Treatment of late time instabilities in finite difference EMP scattering codes

Journal Article · Wed Dec 01 00:00:00 EST 1982 · IEEE Trans. Nucl. Sci.; (United States)

DOI:https://doi.org/10.1109/TNS.1982.4336475· OSTI ID:6093107

Simpson, L T; Arman, S; Holland, R

Time-domain solutions to the finite-differenced Maxwell's equations give rise to several well-known nonphysical propagation anomalies. In particular, when a radiative electric-field look back scheme is employed to terminate the calculation, a high-frequency, growing, numerical instability is introduced. This paper describes the constraints made on the mesh to minimize this instability, and a technique of applying an absorbing sheet to damp out this instability without altering the early time solution. Also described are techniques to extend the data record in the presence of high-frequency noise through application of a low-pass digital filter and the fitting of a damped sinusoid to the late-time tail of the data record. An application of these techniques is illustrated with numerical models of the FB-111 aircraft and the B-52 aircraft in the in-flight refueling configuration using the THREDE finite difference computer code. Comparisons are made with experimental scale model measurements with agreement typically on the order of 3 to 6 dB near the fundamental resonances.

• Research Organization: Mission Research Corporation, 1720 Randolph Road, S.E., Albuquerque, New Mexico 87106
• OSTI ID: 6093107
• Journal Information: IEEE Trans. Nucl. Sci.; (United States), Vol. NS-29:6
• Country of Publication: United States
• Language: English

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46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
ELECTROMAGNETIC PULSES
SCATTERING
AIRCRAFT
DIGITAL FILTERS
ELECTRIC FIELDS
FINITE DIFFERENCE METHOD
INSTABILITY
MAXWELL EQUATIONS
MESH GENERATION
NOISE
NUMERICAL ANALYSIS
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