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131.
Introduction Mantle convection is thought to be the most effective way of heat transportation in the earth and the source of driving lithospheric plates (Elasser, 1971). The velocity field of plate motion can be split into poloidal and toroidal parts, which are corresponding to the vertical (i.e. radial) and horizontal motions, respectively, in global model. The toroidal component is manifested in the existences of transform faults and the poloidal one in the presences of convergence and diver… 相似文献
132.
地磁场模型的计算和评述 总被引:1,自引:0,他引:1
评述了计算地磁场区域模型的各种数学方法,如:利用多项式方法可以计算地磁场的Taylor多项式模型和Legendre多项式模型,利用球冠谐和分析方法可以计算出磁场的冠谐模型。本文指出了建立区域模型各种方法的优缺点,指出球冠谐和分析方法是计算地磁场三维模型的好方法。 相似文献
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Computation and analysis of the geomagnetic field model in China and its adjacent area for 2003 总被引:1,自引:0,他引:1
Based on the geomagnetic data at 135 stations and 35 observatories in China in 2003, the Taylor polynomial model and the spherical cap harmonic model in China and its adjacent area for 2003 were established. In the model calculation, the truncation order of the model and the influences of the boundary restriction on the model calculation were carefully analyzed. The results show that the geomagnetic data used are precise and reliable, and the selection of the truncation order is reasonable. The Taylor polynomial model and the spherical cap harmonic model in China and its adjacent area established in this paper are consistent very well. 相似文献
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Fractures have been recently identified in potential host rock for high level nuclear waste disposal, like indurated argilite formations. These fractures appear as potential rapid pathways for radionuclides transport and hydrodynamic properties of the transport inside these systems must thus be characterized. Miscible non-sorbing and sorbing tracers displacements were performed on a 2-D model derived from a real fracture geometry observed in the Tournemire argilite formation with a lattice-gas cellular automaton (LGA). LGA was shown to easily handle the complex geometry of such a fracture. The numerical breakthrough curves obtained were inverted with the 1-D CDE and MIM transport models. Two main conclusions were drawn: (i) at the length scale of the study, the non-sorbing tracer transport in our fracture geometry was more accurately interpreted in terms of the MIM model rather than in terms of the classical CDE model; (ii) in order to correctly model the sorbing tracers migration, the hydrodynamic dispersion coefficient value was found to increase with the increase of the retardation factor. A semi-empirical relation based on the Taylor–Aris theory was then used to describe this dependency. 相似文献
138.
Olivier Gourgue Richard ComblenJonathan Lambrechts Tuomas KärnäVincent Legat Eric Deleersnijder 《Advances in water resources》2009
We present a flux-limiting wetting–drying approach for finite-element discretizations of the shallow-water equations using discontinuous linear elements for the elevation. The key ingredient of the method is the use of limiters for generalized nodal fluxes. This method is implemented into the Second-generation Louvain-la-Neuve Ice-ocean Model (SLIM), and is verified against standard test cases. The method is further applied to the wetting and drying of sand banks in the Scheldt Estuary, which is located in northern Belgium and the southern Netherlands. The results obtained for both the benchmarks and the realistic problem illustrate the accuracy of the method in describing the hydrodynamics in the vicinity of dry areas. In particular, the method strictly conserves mass, and there is no transport through dry areas. 相似文献
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本文分析了目前直流电阻率正演模拟中的无单元Galerkin法(EFGM)和有限单元法(FEM)的优缺点,针对采用第一类边界条件需要足够大的计算域时EFGM计算成本高的问题,在计算域外围区域采用FEM扩边,提出了直流电阻率的无单元Galerkin-有限单元耦合法(EFG-FE).采用具有Kronecker delta函数性质的径向基点插值法(RPIM)构造EFGM形函数,在外围区域将EFGM与FEM直接耦合,无需其他处理手段,消除了传统EFGM与FEM耦合中存在的界面耦合困难.EFG-FE将模型计算域分割为EFGM区域和FEM区域,模型核心区域采用EFGM计算,发挥EFGM灵活性、适应性强和高精度的优点,使得模型建立简单方便,对任意复杂地电模型适应性强,同时获得高精度模拟结果.在模型计算域外围采用快速扩展的FEM单元网格进行剖分,利用其数值稳定性和高效性,使用少量FEM节点和单元网格将计算域大范围扩大满足第一类边界条件,同时不大幅增加计算成本,进而提高计算效率.最后,通过不同正演方法的模型算例的模拟结果对比,验证了本文提出的EFG-FE有效可行,其模拟结果具有很高的模拟精度,且相比于采用第三类边界条件的EFGM提高了计算效率,具有更好的模拟性能. 相似文献