Thermally Mediated Droplet Breakup Dynamics Within a Symmetric T-Junction

This article presents a computational-based investigation exploring the influence of thermocapillarity and surface wettability on the splitting behavior of a droplet in a three-dimensional T-junction microchannel. The splitting process is triggered by using a heater on two different locations of the microchannel, which induces thermocapillarity and reduces viscosity around the corresponding location. Three different surface wettability conditions are considered to develop a clear understanding of the wettability–thermocapillary interaction. The temporal evolution of the droplet splitting behavior for different heater temperatures, heater positions, and wettability scenarios is discussed in detail to interpret the breakup mechanism. The splitting and nonsplitting droplets of different sizes are observed for the considered temperature range and heater positions, along with the wettability configurations. The findings establish the fact that higher thermal contrast in the flow confinement leads to an asymmetric breakup or even nonsplitting regimes. Changing the wettability of the wall from hydrophilic to hydrophobic provides a wide range of size ratio of the daughter droplets. Furthermore, a novel breakup technique is presented by taking different wall wettability of the daughter branches, which ensures more control to achieve the desired breakup phenomenon.