Hydrodynamic Forces on Near-Bed Cylinders in Steady Currents

Abstract Numerical simulations are carried to investigate hydrodynamic forces and flow patterns around cylinder clusters of equally-spaced tandem cylinders closed to a plane wall in steady flow. The Reynolds number covered in the study are Re = 10000 and 200000. The number of cylinders in the cluster are 2, 3 and 6 with the spacing between the cylinders being 1, 2 and 4 and the gap to diameter D ratio (e/D) ranging from 0.1 to 1. The numerical results show that the sheltering effect of the leading cylinder in the cluster leads to significant reductions of hydrodynamic forces on the downstream cylinders in the cluster, for the parameter ranges considered in this study. A methodology based on the combination of low fidelity computational fluid dynamic simulations and reliable published force coefficients is proposed for estimating hydrodynamic forces acting on individual cylinders in the cluster.