Discussion: “Predictable Model for Characteristics of One-Dimensional Solid-Gas-Liquid Three-Phase Mixtures Flow Along a Vertical Pipeline with an Abrupt Enlargement in Diameter” (Hatta, N., Omodaka, M., Nakajima, F., Takatsu, T., Fujimoto, H., and Takuda, H., 1999, ASME J. Fluids Eng., 121, pp. 330–342)