Finite-difference computation of transient electromagnetic waves for cylindrical geometries in complex media

2000 ◽  
Vol 38 (4) ◽  
pp. 1530-1543 ◽  
Author(s):  
F.L. Teixeira ◽  
Weng Cho Chew
Keyword(s):  
Finite Difference ◽  
Electromagnetic Waves ◽  
Complex Media ◽  
Transient Electromagnetic ◽  
Cylindrical Geometries

scholarly journals Study Effect of Objects Orientation in the Mediums On GPR Signal Reflections Using FDTD Simulation

2018 ◽  
Vol 3 (11) ◽  
pp. 73-77
Author(s):  
Aye Mint Mohamed Mostapha ◽  
Gamil Alsharahi ◽  
Abdellah Driouach
Keyword(s):  
Finite Difference ◽  
Time Domain ◽  
Ground Penetrating Radar ◽  
High Frequency ◽  
Electromagnetic Waves ◽  
Ground Surface ◽  
Propagation Path ◽  
Fdtd Simulation ◽  
Ground Penetrating ◽  
Dielectric Objects

Ground penetrating radar (GPR) is a very effective tool for detecting and identifying objects below the ground surface.  based on  the propagation and reflection of high-frequency electromagnetic waves. The GPR reflection can be affected by many things like the type of objects orientation, their shapes ..ect. The purpose of this paper is to  study by simulation the effect of objects orientation in two different mediums (dry and wet sand) on the GPR signal reflection using Reflexw software which is based on a numerical method known as finite difference in time domain (FDTD).  The simulations that have been realized included a conductor  and dielectric objects. The results obtained have led us to find that the propagation path, the reflection strength and the signal form change with the change of object orientation and nature. To confirm the validity of the results, we compared them with experimental results previously published by researchers under the same conditions.

scholarly journals A parallel finite‐difference approach for 3D transient electromagnetic modeling with galvanic sources

Geophysics ◽  
2004 ◽  
Vol 69 (5) ◽  
pp. 1192-1202 ◽  
Author(s):  
Michael Commer ◽  
Gregory Newman
Keyword(s):  
Magnetic Field ◽  
Finite Difference ◽  
Electric Field ◽  
Electric Fields ◽  
Time Derivative ◽  
Stable Solution ◽  
Parallel Computer ◽  
Staggered Grid ◽  
Electromagnetic Modeling ◽  
Transient Electromagnetic

A parallel finite‐difference algorithm for the solution of diffusive, three‐dimensional (3D) transient electromagnetic field simulations is presented. The purpose of the scheme is the simulation of both electric fields and the time derivative of magnetic fields generated by galvanic sources (grounded wires) over arbitrarily complicated distributions of conductivity and magnetic permeability. Using a staggered grid and a modified DuFort‐Frankel method, the scheme steps Maxwell's equations in time. Electric field initialization is done by a conjugate‐gradient solution of a 3D Poisson problem, as is common in 3D resistivity modeling. Instead of calculating the initial magnetic field directly, its time derivative and curl are employed in order to advance the electric field in time. A divergence‐free condition is enforced for both the magnetic‐field time derivative and the total conduction‐current density, providing accurate results at late times. In order to simulate large realistic earth models, the algorithm has been designed to run on parallel computer platforms. The upward continuation boundary condition for a stable solution in the infinitely resistive air layer involves a two‐dimensional parallel fast Fourier transform. Example simulations are compared with analytical, integral‐equation and spectral Lanczos decomposition solutions and demonstrate the accuracy of the scheme.

Analysis for Scattering of Non-homogeneous Medium by Time Domain Volume Shooting and Bouncing Rays

2021 ◽  
Vol 36 (3) ◽  
pp. 245-251
Author(s):  
Jun Li ◽  
Huaguang Bao ◽  
Dazhi Ding
Keyword(s):  
Time Domain ◽  
Electromagnetic Scattering ◽  
Electromagnetic Waves ◽  
High Efficiency ◽  
Homogeneous Medium ◽  
Reflection And Transmission ◽  
Transmission Coefficients ◽  
Transient Electromagnetic ◽  
Frequency Domain Methods ◽  
Scattered Fields

In order to evaluate scattering from hypersonic vehicles covered with the plasma efficiently, time domain volume shooting and bouncing rays (TDVSBR) is first introduced in this paper. The new method is applied to solve the transient electromagnetic scattering from complex targets, which combines with non-homogeneous dielectric and perfect electric conducting (PEC) bodies. To simplify the problem, objects are discretized into tetrahedrons with different electromagnetic parameters. Then the reflection and transmission coefficients can be obtained by using theory of electromagnetic waves propagation in lossy medium. After that, we simulate the reflection and transmission of rays in different media. At last, the scattered fields or radiation are solved by the last exiting ray from the target. Compared with frequency-domain methods, time-domain methods can obtain the wideband RCS efficiently. Several numerical results are given to demonstrate the high efficiency and accuracy of this proposed scheme.

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