CFD modelling of methane dispersion from buried pipeline leaks: experimental validation and hazard distance estimation

The safe operation of buried pipelines necessitates an understanding of potential leak dynamics and the subsequent formation of flammable clouds defining hazard distances. This paper presents a computational fluid dynamics (CFD) model and its validation against experimental data on the dispersion of methane through a sand layer of 100 mm thickness to the atmosphere. A leak orifice diameter of 4 mm was considered for pipeline gauge pressures in the range of 10 to 300 kPa. This study describes the methane propagation in time through the sand and the development of the flammable cloud in the atmosphere. The simulations demonstrate a high degree of accuracy in capturing the transient behaviour of methane propagation in the sand and dispersion in the atmosphere when compared with a 60 s experiment. The model was applied to predict the development and maximum spread of the flammable cloud and hazard distances are presented. The simulations provide insight into the development of the flammable cloud. The validated CFD model can serve as a predictive tool for hazard distance estimation in case of buried leaks, inform safer pipeline design and improve emergency response strategies for gas leaks.