© 2018 Elsevier Ltd Computations were performed to determine the optimal conditions for the suppression of vortex shedding from circular cylinders at high Reynolds number by means of splitter plates. Previous studies of this mechanism for vortex-shedding control have largely been confined to two-dimensional flows at low Reynolds number, and to a single ratio of splitter plate width to cylinder diameter. In this study, we consider fully-turbulent, three-dimensional flows at high Reynolds number, and investigate the dependence of vortex-shedding suppression on two geometric parameters; namely the ratio of splitter-plate width and height to cylinder diameter and length. The computations were performed with the OpenFOAM software using a well-validated turbulence closure that considers the effects of the organized mean-flow unsteadiness on the random turbulent fluctuations. Comparisons were made with experimental data, and the validated method is used to perform a systematic study to determine the effectiveness of vortex suppression. To aid in the analysis, two-point correlations of forces along span of cylinder were obtained to determine uncoupling conditions of sectional oscillations. The results obtained indicate that splitter plates provide a practical method for vortex suppression at high Reynolds number, and the degree of suppression can be maximized by optimal geometric configuration.