There is a coil inside, seen here when lateral faces are hidden
I have tried using mesh mapping and sizing to no avail. I want to ask for help first before trying other methods to avoid going in circles.
From internal side you have sharp angles. Please remove those sharp angles as shown below. Then use meshing.
Also please select physics preference as CFD in meshing. Please use proximity sizing to capture gaps between faces.
Please see help manual for more details about these commands.
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