DocumentCode :
2596409
Title :
Electromagnetic modeling of subsurface 3D structures
Author :
Newman, Gregory A. ; Alumbaugh, David L.
Author_Institution :
Sandia Nat. Labs., Albuquerque, NM, USA
Volume :
4
fYear :
1996
fDate :
27-31 May 1996
Firstpage :
1941
Abstract :
A 3D frequency domain electromagnetic numerical solution has been implemented for sensing buried structures in a lossy Earth. Because some structures contain metal, it is necessary to treat them as very good conductors residing in a complicated lossy Earth background. To model these scenarios and to avoid excessive gridding in the numerical solution, the authors assume the structures to be perfectly conducting, which forces the total electric field to zero within the conductor. This is accomplished by enforcing internal boundary conditions on the numerical grid. The numerical solution is based on a vector Helmholtz equation for the scattered electric fields, which is approximated using finite differences on a staggered grid. After finite differencing, a complex-symmetric matrix system of equations is assembled and preconditioned using Jacobi scaling before it is iteratively solved using the quasi-minimum residual (qmr) or bi-conjugate gradient (bicg) methods. For frequencies approaching the static limit (<10 kHz), the scheme incorporates a static-divergence correction to accelerate solution convergence. This is accomplished by enforcing the divergence of the scattering current within the Earth as well as the divergence of the scattered electric field in the air
Keywords :
electromagnetic induction; geophysical techniques; terrestrial electricity; EM induction; EM model; Jacobi scaling; buried object detection; complex-symmetric matrix system of equations; electromagnetic modelling; finite difference method; frequency domain electromagnetic numerical solution; geoelectric method; geophysical measurement technique; lossy Earth; numerical model; remote sensing; terrestrial electricity; three dimensional structure; vector Helmholtz equation; Assembly systems; Boundary conditions; Conductors; Difference equations; Earth; Electromagnetic modeling; Electromagnetic scattering; Finite difference methods; Frequency domain analysis; Jacobian matrices;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Geoscience and Remote Sensing Symposium, 1996. IGARSS '96. 'Remote Sensing for a Sustainable Future.', International
Conference_Location :
Lincoln, NE
Print_ISBN :
0-7803-3068-4
Type :
conf
DOI :
10.1109/IGARSS.1996.516849
Filename :
516849
Link To Document :
بازگشت