This study presents two-dimensional numerical simulations to investigate the transition boundaries of deflected flow patterns around an array of four circular cylinders at a Reynolds number of 6000. To improve both computational accuracy and consistency with experimental results, the effects of mesh resolution and time step size were carefully examined. For mesh evaluation, steady-state simulations were conducted, and comparisons of the resulting deflected flow patterns indicated that the mesh with enhanced resolution near the cylinders was the most suitable. To determine an appropriate time step size, unsteady simulations of a single cylinder were performed using the selected mesh. Based on comparisons of the mean drag coefficient and the dominant frequency of fluctuations, a time step of 5×10⁻⁵ seconds was found to be appropriate. Using these settings, unsteady simulations of the four-cylinder configuration successfully reproduced deflected flow patterns in good agreement with experimental observations. Meanwhile, a transitional deflected flow pattern was identified between the metastable and stable states.
SATO et al. (Wed,) studied this question.