Development Of Three Dimensional Finite Element Simulation System For The Analysis Of Magnetic Field Around Large Ferromagnetic Cavities

The study of the magnetic field around underwater vehicles forms foundations for thestudy of underwater navigation. Currently, the project group acquires data mainly fromcomputer simulation. Because the frames of underwater vehicles are mainly consisted ofiron or steel, the project group focuses large ferromagnetic iron cavities. As the analyti-cal method is difcult to be used to obtain the rigorous solution, numerical methods areadopted. Since the change of the cavity motion is relatively slow during the sailing, at thispreliminary stage of study, the induced magnetic field around the cavity can be treated asstatic magnetic fields.In this paper, the general finite element method and the two dimensional and threedimensional functional were introduced, then the creating method of the background mag-netic field was clarified, and the related Dirichlet and Neumann boundary conditions werededuced. Since the general variation method is not suitable for the addition of Neumannboundary conditions, the appropriate variation method should be sought for.The integration method was adopted, and the variation functional was deduced. Be-cause a flux-related term is included in this integration functional, it is the ideal variation forthe addition of Neumann boundary conditions. Then the solving model of this variation waswritten and the finite element simulation system was constructed. Finally, the correctnessof the calculating results was proved by comparing to the manual calculating results.