Liquid-column sustainment driven by acoustic wave guiding.

We report on the formation and sustainment of liquid columns with aspect ratios much larger than the value at the onset of the Rayleigh-Plateau instability. This is achieved by using the passive feedback of the radiation pressure applied on the column surface by an acoustic beam injected at the upper end of the column and guided along it. We develop an analytical model that describes the coupling between the acoustic wave guiding and the balance between acoustic and capillary surface forces exerted on the column surface and find a satisfactory agreement with the experiment.