Exercise N 5. Magnetic field of the cylindrical coil

solenoid magnetic FEA finite element analysis, magnetic flux density at the coil axis

Task Make a plot of magnetic flux density at the axis of the coil with and without steel core.

Experiment Magnetic flux density is measured in laboratory by webermeter.

Problem type Linear axisymmetrical problem of magnetostatics.

Geometry Due to problem symmetry only upper-right quarter a0b is defined, and at the axes of symmetry boundary conditions are set.

Given data Current density in the coil j=100000 A/m^{2}. Relative magnetic permeability of air and copper μ=1. Relative magnetic permeability of steel of the core μ=500.

Boundary conditions At the vertical axis of symmetry (line Ob) H_{t}=0. At the horizontal axis of symmetry Oa B_{n}=0. From B=rotA in the cylindrical coordinate system we have at the
axis Oa A=const. Field fades at the infinity, so at the line Oa A=0 due to continuity of A.

Results: Dependence of the magnetic flux density upon the distance to the coil center: