Effect of soil power law index on submarine slide-pipeline flow mechanisms and forces

Submarine slide flows threaten offshore pipelines, yet the effects of their rheological behaviour remain poorly understood, particularly the soil power law index, β, which controls viscosity variation of the submarine slide flow and thereby influences the flow structure and resulting impact forces on offshore pipelines. While previous studies on submarine slide-pipeline interaction focused on a narrow β range of 0.1–0.14, natural submarine slides exhibit a broader range from 0.05 to 0.2. To bridge this gap, this study establishes a computational fluid dynamic (CFD) framework to investigate submarine slide-pipeline interactions across a broader, realistic β range of 0.05–0.2 and non-Newtonian Reynolds number, Renon-Newtonian=5−350. Flow characteristics, including streamline patterns, pressure coefficient, wall shear stresses, recirculation zone dimensions, Strouhal number, lift and drag coefficient were systematically evaluated. Results reveal that drag coefficient is governed solely by Renon-Newtonian, whereas lift coefficient is influenced by both β and Renon-Newtonian. An empirical equation is proposed to quantify lift as a function of these parameters. These findings underscore the importance of incorporating realistic non-Newtonian rheology in the design and risk assessment of subsea infrastructure exposed to submarine slide hazards