Fridge magnets (refrigerator magnets) are popular application of the Halbach Array. They are designed to increase the magnetic force on one side.
Plane-parallel problem of DC magnetics
Magnet is made from combination of nine triangular prisms (triangle is in the XY plane) arranged into the film 1 mm thick, 20 mm wide.
D = 1 mm,
H = 1 mm,
B = 20 mm,
Magnet material - N35,
Steel fridge door thickness 1 mm, relative magnetic permeability 1000.
Calculate the magnetic field distribution and the magnet attraction force to the fridge door made of steel with the relative magnetic permeability 1000.
Model may be defined and solved as a DC Magnetic Analysis problem.
Magnetic field of the Halbach array fridge magnet in the empty space.
Magnetic field lines of the Halbach array magnet near the steel fridge door.
Fridge magnet attraction force at distance dx=0.01 mm is F = 95 N.
* References: http://en.wikipedia.org/wiki/Refrigerator_magnet