I have issues with a coating layer of Titanium, that I model as a thin panel, in a time domain solver for high frequency.
The coating layer (silver colour) is applied on 2D surfaces, on a squared chamber (made of alumina, ceramic). The coating has a thickness of 0.001mm (applied in the material properties for thin panel):
The chamber with the coating is in the air gap of an electromagnet. The yoke is orange, and the busbars with the current have metal colour:
The current that is applied through the port, that circulates through the busbars, is a half-sine curve. The duration of the half-sine is 0.055ms:
Then, the frequency of the excitation is f=1/(2*0.055ms)=9000 Hz
At this frequency, in a Titanium layer, the skin depth (delta) is:
delta=1/sqrt(pi*conductivity*permeability*frequency)
Where:
Conductivity (Titanium) =2.38e6 S/m
Permeability=pi*4e-7
Frequency=9e3 Hz
Yielding to:
delta=3.4e-3 m = 3.4mm
Since the skin depth (3.4mm) is much bigger than the thickness that I am applying in the model (0.001mm) , the eddy currents should not be strong enough to interfere with the magnetic field, meaning that the Titanium layer should be transparent to the magnetic field, and the magnetic field should completely fill the air gap of the magnet.
However, this is not what I obtain when I run the simulation. In the simulation, the magnetic field is shielded by the coating layer, and it does not fullfill the air gap as it should.
This is the magnetic field at time=0.03 ms (time of maximum current):
I add a picture of the mesh for information:
Why is the thin layer shielding the magnetic field ? Should I model the titanium coating differently ?
Thank you very much in advance for your help.
