In order to study the distribution feature of the underwater electric field intensity produced by a ship in restricted seawaters, the horizontal DC electric dipole is used as the equivalent field source. Firstly, four kinds of field models are established. Secondly, the expressions of underwater electric field strength produced by a a horizontal DC electric dipole in the sea areas with upright bank is derived based on the mirror theory of static electric field. Then, based on this, the distribution features of the electric field intensity and the influence of the bank on the electric field are studied by numerical simulation. The simulated results show that the main characteristics of field strength distribution in restricted seawaters are consistent with those without bank, but it makes the absolute value of electric strength increased. The field point is closer to the vertical bank, and it generally presents greater influence on the absolute value of electric strength. But the influences of single vertical and parallel banks on the three-component field strength are different. The effect of bank on field intensity distribution in other restricted seawaters can be regarded as a superimposed effects of a series of vertical or parallel banks. Finally, the rectangle marine environment is simulated in laboratory, and the horizontal components of electric field intensity distribution on a certain depth plane under the simulated field source are measured. These theoretical derivation and analytical conclusions of simulation are further confirmed by comparing with the simulated results.
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