Use of Divergence Free Basis in Finite Elements Methods

1984 ◽  
pp. 290-316 ◽  
Author(s):  
Frédéric Hecht
Keyword(s):  
Finite Elements ◽  
Free Basis ◽  
Finite Elements Methods ◽  
Divergence Free

A Discretization Scheme for a Quasi-Hydrodynamic Semiconductor Model

1997 ◽  
Vol 07 (07) ◽  
pp. 935-955 ◽  
Author(s):  
Ansgar Jüngel ◽  
Paola Pietra
Keyword(s):  
Finite Elements ◽  
Mixed Finite Elements ◽  
Exponential Fitting ◽  
Discretization Scheme ◽  
Drift Diffusion Model ◽  
Drift Diffusion ◽  
Current Conservation ◽  
Numerical Tests ◽  
Finite Elements Methods ◽  
Degenerate Type

A discretization scheme based on exponential fitting mixed finite elements is developed for the quasi-hydrodynamic (or nonlinear drift–diffusion) model for semiconductors. The diffusion terms are nonlinear and of degenerate type. The presented two-dimensional scheme maintains the good features already shown by the mixed finite elements methods in the discretization of the standard isothermal drift–diffusion equations (mainly, current conservation and good approximation of sharp shapes). Moreover, it deals with the possible formation of vacuum sets. Several numerical tests show the robustness of the method and illustrate the most important novelties of the model.

Finite Elements Methods in Mechanics

2014 ◽  
Author(s):  
M. Reza Eslami
Keyword(s):  
Finite Elements ◽  
Finite Elements Methods

Finite Elements Methods via Tensors

1972 ◽  
Author(s):  
Hayrettin Kardestuncer
Keyword(s):  
Finite Elements ◽  
Finite Elements Methods

scholarly journals Divergence-free Reconstruction Operators for Pressure-Robust Stokes Discretizations with Continuous Pressure Finite Elements

2017 ◽  
Vol 55 (3) ◽  
pp. 1291-1314 ◽  
Author(s):  
Philip L. Lederer ◽  
Alexander Linke ◽  
Christian Merdon ◽  
Joachim Schöberl
Keyword(s):  
Finite Elements ◽  
Divergence Free

Transient electromagnetic responses of high‐contrast prisms in a layered earth

Geophysics ◽  
1988 ◽  
Vol 53 (5) ◽  
pp. 691-706 ◽  
Author(s):  
Gregory A. Newman ◽  
Gerald W. Hohmann
Keyword(s):  
Exponential Decay ◽  
Free Space ◽  
Basis Functions ◽  
Masking Effect ◽  
Power Relationship ◽  
Free Basis ◽  
Transient Electromagnetic ◽  
Wide Range ◽  
Divergence Free ◽  
Central Loop

An integral‐equation solution for transient electromagnetic (TEM) scattering by prisms in layered half‐spaces is formulated to provide meaningful results when the prisms are in highly resistive layers. A prism is replaced with an unknown scattering current, which is approximated with pulse and divergence‐free basis functions in the frequency domain. Divergence‐free basis functions model eddy currents that exist in confined bodies in a very resistive host and hence simulate the inductive responses of the prisms. A Galerkin solution for the scattering current is obtained where the dominant charge operator is eliminated from part of the solution by integrating the tensor Green’s function around rectangular paths. After the scattering current is determined, the electric and magnetic fields scattered by the prisms are calculated; and the corresponding TEM responses are obtained by inverse Fourier transformation. The resulting solution provides meaningful results over a wide range of resistivities in layered hosts including the case of free space. The masking effect of a conductive overburden delays and suppresses the three‐dimensional TEM response of a conductor. The overburden response must be removed for the conductor’s response to be fully interpretable. An interpretation of the conductor with free‐space models is a poor approximation when the basement rock is conductive. Instead of an exponential decay at late times, the conductor’s response decays in an inverse power relationship. When the basement resistivity is increased, the conductor exhibits an exponential decay at late times. For a thin dike, the time constant estimated from this decay is identical to that for a thin plate in free space. However, the response of the dike buried beneath the overburden is larger than the response of the dike in free space. This increase in the response of the dike will bias modeling it in free space with thin plates. We have used the solution to gain insight regarding the lateral resolution of two vertical conductors for the fixed‐loop and central‐loop survey configurations. The results suggest that resolution of multiple conductors is very poor in a fixed‐loop survey; but in a central‐loop survey, the resolution is much better, provided the data are interpreted at early times. At later times, multiple conductors may not be resolvable and interpretational ambiguities could arise.

Application of the finite-elements methods to the optimization of flange joints

1995 ◽  
Vol 31 (5) ◽  
pp. 265-269
Author(s):  
V. M. Bogomol'nyi ◽  
Yu. A. Ivanov
Keyword(s):  
Finite Elements ◽  
Finite Elements Methods

scholarly journals Calculation of Rail Internal Impedance by Using Finite Elements Methods and Complex Magnetic Permeability

2009 ◽  
Vol 2009 ◽  
pp. 1-10 ◽  
Author(s):  
Alberto Dolara ◽  
Sonia Leva
Keyword(s):  
Finite Elements ◽  
Magnetic Permeability ◽  
Magnetization Curve ◽  
Analytical Models ◽  
Internal Parameter ◽  
Internal Inductance ◽  
Internal Impedance ◽  
Normal Magnetization ◽  
Complex Magnetic Permeability ◽  
Finite Elements Methods

The internal parameter of UNI 60 rail is calculated by using finite elements methods. Steel's characterizations by its normal magnetization curve and by complex magnetic permeability are here considered and included into the proposed FEM models. Rail's resistance and internal inductance in function of current and frequency are calculated using both FEM and analytical models. The results obtained at the frequency of 50 Hz are compared with few measurements available, and then they are extended to other frequencies.

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