Objectives To address the challenges of high reliance on physical models and the lack of numerical simulation methods in studying the magnetic evolution during ship degaussing, this study proposes a numerical simulation method based on the equivalent magnetic domain model to investigate the magnetic evolution process.

Methods  First, an equivalent magnetic domain mathematical model is established based on the theoretical morphology of magnetic domains, using a magnetic dipole model representation. Next, the fundamental motion of magnetic domains is analyzed from the perspective of static magnetic energy, and a corresponding mathematical motion model is developed. Finally, based on the Matlab numerical simulation platform, numerical simulations and model-scale ship experiments were conducted to verify the evolution law of ship degaussing magnetism.

Results  The results indicate that the numerical model of ship magnetic domains successfully achieves magnetic equivalence with the ship model, with a relative error controlled at 17.04%. The numerical simulation of the degaussing evolution process accurately reproduces the magnetic variation observed in the physical ship model. After AC degaussing, the residual peak of fixed magnetic field accounts for 15% of the original peak, and the relative error of the fixed magnetic field peak under zero-hysteresis magnetization is 2.58%, thereby validating the effectiveness of the proposed numerical simulation method.

Conclusion  This proposed numerical simulation method effectively replicates the magnetic evolution observed in physical space within a digital framework during ship degaussing. It enables intuitive and dynamical visualization of the magnetic evolution throughout the degaussing process, providing a theoretical foundation for the full-process digital representation of ship degaussing.