Numerical analysis of the flow topology around two rectangular cylinders in a staggered arrangement

In this study the computational analysis of the flow topology around two rectangular cylinders is performed using the lattice Boltzmann method. The cylinders are arranged in a staggered configuration, and both share the same aspect ratio. For simulations, the Reynolds number is kept constant at 150 while the gap spacing, between the cylinders, is varied within the range from 0 to 10 times the width of the cylinders. Four different flow patterns observed in this study are the isolated bluff structure, chaotic flow, modulated synchronized flow, and synchronized flow. The observed flow patterns and the corresponding fluid force parameters such as average drag coefficient, root-mean-square of the drag and lift coefficient, the amplitude of drag and lift, as well as the Strouhal number, are found to be strongly influenced by the gap spacing between cylinders. At low gap spacing values, a robust effect of jet flow disturbs the flow structure, which ultimately results in a complex flow structure in the wake and random fluctuations in drag and lift forces. With an increase in spacing values, the effect of jet flow on fluid flow characteristics gradually minimized, which results in a smooth periodic flow in the wake of both cylinders.