The role of wettability of nonideal nozzle plate: From drop-on-demand droplet jetting to impact on solid substrate

The dynamics of drop-on-demand (DoD) droplet formation and subsequently impact on the solid substrate are investigated using a three-dimensional (3-D) multirelaxation-time (MRT) pseudopotential lattice Boltzmann (LB) model. The wettability of nonideal nozzle plate and solid substrate is modeled by a geometric scheme within the LB framework. The dynamics of droplet formation are explored in a range of the inverse of Ohnesorge number Z=4.95, 11.57, and 28.17, and the Reynolds numberRe=39.6, 58.9, and 136.4. For Z=4.95, no satellite droplet is observed and the wettability of nozzle plate greatly influences the velocity and length of jetting fluids. For Z=11.57, the filament breakup and recombination are observed. The moment of filament breakup is delayed with advancing contact angle A increasing. For Z=28.17 with Re=136.4, the primary and satellite droplets could not be recombined with A=30 degrees and A=60 degrees which agree with the literature. Whereas with A=90 degrees, the recombination occurs. The dynamics of subsequent oscillating droplet impact on the substrate are similar to that of equilibrium droplet which could obtain high-resolution printed features. Consequently, considering A=90 degrees with large Z and Re numbers, the printable range could be extended which could help increase the printing frequency and boost the production outputs of inkjet printing. (c) 2018 American Institute of Chemical Engineers AIChE J, 64: 2837-2850, 2018