Pipeline Flow Modelling with Source Terms Due to Leakage: The Straw Method

A numerical method for calculating the leakage flow rate through a crack in a pressurized pipeline is presented. Calculations of the flow inside, and leakage from, a pipeline with a running crack are performed. For the case of single-phase flow, the flow through the crack can also be calculated using choked-flow theory. The two methods are compared and identical results obtained. The advantage of the present method is that it does not rely on analytical expressions for the flow through the crack, and it is therefore thought to be applicable for two-phase flow, including phase transition. Hence it may be of use in the development of coupled fluid-structure models for the assessment of running ductile fracture in carbon dioxide transport pipelines.