|Manipulation of liquids on
the micro-scale is of fundamental interest in industrial
applications, primarily because of the advent of
microfluidic devices, which often require the interaction
between competing physical effects to operate. Surface
stresses are particularly useful to drive internal flows in
such devices, because of large surface-to-volume ratios.
Surface tension gradients caused by temperature or
surfactant concentration gradients can induce
`Marangoni-driven' flows from regions of high surface
tension to low surface tension.
We study droplet spreading on differentially-heated substrates, which can generate a complex temperature profile within the droplet. We show that competition between surface chemistry (wetting) and thermocapillary flows induced by the thermal gradient gives rise to bistability in certain regions of parameter space.
Present studies concern coupling centrifugal to Marangoni forces.