Spatial modeling of inner-wall morphology in aged water supply pipes: A random field approach

The Graphical Abstract shows the scanned inner wall surface of a pipe and the statistics of the protrusion height in the upper part, while in the lower part displays the random model of inner wall and the simulated hydraulic performance. The hydraulic performance of water supply pipes deteriorates significantly due to inner wall corrosion associated with aging. This study investigated the spatial characteristics of corrosion patterns and their hydraulic impacts based on nine aged pipes, by integrating three-dimensional (3D) scanning, random field modeling, and computational fluid dynamics (CFD) simulation. Inner wall morphology data were acquired via 3D scanning from nine segments of aged cast iron pipes retrieved from a city in northern China. Random field theory was applied to characterize the spatial variability of the scanned morphology. Subsequently, a random field model was developed to reconstruct inner wall profiles, which were then used in CFD simulations to evaluate the hydraulic performance of the corroded pipes. Results indicate that the inner wall morphology exhibits pronounced spatial anisotropy, with a significantly larger correlation length in the circumferential direction than in the axial direction. The heights of corrosion protrusions approximately follow a lognormal distribution. CFD simulations demonstrate that the hydraulic performance of the inner wall morphology reconstructed by the proposed random field model closely matches that of the originally scanned pipes. This confirms the model's effectiveness in statistically reproducing the hydraulic effects of inner wall roughness in aged pipes.