  Pendant droplets of water and paramagnetic solutions are studied in the
presence of uniform and nonuniform magnetic fields produced by small permanent
magnet arrays, both in static conditions and during dynamic pinch-off. Static
measurements of the droplet shape are analysed in terms of an apparent surface
tension {\gamma}app or an effective density \r{ho}eff. The change of surface
tension of deionized water in a uniform field of 450 mT is insignificant, 0.19
- 0.21 mNm-1. Measurements on droplets of compensated zero-susceptibility
solutions of Cu2+, Mn2+ and Dy3+ where the shape is unaffected by any magnetic
body force show changes of surface tension of about -1% in 500 mT. Magnetic
field gradients of up to 100 T2m-1 deform the droplets and lead to changes of
\r{ho}eff that are negative for diamagnetic solutions (buoyancy effect) and
positive for paramagnetic solutions. The droplet profile of
strongly-paramagnetic 0.1 Dy M DyCl3 solution is analysed, treating the
nonuniform vertical field gradient as a spatial variation of gravity. The
influence of Maxwell stress on droplet shape is discussed. In dynamic
measurements, the droplet shape at pinch-off is recorded by high-speed
photography and analysed in terms of a relative change of dynamic surface
tension in the presence of a magnetic field. The surface-tension-dependent
pre-factor of the scaling law that governs the pinch-off dynamics shows no
difference for pure water or 0.11 M DyCl3 solutions in the field. The
nonuniform field has no influence in the pinch-off region because the filament
diameter is much less than the capillary length.

Fluid Dynamics;Chemical Physics