Microdroplet impact onto a commensurate topographical Features

As droplet sizes decrease in the search of increasing resolution in inkjet printing and other applications, substrate features of commensurate size start to have a significant effect on the printed footprint. In particular, they can affect whether consecutive droplets coalesce or not. Here, the deposition of multiple droplets onto a topographical feature of commensurate size is simulated using a 3-D GPU-accelerated multiphase lattice Boltzmann model validated against published experimental work and theoretical predictions. A regime map of coalescence vs. splitting depending on the width and height of the feature is constructed. The effects of substrate properties (advancing and receding contact angles), flow parameters (captured by the Reynolds number), and fluid properties (captured by the Ohnesorge number) on the regime map are also explored.