Abstract:
The article reports the domineering governing role played by the direction of electric and
magnetic fields on the internal advection pattern and strength within salt solution pendant
droplets. Literature shows that solutal advection drives circulation cells within salt based
droplets. Flow visualization and velocimetry reveals that the direction of the applied field
governs the enhancement/reduction in circulation velocity and the directionality of circulation
inside the droplet. Further, it is noted that while magnetic fields augment the circulation velocity,
the electric field leads to deterioration of the same. The concepts of electro and
magnetohydrodynamics are appealed to and a Stokesian stream function based mathematical
model to deduce the field mediated velocities has been proposed. The model is found to reveal
the roles of and degree of dependence on the governing Hartmann, Stuart, Reynolds and Masuda
numbers. The theoretical predictions are observed to be in good agreement with experimental
average spatio-temporal velocities. The present findings may have strong implications in
microscale electro and/or magnetohydrodynamics.
