A study of terrain-induced slugging in two-phase flow pipelines

A transient two-fluid numerical model is developed to predict terrain-induced slugging in two-phase flow pipelines made of several downhill, uphill and level sections. The model is based on the one-dimensional form of the mass and momentum conservation equations for the gas and the liquid phases. The wall to fluid and the interphase interactions are accounted for by constitutive relations which are flow regime dependent. A flow regime model is integrated into the main model. The conservation equations are discretized using a finite volume method. The resulting algebraic equation set is solved directly with a Block TriDiagonal-Matrix Algorithm.; New constitutive relations for the drag coefficient and for the virtual mass force in a slug flow regime are derived. The new models are obtained by applying the conservation equations to a geometrically simplified slug unit. This approach yields a more accurate treatment of the hydrodynamics of the slug flow regime than traditional two-fluid models. The new constitutive relations are validated by comparing the two-fluid model predictions for steady-state and transient slug flow in horizontal and inclined pipes to available numerical and experimental data.; An experimental study of terrain-induced slugging using air and water in a laboratory scale pipeline made of two downhill and two uphill sections is achieved. The experimental data are used to assess the performance of the two-fluid model for such flows. The time evolution of the pressure and outlet water mass flow rate observed during a terrain-induced slugging cycle are generally well reproduced by the model, showing the potential of the present approach to predict terrain-induced slugging.