Numerical investigation of slug flow by smoothed particle method

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The gas-liquid pipe flow is of great interest in the petroleum, chemical and nuclear industries due to its frequent occurrence in process equipment and piping systems. A fundamental difficulty for such flow is on predicting the occurrence and characteristics of the flow regimes, which are highly relevant to the safety design of the oil-pipe lines. Due to lack of the reliable closure models, the current one-dimensional computational methods only achieve very limited successes and very often give erroneous predictions. The long-term objective of the current project is to develop reliable closure relations for one-dimensional transient models of slug flow. During the first funding period of 3 years, we carry out numerical investigation of slug flow by three-dimensional large eddy simulation (LES) with the smoothed particle hydrodynamics (SPH) method, which has great advantages on handling complex inter-phase interactions. Based on our previous work, we will develop new SPH methods suitable for simulating gas-liquid turbulent pipe flow. For typical configurations, we will investigate the growth of hydrodynamic instability, the initiation of slugs and the further development of the initiated slugs. We expect to reproduce the slug flow which is in agreement with both qualitative observations and quantitative measurements from experiments and study the mechanism of the initiation and the after-initiation dynamics which leads to the final sustainable slugs. In the second funding period we will focus on deriving the closures for one-dimensional transient models by using a systematic coarse-graining approach. Furthermore, if time permits, we will optimize the derived closures by extensive simulations of experimental setups and practical pipelines.