Question

Change of viscosity with respect to magnetic field model in comsol

Answer 1

Answer:

Explanation:Ferromagnetic materials are ubiquitous in electronic components and electrical machinery. In EM modeling, we may be interested in the broader application or focus on a certain material characteristic (e.g., the mechanical resistance of structural steel) that happens to be magnetic. In both cases, ferromagnetic parts influence the magnetic field in their surroundings, and identifying exactly how this happens could be crucial to the proper functioning of a device or system.

Classification of Magnetic Materials

To understand the huge variety of magnetic behaviors in different materials, classification is useful. The easiest classification system for magnetic materials is as follows:

Weakly magnetic materials

Slightly alter externally applied magnetic fields (i.e., paramagnetic and diamagnetic materials)

Soft irons

Efficiently concentrate an external magnetic flux, but don’t have an “intrinsic” magnetization (so if they are placed in a region without magnetic fields, it will remain without fields)

Hard irons, which will be referred to from now on as permanent magnets

Produce magnetic flux even in the absence of an externally applied field

Materials in categories 2 and 3 are referred to as ferromagnetic.

However, this classification is not simple, because the separation between soft irons and permanent magnets might not be that sharp and certain behaviors could be intermediate between the two categories. It is possible for a material to have some small magnetization in the absence of external sources (resembling a permanent magnet), but this magnetization increases by a significant amount because of an externally applied magnetic field (resembling a soft iron).

Moreover, a material can exhibit hysteretic behavior, which means that after the application and removal of an external load, the magnetization could be different from the initial one. The external load could not only be the magnetic field generated by an electric current but also a physical displacement