RESUMEN
This numerical investigation deals with study of flow past seven square cylinders arranged in staggered configuration. Simulations to the underlying problem are carried out by using the single relaxation time lattice Boltzmann method. The gap spacing between the staggered rows is varied in streamwise direction from 0.25 to 2 and for three transverse spacing i.e. T* = 1, 1.5 and 2. The complex vortex shedding mechanism is visualized for different streamwise and transverse gap spacings. Furthermore, the vortex shedding mechanisms in the wake of downstream row of cylinders are debated by using vorticity snapshots, time-trace plots of drag and lift coefficients and power spectra visualization of lift coefficient. It is also observed that the secondary cylinder interaction frequency contributes significantly to the hydrodynamic forces experienced by the cylinders. The physical parameters, such as Strouhal number, the drag and lift coefficients and their root-mean-square values have also been discussed in detail.
RESUMEN
A two-dimensional numerical study of flow across rows of identical square cylinders arranged in staggered fashion is carried out. This study will unreveal complex flow physics depending upon the Reynolds number (Re) and gap spacing (g) between the cylinders. The combined effect of Reynolds number and gap spacing on the flow physics around staggered rows of cylinders are numerically studied for 20 ≤ Re ≤ 140 and 1 ≤ g ≤ 6. We use the lattice Boltzmann method for numerical computations. It is found that with increase in gap spacing between the cylinders the critical Reynolds number for the onset of vortex shedding also increases. We observed a strong effect of Reynolds number at g = 2 and 4. Secondary cylinder interaction frequency disappears for large Reynolds number at g = 6 and 5 and the flow around cylinders are fully dominated by the primary vortex shedding frequency. This ensures that at large gap spacing with an increase in the Reynolds number the wakes interaction between and behind the cylinders is weaken. Furthermore, it also ensures that the wake interaction behind the cylinders is strongly influenced by the jets in the gap spacing between the cylinders. We also found that g = 2 is the critical gap spacing for flow across rows of staggered square cylinders for the considered range of Reynolds number. Depending on the Reynolds number we observed; synchronous, quasi-periodic-I, quasi-periodic-II, and chaotic flow patterns. In synchronous flow pattern, an in-phase and anti-phase characteristics of consecutive cylinders has been observed. The important physical parameters are also analyzed and discussed in detail.