Numerical simulations and laboratory experiments show that Marangoni effect
s are responsible for a pushing force on a droplet interacting with a solid
wall in the presence of a temperature gradient. The results clarify questi
ons of interest in the field of material science, in particular, they may p
rovide some explanation for the minority phase separation observed during s
olidification processes under microgravity conditions. (C) 2001 American In
stitute of Physics.