Smoothed particle hydrodynamics simulations of water flow in a vertical pipe with a dead leg: A comparison with experimental measurements

Pipeline systems commonly used in the chemical, petrochemical, and power generation industries include lines with closed block valves, blocked branches, and blinded ends. These are common examples of dead legs, which are, in general, inadvertent sections where the fluid flow is stagnant or characterized by very low velocities. Here we present a comparative analysis of water flow in a dead-leg cavity using experimental measurements and Smoothed Particle Hydrodynamics (SPH) simulations. Experiments were conducted using Particle Image Velocimetry (PIV), while the numerical model employed a Large Eddy Simulation (LES) approach within the SPH framework. Across a range of flow rates, the SPH simulations are effective in capturing global flow structures, such as vortex formation, recirculation zones, and spiral streamline patterns, while quantitative accuracy is seen to depend on the specific flow regime. As compared with the experimental measurements, the numerical results reveal a non-monotonic relationship between the SPH-LES predictive accuracy and the Reynolds number in short dead-leg geometries. This suggests that accuracy is not only a function of resolution but is limited by the barotropic nature of the SPH formulation during transitional/marginally turbulent flow conditions. While the SPH approach remains a valid tool for analyzing the flow topology in complex geometries, the present comparative investigation has been effective in identifying specific pathways for enhancing the thermodynamic representation of the SPH model in future iterations.