系统维度对变密度溶质运移的影响研究  

Effect of the system dimensionality on variable-density solute transport

作　　者：叶逾 蔡芳敏 谢一凡 井淼 鲁春辉 YE Yu;CAI Fangmin;XIE Yifan;JING Miao;LU Chunhui(College of Water Conservancy and Hydropower Engineering,Hohai University,Nanjing,Jiangsu 210098,China;State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering,Hohai University,Nanjing,Jiangsu 210098,China;Yangtze Institute for Conservation and Development,Hohai University,Nanjing,Jiangsu 210098,China)

机构地区：[1]河海大学水利水电学院,江苏南京210098 [2]河海大学水文水资源与水利工程科学国家重点实验室,江苏南京210098 [3]河海大学长江保护与绿色发展研究院,江苏南京210098

出　　处：《水文地质工程地质》2022年第1期146-153,共8页Hydrogeology & Engineering Geology

基　　金：国家重点研发计划项目(2021YFC3200500);中央高校基本科研业务费项目(B200202158)。

摘　　要：关于地下水变密度流与溶质运移的研究通常局限于二维系统中,三维系统中的研究非常有限。然而,仍有零星研究表明,三维系统中的对流过程与二维系统不同。文章通过SEAWAT-2000进行数值模拟,系统研究了二维和三维系统中的变密度溶质运移过程,利用舍伍德数、空间矩和稀释指数量化了系统的不稳定性和溶质扩散、稀释程度。结果表明:二维系统产生分散指流,而三维系统中因扩散程度的增强使得分散指流的产生受到抑制,但是,三维系统的不稳定性比二维系统更强,对流入渗更快,与指流的产生与否并无直接关联。另外,三维系统中溶质的稀释程度大于二维系统,但溶质在二维系统中将更快接近稀释的最大值,传统二阶中心矩可能会造成自由对流和不稳定性溶质运移过程中溶质扩散和稀释程度的错误估计。研究结果将有助于正确预测三维自然含水层中的自由对流和溶质运移。Investigation of groundwater variable-density flow and solute transport is usually limited in a 2D system.There are only a few studies performed in a 3D system.However,there are still studies showing differences in free convection between the 2D and 3D systems.This study systematically investigates the variable-density solute transport processes in the 2D and 3D systems through numerical simulations of SEAWAT-2000 and quantifies the system instability,solute spreading and dilution using the Sherwood number,spatial moments and dilution index.The results show that the separate fingers form in the 2D system while they are suppressed in the 3D system due to the enhanced diffusion.However,the instability is stronger and the convective infiltration is faster in the 3D system,which is not directly related to the fingering phenomenon.Furthermore,dilution is stronger in the 3D system,and it reaches to the maximum values at a faster rate in the 2D system.The traditional second central moment may lead to the wrong estimation of spreading and solute dilution in free convection and unstable solute transport.These outcomes help predict properly free convection and solute transport in three-dimensional natural aquifers.

关 键 词：系统维度 自由对流 不稳定性 指流 扩散 稀释 数值模拟 

分 类 号：P641.2[天文地球—地质矿产勘探]