To investigate groundwater flow and solute transport characteristics of the karst trough zone in China,tracer experiments were conducted at two adjacent typical karst groundwater flow systems(Yuquandong(YQD)and Migong...To investigate groundwater flow and solute transport characteristics of the karst trough zone in China,tracer experiments were conducted at two adjacent typical karst groundwater flow systems(Yuquandong(YQD)and Migongquan(MGQ))in Sixi valley,western Hubei,China.Highresolution continuous monitoring was utilized to obtain breakthrough curves(BTCs),which were then analyzed using the multi-dispersion model(MDM)and the two-region nonequilibrium model(2RNE)with basic parameters calculated by CXTFIT and QTRACER2.Results showed that:(1)YQD flow system had a complex infiltration matrix with overland flow,conduit flow and fracture flow,while the MGQ flow system was dominated by conduit flow with fast flow transport velocity,but also small amount of fracture flow there;(2)They were well fitted based on the MDM(R^2=0.928)and 2RNE(R^2=0.947)models,indicating that they had strong adaptability in the karst trough zone;(3)conceptual models for YQD and MGQ groundwater systems were generalized.In YQD system,the solute was transported via overland flow during intense rainfall,while some infiltrated down into fissures and conduits.In MGQ system,most were directly transported to spring outlet in the fissureconduit network.展开更多
在实际应用中互连结构的导体是有损耗的,在低频时其趋肤深度会很大,电流会渗入导体内部并覆盖整个导体横截面,这时传统上采用完全电导体(Perfect Electric Conductor,PEC)近似或采用表面阻抗计入损耗的单一区域形式的积分方程可能不再有...在实际应用中互连结构的导体是有损耗的,在低频时其趋肤深度会很大,电流会渗入导体内部并覆盖整个导体横截面,这时传统上采用完全电导体(Perfect Electric Conductor,PEC)近似或采用表面阻抗计入损耗的单一区域形式的积分方程可能不再有效,因此在积分方程法中需要采用双区域积分方程形式来描述.在低频时电场积分方程(Electric Feld Integral Equation,EFIE)容易出现崩溃现象,为此人们提出了采用增强电场积分方程(Augmented Electric Field Integral Equations,AEFIEs)来解决单一导体或介质结构中的低频崩溃问题.文章将有损导体视为可穿透的介质物体,提出了采用双区域增强混合场积分方程(Augmented Hybrid Field Integral Equations,AHFIEs)来解决有耗导体互连结构的低频崩溃问题.混合场积分方程(Hybrid Field Integral Equations,HFIEs)由描述导体外部的EFIE和描述导体内部的磁场积分方程(Magnetic Field Integral Equation,MFIE)组成.由于磁荷密度出现在HFIEs的L算子中,文章将磁荷密度作为新的独立未知函数并引入磁流密度连续性方程作为附加约束方程描述导体部分,对互连结构中任意可穿透的介质部分则采用体积分方程(Volume Integral Equations,VIEs)描述,将2类方程通过场耦合结合起来便建立了整个结构的双区域增强体-面积分方程(Augmented Volume-Surface Integral Equations,AVSIEs).基于AEFIEs的传统方法只能求解包含PEC和各向同性及均匀介质衬底的封装结构,而文章提出的基于AVSIEs的方法可以求解包含有损耗的导体和任意性质的介质衬底的封装结构,因而大大增强了求解此类问题的能力.AVSIEs采用矩量法求解,其中RWG(Rao-Wilton-Glisson)基函数用来表示增强混合场积分方程(AHFIEs)中的表面电流密度和表面磁流密度,而SWG(Schaubert-Wilton-Glisson)基函数则用来表示体积分方程(VIEs)中的体电流密度或体磁流密度,脉冲基函数用来表示AHFIEs中的电荷密度和磁荷密度.文章通过数值算例验证了提出方法的有效性和优越性.展开更多
基金supported by the National Natural Science Foundation of China(Nos.42007178 and 41907327)the Natural Science Foundation of Hubei(Nos.2020CFB463 and 2019CFB372)+4 种基金China Geological Survey(Nos.DD20160304 and DD20190824)Fundamental Research Funds for the Central Universities(Nos.CUG 190644 and CUGL180817)National Key Research and Development Program(No.2019YFC1805502)Key Laboratory of Karst Dynamics,MNR and GZAR(Institute of Karst Geology,CAGS)Guilin(No.KDL201703)Key Laboratory of Karst Ecosystem and Treatment of Rocky Desertification,MNR and IRCK by UNESCO(No.KDL201903)。
文摘To investigate groundwater flow and solute transport characteristics of the karst trough zone in China,tracer experiments were conducted at two adjacent typical karst groundwater flow systems(Yuquandong(YQD)and Migongquan(MGQ))in Sixi valley,western Hubei,China.Highresolution continuous monitoring was utilized to obtain breakthrough curves(BTCs),which were then analyzed using the multi-dispersion model(MDM)and the two-region nonequilibrium model(2RNE)with basic parameters calculated by CXTFIT and QTRACER2.Results showed that:(1)YQD flow system had a complex infiltration matrix with overland flow,conduit flow and fracture flow,while the MGQ flow system was dominated by conduit flow with fast flow transport velocity,but also small amount of fracture flow there;(2)They were well fitted based on the MDM(R^2=0.928)and 2RNE(R^2=0.947)models,indicating that they had strong adaptability in the karst trough zone;(3)conceptual models for YQD and MGQ groundwater systems were generalized.In YQD system,the solute was transported via overland flow during intense rainfall,while some infiltrated down into fissures and conduits.In MGQ system,most were directly transported to spring outlet in the fissureconduit network.
文摘在实际应用中互连结构的导体是有损耗的,在低频时其趋肤深度会很大,电流会渗入导体内部并覆盖整个导体横截面,这时传统上采用完全电导体(Perfect Electric Conductor,PEC)近似或采用表面阻抗计入损耗的单一区域形式的积分方程可能不再有效,因此在积分方程法中需要采用双区域积分方程形式来描述.在低频时电场积分方程(Electric Feld Integral Equation,EFIE)容易出现崩溃现象,为此人们提出了采用增强电场积分方程(Augmented Electric Field Integral Equations,AEFIEs)来解决单一导体或介质结构中的低频崩溃问题.文章将有损导体视为可穿透的介质物体,提出了采用双区域增强混合场积分方程(Augmented Hybrid Field Integral Equations,AHFIEs)来解决有耗导体互连结构的低频崩溃问题.混合场积分方程(Hybrid Field Integral Equations,HFIEs)由描述导体外部的EFIE和描述导体内部的磁场积分方程(Magnetic Field Integral Equation,MFIE)组成.由于磁荷密度出现在HFIEs的L算子中,文章将磁荷密度作为新的独立未知函数并引入磁流密度连续性方程作为附加约束方程描述导体部分,对互连结构中任意可穿透的介质部分则采用体积分方程(Volume Integral Equations,VIEs)描述,将2类方程通过场耦合结合起来便建立了整个结构的双区域增强体-面积分方程(Augmented Volume-Surface Integral Equations,AVSIEs).基于AEFIEs的传统方法只能求解包含PEC和各向同性及均匀介质衬底的封装结构,而文章提出的基于AVSIEs的方法可以求解包含有损耗的导体和任意性质的介质衬底的封装结构,因而大大增强了求解此类问题的能力.AVSIEs采用矩量法求解,其中RWG(Rao-Wilton-Glisson)基函数用来表示增强混合场积分方程(AHFIEs)中的表面电流密度和表面磁流密度,而SWG(Schaubert-Wilton-Glisson)基函数则用来表示体积分方程(VIEs)中的体电流密度或体磁流密度,脉冲基函数用来表示AHFIEs中的电荷密度和磁荷密度.文章通过数值算例验证了提出方法的有效性和优越性.
