Mechanism and evolution of the wake magnetic field generated by underwater vehicles

The motion of charged seawater in a submarine wake, which is affected by the variance in the ion mass and the presence of a background geomagnetic field, results in a consequential wake magnetic field. The magnetic field is critical for the detection and monitoring of underwater targets. Despite its importance, the intricate relationship among hydrodynamics, ion transport, and electromagnetic fields, which collectively affect the generation of magnetic fields in submarine wakes, has yet to be sufficiently and systematically investigated. Hence, we formulate a theoretical model of the submarine wake magnetic field. This innovative interdisciplinary model seamlessly integrates the effects of ion inertia and ion induction in the marine environment. By performing multiphysics coupling simulations, we meticulously replicate the evolution of the wake magnetic field induced by the movement of a submarine propeller system. We comprehensively examine the velocity and magnetic-field components to elucidate the intricate mechanism of wake magnetic field generation. Furthermore, we comprehensively analyze the effects of ion inertia and ion induction on the wake magnetic field. Our findings highlight the predominant role of the ion-induction effect in determining the wake magnetic field when a submarine maintains a constant speed. Additionally, we investigate the effect of the submarine heading on the wake magnetic field and discuss the magnetic-field characteristics and attenuation rules at various axial and radial positions in the wake for different headings. Our scientific insights contribute considerably to the understanding of wake magnetic fields and offer valuable perspectives that can potentially advance future underwater target-detection methodologies based on wake magnetic fields.