Numerical investigation of Strouhal number discontinuity and flow characteristics around single rectangular cylinder at low aspect ratios and Reynolds numbers

Two-dimensional unsteady wake characteristics and Strouhal number discontinuity have been investigated numerically in flow past rectangular cylinder of different aspect ratio using lattice Boltzmann method. Effect (AR) has studied for Reynolds (Re) the range from 75 to 150. For investigation between 0.05 1 considered. Different regimes, such as two-rows regime, modulated fully developed regime irregular identified based on values ratios cylinder. The effects numbers fluid forces, separation vortex shedding frequency examined detail. results reveal that there exists an where shows discontinuity. Especially Re = 145 150, a number, is observed at around 0.5 ≤ AR 0.6 few extra small peaks are found power spectra result lift coefficient pattern behind with no fixed vorticity contour streamline visualization. further show change by changing AR.