou Vocational and Technical College，Luzhou，Zhejiang 324000，China）

【Abstract】When external pollution is controlled， pollutants in sediments of rivers and lakes may cause re-contamination of overlying water. Flows in natural rivers and lakes， due to various factors， flow rate and other parameters often change over time. In this paper， under the condition that the overlying water flow does not initiate the suspension of the sediment， the release of contaminants through the sediment-overlying water interface in one-way unsteady flow is numerically simulated. The turbulence model was used to calculate the flow of overlying water. The Darcy's law was used to describe the seepage flow in porous media and the coupled calculation of the unsteady flow of water in the overlying water and the pore water in the sediment. On this basis， the pollutant solute in the overlying water and the bottom was calculated. Mud pore water transport process. The numerical results show that， compared with the constant flow， the concentration of pollutants in the overlying water in the unsteady flow has a peak value， which affects the water quality of the overlying water.

【Key words】Sediment-overlying water interface； Numerical simulation； Pollutant； Unsteady flow

0 引言

底泥一般是指江河湖海的沉積物，是自然水域的重要组成部分，可以成为江河湖海水体中污染物的源或汇。水体中的污染物在各种因素的作用下可能会进入到底泥中，减轻水体的污染。同样，当水体的外源污染物排放得到控制，底泥中的污染物释放也可能会引起上覆水体的再次污染[1-3]。因此，污染物在上覆水和底泥之间的迁移对水环境的影响非常重要。

底泥-上覆水界面粗糙形态或者其它不规则性（如原木、石块和地形等）都会引起底泥-上覆水界面压力变化，诱导孔隙水流动[4]。刘勇[5]采用有限元方法模拟了孔隙水流动和不同时间条件下孔隙水系统中可溶性污染物的动态变化规律。……