Finite element simulations of multi-component droplets

In many applications in fluid dynamics, one encounters problems that
require the treatment of multiple phases, where each phase is
constituted by more than one component.
As an example, one can consider the field of inkjet printing, where the
printed droplets are constituted by a mixture of several components
with different volatilities.
Due to the different mass transfer rates of the individual components,
solutal gradients emerge and intriguing phenomena can be observed,
including regular or chaotic solutal Marangoni flow or significant
natural convection, even below the millimeter scale.

In order to treat these problems numerically, we have developed a sharp
interface finite element method using an arbitrary Lagrangian-Eulerian
approach. While the usage of a sharp and mesh-aligned interface comes
with some drawbacks for topological changes of the phase distribution,
it can easily treat arbitrary density ratios and accurately account for
capillary effects including Marangoni flow. 

The potential of this versatile method is illustrated by representative
simulations of the complex and intriguing field of evaporating and
dissolving multi-component droplets, which show a perfect agreement
with the corresponding experiments.