We want to use permanent magnets to attract iron filings. For this, we have several neodynium magnets shaped as disks and we would like to lay them out to have the highest possible attraction along the entire surface, not only at the poles.
I have read that the magnetic attraction is strongest at the poles where there is a larger gradient
If the magnets are stacked on each other (configuration A) the field lines will flatten along the magnet construct body and the attraction will be lower than in layout B or C.
What would be the most adequate magnet layout to increase the attraction as much as possible?