  Evaporation kinetics of pendant droplets is an area of immense importance in
several applications in addition to possessing rich fluid and thermal transport
physics. The present article experimentally and analytically sheds insight into
the augmented evaporation dynamics of paramagnetic pendent droplets in the
presence of a magnetic field stimulus. Literature provides information that
solutal advection and solutal Marangoni effect lead to enhancement of
evaporation in droplets with ionic inclusions. The major crux of the present
article remains to modulate the thermosolutal advection with the aid of
magnetic field and comprehend the dynamics of the evaporation process under
such complex multiphysics interactions. Experimental observations reveal that
the evaporation rate enhances as a direct function of the magnetic moment of
the solvated magnetic element ions, thereby pinpointing at the magnetophoretic
and magneto-solutal advection. Additionally, flow visualization by PIV
illustrates that the internal advection currents within the droplet are
strengthened in magnitude as well as distorted in orientation by the magnetic
field. A mathematical formalism based on magnetothermal and magnetosolutal
advection effects has been proposed via scaling analysis of the species and
energy conservation equations. The formalism takes into account all major
governing factors such as the magnetothermal and magnetosolutal Marangoni
numbers, magneto Prandtl and magneto Schmidt numbers and the Hartmann number.
The modeling establishes the magnetosolutal advection component to be the
domineering factor in augmented evaporation dynamics. Accurate validation of
the experimental internal circulation velocity is obtained from the proposed
model. The present study reveals rich insight on the magneto thermosolutal
hydrodynamics aspects in paramagnetic droplets.
