Process Modelling and Simulation of Ink Jet Printing

Also Rayleigh time scale for capillary break up (t ) = 

It is considered that the drop formation in the ink jet printing process is e governed by the timing of the electric pulse. This piezoelectrically controls the ink flow, inertia forces, viscous forces, surface tension and gravity. The final process model consists of two, one-dimensional equations originating from the kinematic boundary condition, the normal and tangential components of the traction boundary condition and the z-component of the momentum equation, thus  

An experimental case-study [9] of ink jet printing was considered to validate the computer simulations, where p =1000 kg/m, p=1.3 mPa-s, G = 60 mN/m, = 20 pm, flowrate = 38.4 ml/h, tp ig = 100 ps. Drop formation and break up were predicted at about 50 pm distance from the nozzle. The falling droplet grew and evolved to a cap. The experimental case study showed many similarities, including the droplet break up time of about 123 ps, which agrees very well with the predictions. However, the predicted travelled distance is smaller than in the experiment. This is attributed to the fact that the experiment is not under constant flow rate during the pulse. As a result, the computer model needs modifications to account for a pressure waveform at inlet. 

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