Numerical research on the wake characteristics and drag reduction of a square cylinder in the presence of control partitions

This study presents the effect of the position of the control partitions on fluid flow around a square cylinder in a rectangular open channel. The numerical simulations are carried out with the lattice Boltzmann method at a fixed Reynolds number (Re=150). In the first case, two downstream partitions are inserted, whose spacing gap (g) varies as a function of the cylinder dimension (d), ranging from 0 to 13d. In the second case, four partitions are implemented such that g is fixed at 3.9d and the upstream spacing varies from 0 to 4d. The numerical results of the first study reveal the existence of a critical spacing at g=3.9d, where the average drag coefficient reaches a minimum (16.28%). Likewise, the vortex shedding between the square cylinder and the two detached partitions or behind these two partitions are also affected. Furthermore, a significant decrease in the drag coefficient, reaching 36.33%, is attained when situating the two upstream partitions at a distance of g1=0.25d.