Trajectories of charged droplets in transverse airflows

A three-dimensional time-transient numerical algorithm is developed for the calculation of ink drop trajectories in transverse airflows. The drop is charged, and is ejected with some initial velocity. The simulation requires the solution of Laplace´s equation subject to charge conservation on the drop, together with integration of the dynamical equation of motion. The model considers the “floating” potential on the drop as it traverses the air gap, and Stoke´s drag due to the prevailing airflow. The specific case of a spherical drop in a uniform electric field is amenable to analytic solution, and is used to verify the model. Important parameters calculated for the drop include: the initial drop charge; time-of-flight; and velocity of impact on the receiver. The more general model will allow the study of transverse airflows and non-uniform E-Field effects on the drop