Numerical simulations of flow around three cylinders using momentum exchange-based immersed boundary-lattice Boltzmann method

Wake flow behind multiple bluff bodies is of critical significance in ocean engineering and has important scientific significance in fluid mechanics and dynamics. Three cylinders arranged in side-by-side, tandem, equilateral-triangular, and staggered arrangements were extensively researched in the previous study. In this study, the flow passing through three cylinders in staggered and equilateral-triangular arrangement were numerical calculated using a momentum exchange-based immersed boundary-lattice Boltzmann method. The numerical investigations for staggered arrangement were carried out by changing the Reynolds number (Re) from 10 to 200 with an increment of 1, and varying the gap ratio (δ = ΔP/D) from 0.1 to 8.0 with an increment of 0.1. The flow patterns of three equilateral-triangular cylinders with different gap ratios at Re = 100 were also numerical studied. The numerical results identified various flow patterns, and the variations of the above two parameters have a decisive influence on the vortex shedding patterns and flow properties. The drag coefficient, lift coefficient, and Strouhal number (St) were also surveyed to demonstrate the relationship among flow pattern, parameters δ and Re. The outcomes in this paper provide a relatively comprehensive understanding to the vortex shedding patterns and flow properties of three circular cylinders with different gap ratios and Reynolds number. •Flow around three cylinders in staggered and equilateral-triangle arrangement were numerical calculated using momentum exchange-IB-LBM.•The flow modes for three staggered cylinders with incidence angle 45o at Re = 100 are divided into single bluff body, deflected, flip-flopping, and fully developed wake flow pattern.•The wake flow characteristics for three equilateral-triangle cylinders can be split into proximity interference, combined interference, and wake interference.•The variations of the gap ratio and Reynolds number have a decisive influence on the wake flow properties.•The outcomes provide a relatively comprehensive understanding to the flow properties of three cylinders arranged in staggered and equilateral-triangular with different gap ratio and Reynolds number.