Abstract

This research is intended to study the effect of water flow on the release flux of DNAPLs, which have been deposited on the riverbed surface after sudden water pollution accidents. Those contaminants will slowly diffuse from the riverbed into the overlying water body through hydrodynamic action, causing ongoing and serious water pollution. By taking dichloromethane as a typical contaminant, the release form under different hydrodynamic conditions was observed through flume experiments, and the response relationship between the release flux and hydrodynamic factors was analyzed, with an emphasis on parameterizing the release rate. The results suggested that stronger water disturbance significantly enhanced the release of contaminants. And the relationship between the release flux and hydrodynamic factors generally followed an exponential distribution (R² > 0.94). Besides, the mathematical relationships between the release flux and the average flow velocity, shear force and turbulent intensity were established as follows: $\mathrm{F}=183.63\mathrm{\times }{\mathrm{e}}^{0.332\stackrel{\mathrm{-}}{\mathrm{u}}},$$\mathrm{}\mathrm{F}=617.78\mathrm{\times }{\mathrm{e}}^{22.292\mathrm{\tau }}$ and$\mathrm{}\mathrm{F}=119.03\mathrm{\times }{\mathrm{e}}^{2.127\text{TKE}}.$ Thus, this study has offered a solution to solve the source term quantification problem of the differential equation of convective diffusion, which can provide the basis for further developing the mathematical models of this kind of pollutants.

摘要

本研究旨在研究水流对突发水污染事故后沉积在河床表面的DNAPLs释放通量的影响。这些污染物会通过水动力作用从河床缓慢扩散到上覆水体，造成持续和严重的水污染。以二氯甲烷为典型污染物，通过水槽实验观察了不同水动力条件下的释放形态，分析了释放通量与水动力因素的响应关系，重点对释放速率进行了参数化。结果表明，较强的水扰动显着增强了污染物的释放。² > 0.94）。此外，释放通量与平均流速、剪切力和湍流强度之间的数学关系建立如下：$\mathrm{F}=183.63\mathrm{\times }{\mathrm{电子}}^{0.332\stackrel{\mathrm{——}}{\mathrm{你}}},$$\mathrm{}\mathrm{F}=617.78\mathrm{\times }{\mathrm{电子}}^{22.292\mathrm{\tau }}$ 和$\mathrm{}\mathrm{F}=119.03\mathrm{\times }{\mathrm{电子}}^{2.127\text{通用电气}}.$ 因此，本研究为求解对流扩散微分方程的源项量化问题提供了一种解决方案，可为进一步开发此类污染物的数学模型提供依据。