Influence of viscosity and interface tension on water droplet injection in oil

Drop-on-demand technique was developed, based on multi-stage high voltage electric pulse applied on conductive liquid meniscus hanging from a needle [1]. It is applied to the injection of a water droplet in oil, and allows injecting droplets from the same needle in a wide range of diameter, smaller than the needle one. The paper presents experiments of droplet injection in two types of mineral oil: Marcol 52, Primol 352, for varying interface tension and viscosity parameters. High speed video and numerical simulations helped understanding the main physical effects occurring during water droplet formation.