利用CE/SE(conservation element and solution element)格式研究了柱面会聚波在气体中传播时间断面的不稳定问题和波阵面的演变问题,并利用level set函数追踪了驱动气体与低压气体间断面的发展过程。得到了间断面的Rayleigh-Taylor(R-T...利用CE/SE(conservation element and solution element)格式研究了柱面会聚波在气体中传播时间断面的不稳定问题和波阵面的演变问题,并利用level set函数追踪了驱动气体与低压气体间断面的发展过程。得到了间断面的Rayleigh-Taylor(R-T)和Richt myer-Meshkov(R-M)不稳定性发展成典型的"尖钉"和"气泡"结构的图像,初始正弦扰动下的会聚波产生"尖角"和"尖瓣"结构。结果表明,CE/SE格式在涉及会聚波的数值计算中是可行的。展开更多
To date, efficient numerical simulation of contaminant transport in geologic porous media is challenged by parametric jumps resulting from stratification and the use of ideal initial/boundary conditions. Thus, to reso...To date, efficient numerical simulation of contaminant transport in geologic porous media is challenged by parametric jumps resulting from stratification and the use of ideal initial/boundary conditions. Thus, to resolve some contaminant hydrology problems, this work presents the development of the Space-Time Conservation Element/Solution Element (CE/SE) scheme for advection-dispersion-reaction a-d-r transport in geologic media. The CE/SE method derives from the native form of Gauss conservation law. Therefore, it is able to effectively handle non-trivial discontinuities that may exist within the problem domain. In freshwater aquifer, stratification and other parametric jumps are examples of such discontinuity. To simulate the Nigerian experience of nitrate pollution of freshwater aquifers;the a-d-r contaminant transport model is herein solved under a time periodic nitrate fertilizer loading condition on farmlands. Results show that this approach is able to recover the well-known field pattern of nitrate profiles under farmlands. Cyclic loading impacts more on the dispersivity of an aquifer. Hence, dispersion coefficient modulates the response of aquifers to loading frequency. However, aquifers with conductivity less than 10-6 m/day are almost insensitive to periodic loads. The CE/SE method is able to sense slight (i.e. order of 10-3) variation in hydrological parameters. Also, CE/SE computes contaminant concentration and its flux simultaneously. Thus, it facilitates a better understanding of some reported phenomena such as contaminant accumulation and localized reverse transport at the interface between fracture and matrix in geologic medium. Clearly, CE/SE is an efficient and admissible tool into the family of numerical methods available for tracking contaminant transport in porous media.展开更多
文摘利用CE/SE(conservation element and solution element)格式研究了柱面会聚波在气体中传播时间断面的不稳定问题和波阵面的演变问题,并利用level set函数追踪了驱动气体与低压气体间断面的发展过程。得到了间断面的Rayleigh-Taylor(R-T)和Richt myer-Meshkov(R-M)不稳定性发展成典型的"尖钉"和"气泡"结构的图像,初始正弦扰动下的会聚波产生"尖角"和"尖瓣"结构。结果表明,CE/SE格式在涉及会聚波的数值计算中是可行的。
文摘To date, efficient numerical simulation of contaminant transport in geologic porous media is challenged by parametric jumps resulting from stratification and the use of ideal initial/boundary conditions. Thus, to resolve some contaminant hydrology problems, this work presents the development of the Space-Time Conservation Element/Solution Element (CE/SE) scheme for advection-dispersion-reaction a-d-r transport in geologic media. The CE/SE method derives from the native form of Gauss conservation law. Therefore, it is able to effectively handle non-trivial discontinuities that may exist within the problem domain. In freshwater aquifer, stratification and other parametric jumps are examples of such discontinuity. To simulate the Nigerian experience of nitrate pollution of freshwater aquifers;the a-d-r contaminant transport model is herein solved under a time periodic nitrate fertilizer loading condition on farmlands. Results show that this approach is able to recover the well-known field pattern of nitrate profiles under farmlands. Cyclic loading impacts more on the dispersivity of an aquifer. Hence, dispersion coefficient modulates the response of aquifers to loading frequency. However, aquifers with conductivity less than 10-6 m/day are almost insensitive to periodic loads. The CE/SE method is able to sense slight (i.e. order of 10-3) variation in hydrological parameters. Also, CE/SE computes contaminant concentration and its flux simultaneously. Thus, it facilitates a better understanding of some reported phenomena such as contaminant accumulation and localized reverse transport at the interface between fracture and matrix in geologic medium. Clearly, CE/SE is an efficient and admissible tool into the family of numerical methods available for tracking contaminant transport in porous media.
