Hydrodynamic Loads on a Group of Six Structures of Different Cross-Sections in Uniform and Sheared Flow

Abstract

The estimates of hydrodynamic forces for a group of structures represent a challenge for the design of offshore systems, as they are subject to changes with a variation in flow profiles. The fluctuating effects may be more pronounced or, on the contrary, suppressed if the cross-sectional shape of structures in an array is altered. The present work performs a series of 2D numerical simulations for the flow past six identical stationary cylinders of three distinct geometrical shapes arranged in a 2 × 3 matrix configuration. The flow profiles considered have an averaged velocity corresponding to the critical flow regime of a Reynolds number of 2.5 × 105. The detached eddy simulation k–ω SST turbulence model is employed to perform a comprehensive investigation of the fluid force coefficients, their frequencies and vortex formation patterns. The effect of the spacing ratio varied simultaneously among the structures from 2 to 7 is considered in conjunction with the change in the flow profile and the cylinders’ cross-section. The results of simulations show a higher mean drag on the upstream cylinders, reduced mean drag on the mid- and downstream cylinders with the second cross-sectional shape, and a higher mean drag on the cylinders with the third cross-sectional shape, compared to the original circular cylinders.