(403j) A Transient, Two Fluid Model for Slug Flow Characterization

In this work, we propose a numerical resolution of a 1D, transient, simplified two-fluid model regularized with an artificial diffusion term to model stratified, wavy, and slug flow in horizontal and nearly horizontal pipes.

The final aim is to provide transient model to predict slug formation and evolution that can be used in pipelines.

The artificial diffusion is adopted to prevent the unbounded growth of instabilities outside the confines of the conditions under which the one-dimensional transient two-fluid model is well-posed; the artificial diffusion values are set case by case to obtain the desired cut-off at short wavelengths: the choice is based on the analysis of the linear stability results. A proper criterion to simulate two-phase to single phase flow transition, which occurs during slug formation, was developed. Flow patterns transitions have been numerically computed and compared against theoretical transition boundaries and experimental observations. Moreover, we showed that the code computes slug initiation and slug characteristics, in a reasonable accurate way considering the simplicity of the model, comparing numerical results with well-known empirical relations and experimental data.

Geometries involving slope changes and different inclinations are tested.

Furthermore, the model simplicity leads to a computationally cheap numerical resolution; this can be useful in engineering applications where obtaining fast numerical results is fundamental, such as application involving automated control for two-phase flows