Drop-on-demand printing applications involve a drop connected to fluid reservoir between which volume can be exchanged, situation that idealized as sessile with prescribed flux across the drop/reservoir boundary. Here we compute frequency spectrum for these pressure disturbances, it depends upon static contact-angle $\alpha$ (CA) and an empirical constant $\chi$ relating either (i) pinned or (i...

When an oil drop is placed on a water surface, it assumes the form of a sessile lens. We consider the curious behaviour that may arise when the oil contains a water-insoluble surfactant: the lens radius oscillates in a quasi-periodic fashion. While this oscillatory behaviour has been reported elsewhere, a consistent physical explanation has yet to be given. We present the results of an experime...