136 / 2025-08-26 00:30:54

Hydrodynamics and sediment transport around submarine pipeline under high Reynolds number oscillatory flow

submarine pipeline,high Reynolds number,sediment transport

Hydrodynamic forces and sediment transport around submarine pipelines are intimately coupled with seabed erosion and scour. Existing studies on wave-induced flow around and sediment transport beneath pipelines have primarily concentrated on low-to-moderate Reynolds numbers (O(10²) to O(10⁴)). Systematic investigations of full-scale, high-Reynolds-number conditions -  O(10⁵) to O(10⁶) - remain scarce. Based on the k-ω turbulence model with the generalized wall function, the vortex structures around the pipeline, the hydrodynamic forces and the bed shear stresses are calculated. The advection-diffusion equation for suspended sediment are solved to compute the suspended-load transport. The reliability of the present model at high Reynolds numbers is verified by comparison with experimental force-coefficient measurements. The wall shear-stress and pressure distributions on the pipeline surface are computed for various Reynolds and KC numbers. Using the zero wall-shear stress criterion, the separation points along the pipeline surface were identified. It is found that the width of the separation area significantly increases under high Reynolds number, which in turn elucidated how the inline force coefficient (C_Frms) vary with Re and KC numbers. The influences of wall roughness, gap ratio and Shields number on the hydrodynamics and sediment transport are further analyzed.