squeezing a field

I'm designing a small PCB with essentially 5 sync buck switching
regulators. Board space is tight so I want to put the inductors on the
bottom of the multilayer board. There's a 0.2" gap between the bottom
of the board and a big aluminum flange.

Unshielded drum cores have the most energy storage per volume or
dollars. They store energy in the universe instead of in ferrite. Good
cooling too.

Something like this just fits

https://www.digikey.com/en/products/detail/bourns-inc/SRN8040TA-470M/6155133

Its mag field lines will bounce off the PCB planes and the flange,
change from the classic bar magnet pattern into a pancake . I wonder
what that will do to its electrical behavior.