FDTD analysis of the effects of indirect lightning on large floating roof oil tanks

• A numerical procedure based on finite difference time domain method to analyze the electric field strength distribution on large floating oil tanks and calculate the lightning discharge radiation power is proposed.
• The electric field strength gets higher with the lightning current amplitude and the soil resistivity increasing.
• The electric field strength decays with the distance increase between stroke point and oil tank.
• The fitting curves representing the relationship among lightning current amplitude, stroke distance and electric field strength is deduced.

Lightning is one of the major hazards for large floating oil tanks. In order to research the effect of indirect lightning on floating roof oil tanks, this paper proposes a numerical procedure based on finite difference time domain (FDTD) method to analyze the electric field strength distribution on large floating oil tanks and calculate the lightning discharge radiation power. The impacts of lightning current amplitude, strike position and soil resistivity on the electric field strength are analyzed. The calculation results show that it may trigger oil tanks ignition if the lightning strikes within a dangerous distance with certain lightning current amplitude. And it is dangerous for electronic equipment on oil tanks when the lightning strikes within 500 m from the oil tank. The electric field strength gets higher with the lightning current amplitude and the soil resistivity increasing; decays with the distance increase between the stroke point and the oil tank. For the convenience and simplicity in engineering analysis, the fitting curves representing the relationship among lightning current amplitude, stroke distance and electric field strength is deduced.

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