In this numerical exploration, the combined effect of Reynolds number (30 ≤ Re ≤ 150) and gap spacing (1 ≤ g ≤ 7) is studied for two dimensional cross flow across multiple staggered rows of square cylinders. Flow is simulated by using lattice Boltzmann method. Outcomes show that for the outset of vortex shedding phenomenon, the critical Re increases as the normalized g increases. At large Re and at g = 7, 6 and 5, the primary vortex shedding frequency controls the flow whereas the secondary frequency almost vanishes. The jets in the gap region have strong influence upon the wake interaction. The nature of the wakes is changed by changing the g and Re which is visualized by the change of wake size behind the cylinders. These g depending on the Re are used to split the flow regimes into chaotic, quasiperiodic-I and quasiperiodic-II flow regimes. Some physical parameters of practical importance are also analysed.

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.

The flow past three unequal sized side-by-side square cylinders placed in different vertical configurations is investigated numerically using the lattice Boltzmann method for the Reynolds number Re = 160 and different values of the gap spacing between the cylinders, g, (ranging between 0.5 and 5). The present study is devoted to systematic investigation of the effects of cylinders position on the flow patterns. The reported results reveal that the flow patterns change significantly by the variation of cylinders configuration. Depending on the cylinders positions we observed; chaotic, base bleed, binary vortex street, modulated synchronized, inphase vortex shedding, antiphase vortex shedding, and in-antiphase vortex shedding flow patterns. The characteristics of the flow patterns are discussed with the aid of time history analysis of drag and lift coefficients, power spectra analysis of lift coefficients and vorticity contours visualization. The study also includes a detailed discussion on the aerodynamic forces, such as mean drag coefficient, Strouhal number and root-mean-square values of drag and lift coefficients. Our results show that the flow patterns behind three unequal cylinders are distinctly different compared to the flow past equisized square cylinders placed side-by-side. In chaotic flow pattern the secondary cylinder interaction frequency plays an important role especially at the second, third and fourth configurations for all gap spacings. At larger gap spacings for the first and sixth configurations, the primary vortex shedding frequency plays a dominant role and the jet effect almost diminishes between the cylinders.

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