Jet break-up of polymer solutions in inkjet printing

Thursday, October 15, 2009 - 1:30pm - 2:10pm
EE/CS 3-180
Oliver Harlen (University of Leeds)
Keywords: dilute polymer solutions, FENE model, free surface flows, Finite

Abstract: The effects of polymer additives on the break-up of jets in continuous (CIJ)
and drop on demand (DOD) inkjet printing are considered. In continuous
inkjet printing the fluid jet is modulated at close to the Rayleigh
frequency to produce a steady stream of uniform drops, while in drop on
demand printing individual drops are generated by applying an impulse to the
fluid. Even at very low concentrations the presence of high molecular weight
polymers significantly affects how jets break-up into drops, due to the high
extension-rates involved. By simulating these flows with the FENE dumbbell
constitutive equation we are able to establish the parameter values
controlling the break-up length and character of jet break-up, such as the
production of small satellite droplets (which are detrimental to the
inkjetting process). For the case of drop on demand printing, we compare our
predictions to experimental measurements on dilute solutions of monodisperse
polystyrene. By using Zimm theory to predict the parameter values in the
FENE model, we are able to demonstrate quantitative agreement between
simulations and experiments.
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