I have recently modeled a iron particle in fluid using Comsol multiphysics 35a and added a magnet to the model in order to add a force to the particle. The force is defined by the magnetization of the particle and can be found derived in the "magnetic drug targeting" model paper from the Comsol website. As the particle moves with the ALE moving mesh method, the moving mesh moves the magnetic flux from the source magnet, as well. this results in flux lines that never change. I would like the flux lines to offer a greater force the closer the particle gets to the magnet, instead of staying constant because the flux lines move with the mesh. I have defined the moving mesh to move with a velocity derived from the force of the magnet. My problem is, whenever I try and attach the magnetostatics to the reference frame, it model will not run. Does anyone have any ideas on how to fix this issue?