... of superficial gas and liquid velocities (⟨j g ⟩ ≈ 0.02–30 m/s and ⟨j f ⟩ ≈ 0.02–2 m/s) for the investigation of flow regime identification. The probability density function (PDF) of transient void fraction signals and its full-width at half-maximum (FWHM) were obtained and used for analysis and data...