A New Analytical Model for Impact and Spreading of One Drop Application to Inkjet Printing, 2006 TAPPI Advanced Coating Fundamentals Symposium

camera. An optical arrangement allows catching top and side views of the impact. Diameter and velocity of the drops fulfil similarity rules with ink-jet process. At short time, no penetration in the porous substrate is observed and droplet behaviour is qualitatively the same for plane and porous substrates with however differences in the maximal wetted area. To help understanding these differences, an I-D analytical model that predicts the radius of the wetted area at short time after the impact is developed. In our model, kinetic energy and dissipation in the bulk are estimated in a self-consistent way. An additional mechanism of dissipation due to the rolling motion near the moving contact line is introduced. The model closely predicts literature data for plane smooth substrates with an empirical dissipation factor function of the only Ohnesorge number. Our results show that the dissipation at the moving contact line depends upon the nature of the paper and influences the maximal wetted area.