Waterbells and liquid sheets

Waterbells result from the impact of a low-viscosity liquid jet (diameter velocity D₀, velocity U₀) on a solid surface (characteristic length D_i) of similar size (D_i ∼ D₀). Their stationary shape mainly results from the equilibrium between inertia and surface tension. When closed, this shape becomes.sensitive to the pressure difference that occurs across the sheet and the bell can become unstable or exhibit stationary cusps. We first review the work done on the shape and stability of waterbells, and then address the case of "special bells," like swirling bells, polygonal bells, and reverse bells. Finally, we discuss the singular limit of the "flat bell" or liquid sheet.