Analysis of the effect on the large floating roof oil tanks struck by indirect lightning based on FDTD

According to the statistical data, lightning strike is the major cause of the large floating oil tanks ignition. The accident is usually caused by the direct and indirect lightning stroke. The effects of direct lightning stroke on floating oil tank have been studied a lot in previous works and there is little research on the influence of lightning stroke in the vicinity of tank. In order to study the indirect effect of lightning on the floating roof oil tanks, this paper proposes a numerical procedure based on finite difference time domain(FDTD) method to compute the electric potential distribution on the large floating oil tanks. The impact of lightning current amplitude, stoke position and soil resistivity on the potential distribution are taken into consideration. From the result, we can conclude that the field strength gets higher with the lightning current amplitude and the soil resistivity increases; decays with the distance further between the stoke point and the oil tank. Besides we calculate the lightning discharge radiation power.