THREDS: A Finite-Difference Time-Domain EMP Code in 3d Spherical Coordinates

Holland, Robert C.

doi:10.1109/tns.1983.4333177

Cited by 74 publications

(69 citation statements)

References 4 publications

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“…Both groups used sphericalcoordinate, latitude-longitude grids based upon fundamental work by Holland [19]. Hayakawa et al reported no improvements relative to Holland's grid, which is subject to increasing space-cell eccentricity upon approaching the poles due to converging lines of longitude.…”

Section: Introductionmentioning

confidence: 99%

Efficient modeling of impulsive ELF antipodal propagation about the Earth sphere using an optimized two-dimensional geodesic FDTD grid

Simpson

Taflove

2004

Antennas Wirel. Propag. Lett.

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Abstract-This letter reports the initial application of a geodesic finite-difference time-domain (FDTD) grid to model impulsive extremely low frequency electromagnetic wave propagation about the Earth sphere. The two-dimensional transverse-magnetic grid is comprised entirely of hexagonal cells, except for a small fixed number of pentagonal cells needed for grid completion. Grid-cell areas and locations are optimized to yield a smoothly varying area difference between adjacent cells, thereby maximizing numerical convergence. The new FDTD grid model is considerably superior to our previously reported latitude-longitude grid because it is simpler to construct, avoids geometrical singularities at the poles, executes about 14 times faster, provides much more isotropic wave propagation, and permits an easier interchange of data with state-of-the-art Earth-simulation codes used by the geophysics community. We verify our new model by conducting numerical studies of impulsive antipodal propagation and the Schumann resonance.

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Section: Introductionmentioning

confidence: 99%

Efficient modeling of impulsive ELF antipodal propagation about the Earth sphere using an optimized two-dimensional geodesic FDTD grid

Simpson

Taflove

2004

Antennas Wirel. Propag. Lett.

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“…The S-FDTD of [23] is used for comparison with WRG-FDTD. The E θ = E th component propagated along rays ( Figure 5) into the inhomogeneous region is calculated.…”

Section: Sample Problem and Numerical Studiesmentioning

confidence: 99%

Wavefront-ray grid FDTD algorithm

Çiydem¹,

Koc²

2016

Turk J Elec Eng & Comp Sci

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Abstract:A finite difference time domain algorithm on a wavefront-ray grid (WRG-FDTD) is proposed in this study to reduce numerical dispersion of conventional FDTD methods. A FDTD algorithm conforming to a wavefront-ray grid can be useful to take into account anisotropy effects of numerical grids since it features directional energy flow along the rays. An explicit and second-order accurate WRG-FDTD algorithm is provided in generalized curvilinear coordinates for an inhomogeneous isotropic medium. Numerical simulations for a vertical electrical dipole have been conducted to demonstrate the benefits of the proposed method. Results have been compared with those of the spherical FDTD algorithm and it is showed that numerical grid anisotropy can be reduced highly by WRG-FDTD.

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“…Other the radial electric field quantities can be updated using normal geodesic FDTD algorithm. For the tangential magnetic field ht inside grid-cell that is subgridded, we have ht n+1.5 = ht n+0.5 + ∆t µδ t,sub × er n+1 (10) where δ t,sub is the distance between adjacent er 's at ht, and δ r is the distance between adjacent TE planes. To calculate the ht field quantities in the edge of the subgrid cells, we assume that the field quantities inside the normal grid-cells are distributed evenly, and obtain the approximation update equation…”

Section: The 2d Subgrid Technologymentioning

confidence: 99%

“…After that, they also extended this 2D grid into a fully 3-D space lattice [8,9]. This geodesic FDTD method is superior to the previous widely-used latitude-longitude FDTD method [5,6,[10][11][12] because it has provided much more numerically isotropic wave propagation, and completely has avoided grid-cell convergences at the Earth's poles [1].…”

Section: Introductionmentioning

confidence: 99%

Subgridding Technique for the Geodesic FDTD Algorithm

Wang¹,

Cao²

2011

PIER M

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Abstract-This work presents a two-dimensional (2D) subgrid technique for the geodesic finite different time-domain (FDTD) algorithm, which is applied to solve global extremely low frequency (ELF) electromagnetic (EM) wave propagation problems in the Earthionosphere system. The new technology provides arbitrarily locale resolution to study finer structure without disturb the global grid structure. Combined with the subgrid technique, the new geodesic FDTD algorithm can solve EM propagation problems in specific locale regions without extra computational burden. Based on the original geodesic FDTD formulations, the 2D subgrid technique is developed, and its computational stable relation is derived and analyzed. Then, possible three-dimensional (3D) subgrid structure is proposed. Finally, potential applications for the subgrid technique are suggested.

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THREDS: A Finite-Difference Time-Domain EMP Code in 3d Spherical Coordinates

Cited by 74 publications

References 4 publications

Efficient modeling of impulsive ELF antipodal propagation about the Earth sphere using an optimized two-dimensional geodesic FDTD grid

Efficient modeling of impulsive ELF antipodal propagation about the Earth sphere using an optimized two-dimensional geodesic FDTD grid

Wavefront-ray grid FDTD algorithm

Subgridding Technique for the Geodesic FDTD Algorithm

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