Single Droplet Dynamics in the Framework of Non-equilibrium Thermodynamics
M. Dressler [1], B.J. Edwards [2]

[1] ETH Zurich, Switzerland, [2] Department of Chemical Engineering, UT Knoxville, U.S.A.

Abstract: During the past few years, models to describe the shape and orientation of a single droplet in a flowing liquid phase have become very popular, e.g. the Maffettone--Minale Model and its various generalizations which take into account the elasticity of either one or both phases. In this talk we discuss dynamic models for single droplet deformation in the framework of non--equilibrium Thermodynamics. We introduce a set of thermodynamic variables for this dynamic problem and we use the bracket formalism of non--equilibrium Thermodynamics to derive thermodynamically consistent flow equations for a single deforming droplet in a deforming matrix fluid.
We take into account droplet shape, coverage of droplets by surfactants, and inertia of the droplet phase. We propose new models for single droplet deformation, we discuss their thermodynamic consistency, their predictive power, and we compare with existing models in the literature.