Impacts of Small Gaps and Embedment Depths on Forces of a Circular Cylinder Near a Plane Wall

Numerical simulations of a cylinder placed on or near a plane wall are often required in engineering design of offshore structures to determine hydrodynamic forces, such as a power cable laid directly on the seabed. Generation of computational mesh around such a configuration has been a challenge of conducting simulations, primarily due to the narrow gaps formed between the cylinder and the plane wall. Extremely fine meshes are often required around the narrow gaps to achieve reliable numerical results, leading to additional computational costs. To alleviate this problem, this study examines the hydrodynamic features of two alternative geometric configurations, namely (1) a near-wall cylinder with sealed gap and (2) a cylinder shallowly embedded in the plane wall, whose meshing and simulation are less challenging than that would otherwise be needed for a cylinder placed on the wall. A series of three-dimensional numerical simulations for a constant Reynolds number 3900 and a range of narrow gap distances / embedment depths from 0.001 to 0.1 cylinder diameters are conducted. The possibility of employing the three configurations to determine the hydrodynamic forces on a cylinder placed on a wall is examined in this study.