Validation of Equilibrium-Based, One-Dimensional, Two-Phase Pipe Flow Models With Transient, Three-Dimensional, CFD Simulations for Horizontal Flows

One-dimensional (1D), equilibrium-based mechanistic model predictions are compared to three-dimensional (3D) transient computational fluid dynamics results for horizontal two-phase, gas-liquid pipe flow. The 3D regions of interest include both those expected to be in equilibrium conditions and those where transitions between flow regimes occur. Equilibrium simulations, such as those for stratified flow in a horizontal pipe, allow crucial validation of the equilibrium-based closure relations by means of numerical experiments. In the transitional regions, fully 3D, time-dependent numerical simulations provide a means to estimate the error in the equilibrium-based models and suggest how reasonable approximations can be made in these regions.