In the offshore oil & gas industry, transportation of hydrocarbons in very long flowlines or risers involves some technical challenges due to the fluid-structure interaction effects of internal travelling multiphase flow-induced vibrations, for instance, the two-phase (liquid-gas) flows. FlexNARA has performed a critical review on features of two-phase flows and potential models for predicting the flowing pipe dynamical behaviours through fundamental knowledge of flow pattern transition maps which depend on several fluid-structure parameters including phase velocity, pipe diameter and inclination etc.

Slug liquid-gas flows in horizontal/vertical pipes

Slug (stable, steady or unstable intermittent) flows are of industrial and practical interest due to the potential greatest impact on fatigue life of the containing flowlines, risers and subsea jumpers, in combination with external flow VIV effects. Mechanisms of combined MFIV-VIV are relatively unknown and FlexNARA has been working to understand and unlock their intrinsic dynamic phenomena.

Prediction of liquid volumetric fraction of intermittent slug flows in a riser section