Marangoni-driven thin film flows 


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.

Typical thermal field (left) and streamlines (right) for a droplet on a differentially-heated substrate


PUBLICATIONS
  1. J.B. Bostwick, J.A. Dijksman, and M. Shearer. "Wetting dynamics of a collapsing fluid hole." Physical Review Fluids. 2, 014006 (2017). [Link]
  2. J.B. Bostwick. "Spreading and bistability of droplets on differentially-heated substrates". Journal of Fluid Mechanics. 725, 566-587, (2013). [Link]