Dynamics of Compound Droplets: Rolling and Evaporation

• Author / Creator

  Rahman, Muhammad Rizwanur

• Superior control of multiphase micro-drops owns much of the future in microfluidic technology. Understanding the dynamics of such compound systems is the key to its large-scale applications. Interfacial interaction of a droplet at a liquid-fluid interface dictates its successful generation and stability. The knowledge of the interface dynamics creates a rich profusion of domains that were previously unexplored. The century-old power law, which was believed to be universal in governing temporal drop spreading on solid substrates, is seen to fail in predicting spreading on liquid-fluid interface. Rather a coalescence like behavior becomes imminent. The study of the fundamental physics of evaporation of double emulsion droplets and under liquid rolling dynamics are extensions of the successful generation technique. In contrast to the rigid body motion, dissipation inside and outside of a deformable drop always results in convoluted physics. While rolling on an incline, single-phase drops travel slower with increase in size. But a concealed direct dependency between the drop size and traveling velocity can be exposed by merely altering the medium resistance. Rolling motion of double emulsion droplets even affirms the presence of both of these dependencies and a control over the transition from one to the other is achievable. A threshold size limit for such a transition has been identified demonstrating that the dependency between drop size and its velocity is not unidirectional. This thesis further explores the evaporation of double emulsion droplets and identifies two new regimes of evaporation. Resurfacing of a daughter droplet from an evanescing drop preceded by sudden spreading are uncommon observations in the literature. Detailed comprehension of the resurfacing of micro-droplets provides a possibility to control the evaporation mode, which was considered to be a random occurrence in the past.

• Subjects / Keywords

  • Drop evaporation
  • Rolling drop
  • Liquid fluid interface
  • Viscous medium
  • Compound drops

• Graduation date

  Spring 2018

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3D21S05K

• License

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