Microdroplet generators are potentially useful for inkjet printing, fuel injection, drug delivey and cell sorting among other applications. In this paper, a new drop-on-demand (DOD) droplet generator is proposed and its feasiblility is investigated numerically. In this mechanism, the actuator is an oscillating non-equilibrium bubble, which pressurises the fluid inside a chamber during its expansion phase and pushes a liquid column through the nozzle leading to the droplet ejection. The bubble can be initiated using the electrical discharge technique, where the intense current passage through two electrodes submerged in an initially quiescent liquid causes local overheating accompanied by the explosive vaporization. This incepts a high pressure vapor bubble, which will first expand to a maximum size fairly symmetrically and then contract non-symmetrically with a reentrant jet directed away from the free surface accorded by the nozzle opening. The proposed actuation mechanism is capable of producing a droplet much smaller than the nozzle size and under certain conditions monodisperse satellite-free droplet.
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