Impact of the convex pattern placed on the bottom part of the pipe on mixture flow assurance and behavior
Type:
Presented during:
CEDA Dredging Days 2026
Authors:
D.M. Samosir, E. de Hoog and R. Helmons
Abstract
Pipelines play a crucial role in dredging operations, transporting sediment efficiently. To improve sustainability, one potential strategy is reducing the pipe wear and making a longer lifespan of the pipe. A previous study found that a convex pattern on wear surfaces resulted in reduced wear in dry bulk material transport by inducing particles rolling through bed layer dilation. This study aims to examine the effect of a convex-pattern on wear path under wet conditions in a pipe and how it affects flow resistance and wear distribution in a gravel-water mixture. Experiments were conducted using gravel with an average particle diameter of 3 mm, comparing a convex-patterned plate with a plain reference plate at the pipe bottom. The pipe diameter is 40 mm. Results showed that both plates exhibited abrasive wear at lower velocities. At higher velocities, the plain plate showed concentrated wear at pipe joints due to intensified abrasion, while the convex plate experienced reduced wear at joints and top surfaces. However, increased movement in the upper bed layers led to impact wear on the convex crests, shifting the dominant wear mechanism. The presence of a convex pattern on the bottom part of the pipe causes an increase in flow resistance. The hydraulic gradient of the mixture flow is higher for the convex-pattern plate in both the stationary and sliding bed regimes. The deposition limit velocity increases slightly from 0.9 m/s for the plain plate to 1.0 m/s when the convex-pattern plate is installed. Overall, convex patterns did not improve flow efficiency and may increase resistance, limiting their use as a general wear-reduction strategy. Based on Newitt's theory and the Darcy-Weisbach relation, the negative effects may scale down with larger pipe diameters. Nevertheless, due to localized wear protection, convex patterns could still be beneficial in specific, high-wear pipeline sections.