Solid Particle Erosion in Pipeline Expansions: CFD Flow Validation, Mesh Sensitivity, and Experimental Visualization

Abstract Solid particle erosion is a critical concern in oil and gas pipelines, especially for pipe fitting geometries such as elbows, tees, expansions and contractions. While erosion in elbows and chokes is well studied, erosion in contractions and expansion, especially the influence of cross-flow velocities and turbulence— remains less understood. This study addresses this gap by integrating computational fluid dynamics (CFD) simulations with experimental visualization to assess erosion patterns and model accuracy, in sudden and gradual expansions where flow deceleration, turbulence, and particle dispersion cause unpredictable material loss. CFD predictions were validated against laser Doppler velocimetry (LDV) velocity and turbulence measurements from prior studies on sudden expansions. Erosion predictions were compared with published data for sudden expansions at 68 m/s using a Rosin-Rammler particle size distribution and radial velocity analysis. For gradual expansions, qualitative visualization has been achieved through paint removal tests in an acrylic section using water-sand mixtures with particle sizes of 25, 75, and 300 μm at 6 m/s. CFD results were compared with observed erosion patterns. Mesh-dependency has been examined by varying grid resolution from 0.8 to over 8 million cells. Results revealed high sensitivity for small particles and minimal impact for larger ones, highlighting the importance of mesh quality and accurate particle modeling in erosion risk assessment.