Assessment of the barotropic one-velocity, one-pressure two-phase flow model to cavitating water-hammer

This paper presents a numerical and experimental assessment of a barotropic one-velocity, one-pressure two-phase flow model for the simulation of cavitating two-phase water-hammer phenomena. The model is formulated as a hyperbolic system of three conservation laws, consisting of two phasic mass conservation equations and one mixture momentum equation. This reduced formulation describes the transient interaction between the liquid and gas phases under mechanical equilibrium, assuming a common pressure and velocity, while also accounting for pipe hoop elasticity. The novelty of this work lies in the systematic evaluation of this reduced two-phase formulation, coupled with an exact Riemann-solver-based Godunov finite-volume method, for experimentally validated cavitating water-hammer configurations. A series of Riemann problems is first considered to assess the first-order Godunov-type solver in cases where analytical solutions are available. The model is then evaluated using experimental gas–liquid water-hammer configurations in which the dispersed gas phase significantly affects the effective wave speed, pressure amplitude, and damping behavior. Numerical predictions are validated against experimental measurements and compared with reference numerical results available in the literature. The results show good agreement with the available data, demonstrating the capability of the barotropic one-velocity, one-pressure model to reproduce the main features of cavitating two-phase water-hammer flows, including pressure-wave attenuation, wave-speed reduction, and the influence of gas content and pipe elasticity on the transient hydraulic response.