On the hydrodynamics of three in-line square cylinders in a uniform flow

In this paper, is the hydrodynamics of three in-line square cylinders in a uniform flow, where the gap between two neighboring square cylinders is equivalent is under investigation. The fluid dynamics around those multiple bluff bodies, including time-mean drag coefficients, time-mean lift coefficients and Strouhal numbers, are considered at the Reynolds number Re ≈ 100. Through numerically solving the nonlinear hydrodynamic problem, we show that the drag force acting on the first square cylinder is always larger than that acting on the remaining two square cylinders. From the perspective of wake structures, with keeping the increase of the gap between two neighboring square cylinders, the wake structures become much more complicated, including attachment of shear layer, interaction between shear layer and vortex, interaction between vortex and vortex, etc. Moreover, the Strouhal number of three square cylinders are approximately equaled when the dimensionless gap between two neighboring square cylinders is less than 2.