Resumo:
Two-phase flows are widely found in the most diverse practical applications, such as
refrigeration systems, nuclear reactors, oil refineries, power generation units and many others.
Among the equipment employing two-phase flows, microfluidic devices have been gaining
more prominence lately. These devices have dimensions on the order of a few microns and are
used in different branches of industry (pharmaceutical, electronics, cosmetics, medical, etc.). In
this context, the importance of studying the characteristics of two-phase flows is highlighted,
as well as the processes involved in them, such as the formation, breakup and coalescence of
droplets/bubbles. This work aims to study the flow of a droplet in a two-dimensional
microchannel with a T-shaped junction. The behavior of the droplet at the junction and the
breakup or non-breakup regimes of the droplet are investigated, as well as the influence of
parameters such as capillary number and droplet length on its flow. The study is conducted by
means of numerical simulations performed in the commercial software COMSOL
Multiphysics®, which uses the Finite Element Method to discretize the governing equations of
a physical phenomenon. The Phase Field Method, available in COMSOL, is used to represent
the interface between the continuous phase and the dispersed phase of the two-phase flow. In
addition, local mesh refinement and adaptive mesh refinement techniques are applied in regions
of greater interest in the domain, such as the walls and the interface between the fluids, in order
to improve the accuracy of the numerical solution. Different cases were studied, each with a
combination of capillary number and droplet length as it reaches the T-junction. Data such as
the droplet breakup regime and the temporal evolution of the minimum thickness of the droplet
neck at the junction were obtained. All results were compared with results present in the
literature, in order to validate the methodology used. Finally, it was found that the numerical
results obtained were in good agreement with the literature.
