Evaluation of Electromagnetic Fields Induced by Wake of an Undersea-Moving Slender Body

This paper presents the procedure for evaluating the electromagnetic field induced by the wake of an undersea-moving slender body. The slender body is considered equivalent to a pair of Havelock point sources that can generate wake flow fields. The electric current generated in the seawater is calculated by means of the moving conductive seawater that cuts the earth's magnetic field. The electromagnetic fields in the air and in the seawater are then determined by solving the Maxwell equations with appropriate boundary conditions. The induced electromagnetic fields include two parts: One is the attenuating oscillation that can be ascribed to the free surface Kelvin wake, and the other is the bipolar pulse that can be ascribed to the localized volume wake. Near the sea surface, the magnitude of the former is typically a few hundred picotesla, while that of the latter could be greater by ten times.